diff --git a/compiler/rustc_typeck/src/check/fn_ctxt.rs b/compiler/rustc_typeck/src/check/fn_ctxt.rs new file mode 100644 index 00000000000..f7046468511 --- /dev/null +++ b/compiler/rustc_typeck/src/check/fn_ctxt.rs @@ -0,0 +1,3198 @@ +use super::callee::{self, DeferredCallResolution}; +use super::coercion::{CoerceMany, DynamicCoerceMany}; +use super::method::{MethodCallee, SelfSource}; +use super::Expectation::*; +use super::TupleArgumentsFlag::*; +use super::{ + method, potentially_plural_count, struct_span_err, BreakableCtxt, Diverges, + EnclosingBreakables, Expectation, FallbackMode, Inherited, LocalTy, Needs, TupleArgumentsFlag, + UnsafetyState, +}; +use crate::astconv::{ + AstConv, ExplicitLateBound, GenericArgCountMismatch, GenericArgCountResult, PathSeg, +}; + +use rustc_ast as ast; +use rustc_ast::util::parser::ExprPrecedence; +use rustc_data_structures::captures::Captures; +use rustc_data_structures::fx::FxHashSet; +use rustc_errors::ErrorReported; +use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticId}; +use rustc_hir as hir; +use rustc_hir::def::{CtorOf, DefKind, Res}; +use rustc_hir::def_id::DefId; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{ExprKind, GenericArg, ItemKind, Node, QPath}; +use rustc_infer::infer; +use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse}; +use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind}; +use rustc_infer::infer::{InferOk, InferResult}; +use rustc_middle::hir::map::blocks::FnLikeNode; +use rustc_middle::ty::adjustment::{ + Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, +}; +use rustc_middle::ty::fold::TypeFoldable; +use rustc_middle::ty::subst::{ + self, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSelfTy, UserSubsts, +}; +use rustc_middle::ty::{ + self, AdtKind, CanonicalUserType, Const, DefIdTree, GenericParamDefKind, ToPolyTraitRef, + ToPredicate, Ty, TyCtxt, UserType, +}; +use rustc_session::lint; +use rustc_session::Session; +use rustc_span::hygiene::DesugaringKind; +use rustc_span::source_map::{original_sp, DUMMY_SP}; +use rustc_span::symbol::{kw, sym, Ident}; +use rustc_span::{self, BytePos, MultiSpan, Span}; +use rustc_trait_selection::infer::InferCtxtExt as _; +use rustc_trait_selection::opaque_types::InferCtxtExt as _; +use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _; +use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; +use rustc_trait_selection::traits::{ + self, ObligationCause, ObligationCauseCode, TraitEngine, TraitEngineExt, +}; + +use std::cell::{Cell, RefCell}; +use std::collections::hash_map::Entry; +use std::iter; +use std::mem::replace; +use std::ops::Deref; +use std::slice; + +pub struct FnCtxt<'a, 'tcx> { + pub(super) body_id: hir::HirId, + + /// The parameter environment used for proving trait obligations + /// in this function. This can change when we descend into + /// closures (as they bring new things into scope), hence it is + /// not part of `Inherited` (as of the time of this writing, + /// closures do not yet change the environment, but they will + /// eventually). + pub(super) param_env: ty::ParamEnv<'tcx>, + + /// Number of errors that had been reported when we started + /// checking this function. On exit, if we find that *more* errors + /// have been reported, we will skip regionck and other work that + /// expects the types within the function to be consistent. + // FIXME(matthewjasper) This should not exist, and it's not correct + // if type checking is run in parallel. + err_count_on_creation: usize, + + /// If `Some`, this stores coercion information for returned + /// expressions. If `None`, this is in a context where return is + /// inappropriate, such as a const expression. + /// + /// This is a `RefCell`, which means that we + /// can track all the return expressions and then use them to + /// compute a useful coercion from the set, similar to a match + /// expression or other branching context. You can use methods + /// like `expected_ty` to access the declared return type (if + /// any). + pub(super) ret_coercion: Option>>, + + pub(super) ret_coercion_impl_trait: Option>, + + pub(super) ret_type_span: Option, + + /// Used exclusively to reduce cost of advanced evaluation used for + /// more helpful diagnostics. + pub(super) in_tail_expr: bool, + + /// First span of a return site that we find. Used in error messages. + pub(super) ret_coercion_span: RefCell>, + + pub(super) resume_yield_tys: Option<(Ty<'tcx>, Ty<'tcx>)>, + + pub(super) ps: RefCell, + + /// Whether the last checked node generates a divergence (e.g., + /// `return` will set this to `Always`). In general, when entering + /// an expression or other node in the tree, the initial value + /// indicates whether prior parts of the containing expression may + /// have diverged. It is then typically set to `Maybe` (and the + /// old value remembered) for processing the subparts of the + /// current expression. As each subpart is processed, they may set + /// the flag to `Always`, etc. Finally, at the end, we take the + /// result and "union" it with the original value, so that when we + /// return the flag indicates if any subpart of the parent + /// expression (up to and including this part) has diverged. So, + /// if you read it after evaluating a subexpression `X`, the value + /// you get indicates whether any subexpression that was + /// evaluating up to and including `X` diverged. + /// + /// We currently use this flag only for diagnostic purposes: + /// + /// - To warn about unreachable code: if, after processing a + /// sub-expression but before we have applied the effects of the + /// current node, we see that the flag is set to `Always`, we + /// can issue a warning. This corresponds to something like + /// `foo(return)`; we warn on the `foo()` expression. (We then + /// update the flag to `WarnedAlways` to suppress duplicate + /// reports.) Similarly, if we traverse to a fresh statement (or + /// tail expression) from a `Always` setting, we will issue a + /// warning. This corresponds to something like `{return; + /// foo();}` or `{return; 22}`, where we would warn on the + /// `foo()` or `22`. + /// + /// An expression represents dead code if, after checking it, + /// the diverges flag is set to something other than `Maybe`. + pub(super) diverges: Cell, + + /// Whether any child nodes have any type errors. + pub(super) has_errors: Cell, + + pub(super) enclosing_breakables: RefCell>, + + pub(super) inh: &'a Inherited<'a, 'tcx>, +} + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + pub fn new( + inh: &'a Inherited<'a, 'tcx>, + param_env: ty::ParamEnv<'tcx>, + body_id: hir::HirId, + ) -> FnCtxt<'a, 'tcx> { + FnCtxt { + body_id, + param_env, + err_count_on_creation: inh.tcx.sess.err_count(), + ret_coercion: None, + ret_coercion_impl_trait: None, + ret_type_span: None, + in_tail_expr: false, + ret_coercion_span: RefCell::new(None), + resume_yield_tys: None, + ps: RefCell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)), + diverges: Cell::new(Diverges::Maybe), + has_errors: Cell::new(false), + enclosing_breakables: RefCell::new(EnclosingBreakables { + stack: Vec::new(), + by_id: Default::default(), + }), + inh, + } + } + + pub fn sess(&self) -> &Session { + &self.tcx.sess + } + + pub fn errors_reported_since_creation(&self) -> bool { + self.tcx.sess.err_count() > self.err_count_on_creation + } + + /// Produces warning on the given node, if the current point in the + /// function is unreachable, and there hasn't been another warning. + pub(super) fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) { + // FIXME: Combine these two 'if' expressions into one once + // let chains are implemented + if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() { + // If span arose from a desugaring of `if` or `while`, then it is the condition itself, + // which diverges, that we are about to lint on. This gives suboptimal diagnostics. + // Instead, stop here so that the `if`- or `while`-expression's block is linted instead. + if !span.is_desugaring(DesugaringKind::CondTemporary) + && !span.is_desugaring(DesugaringKind::Async) + && !orig_span.is_desugaring(DesugaringKind::Await) + { + self.diverges.set(Diverges::WarnedAlways); + + debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind); + + self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, |lint| { + let msg = format!("unreachable {}", kind); + lint.build(&msg) + .span_label(span, &msg) + .span_label( + orig_span, + custom_note + .unwrap_or("any code following this expression is unreachable"), + ) + .emit(); + }) + } + } + } + + pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> { + ObligationCause::new(span, self.body_id, code) + } + + pub fn misc(&self, span: Span) -> ObligationCause<'tcx> { + self.cause(span, ObligationCauseCode::MiscObligation) + } + + /// Resolves type and const variables in `ty` if possible. Unlike the infcx + /// version (resolve_vars_if_possible), this version will + /// also select obligations if it seems useful, in an effort + /// to get more type information. + pub(super) fn resolve_vars_with_obligations(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> { + debug!("resolve_vars_with_obligations(ty={:?})", ty); + + // No Infer()? Nothing needs doing. + if !ty.has_infer_types_or_consts() { + debug!("resolve_vars_with_obligations: ty={:?}", ty); + return ty; + } + + // If `ty` is a type variable, see whether we already know what it is. + ty = self.resolve_vars_if_possible(&ty); + if !ty.has_infer_types_or_consts() { + debug!("resolve_vars_with_obligations: ty={:?}", ty); + return ty; + } + + // If not, try resolving pending obligations as much as + // possible. This can help substantially when there are + // indirect dependencies that don't seem worth tracking + // precisely. + self.select_obligations_where_possible(false, |_| {}); + ty = self.resolve_vars_if_possible(&ty); + + debug!("resolve_vars_with_obligations: ty={:?}", ty); + ty + } + + pub(super) fn record_deferred_call_resolution( + &self, + closure_def_id: DefId, + r: DeferredCallResolution<'tcx>, + ) { + let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); + deferred_call_resolutions.entry(closure_def_id).or_default().push(r); + } + + pub(super) fn remove_deferred_call_resolutions( + &self, + closure_def_id: DefId, + ) -> Vec> { + let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); + deferred_call_resolutions.remove(&closure_def_id).unwrap_or(vec![]) + } + + pub fn tag(&self) -> String { + format!("{:p}", self) + } + + pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> { + self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| { + span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid)) + }) + } + + #[inline] + pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) { + debug!( + "write_ty({:?}, {:?}) in fcx {}", + id, + self.resolve_vars_if_possible(&ty), + self.tag() + ); + self.typeck_results.borrow_mut().node_types_mut().insert(id, ty); + + if ty.references_error() { + self.has_errors.set(true); + self.set_tainted_by_errors(); + } + } + + pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) { + self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index); + } + + fn write_resolution(&self, hir_id: hir::HirId, r: Result<(DefKind, DefId), ErrorReported>) { + self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r); + } + + pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) { + debug!("write_method_call(hir_id={:?}, method={:?})", hir_id, method); + self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id))); + self.write_substs(hir_id, method.substs); + + // When the method is confirmed, the `method.substs` includes + // parameters from not just the method, but also the impl of + // the method -- in particular, the `Self` type will be fully + // resolved. However, those are not something that the "user + // specified" -- i.e., those types come from the inferred type + // of the receiver, not something the user wrote. So when we + // create the user-substs, we want to replace those earlier + // types with just the types that the user actually wrote -- + // that is, those that appear on the *method itself*. + // + // As an example, if the user wrote something like + // `foo.bar::(...)` -- the `Self` type here will be the + // type of `foo` (possibly adjusted), but we don't want to + // include that. We want just the `[_, u32]` part. + if !method.substs.is_noop() { + let method_generics = self.tcx.generics_of(method.def_id); + if !method_generics.params.is_empty() { + let user_type_annotation = self.infcx.probe(|_| { + let user_substs = UserSubsts { + substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| { + let i = param.index as usize; + if i < method_generics.parent_count { + self.infcx.var_for_def(DUMMY_SP, param) + } else { + method.substs[i] + } + }), + user_self_ty: None, // not relevant here + }; + + self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf( + method.def_id, + user_substs, + )) + }); + + debug!("write_method_call: user_type_annotation={:?}", user_type_annotation); + self.write_user_type_annotation(hir_id, user_type_annotation); + } + } + } + + pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) { + if !substs.is_noop() { + debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag()); + + self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs); + } + } + + /// Given the substs that we just converted from the HIR, try to + /// canonicalize them and store them as user-given substitutions + /// (i.e., substitutions that must be respected by the NLL check). + /// + /// This should be invoked **before any unifications have + /// occurred**, so that annotations like `Vec<_>` are preserved + /// properly. + pub fn write_user_type_annotation_from_substs( + &self, + hir_id: hir::HirId, + def_id: DefId, + substs: SubstsRef<'tcx>, + user_self_ty: Option>, + ) { + debug!( + "write_user_type_annotation_from_substs: hir_id={:?} def_id={:?} substs={:?} \ + user_self_ty={:?} in fcx {}", + hir_id, + def_id, + substs, + user_self_ty, + self.tag(), + ); + + if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) { + let canonicalized = self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf( + def_id, + UserSubsts { substs, user_self_ty }, + )); + debug!("write_user_type_annotation_from_substs: canonicalized={:?}", canonicalized); + self.write_user_type_annotation(hir_id, canonicalized); + } + } + + pub fn write_user_type_annotation( + &self, + hir_id: hir::HirId, + canonical_user_type_annotation: CanonicalUserType<'tcx>, + ) { + debug!( + "write_user_type_annotation: hir_id={:?} canonical_user_type_annotation={:?} tag={}", + hir_id, + canonical_user_type_annotation, + self.tag(), + ); + + if !canonical_user_type_annotation.is_identity() { + self.typeck_results + .borrow_mut() + .user_provided_types_mut() + .insert(hir_id, canonical_user_type_annotation); + } else { + debug!("write_user_type_annotation: skipping identity substs"); + } + } + + pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec>) { + debug!("apply_adjustments(expr={:?}, adj={:?})", expr, adj); + + if adj.is_empty() { + return; + } + + let autoborrow_mut = adj.iter().any(|adj| { + matches!(adj, &Adjustment { + kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })), + .. + }) + }); + + match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) { + Entry::Vacant(entry) => { + entry.insert(adj); + } + Entry::Occupied(mut entry) => { + debug!(" - composing on top of {:?}", entry.get()); + match (&entry.get()[..], &adj[..]) { + // Applying any adjustment on top of a NeverToAny + // is a valid NeverToAny adjustment, because it can't + // be reached. + (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return, + (&[ + Adjustment { kind: Adjust::Deref(_), .. }, + Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. }, + ], &[ + Adjustment { kind: Adjust::Deref(_), .. }, + .. // Any following adjustments are allowed. + ]) => { + // A reborrow has no effect before a dereference. + } + // FIXME: currently we never try to compose autoderefs + // and ReifyFnPointer/UnsafeFnPointer, but we could. + _ => + bug!("while adjusting {:?}, can't compose {:?} and {:?}", + expr, entry.get(), adj) + }; + *entry.get_mut() = adj; + } + } + + // If there is an mutable auto-borrow, it is equivalent to `&mut `. + // In this case implicit use of `Deref` and `Index` within `` should + // instead be `DerefMut` and `IndexMut`, so fix those up. + if autoborrow_mut { + self.convert_place_derefs_to_mutable(expr); + } + } + + /// Basically whenever we are converting from a type scheme into + /// the fn body space, we always want to normalize associated + /// types as well. This function combines the two. + fn instantiate_type_scheme(&self, span: Span, substs: SubstsRef<'tcx>, value: &T) -> T + where + T: TypeFoldable<'tcx>, + { + let value = value.subst(self.tcx, substs); + let result = self.normalize_associated_types_in(span, &value); + debug!("instantiate_type_scheme(value={:?}, substs={:?}) = {:?}", value, substs, result); + result + } + + /// As `instantiate_type_scheme`, but for the bounds found in a + /// generic type scheme. + fn instantiate_bounds( + &self, + span: Span, + def_id: DefId, + substs: SubstsRef<'tcx>, + ) -> (ty::InstantiatedPredicates<'tcx>, Vec) { + let bounds = self.tcx.predicates_of(def_id); + let spans: Vec = bounds.predicates.iter().map(|(_, span)| *span).collect(); + let result = bounds.instantiate(self.tcx, substs); + let result = self.normalize_associated_types_in(span, &result); + debug!( + "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}", + bounds, substs, result, spans, + ); + (result, spans) + } + + /// Replaces the opaque types from the given value with type variables, + /// and records the `OpaqueTypeMap` for later use during writeback. See + /// `InferCtxt::instantiate_opaque_types` for more details. + pub(super) fn instantiate_opaque_types_from_value>( + &self, + parent_id: hir::HirId, + value: &T, + value_span: Span, + ) -> T { + let parent_def_id = self.tcx.hir().local_def_id(parent_id); + debug!( + "instantiate_opaque_types_from_value(parent_def_id={:?}, value={:?})", + parent_def_id, value + ); + + let (value, opaque_type_map) = + self.register_infer_ok_obligations(self.instantiate_opaque_types( + parent_def_id, + self.body_id, + self.param_env, + value, + value_span, + )); + + let mut opaque_types = self.opaque_types.borrow_mut(); + let mut opaque_types_vars = self.opaque_types_vars.borrow_mut(); + for (ty, decl) in opaque_type_map { + let _ = opaque_types.insert(ty, decl); + let _ = opaque_types_vars.insert(decl.concrete_ty, decl.opaque_type); + } + + value + } + + pub(super) fn normalize_associated_types_in(&self, span: Span, value: &T) -> T + where + T: TypeFoldable<'tcx>, + { + self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value) + } + + pub(super) fn normalize_associated_types_in_as_infer_ok( + &self, + span: Span, + value: &T, + ) -> InferOk<'tcx, T> + where + T: TypeFoldable<'tcx>, + { + self.inh.partially_normalize_associated_types_in(span, self.body_id, self.param_env, value) + } + + pub fn require_type_meets( + &self, + ty: Ty<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + def_id: DefId, + ) { + self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code)); + } + + pub fn require_type_is_sized( + &self, + ty: Ty<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + ) { + if !ty.references_error() { + let lang_item = self.tcx.require_lang_item(LangItem::Sized, None); + self.require_type_meets(ty, span, code, lang_item); + } + } + + pub fn require_type_is_sized_deferred( + &self, + ty: Ty<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + ) { + if !ty.references_error() { + self.deferred_sized_obligations.borrow_mut().push((ty, span, code)); + } + } + + pub fn register_bound( + &self, + ty: Ty<'tcx>, + def_id: DefId, + cause: traits::ObligationCause<'tcx>, + ) { + if !ty.references_error() { + self.fulfillment_cx.borrow_mut().register_bound( + self, + self.param_env, + ty, + def_id, + cause, + ); + } + } + + pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> { + let t = AstConv::ast_ty_to_ty(self, ast_t); + self.register_wf_obligation(t.into(), ast_t.span, traits::MiscObligation); + t + } + + pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> { + let ty = self.to_ty(ast_ty); + debug!("to_ty_saving_user_provided_ty: ty={:?}", ty); + + if Self::can_contain_user_lifetime_bounds(ty) { + let c_ty = self.infcx.canonicalize_response(&UserType::Ty(ty)); + debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty); + self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty); + } + + ty + } + + pub fn to_const(&self, ast_c: &hir::AnonConst) -> &'tcx ty::Const<'tcx> { + let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id); + let c = ty::Const::from_anon_const(self.tcx, const_def_id); + self.register_wf_obligation( + c.into(), + self.tcx.hir().span(ast_c.hir_id), + ObligationCauseCode::MiscObligation, + ); + c + } + + pub fn const_arg_to_const( + &self, + ast_c: &hir::AnonConst, + param_def_id: DefId, + ) -> &'tcx ty::Const<'tcx> { + let const_def = ty::WithOptConstParam { + did: self.tcx.hir().local_def_id(ast_c.hir_id), + const_param_did: Some(param_def_id), + }; + let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def); + self.register_wf_obligation( + c.into(), + self.tcx.hir().span(ast_c.hir_id), + ObligationCauseCode::MiscObligation, + ); + c + } + + // If the type given by the user has free regions, save it for later, since + // NLL would like to enforce those. Also pass in types that involve + // projections, since those can resolve to `'static` bounds (modulo #54940, + // which hopefully will be fixed by the time you see this comment, dear + // reader, although I have my doubts). Also pass in types with inference + // types, because they may be repeated. Other sorts of things are already + // sufficiently enforced with erased regions. =) + fn can_contain_user_lifetime_bounds(t: T) -> bool + where + T: TypeFoldable<'tcx>, + { + t.has_free_regions() || t.has_projections() || t.has_infer_types() + } + + pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> { + match self.typeck_results.borrow().node_types().get(id) { + Some(&t) => t, + None if self.is_tainted_by_errors() => self.tcx.ty_error(), + None => { + bug!( + "no type for node {}: {} in fcx {}", + id, + self.tcx.hir().node_to_string(id), + self.tag() + ); + } + } + } + + /// Registers an obligation for checking later, during regionck, that `arg` is well-formed. + pub fn register_wf_obligation( + &self, + arg: subst::GenericArg<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + ) { + // WF obligations never themselves fail, so no real need to give a detailed cause: + let cause = traits::ObligationCause::new(span, self.body_id, code); + self.register_predicate(traits::Obligation::new( + cause, + self.param_env, + ty::PredicateAtom::WellFormed(arg).to_predicate(self.tcx), + )); + } + + /// Registers obligations that all `substs` are well-formed. + pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) { + for arg in substs.iter().filter(|arg| { + matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..)) + }) { + self.register_wf_obligation(arg, expr.span, traits::MiscObligation); + } + } + + /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each + /// type/region parameter was instantiated (`substs`), creates and registers suitable + /// trait/region obligations. + /// + /// For example, if there is a function: + /// + /// ``` + /// fn foo<'a,T:'a>(...) + /// ``` + /// + /// and a reference: + /// + /// ``` + /// let f = foo; + /// ``` + /// + /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a` + /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally. + pub fn add_obligations_for_parameters( + &self, + cause: traits::ObligationCause<'tcx>, + predicates: ty::InstantiatedPredicates<'tcx>, + ) { + assert!(!predicates.has_escaping_bound_vars()); + + debug!("add_obligations_for_parameters(predicates={:?})", predicates); + + for obligation in traits::predicates_for_generics(cause, self.param_env, predicates) { + self.register_predicate(obligation); + } + } + + // FIXME(arielb1): use this instead of field.ty everywhere + // Only for fields! Returns for methods> + // Indifferent to privacy flags + pub fn field_ty( + &self, + span: Span, + field: &'tcx ty::FieldDef, + substs: SubstsRef<'tcx>, + ) -> Ty<'tcx> { + self.normalize_associated_types_in(span, &field.ty(self.tcx, substs)) + } + + pub(super) fn check_casts(&self) { + let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut(); + for cast in deferred_cast_checks.drain(..) { + cast.check(self); + } + } + + pub(super) fn resolve_generator_interiors(&self, def_id: DefId) { + let mut generators = self.deferred_generator_interiors.borrow_mut(); + for (body_id, interior, kind) in generators.drain(..) { + self.select_obligations_where_possible(false, |_| {}); + super::generator_interior::resolve_interior(self, def_id, body_id, interior, kind); + } + } + + // Tries to apply a fallback to `ty` if it is an unsolved variable. + // + // - Unconstrained ints are replaced with `i32`. + // + // - Unconstrained floats are replaced with with `f64`. + // + // - Non-numerics get replaced with `!` when `#![feature(never_type_fallback)]` + // is enabled. Otherwise, they are replaced with `()`. + // + // Fallback becomes very dubious if we have encountered type-checking errors. + // In that case, fallback to Error. + // The return value indicates whether fallback has occurred. + pub(super) fn fallback_if_possible(&self, ty: Ty<'tcx>, mode: FallbackMode) -> bool { + use rustc_middle::ty::error::UnconstrainedNumeric::Neither; + use rustc_middle::ty::error::UnconstrainedNumeric::{UnconstrainedFloat, UnconstrainedInt}; + + assert!(ty.is_ty_infer()); + let fallback = match self.type_is_unconstrained_numeric(ty) { + _ if self.is_tainted_by_errors() => self.tcx().ty_error(), + UnconstrainedInt => self.tcx.types.i32, + UnconstrainedFloat => self.tcx.types.f64, + Neither if self.type_var_diverges(ty) => self.tcx.mk_diverging_default(), + Neither => { + // This type variable was created from the instantiation of an opaque + // type. The fact that we're attempting to perform fallback for it + // means that the function neither constrained it to a concrete + // type, nor to the opaque type itself. + // + // For example, in this code: + // + //``` + // type MyType = impl Copy; + // fn defining_use() -> MyType { true } + // fn other_use() -> MyType { defining_use() } + // ``` + // + // `defining_use` will constrain the instantiated inference + // variable to `bool`, while `other_use` will constrain + // the instantiated inference variable to `MyType`. + // + // When we process opaque types during writeback, we + // will handle cases like `other_use`, and not count + // them as defining usages + // + // However, we also need to handle cases like this: + // + // ```rust + // pub type Foo = impl Copy; + // fn produce() -> Option { + // None + // } + // ``` + // + // In the above snippet, the inference variable created by + // instantiating `Option` will be completely unconstrained. + // We treat this as a non-defining use by making the inference + // variable fall back to the opaque type itself. + if let FallbackMode::All = mode { + if let Some(opaque_ty) = self.opaque_types_vars.borrow().get(ty) { + debug!( + "fallback_if_possible: falling back opaque type var {:?} to {:?}", + ty, opaque_ty + ); + *opaque_ty + } else { + return false; + } + } else { + return false; + } + } + }; + debug!("fallback_if_possible: defaulting `{:?}` to `{:?}`", ty, fallback); + self.demand_eqtype(rustc_span::DUMMY_SP, ty, fallback); + true + } + + pub(super) fn select_all_obligations_or_error(&self) { + debug!("select_all_obligations_or_error"); + if let Err(errors) = self.fulfillment_cx.borrow_mut().select_all_or_error(&self) { + self.report_fulfillment_errors(&errors, self.inh.body_id, false); + } + } + + /// Select as many obligations as we can at present. + pub(super) fn select_obligations_where_possible( + &self, + fallback_has_occurred: bool, + mutate_fullfillment_errors: impl Fn(&mut Vec>), + ) { + let result = self.fulfillment_cx.borrow_mut().select_where_possible(self); + if let Err(mut errors) = result { + mutate_fullfillment_errors(&mut errors); + self.report_fulfillment_errors(&errors, self.inh.body_id, fallback_has_occurred); + } + } + + /// For the overloaded place expressions (`*x`, `x[3]`), the trait + /// returns a type of `&T`, but the actual type we assign to the + /// *expression* is `T`. So this function just peels off the return + /// type by one layer to yield `T`. + pub(super) fn make_overloaded_place_return_type( + &self, + method: MethodCallee<'tcx>, + ) -> ty::TypeAndMut<'tcx> { + // extract method return type, which will be &T; + let ret_ty = method.sig.output(); + + // method returns &T, but the type as visible to user is T, so deref + ret_ty.builtin_deref(true).unwrap() + } + + pub(super) fn check_method_argument_types( + &self, + sp: Span, + expr: &'tcx hir::Expr<'tcx>, + method: Result, ()>, + args_no_rcvr: &'tcx [hir::Expr<'tcx>], + tuple_arguments: TupleArgumentsFlag, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let has_error = match method { + Ok(method) => method.substs.references_error() || method.sig.references_error(), + Err(_) => true, + }; + if has_error { + let err_inputs = self.err_args(args_no_rcvr.len()); + + let err_inputs = match tuple_arguments { + DontTupleArguments => err_inputs, + TupleArguments => vec![self.tcx.intern_tup(&err_inputs[..])], + }; + + self.check_argument_types( + sp, + expr, + &err_inputs[..], + &[], + args_no_rcvr, + false, + tuple_arguments, + None, + ); + return self.tcx.ty_error(); + } + + let method = method.unwrap(); + // HACK(eddyb) ignore self in the definition (see above). + let expected_arg_tys = self.expected_inputs_for_expected_output( + sp, + expected, + method.sig.output(), + &method.sig.inputs()[1..], + ); + self.check_argument_types( + sp, + expr, + &method.sig.inputs()[1..], + &expected_arg_tys[..], + args_no_rcvr, + method.sig.c_variadic, + tuple_arguments, + self.tcx.hir().span_if_local(method.def_id), + ); + method.sig.output() + } + + fn self_type_matches_expected_vid( + &self, + trait_ref: ty::PolyTraitRef<'tcx>, + expected_vid: ty::TyVid, + ) -> bool { + let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty()); + debug!( + "self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?}, expected_vid={:?})", + trait_ref, self_ty, expected_vid + ); + match *self_ty.kind() { + ty::Infer(ty::TyVar(found_vid)) => { + // FIXME: consider using `sub_root_var` here so we + // can see through subtyping. + let found_vid = self.root_var(found_vid); + debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid); + expected_vid == found_vid + } + _ => false, + } + } + + pub(super) fn obligations_for_self_ty<'b>( + &'b self, + self_ty: ty::TyVid, + ) -> impl Iterator, traits::PredicateObligation<'tcx>)> + + Captures<'tcx> + + 'b { + // FIXME: consider using `sub_root_var` here so we + // can see through subtyping. + let ty_var_root = self.root_var(self_ty); + debug!( + "obligations_for_self_ty: self_ty={:?} ty_var_root={:?} pending_obligations={:?}", + self_ty, + ty_var_root, + self.fulfillment_cx.borrow().pending_obligations() + ); + + self.fulfillment_cx + .borrow() + .pending_obligations() + .into_iter() + .filter_map(move |obligation| { + match obligation.predicate.skip_binders() { + ty::PredicateAtom::Projection(data) => { + Some((ty::Binder::bind(data).to_poly_trait_ref(self.tcx), obligation)) + } + ty::PredicateAtom::Trait(data, _) => { + Some((ty::Binder::bind(data).to_poly_trait_ref(), obligation)) + } + ty::PredicateAtom::Subtype(..) => None, + ty::PredicateAtom::RegionOutlives(..) => None, + ty::PredicateAtom::TypeOutlives(..) => None, + ty::PredicateAtom::WellFormed(..) => None, + ty::PredicateAtom::ObjectSafe(..) => None, + ty::PredicateAtom::ConstEvaluatable(..) => None, + ty::PredicateAtom::ConstEquate(..) => None, + // N.B., this predicate is created by breaking down a + // `ClosureType: FnFoo()` predicate, where + // `ClosureType` represents some `Closure`. It can't + // possibly be referring to the current closure, + // because we haven't produced the `Closure` for + // this closure yet; this is exactly why the other + // code is looking for a self type of a unresolved + // inference variable. + ty::PredicateAtom::ClosureKind(..) => None, + ty::PredicateAtom::TypeWellFormedFromEnv(..) => None, + } + }) + .filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root)) + } + + pub(super) fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool { + self.obligations_for_self_ty(self_ty) + .any(|(tr, _)| Some(tr.def_id()) == self.tcx.lang_items().sized_trait()) + } + + /// Generic function that factors out common logic from function calls, + /// method calls and overloaded operators. + pub(super) fn check_argument_types( + &self, + sp: Span, + expr: &'tcx hir::Expr<'tcx>, + fn_inputs: &[Ty<'tcx>], + expected_arg_tys: &[Ty<'tcx>], + args: &'tcx [hir::Expr<'tcx>], + c_variadic: bool, + tuple_arguments: TupleArgumentsFlag, + def_span: Option, + ) { + let tcx = self.tcx; + // Grab the argument types, supplying fresh type variables + // if the wrong number of arguments were supplied + let supplied_arg_count = if tuple_arguments == DontTupleArguments { args.len() } else { 1 }; + + // All the input types from the fn signature must outlive the call + // so as to validate implied bounds. + for (&fn_input_ty, arg_expr) in fn_inputs.iter().zip(args.iter()) { + self.register_wf_obligation(fn_input_ty.into(), arg_expr.span, traits::MiscObligation); + } + + let expected_arg_count = fn_inputs.len(); + + let param_count_error = |expected_count: usize, + arg_count: usize, + error_code: &str, + c_variadic: bool, + sugg_unit: bool| { + let (span, start_span, args) = match &expr.kind { + hir::ExprKind::Call(hir::Expr { span, .. }, args) => (*span, *span, &args[..]), + hir::ExprKind::MethodCall(path_segment, span, args, _) => ( + *span, + // `sp` doesn't point at the whole `foo.bar()`, only at `bar`. + path_segment + .args + .and_then(|args| args.args.iter().last()) + // Account for `foo.bar::()`. + .map(|arg| { + // Skip the closing `>`. + tcx.sess + .source_map() + .next_point(tcx.sess.source_map().next_point(arg.span())) + }) + .unwrap_or(*span), + &args[1..], // Skip the receiver. + ), + k => span_bug!(sp, "checking argument types on a non-call: `{:?}`", k), + }; + let arg_spans = if args.is_empty() { + // foo() + // ^^^-- supplied 0 arguments + // | + // expected 2 arguments + vec![tcx.sess.source_map().next_point(start_span).with_hi(sp.hi())] + } else { + // foo(1, 2, 3) + // ^^^ - - - supplied 3 arguments + // | + // expected 2 arguments + args.iter().map(|arg| arg.span).collect::>() + }; + + let mut err = tcx.sess.struct_span_err_with_code( + span, + &format!( + "this function takes {}{} but {} {} supplied", + if c_variadic { "at least " } else { "" }, + potentially_plural_count(expected_count, "argument"), + potentially_plural_count(arg_count, "argument"), + if arg_count == 1 { "was" } else { "were" } + ), + DiagnosticId::Error(error_code.to_owned()), + ); + let label = format!("supplied {}", potentially_plural_count(arg_count, "argument")); + for (i, span) in arg_spans.into_iter().enumerate() { + err.span_label( + span, + if arg_count == 0 || i + 1 == arg_count { &label } else { "" }, + ); + } + + if let Some(def_s) = def_span.map(|sp| tcx.sess.source_map().guess_head_span(sp)) { + err.span_label(def_s, "defined here"); + } + if sugg_unit { + let sugg_span = tcx.sess.source_map().end_point(expr.span); + // remove closing `)` from the span + let sugg_span = sugg_span.shrink_to_lo(); + err.span_suggestion( + sugg_span, + "expected the unit value `()`; create it with empty parentheses", + String::from("()"), + Applicability::MachineApplicable, + ); + } else { + err.span_label( + span, + format!( + "expected {}{}", + if c_variadic { "at least " } else { "" }, + potentially_plural_count(expected_count, "argument") + ), + ); + } + err.emit(); + }; + + let mut expected_arg_tys = expected_arg_tys.to_vec(); + + let formal_tys = if tuple_arguments == TupleArguments { + let tuple_type = self.structurally_resolved_type(sp, fn_inputs[0]); + match tuple_type.kind() { + ty::Tuple(arg_types) if arg_types.len() != args.len() => { + param_count_error(arg_types.len(), args.len(), "E0057", false, false); + expected_arg_tys = vec![]; + self.err_args(args.len()) + } + ty::Tuple(arg_types) => { + expected_arg_tys = match expected_arg_tys.get(0) { + Some(&ty) => match ty.kind() { + ty::Tuple(ref tys) => tys.iter().map(|k| k.expect_ty()).collect(), + _ => vec![], + }, + None => vec![], + }; + arg_types.iter().map(|k| k.expect_ty()).collect() + } + _ => { + struct_span_err!( + tcx.sess, + sp, + E0059, + "cannot use call notation; the first type parameter \ + for the function trait is neither a tuple nor unit" + ) + .emit(); + expected_arg_tys = vec![]; + self.err_args(args.len()) + } + } + } else if expected_arg_count == supplied_arg_count { + fn_inputs.to_vec() + } else if c_variadic { + if supplied_arg_count >= expected_arg_count { + fn_inputs.to_vec() + } else { + param_count_error(expected_arg_count, supplied_arg_count, "E0060", true, false); + expected_arg_tys = vec![]; + self.err_args(supplied_arg_count) + } + } else { + // is the missing argument of type `()`? + let sugg_unit = if expected_arg_tys.len() == 1 && supplied_arg_count == 0 { + self.resolve_vars_if_possible(&expected_arg_tys[0]).is_unit() + } else if fn_inputs.len() == 1 && supplied_arg_count == 0 { + self.resolve_vars_if_possible(&fn_inputs[0]).is_unit() + } else { + false + }; + param_count_error(expected_arg_count, supplied_arg_count, "E0061", false, sugg_unit); + + expected_arg_tys = vec![]; + self.err_args(supplied_arg_count) + }; + + debug!( + "check_argument_types: formal_tys={:?}", + formal_tys.iter().map(|t| self.ty_to_string(*t)).collect::>() + ); + + // If there is no expectation, expect formal_tys. + let expected_arg_tys = + if !expected_arg_tys.is_empty() { expected_arg_tys } else { formal_tys.clone() }; + + let mut final_arg_types: Vec<(usize, Ty<'_>, Ty<'_>)> = vec![]; + + // Check the arguments. + // We do this in a pretty awful way: first we type-check any arguments + // that are not closures, then we type-check the closures. This is so + // that we have more information about the types of arguments when we + // type-check the functions. This isn't really the right way to do this. + for &check_closures in &[false, true] { + debug!("check_closures={}", check_closures); + + // More awful hacks: before we check argument types, try to do + // an "opportunistic" trait resolution of any trait bounds on + // the call. This helps coercions. + if check_closures { + self.select_obligations_where_possible(false, |errors| { + self.point_at_type_arg_instead_of_call_if_possible(errors, expr); + self.point_at_arg_instead_of_call_if_possible( + errors, + &final_arg_types[..], + sp, + &args, + ); + }) + } + + // For C-variadic functions, we don't have a declared type for all of + // the arguments hence we only do our usual type checking with + // the arguments who's types we do know. + let t = if c_variadic { + expected_arg_count + } else if tuple_arguments == TupleArguments { + args.len() + } else { + supplied_arg_count + }; + for (i, arg) in args.iter().take(t).enumerate() { + // Warn only for the first loop (the "no closures" one). + // Closure arguments themselves can't be diverging, but + // a previous argument can, e.g., `foo(panic!(), || {})`. + if !check_closures { + self.warn_if_unreachable(arg.hir_id, arg.span, "expression"); + } + + let is_closure = match arg.kind { + ExprKind::Closure(..) => true, + _ => false, + }; + + if is_closure != check_closures { + continue; + } + + debug!("checking the argument"); + let formal_ty = formal_tys[i]; + + // The special-cased logic below has three functions: + // 1. Provide as good of an expected type as possible. + let expected = Expectation::rvalue_hint(self, expected_arg_tys[i]); + + let checked_ty = self.check_expr_with_expectation(&arg, expected); + + // 2. Coerce to the most detailed type that could be coerced + // to, which is `expected_ty` if `rvalue_hint` returns an + // `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise. + let coerce_ty = expected.only_has_type(self).unwrap_or(formal_ty); + // We're processing function arguments so we definitely want to use + // two-phase borrows. + self.demand_coerce(&arg, checked_ty, coerce_ty, None, AllowTwoPhase::Yes); + final_arg_types.push((i, checked_ty, coerce_ty)); + + // 3. Relate the expected type and the formal one, + // if the expected type was used for the coercion. + self.demand_suptype(arg.span, formal_ty, coerce_ty); + } + } + + // We also need to make sure we at least write the ty of the other + // arguments which we skipped above. + if c_variadic { + fn variadic_error<'tcx>(s: &Session, span: Span, t: Ty<'tcx>, cast_ty: &str) { + use crate::structured_errors::{StructuredDiagnostic, VariadicError}; + VariadicError::new(s, span, t, cast_ty).diagnostic().emit(); + } + + for arg in args.iter().skip(expected_arg_count) { + let arg_ty = self.check_expr(&arg); + + // There are a few types which get autopromoted when passed via varargs + // in C but we just error out instead and require explicit casts. + let arg_ty = self.structurally_resolved_type(arg.span, arg_ty); + match arg_ty.kind() { + ty::Float(ast::FloatTy::F32) => { + variadic_error(tcx.sess, arg.span, arg_ty, "c_double"); + } + ty::Int(ast::IntTy::I8 | ast::IntTy::I16) | ty::Bool => { + variadic_error(tcx.sess, arg.span, arg_ty, "c_int"); + } + ty::Uint(ast::UintTy::U8 | ast::UintTy::U16) => { + variadic_error(tcx.sess, arg.span, arg_ty, "c_uint"); + } + ty::FnDef(..) => { + let ptr_ty = self.tcx.mk_fn_ptr(arg_ty.fn_sig(self.tcx)); + let ptr_ty = self.resolve_vars_if_possible(&ptr_ty); + variadic_error(tcx.sess, arg.span, arg_ty, &ptr_ty.to_string()); + } + _ => {} + } + } + } + } + + pub(super) fn err_args(&self, len: usize) -> Vec> { + vec![self.tcx.ty_error(); len] + } + + /// Given a vec of evaluated `FulfillmentError`s and an `fn` call argument expressions, we walk + /// the checked and coerced types for each argument to see if any of the `FulfillmentError`s + /// reference a type argument. The reason to walk also the checked type is that the coerced type + /// can be not easily comparable with predicate type (because of coercion). If the types match + /// for either checked or coerced type, and there's only *one* argument that does, we point at + /// the corresponding argument's expression span instead of the `fn` call path span. + fn point_at_arg_instead_of_call_if_possible( + &self, + errors: &mut Vec>, + final_arg_types: &[(usize, Ty<'tcx>, Ty<'tcx>)], + call_sp: Span, + args: &'tcx [hir::Expr<'tcx>], + ) { + // We *do not* do this for desugared call spans to keep good diagnostics when involving + // the `?` operator. + if call_sp.desugaring_kind().is_some() { + return; + } + + for error in errors { + // Only if the cause is somewhere inside the expression we want try to point at arg. + // Otherwise, it means that the cause is somewhere else and we should not change + // anything because we can break the correct span. + if !call_sp.contains(error.obligation.cause.span) { + continue; + } + + if let ty::PredicateAtom::Trait(predicate, _) = + error.obligation.predicate.skip_binders() + { + // Collect the argument position for all arguments that could have caused this + // `FulfillmentError`. + let mut referenced_in = final_arg_types + .iter() + .map(|&(i, checked_ty, _)| (i, checked_ty)) + .chain(final_arg_types.iter().map(|&(i, _, coerced_ty)| (i, coerced_ty))) + .flat_map(|(i, ty)| { + let ty = self.resolve_vars_if_possible(&ty); + // We walk the argument type because the argument's type could have + // been `Option`, but the `FulfillmentError` references `T`. + if ty.walk().any(|arg| arg == predicate.self_ty().into()) { + Some(i) + } else { + None + } + }) + .collect::>(); + + // Both checked and coerced types could have matched, thus we need to remove + // duplicates. + + // We sort primitive type usize here and can use unstable sort + referenced_in.sort_unstable(); + referenced_in.dedup(); + + if let (Some(ref_in), None) = (referenced_in.pop(), referenced_in.pop()) { + // We make sure that only *one* argument matches the obligation failure + // and we assign the obligation's span to its expression's. + error.obligation.cause.make_mut().span = args[ref_in].span; + error.points_at_arg_span = true; + } + } + } + } + + /// Given a vec of evaluated `FulfillmentError`s and an `fn` call expression, we walk the + /// `PathSegment`s and resolve their type parameters to see if any of the `FulfillmentError`s + /// were caused by them. If they were, we point at the corresponding type argument's span + /// instead of the `fn` call path span. + fn point_at_type_arg_instead_of_call_if_possible( + &self, + errors: &mut Vec>, + call_expr: &'tcx hir::Expr<'tcx>, + ) { + if let hir::ExprKind::Call(path, _) = &call_expr.kind { + if let hir::ExprKind::Path(qpath) = &path.kind { + if let hir::QPath::Resolved(_, path) = &qpath { + for error in errors { + if let ty::PredicateAtom::Trait(predicate, _) = + error.obligation.predicate.skip_binders() + { + // If any of the type arguments in this path segment caused the + // `FullfillmentError`, point at its span (#61860). + for arg in path + .segments + .iter() + .filter_map(|seg| seg.args.as_ref()) + .flat_map(|a| a.args.iter()) + { + if let hir::GenericArg::Type(hir_ty) = &arg { + if let hir::TyKind::Path(hir::QPath::TypeRelative(..)) = + &hir_ty.kind + { + // Avoid ICE with associated types. As this is best + // effort only, it's ok to ignore the case. It + // would trigger in `is_send::();` + // from `typeck-default-trait-impl-assoc-type.rs`. + } else { + let ty = AstConv::ast_ty_to_ty(self, hir_ty); + let ty = self.resolve_vars_if_possible(&ty); + if ty == predicate.self_ty() { + error.obligation.cause.make_mut().span = hir_ty.span; + } + } + } + } + } + } + } + } + } + } + + // AST fragment checking + pub(super) fn check_lit(&self, lit: &hir::Lit, expected: Expectation<'tcx>) -> Ty<'tcx> { + let tcx = self.tcx; + + match lit.node { + ast::LitKind::Str(..) => tcx.mk_static_str(), + ast::LitKind::ByteStr(ref v) => { + tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.u8, v.len() as u64)) + } + ast::LitKind::Byte(_) => tcx.types.u8, + ast::LitKind::Char(_) => tcx.types.char, + ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(t), + ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(t), + ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => { + let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() { + ty::Int(_) | ty::Uint(_) => Some(ty), + ty::Char => Some(tcx.types.u8), + ty::RawPtr(..) => Some(tcx.types.usize), + ty::FnDef(..) | ty::FnPtr(_) => Some(tcx.types.usize), + _ => None, + }); + opt_ty.unwrap_or_else(|| self.next_int_var()) + } + ast::LitKind::Float(_, ast::LitFloatType::Suffixed(t)) => tcx.mk_mach_float(t), + ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) => { + let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() { + ty::Float(_) => Some(ty), + _ => None, + }); + opt_ty.unwrap_or_else(|| self.next_float_var()) + } + ast::LitKind::Bool(_) => tcx.types.bool, + ast::LitKind::Err(_) => tcx.ty_error(), + } + } + + /// Unifies the output type with the expected type early, for more coercions + /// and forward type information on the input expressions. + pub(super) fn expected_inputs_for_expected_output( + &self, + call_span: Span, + expected_ret: Expectation<'tcx>, + formal_ret: Ty<'tcx>, + formal_args: &[Ty<'tcx>], + ) -> Vec> { + let formal_ret = self.resolve_vars_with_obligations(formal_ret); + let ret_ty = match expected_ret.only_has_type(self) { + Some(ret) => ret, + None => return Vec::new(), + }; + let expect_args = self + .fudge_inference_if_ok(|| { + // Attempt to apply a subtyping relationship between the formal + // return type (likely containing type variables if the function + // is polymorphic) and the expected return type. + // No argument expectations are produced if unification fails. + let origin = self.misc(call_span); + let ures = self.at(&origin, self.param_env).sup(ret_ty, &formal_ret); + + // FIXME(#27336) can't use ? here, Try::from_error doesn't default + // to identity so the resulting type is not constrained. + match ures { + Ok(ok) => { + // Process any obligations locally as much as + // we can. We don't care if some things turn + // out unconstrained or ambiguous, as we're + // just trying to get hints here. + self.save_and_restore_in_snapshot_flag(|_| { + let mut fulfill = TraitEngine::new(self.tcx); + for obligation in ok.obligations { + fulfill.register_predicate_obligation(self, obligation); + } + fulfill.select_where_possible(self) + }) + .map_err(|_| ())?; + } + Err(_) => return Err(()), + } + + // Record all the argument types, with the substitutions + // produced from the above subtyping unification. + Ok(formal_args.iter().map(|ty| self.resolve_vars_if_possible(ty)).collect()) + }) + .unwrap_or_default(); + debug!( + "expected_inputs_for_expected_output(formal={:?} -> {:?}, expected={:?} -> {:?})", + formal_args, formal_ret, expect_args, expected_ret + ); + expect_args + } + + pub fn check_struct_path( + &self, + qpath: &QPath<'_>, + hir_id: hir::HirId, + ) -> Option<(&'tcx ty::VariantDef, Ty<'tcx>)> { + let path_span = qpath.qself_span(); + let (def, ty) = self.finish_resolving_struct_path(qpath, path_span, hir_id); + let variant = match def { + Res::Err => { + self.set_tainted_by_errors(); + return None; + } + Res::Def(DefKind::Variant, _) => match ty.kind() { + ty::Adt(adt, substs) => Some((adt.variant_of_res(def), adt.did, substs)), + _ => bug!("unexpected type: {:?}", ty), + }, + Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _) + | Res::SelfTy(..) => match ty.kind() { + ty::Adt(adt, substs) if !adt.is_enum() => { + Some((adt.non_enum_variant(), adt.did, substs)) + } + _ => None, + }, + _ => bug!("unexpected definition: {:?}", def), + }; + + if let Some((variant, did, substs)) = variant { + debug!("check_struct_path: did={:?} substs={:?}", did, substs); + self.write_user_type_annotation_from_substs(hir_id, did, substs, None); + + // Check bounds on type arguments used in the path. + let (bounds, _) = self.instantiate_bounds(path_span, did, substs); + let cause = + traits::ObligationCause::new(path_span, self.body_id, traits::ItemObligation(did)); + self.add_obligations_for_parameters(cause, bounds); + + Some((variant, ty)) + } else { + struct_span_err!( + self.tcx.sess, + path_span, + E0071, + "expected struct, variant or union type, found {}", + ty.sort_string(self.tcx) + ) + .span_label(path_span, "not a struct") + .emit(); + None + } + } + + // Finish resolving a path in a struct expression or pattern `S::A { .. }` if necessary. + // The newly resolved definition is written into `type_dependent_defs`. + fn finish_resolving_struct_path( + &self, + qpath: &QPath<'_>, + path_span: Span, + hir_id: hir::HirId, + ) -> (Res, Ty<'tcx>) { + match *qpath { + QPath::Resolved(ref maybe_qself, ref path) => { + let self_ty = maybe_qself.as_ref().map(|qself| self.to_ty(qself)); + let ty = AstConv::res_to_ty(self, self_ty, path, true); + (path.res, ty) + } + QPath::TypeRelative(ref qself, ref segment) => { + let ty = self.to_ty(qself); + + let res = if let hir::TyKind::Path(QPath::Resolved(_, ref path)) = qself.kind { + path.res + } else { + Res::Err + }; + let result = + AstConv::associated_path_to_ty(self, hir_id, path_span, ty, res, segment, true); + let ty = result.map(|(ty, _, _)| ty).unwrap_or_else(|_| self.tcx().ty_error()); + let result = result.map(|(_, kind, def_id)| (kind, def_id)); + + // Write back the new resolution. + self.write_resolution(hir_id, result); + + (result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), ty) + } + QPath::LangItem(lang_item, span) => { + self.resolve_lang_item_path(lang_item, span, hir_id) + } + } + } + + pub(super) fn resolve_lang_item_path( + &self, + lang_item: hir::LangItem, + span: Span, + hir_id: hir::HirId, + ) -> (Res, Ty<'tcx>) { + let def_id = self.tcx.require_lang_item(lang_item, Some(span)); + let def_kind = self.tcx.def_kind(def_id); + + let item_ty = if let DefKind::Variant = def_kind { + self.tcx.type_of(self.tcx.parent(def_id).expect("variant w/out parent")) + } else { + self.tcx.type_of(def_id) + }; + let substs = self.infcx.fresh_substs_for_item(span, def_id); + let ty = item_ty.subst(self.tcx, substs); + + self.write_resolution(hir_id, Ok((def_kind, def_id))); + self.add_required_obligations(span, def_id, &substs); + (Res::Def(def_kind, def_id), ty) + } + + /// Resolves an associated value path into a base type and associated constant, or method + /// resolution. The newly resolved definition is written into `type_dependent_defs`. + pub fn resolve_ty_and_res_ufcs<'b>( + &self, + qpath: &'b QPath<'b>, + hir_id: hir::HirId, + span: Span, + ) -> (Res, Option>, &'b [hir::PathSegment<'b>]) { + debug!("resolve_ty_and_res_ufcs: qpath={:?} hir_id={:?} span={:?}", qpath, hir_id, span); + let (ty, qself, item_segment) = match *qpath { + QPath::Resolved(ref opt_qself, ref path) => { + return ( + path.res, + opt_qself.as_ref().map(|qself| self.to_ty(qself)), + &path.segments[..], + ); + } + QPath::TypeRelative(ref qself, ref segment) => (self.to_ty(qself), qself, segment), + QPath::LangItem(..) => bug!("`resolve_ty_and_res_ufcs` called on `LangItem`"), + }; + if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id) + { + // Return directly on cache hit. This is useful to avoid doubly reporting + // errors with default match binding modes. See #44614. + let def = + cached_result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err); + return (def, Some(ty), slice::from_ref(&**item_segment)); + } + let item_name = item_segment.ident; + let result = self.resolve_ufcs(span, item_name, ty, hir_id).or_else(|error| { + let result = match error { + method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)), + _ => Err(ErrorReported), + }; + if item_name.name != kw::Invalid { + if let Some(mut e) = self.report_method_error( + span, + ty, + item_name, + SelfSource::QPath(qself), + error, + None, + ) { + e.emit(); + } + } + result + }); + + // Write back the new resolution. + self.write_resolution(hir_id, result); + ( + result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), + Some(ty), + slice::from_ref(&**item_segment), + ) + } + + pub fn check_decl_initializer( + &self, + local: &'tcx hir::Local<'tcx>, + init: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + // FIXME(tschottdorf): `contains_explicit_ref_binding()` must be removed + // for #42640 (default match binding modes). + // + // See #44848. + let ref_bindings = local.pat.contains_explicit_ref_binding(); + + let local_ty = self.local_ty(init.span, local.hir_id).revealed_ty; + if let Some(m) = ref_bindings { + // Somewhat subtle: if we have a `ref` binding in the pattern, + // we want to avoid introducing coercions for the RHS. This is + // both because it helps preserve sanity and, in the case of + // ref mut, for soundness (issue #23116). In particular, in + // the latter case, we need to be clear that the type of the + // referent for the reference that results is *equal to* the + // type of the place it is referencing, and not some + // supertype thereof. + let init_ty = self.check_expr_with_needs(init, Needs::maybe_mut_place(m)); + self.demand_eqtype(init.span, local_ty, init_ty); + init_ty + } else { + self.check_expr_coercable_to_type(init, local_ty, None) + } + } + + /// Type check a `let` statement. + pub fn check_decl_local(&self, local: &'tcx hir::Local<'tcx>) { + // Determine and write the type which we'll check the pattern against. + let ty = self.local_ty(local.span, local.hir_id).decl_ty; + self.write_ty(local.hir_id, ty); + + // Type check the initializer. + if let Some(ref init) = local.init { + let init_ty = self.check_decl_initializer(local, &init); + self.overwrite_local_ty_if_err(local, ty, init_ty); + } + + // Does the expected pattern type originate from an expression and what is the span? + let (origin_expr, ty_span) = match (local.ty, local.init) { + (Some(ty), _) => (false, Some(ty.span)), // Bias towards the explicit user type. + (_, Some(init)) => (true, Some(init.span)), // No explicit type; so use the scrutinee. + _ => (false, None), // We have `let $pat;`, so the expected type is unconstrained. + }; + + // Type check the pattern. Override if necessary to avoid knock-on errors. + self.check_pat_top(&local.pat, ty, ty_span, origin_expr); + let pat_ty = self.node_ty(local.pat.hir_id); + self.overwrite_local_ty_if_err(local, ty, pat_ty); + } + + fn overwrite_local_ty_if_err( + &self, + local: &'tcx hir::Local<'tcx>, + decl_ty: Ty<'tcx>, + ty: Ty<'tcx>, + ) { + if ty.references_error() { + // Override the types everywhere with `err()` to avoid knock on errors. + self.write_ty(local.hir_id, ty); + self.write_ty(local.pat.hir_id, ty); + let local_ty = LocalTy { decl_ty, revealed_ty: ty }; + self.locals.borrow_mut().insert(local.hir_id, local_ty); + self.locals.borrow_mut().insert(local.pat.hir_id, local_ty); + } + } + + pub(super) fn suggest_semicolon_at_end(&self, span: Span, err: &mut DiagnosticBuilder<'_>) { + err.span_suggestion_short( + span.shrink_to_hi(), + "consider using a semicolon here", + ";".to_string(), + Applicability::MachineApplicable, + ); + } + + pub fn check_stmt(&self, stmt: &'tcx hir::Stmt<'tcx>) { + // Don't do all the complex logic below for `DeclItem`. + match stmt.kind { + hir::StmtKind::Item(..) => return, + hir::StmtKind::Local(..) | hir::StmtKind::Expr(..) | hir::StmtKind::Semi(..) => {} + } + + self.warn_if_unreachable(stmt.hir_id, stmt.span, "statement"); + + // Hide the outer diverging and `has_errors` flags. + let old_diverges = self.diverges.replace(Diverges::Maybe); + let old_has_errors = self.has_errors.replace(false); + + match stmt.kind { + hir::StmtKind::Local(ref l) => { + self.check_decl_local(&l); + } + // Ignore for now. + hir::StmtKind::Item(_) => {} + hir::StmtKind::Expr(ref expr) => { + // Check with expected type of `()`. + self.check_expr_has_type_or_error(&expr, self.tcx.mk_unit(), |err| { + self.suggest_semicolon_at_end(expr.span, err); + }); + } + hir::StmtKind::Semi(ref expr) => { + self.check_expr(&expr); + } + } + + // Combine the diverging and `has_error` flags. + self.diverges.set(self.diverges.get() | old_diverges); + self.has_errors.set(self.has_errors.get() | old_has_errors); + } + + pub fn check_block_no_value(&self, blk: &'tcx hir::Block<'tcx>) { + let unit = self.tcx.mk_unit(); + let ty = self.check_block_with_expected(blk, ExpectHasType(unit)); + + // if the block produces a `!` value, that can always be + // (effectively) coerced to unit. + if !ty.is_never() { + self.demand_suptype(blk.span, unit, ty); + } + } + + /// If `expr` is a `match` expression that has only one non-`!` arm, use that arm's tail + /// expression's `Span`, otherwise return `expr.span`. This is done to give better errors + /// when given code like the following: + /// ```text + /// if false { return 0i32; } else { 1u32 } + /// // ^^^^ point at this instead of the whole `if` expression + /// ``` + fn get_expr_coercion_span(&self, expr: &hir::Expr<'_>) -> rustc_span::Span { + if let hir::ExprKind::Match(_, arms, _) = &expr.kind { + let arm_spans: Vec = arms + .iter() + .filter_map(|arm| { + self.in_progress_typeck_results + .and_then(|typeck_results| { + typeck_results.borrow().node_type_opt(arm.body.hir_id) + }) + .and_then(|arm_ty| { + if arm_ty.is_never() { + None + } else { + Some(match &arm.body.kind { + // Point at the tail expression when possible. + hir::ExprKind::Block(block, _) => { + block.expr.as_ref().map(|e| e.span).unwrap_or(block.span) + } + _ => arm.body.span, + }) + } + }) + }) + .collect(); + if arm_spans.len() == 1 { + return arm_spans[0]; + } + } + expr.span + } + + pub(super) fn check_block_with_expected( + &self, + blk: &'tcx hir::Block<'tcx>, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let prev = { + let mut fcx_ps = self.ps.borrow_mut(); + let unsafety_state = fcx_ps.recurse(blk); + replace(&mut *fcx_ps, unsafety_state) + }; + + // In some cases, blocks have just one exit, but other blocks + // can be targeted by multiple breaks. This can happen both + // with labeled blocks as well as when we desugar + // a `try { ... }` expression. + // + // Example 1: + // + // 'a: { if true { break 'a Err(()); } Ok(()) } + // + // Here we would wind up with two coercions, one from + // `Err(())` and the other from the tail expression + // `Ok(())`. If the tail expression is omitted, that's a + // "forced unit" -- unless the block diverges, in which + // case we can ignore the tail expression (e.g., `'a: { + // break 'a 22; }` would not force the type of the block + // to be `()`). + let tail_expr = blk.expr.as_ref(); + let coerce_to_ty = expected.coercion_target_type(self, blk.span); + let coerce = if blk.targeted_by_break { + CoerceMany::new(coerce_to_ty) + } else { + let tail_expr: &[&hir::Expr<'_>] = match tail_expr { + Some(e) => slice::from_ref(e), + None => &[], + }; + CoerceMany::with_coercion_sites(coerce_to_ty, tail_expr) + }; + + let prev_diverges = self.diverges.get(); + let ctxt = BreakableCtxt { coerce: Some(coerce), may_break: false }; + + let (ctxt, ()) = self.with_breakable_ctxt(blk.hir_id, ctxt, || { + for s in blk.stmts { + self.check_stmt(s); + } + + // check the tail expression **without** holding the + // `enclosing_breakables` lock below. + let tail_expr_ty = tail_expr.map(|t| self.check_expr_with_expectation(t, expected)); + + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + let ctxt = enclosing_breakables.find_breakable(blk.hir_id); + let coerce = ctxt.coerce.as_mut().unwrap(); + if let Some(tail_expr_ty) = tail_expr_ty { + let tail_expr = tail_expr.unwrap(); + let span = self.get_expr_coercion_span(tail_expr); + let cause = self.cause(span, ObligationCauseCode::BlockTailExpression(blk.hir_id)); + coerce.coerce(self, &cause, tail_expr, tail_expr_ty); + } else { + // Subtle: if there is no explicit tail expression, + // that is typically equivalent to a tail expression + // of `()` -- except if the block diverges. In that + // case, there is no value supplied from the tail + // expression (assuming there are no other breaks, + // this implies that the type of the block will be + // `!`). + // + // #41425 -- label the implicit `()` as being the + // "found type" here, rather than the "expected type". + if !self.diverges.get().is_always() { + // #50009 -- Do not point at the entire fn block span, point at the return type + // span, as it is the cause of the requirement, and + // `consider_hint_about_removing_semicolon` will point at the last expression + // if it were a relevant part of the error. This improves usability in editors + // that highlight errors inline. + let mut sp = blk.span; + let mut fn_span = None; + if let Some((decl, ident)) = self.get_parent_fn_decl(blk.hir_id) { + let ret_sp = decl.output.span(); + if let Some(block_sp) = self.parent_item_span(blk.hir_id) { + // HACK: on some cases (`ui/liveness/liveness-issue-2163.rs`) the + // output would otherwise be incorrect and even misleading. Make sure + // the span we're aiming at correspond to a `fn` body. + if block_sp == blk.span { + sp = ret_sp; + fn_span = Some(ident.span); + } + } + } + coerce.coerce_forced_unit( + self, + &self.misc(sp), + &mut |err| { + if let Some(expected_ty) = expected.only_has_type(self) { + self.consider_hint_about_removing_semicolon(blk, expected_ty, err); + } + if let Some(fn_span) = fn_span { + err.span_label( + fn_span, + "implicitly returns `()` as its body has no tail or `return` \ + expression", + ); + } + }, + false, + ); + } + } + }); + + if ctxt.may_break { + // If we can break from the block, then the block's exit is always reachable + // (... as long as the entry is reachable) - regardless of the tail of the block. + self.diverges.set(prev_diverges); + } + + let mut ty = ctxt.coerce.unwrap().complete(self); + + if self.has_errors.get() || ty.references_error() { + ty = self.tcx.ty_error() + } + + self.write_ty(blk.hir_id, ty); + + *self.ps.borrow_mut() = prev; + ty + } + + fn parent_item_span(&self, id: hir::HirId) -> Option { + let node = self.tcx.hir().get(self.tcx.hir().get_parent_item(id)); + match node { + Node::Item(&hir::Item { kind: hir::ItemKind::Fn(_, _, body_id), .. }) + | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(_, body_id), .. }) => { + let body = self.tcx.hir().body(body_id); + if let ExprKind::Block(block, _) = &body.value.kind { + return Some(block.span); + } + } + _ => {} + } + None + } + + /// Given a function block's `HirId`, returns its `FnDecl` if it exists, or `None` otherwise. + fn get_parent_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident)> { + let parent = self.tcx.hir().get(self.tcx.hir().get_parent_item(blk_id)); + self.get_node_fn_decl(parent).map(|(fn_decl, ident, _)| (fn_decl, ident)) + } + + /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise. + pub(super) fn get_node_fn_decl( + &self, + node: Node<'tcx>, + ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> { + match node { + Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => { + // This is less than ideal, it will not suggest a return type span on any + // method called `main`, regardless of whether it is actually the entry point, + // but it will still present it as the reason for the expected type. + Some((&sig.decl, ident, ident.name != sym::main)) + } + Node::TraitItem(&hir::TraitItem { + ident, + kind: hir::TraitItemKind::Fn(ref sig, ..), + .. + }) => Some((&sig.decl, ident, true)), + Node::ImplItem(&hir::ImplItem { + ident, + kind: hir::ImplItemKind::Fn(ref sig, ..), + .. + }) => Some((&sig.decl, ident, false)), + _ => None, + } + } + + /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a + /// suggestion can be made, `None` otherwise. + pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> { + // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or + // `while` before reaching it, as block tail returns are not available in them. + self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| { + let parent = self.tcx.hir().get(blk_id); + self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main)) + }) + } + + /// On implicit return expressions with mismatched types, provides the following suggestions: + /// + /// - Points out the method's return type as the reason for the expected type. + /// - Possible missing semicolon. + /// - Possible missing return type if the return type is the default, and not `fn main()`. + pub fn suggest_mismatched_types_on_tail( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &'tcx hir::Expr<'tcx>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + cause_span: Span, + blk_id: hir::HirId, + ) -> bool { + let expr = expr.peel_drop_temps(); + self.suggest_missing_semicolon(err, expr, expected, cause_span); + let mut pointing_at_return_type = false; + if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) { + pointing_at_return_type = + self.suggest_missing_return_type(err, &fn_decl, expected, found, can_suggest); + } + pointing_at_return_type + } + + /// When encountering an fn-like ctor that needs to unify with a value, check whether calling + /// the ctor would successfully solve the type mismatch and if so, suggest it: + /// ``` + /// fn foo(x: usize) -> usize { x } + /// let x: usize = foo; // suggest calling the `foo` function: `foo(42)` + /// ``` + fn suggest_fn_call( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) -> bool { + let hir = self.tcx.hir(); + let (def_id, sig) = match *found.kind() { + ty::FnDef(def_id, _) => (def_id, found.fn_sig(self.tcx)), + ty::Closure(def_id, substs) => (def_id, substs.as_closure().sig()), + _ => return false, + }; + + let sig = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, &sig).0; + let sig = self.normalize_associated_types_in(expr.span, &sig); + if self.can_coerce(sig.output(), expected) { + let (mut sugg_call, applicability) = if sig.inputs().is_empty() { + (String::new(), Applicability::MachineApplicable) + } else { + ("...".to_string(), Applicability::HasPlaceholders) + }; + let mut msg = "call this function"; + match hir.get_if_local(def_id) { + Some( + Node::Item(hir::Item { kind: ItemKind::Fn(.., body_id), .. }) + | Node::ImplItem(hir::ImplItem { + kind: hir::ImplItemKind::Fn(_, body_id), .. + }) + | Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Provided(body_id)), + .. + }), + ) => { + let body = hir.body(*body_id); + sugg_call = body + .params + .iter() + .map(|param| match ¶m.pat.kind { + hir::PatKind::Binding(_, _, ident, None) + if ident.name != kw::SelfLower => + { + ident.to_string() + } + _ => "_".to_string(), + }) + .collect::>() + .join(", "); + } + Some(Node::Expr(hir::Expr { + kind: ExprKind::Closure(_, _, body_id, _, _), + span: full_closure_span, + .. + })) => { + if *full_closure_span == expr.span { + return false; + } + msg = "call this closure"; + let body = hir.body(*body_id); + sugg_call = body + .params + .iter() + .map(|param| match ¶m.pat.kind { + hir::PatKind::Binding(_, _, ident, None) + if ident.name != kw::SelfLower => + { + ident.to_string() + } + _ => "_".to_string(), + }) + .collect::>() + .join(", "); + } + Some(Node::Ctor(hir::VariantData::Tuple(fields, _))) => { + sugg_call = fields.iter().map(|_| "_").collect::>().join(", "); + match def_id.as_local().map(|def_id| hir.def_kind(def_id)) { + Some(DefKind::Ctor(hir::def::CtorOf::Variant, _)) => { + msg = "instantiate this tuple variant"; + } + Some(DefKind::Ctor(CtorOf::Struct, _)) => { + msg = "instantiate this tuple struct"; + } + _ => {} + } + } + Some(Node::ForeignItem(hir::ForeignItem { + kind: hir::ForeignItemKind::Fn(_, idents, _), + .. + })) => { + sugg_call = idents + .iter() + .map(|ident| { + if ident.name != kw::SelfLower { + ident.to_string() + } else { + "_".to_string() + } + }) + .collect::>() + .join(", ") + } + Some(Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Required(idents)), + .. + })) => { + sugg_call = idents + .iter() + .map(|ident| { + if ident.name != kw::SelfLower { + ident.to_string() + } else { + "_".to_string() + } + }) + .collect::>() + .join(", ") + } + _ => {} + } + err.span_suggestion_verbose( + expr.span.shrink_to_hi(), + &format!("use parentheses to {}", msg), + format!("({})", sugg_call), + applicability, + ); + return true; + } + false + } + + pub fn suggest_deref_ref_or_into( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, + ) { + if let Some((sp, msg, suggestion, applicability)) = self.check_ref(expr, found, expected) { + err.span_suggestion(sp, msg, suggestion, applicability); + } else if let (ty::FnDef(def_id, ..), true) = + (&found.kind(), self.suggest_fn_call(err, expr, expected, found)) + { + if let Some(sp) = self.tcx.hir().span_if_local(*def_id) { + let sp = self.sess().source_map().guess_head_span(sp); + err.span_label(sp, &format!("{} defined here", found)); + } + } else if !self.check_for_cast(err, expr, found, expected, expected_ty_expr) { + let is_struct_pat_shorthand_field = + self.is_hir_id_from_struct_pattern_shorthand_field(expr.hir_id, expr.span); + let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id); + if let Ok(expr_text) = self.sess().source_map().span_to_snippet(expr.span) { + let mut suggestions = iter::repeat(&expr_text) + .zip(methods.iter()) + .filter_map(|(receiver, method)| { + let method_call = format!(".{}()", method.ident); + if receiver.ends_with(&method_call) { + None // do not suggest code that is already there (#53348) + } else { + let method_call_list = [".to_vec()", ".to_string()"]; + let sugg = if receiver.ends_with(".clone()") + && method_call_list.contains(&method_call.as_str()) + { + let max_len = receiver.rfind('.').unwrap(); + format!("{}{}", &receiver[..max_len], method_call) + } else { + if expr.precedence().order() < ExprPrecedence::MethodCall.order() { + format!("({}){}", receiver, method_call) + } else { + format!("{}{}", receiver, method_call) + } + }; + Some(if is_struct_pat_shorthand_field { + format!("{}: {}", receiver, sugg) + } else { + sugg + }) + } + }) + .peekable(); + if suggestions.peek().is_some() { + err.span_suggestions( + expr.span, + "try using a conversion method", + suggestions, + Applicability::MaybeIncorrect, + ); + } + } + } + } + + /// When encountering the expected boxed value allocated in the stack, suggest allocating it + /// in the heap by calling `Box::new()`. + pub(super) fn suggest_boxing_when_appropriate( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) { + if self.tcx.hir().is_inside_const_context(expr.hir_id) { + // Do not suggest `Box::new` in const context. + return; + } + if !expected.is_box() || found.is_box() { + return; + } + let boxed_found = self.tcx.mk_box(found); + if let (true, Ok(snippet)) = ( + self.can_coerce(boxed_found, expected), + self.sess().source_map().span_to_snippet(expr.span), + ) { + err.span_suggestion( + expr.span, + "store this in the heap by calling `Box::new`", + format!("Box::new({})", snippet), + Applicability::MachineApplicable, + ); + err.note( + "for more on the distinction between the stack and the heap, read \ + https://doc.rust-lang.org/book/ch15-01-box.html, \ + https://doc.rust-lang.org/rust-by-example/std/box.html, and \ + https://doc.rust-lang.org/std/boxed/index.html", + ); + } + } + + pub(super) fn note_internal_mutation_in_method( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) { + if found != self.tcx.types.unit { + return; + } + if let ExprKind::MethodCall(path_segment, _, [rcvr, ..], _) = expr.kind { + if self + .typeck_results + .borrow() + .expr_ty_adjusted_opt(rcvr) + .map_or(true, |ty| expected.peel_refs() != ty.peel_refs()) + { + return; + } + let mut sp = MultiSpan::from_span(path_segment.ident.span); + sp.push_span_label( + path_segment.ident.span, + format!( + "this call modifies {} in-place", + match rcvr.kind { + ExprKind::Path(QPath::Resolved( + None, + hir::Path { segments: [segment], .. }, + )) => format!("`{}`", segment.ident), + _ => "its receiver".to_string(), + } + ), + ); + sp.push_span_label( + rcvr.span, + "you probably want to use this value after calling the method...".to_string(), + ); + err.span_note( + sp, + &format!("method `{}` modifies its receiver in-place", path_segment.ident), + ); + err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident)); + } + } + + /// When encountering an `impl Future` where `BoxFuture` is expected, suggest `Box::pin`. + pub(super) fn suggest_calling_boxed_future_when_appropriate( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) -> bool { + // Handle #68197. + + if self.tcx.hir().is_inside_const_context(expr.hir_id) { + // Do not suggest `Box::new` in const context. + return false; + } + let pin_did = self.tcx.lang_items().pin_type(); + match expected.kind() { + ty::Adt(def, _) if Some(def.did) != pin_did => return false, + // This guards the `unwrap` and `mk_box` below. + _ if pin_did.is_none() || self.tcx.lang_items().owned_box().is_none() => return false, + _ => {} + } + let boxed_found = self.tcx.mk_box(found); + let new_found = self.tcx.mk_lang_item(boxed_found, LangItem::Pin).unwrap(); + if let (true, Ok(snippet)) = ( + self.can_coerce(new_found, expected), + self.sess().source_map().span_to_snippet(expr.span), + ) { + match found.kind() { + ty::Adt(def, _) if def.is_box() => { + err.help("use `Box::pin`"); + } + _ => { + err.span_suggestion( + expr.span, + "you need to pin and box this expression", + format!("Box::pin({})", snippet), + Applicability::MachineApplicable, + ); + } + } + true + } else { + false + } + } + + /// A common error is to forget to add a semicolon at the end of a block, e.g., + /// + /// ``` + /// fn foo() { + /// bar_that_returns_u32() + /// } + /// ``` + /// + /// This routine checks if the return expression in a block would make sense on its own as a + /// statement and the return type has been left as default or has been specified as `()`. If so, + /// it suggests adding a semicolon. + fn suggest_missing_semicolon( + &self, + err: &mut DiagnosticBuilder<'_>, + expression: &'tcx hir::Expr<'tcx>, + expected: Ty<'tcx>, + cause_span: Span, + ) { + if expected.is_unit() { + // `BlockTailExpression` only relevant if the tail expr would be + // useful on its own. + match expression.kind { + ExprKind::Call(..) + | ExprKind::MethodCall(..) + | ExprKind::Loop(..) + | ExprKind::Match(..) + | ExprKind::Block(..) => { + err.span_suggestion( + cause_span.shrink_to_hi(), + "try adding a semicolon", + ";".to_string(), + Applicability::MachineApplicable, + ); + } + _ => (), + } + } + } + + /// A possible error is to forget to add a return type that is needed: + /// + /// ``` + /// fn foo() { + /// bar_that_returns_u32() + /// } + /// ``` + /// + /// This routine checks if the return type is left as default, the method is not part of an + /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return + /// type. + pub(super) fn suggest_missing_return_type( + &self, + err: &mut DiagnosticBuilder<'_>, + fn_decl: &hir::FnDecl<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + can_suggest: bool, + ) -> bool { + // Only suggest changing the return type for methods that + // haven't set a return type at all (and aren't `fn main()` or an impl). + match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) { + (&hir::FnRetTy::DefaultReturn(span), true, true, true) => { + err.span_suggestion( + span, + "try adding a return type", + format!("-> {} ", self.resolve_vars_with_obligations(found)), + Applicability::MachineApplicable, + ); + true + } + (&hir::FnRetTy::DefaultReturn(span), false, true, true) => { + err.span_label(span, "possibly return type missing here?"); + true + } + (&hir::FnRetTy::DefaultReturn(span), _, false, true) => { + // `fn main()` must return `()`, do not suggest changing return type + err.span_label(span, "expected `()` because of default return type"); + true + } + // expectation was caused by something else, not the default return + (&hir::FnRetTy::DefaultReturn(_), _, _, false) => false, + (&hir::FnRetTy::Return(ref ty), _, _, _) => { + // Only point to return type if the expected type is the return type, as if they + // are not, the expectation must have been caused by something else. + debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind); + let sp = ty.span; + let ty = AstConv::ast_ty_to_ty(self, ty); + debug!("suggest_missing_return_type: return type {:?}", ty); + debug!("suggest_missing_return_type: expected type {:?}", ty); + if ty.kind() == expected.kind() { + err.span_label(sp, format!("expected `{}` because of return type", expected)); + return true; + } + false + } + } + } + + /// A possible error is to forget to add `.await` when using futures: + /// + /// ``` + /// async fn make_u32() -> u32 { + /// 22 + /// } + /// + /// fn take_u32(x: u32) {} + /// + /// async fn foo() { + /// let x = make_u32(); + /// take_u32(x); + /// } + /// ``` + /// + /// This routine checks if the found type `T` implements `Future` where `U` is the + /// expected type. If this is the case, and we are inside of an async body, it suggests adding + /// `.await` to the tail of the expression. + pub(super) fn suggest_missing_await( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) { + debug!("suggest_missing_await: expr={:?} expected={:?}, found={:?}", expr, expected, found); + // `.await` is not permitted outside of `async` bodies, so don't bother to suggest if the + // body isn't `async`. + let item_id = self.tcx().hir().get_parent_node(self.body_id); + if let Some(body_id) = self.tcx().hir().maybe_body_owned_by(item_id) { + let body = self.tcx().hir().body(body_id); + if let Some(hir::GeneratorKind::Async(_)) = body.generator_kind { + let sp = expr.span; + // Check for `Future` implementations by constructing a predicate to + // prove: `::Output == U` + let future_trait = self.tcx.require_lang_item(LangItem::Future, Some(sp)); + let item_def_id = self + .tcx + .associated_items(future_trait) + .in_definition_order() + .next() + .unwrap() + .def_id; + // `::Output` + let projection_ty = ty::ProjectionTy { + // `T` + substs: self + .tcx + .mk_substs_trait(found, self.fresh_substs_for_item(sp, item_def_id)), + // `Future::Output` + item_def_id, + }; + + let predicate = ty::PredicateAtom::Projection(ty::ProjectionPredicate { + projection_ty, + ty: expected, + }) + .potentially_quantified(self.tcx, ty::PredicateKind::ForAll); + let obligation = traits::Obligation::new(self.misc(sp), self.param_env, predicate); + + debug!("suggest_missing_await: trying obligation {:?}", obligation); + + if self.infcx.predicate_may_hold(&obligation) { + debug!("suggest_missing_await: obligation held: {:?}", obligation); + if let Ok(code) = self.sess().source_map().span_to_snippet(sp) { + err.span_suggestion( + sp, + "consider using `.await` here", + format!("{}.await", code), + Applicability::MaybeIncorrect, + ); + } else { + debug!("suggest_missing_await: no snippet for {:?}", sp); + } + } else { + debug!("suggest_missing_await: obligation did not hold: {:?}", obligation) + } + } + } + } + + pub(super) fn suggest_missing_parentheses( + &self, + err: &mut DiagnosticBuilder<'_>, + expr: &hir::Expr<'_>, + ) { + let sp = self.tcx.sess.source_map().start_point(expr.span); + if let Some(sp) = self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) { + // `{ 42 } &&x` (#61475) or `{ 42 } && if x { 1 } else { 0 }` + self.tcx.sess.parse_sess.expr_parentheses_needed(err, *sp, None); + } + } + + pub(super) fn note_need_for_fn_pointer( + &self, + err: &mut DiagnosticBuilder<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) { + let (sig, did, substs) = match (&expected.kind(), &found.kind()) { + (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => { + let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1); + let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2); + if sig1 != sig2 { + return; + } + err.note( + "different `fn` items always have unique types, even if their signatures are \ + the same", + ); + (sig1, *did1, substs1) + } + (ty::FnDef(did, substs), ty::FnPtr(sig2)) => { + let sig1 = self.tcx.fn_sig(*did).subst(self.tcx, substs); + if sig1 != *sig2 { + return; + } + (sig1, *did, substs) + } + _ => return, + }; + err.help(&format!("change the expected type to be function pointer `{}`", sig)); + err.help(&format!( + "if the expected type is due to type inference, cast the expected `fn` to a function \ + pointer: `{} as {}`", + self.tcx.def_path_str_with_substs(did, substs), + sig + )); + } + + /// A common error is to add an extra semicolon: + /// + /// ``` + /// fn foo() -> usize { + /// 22; + /// } + /// ``` + /// + /// This routine checks if the final statement in a block is an + /// expression with an explicit semicolon whose type is compatible + /// with `expected_ty`. If so, it suggests removing the semicolon. + fn consider_hint_about_removing_semicolon( + &self, + blk: &'tcx hir::Block<'tcx>, + expected_ty: Ty<'tcx>, + err: &mut DiagnosticBuilder<'_>, + ) { + if let Some(span_semi) = self.could_remove_semicolon(blk, expected_ty) { + err.span_suggestion( + span_semi, + "consider removing this semicolon", + String::new(), + Applicability::MachineApplicable, + ); + } + } + + pub(super) fn could_remove_semicolon( + &self, + blk: &'tcx hir::Block<'tcx>, + expected_ty: Ty<'tcx>, + ) -> Option { + // Be helpful when the user wrote `{... expr;}` and + // taking the `;` off is enough to fix the error. + let last_stmt = blk.stmts.last()?; + let last_expr = match last_stmt.kind { + hir::StmtKind::Semi(ref e) => e, + _ => return None, + }; + let last_expr_ty = self.node_ty(last_expr.hir_id); + if matches!(last_expr_ty.kind(), ty::Error(_)) + || self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err() + { + return None; + } + let original_span = original_sp(last_stmt.span, blk.span); + Some(original_span.with_lo(original_span.hi() - BytePos(1))) + } + + // Instantiates the given path, which must refer to an item with the given + // number of type parameters and type. + pub fn instantiate_value_path( + &self, + segments: &[hir::PathSegment<'_>], + self_ty: Option>, + res: Res, + span: Span, + hir_id: hir::HirId, + ) -> (Ty<'tcx>, Res) { + debug!( + "instantiate_value_path(segments={:?}, self_ty={:?}, res={:?}, hir_id={})", + segments, self_ty, res, hir_id, + ); + + let tcx = self.tcx; + + let path_segs = match res { + Res::Local(_) | Res::SelfCtor(_) => vec![], + Res::Def(kind, def_id) => { + AstConv::def_ids_for_value_path_segments(self, segments, self_ty, kind, def_id) + } + _ => bug!("instantiate_value_path on {:?}", res), + }; + + let mut user_self_ty = None; + let mut is_alias_variant_ctor = false; + match res { + Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) => { + if let Some(self_ty) = self_ty { + let adt_def = self_ty.ty_adt_def().unwrap(); + user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did, self_ty }); + is_alias_variant_ctor = true; + } + } + Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => { + let container = tcx.associated_item(def_id).container; + debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container); + match container { + ty::TraitContainer(trait_did) => { + callee::check_legal_trait_for_method_call(tcx, span, None, trait_did) + } + ty::ImplContainer(impl_def_id) => { + if segments.len() == 1 { + // `::assoc` will end up here, and so + // can `T::assoc`. It this came from an + // inherent impl, we need to record the + // `T` for posterity (see `UserSelfTy` for + // details). + let self_ty = self_ty.expect("UFCS sugared assoc missing Self"); + user_self_ty = Some(UserSelfTy { impl_def_id, self_ty }); + } + } + } + } + _ => {} + } + + // Now that we have categorized what space the parameters for each + // segment belong to, let's sort out the parameters that the user + // provided (if any) into their appropriate spaces. We'll also report + // errors if type parameters are provided in an inappropriate place. + + let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect(); + let generics_has_err = AstConv::prohibit_generics( + self, + segments.iter().enumerate().filter_map(|(index, seg)| { + if !generic_segs.contains(&index) || is_alias_variant_ctor { + Some(seg) + } else { + None + } + }), + ); + + if let Res::Local(hid) = res { + let ty = self.local_ty(span, hid).decl_ty; + let ty = self.normalize_associated_types_in(span, &ty); + self.write_ty(hir_id, ty); + return (ty, res); + } + + if generics_has_err { + // Don't try to infer type parameters when prohibited generic arguments were given. + user_self_ty = None; + } + + // Now we have to compare the types that the user *actually* + // provided against the types that were *expected*. If the user + // did not provide any types, then we want to substitute inference + // variables. If the user provided some types, we may still need + // to add defaults. If the user provided *too many* types, that's + // a problem. + + let mut infer_args_for_err = FxHashSet::default(); + for &PathSeg(def_id, index) in &path_segs { + let seg = &segments[index]; + let generics = tcx.generics_of(def_id); + // Argument-position `impl Trait` is treated as a normal generic + // parameter internally, but we don't allow users to specify the + // parameter's value explicitly, so we have to do some error- + // checking here. + if let GenericArgCountResult { + correct: Err(GenericArgCountMismatch { reported: Some(ErrorReported), .. }), + .. + } = AstConv::check_generic_arg_count_for_call( + tcx, span, &generics, &seg, false, // `is_method_call` + ) { + infer_args_for_err.insert(index); + self.set_tainted_by_errors(); // See issue #53251. + } + } + + let has_self = path_segs + .last() + .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self) + .unwrap_or(false); + + let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res { + let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id)); + match *ty.kind() { + ty::Adt(adt_def, substs) if adt_def.has_ctor() => { + let variant = adt_def.non_enum_variant(); + let ctor_def_id = variant.ctor_def_id.unwrap(); + ( + Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id), + Some(substs), + ) + } + _ => { + let mut err = tcx.sess.struct_span_err( + span, + "the `Self` constructor can only be used with tuple or unit structs", + ); + if let Some(adt_def) = ty.ty_adt_def() { + match adt_def.adt_kind() { + AdtKind::Enum => { + err.help("did you mean to use one of the enum's variants?"); + } + AdtKind::Struct | AdtKind::Union => { + err.span_suggestion( + span, + "use curly brackets", + String::from("Self { /* fields */ }"), + Applicability::HasPlaceholders, + ); + } + } + } + err.emit(); + + return (tcx.ty_error(), res); + } + } + } else { + (res, None) + }; + let def_id = res.def_id(); + + // The things we are substituting into the type should not contain + // escaping late-bound regions, and nor should the base type scheme. + let ty = tcx.type_of(def_id); + + let arg_count = GenericArgCountResult { + explicit_late_bound: ExplicitLateBound::No, + correct: if infer_args_for_err.is_empty() { + Ok(()) + } else { + Err(GenericArgCountMismatch::default()) + }, + }; + + let substs = self_ctor_substs.unwrap_or_else(|| { + AstConv::create_substs_for_generic_args( + tcx, + def_id, + &[][..], + has_self, + self_ty, + arg_count, + // Provide the generic args, and whether types should be inferred. + |def_id| { + if let Some(&PathSeg(_, index)) = + path_segs.iter().find(|&PathSeg(did, _)| *did == def_id) + { + // If we've encountered an `impl Trait`-related error, we're just + // going to infer the arguments for better error messages. + if !infer_args_for_err.contains(&index) { + // Check whether the user has provided generic arguments. + if let Some(ref data) = segments[index].args { + return (Some(data), segments[index].infer_args); + } + } + return (None, segments[index].infer_args); + } + + (None, true) + }, + // Provide substitutions for parameters for which (valid) arguments have been provided. + |param, arg| match (¶m.kind, arg) { + (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => { + AstConv::ast_region_to_region(self, lt, Some(param)).into() + } + (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => { + self.to_ty(ty).into() + } + (GenericParamDefKind::Const, GenericArg::Const(ct)) => { + self.const_arg_to_const(&ct.value, param.def_id).into() + } + _ => unreachable!(), + }, + // Provide substitutions for parameters for which arguments are inferred. + |substs, param, infer_args| { + match param.kind { + GenericParamDefKind::Lifetime => { + self.re_infer(Some(param), span).unwrap().into() + } + GenericParamDefKind::Type { has_default, .. } => { + if !infer_args && has_default { + // If we have a default, then we it doesn't matter that we're not + // inferring the type arguments: we provide the default where any + // is missing. + let default = tcx.type_of(param.def_id); + self.normalize_ty( + span, + default.subst_spanned(tcx, substs.unwrap(), Some(span)), + ) + .into() + } else { + // If no type arguments were provided, we have to infer them. + // This case also occurs as a result of some malformed input, e.g. + // a lifetime argument being given instead of a type parameter. + // Using inference instead of `Error` gives better error messages. + self.var_for_def(span, param) + } + } + GenericParamDefKind::Const => { + // FIXME(const_generics:defaults) + // No const parameters were provided, we have to infer them. + self.var_for_def(span, param) + } + } + }, + ) + }); + assert!(!substs.has_escaping_bound_vars()); + assert!(!ty.has_escaping_bound_vars()); + + // First, store the "user substs" for later. + self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty); + + self.add_required_obligations(span, def_id, &substs); + + // Substitute the values for the type parameters into the type of + // the referenced item. + let ty_substituted = self.instantiate_type_scheme(span, &substs, &ty); + + if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty { + // In the case of `Foo::method` and `>::method`, if `method` + // is inherent, there is no `Self` parameter; instead, the impl needs + // type parameters, which we can infer by unifying the provided `Self` + // with the substituted impl type. + // This also occurs for an enum variant on a type alias. + let ty = tcx.type_of(impl_def_id); + + let impl_ty = self.instantiate_type_scheme(span, &substs, &ty); + match self.at(&self.misc(span), self.param_env).sup(impl_ty, self_ty) { + Ok(ok) => self.register_infer_ok_obligations(ok), + Err(_) => { + self.tcx.sess.delay_span_bug( + span, + &format!( + "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?", + self_ty, + impl_ty, + ), + ); + } + } + } + + self.check_rustc_args_require_const(def_id, hir_id, span); + + debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted); + self.write_substs(hir_id, substs); + + (ty_substituted, res) + } + + /// Add all the obligations that are required, substituting and normalized appropriately. + fn add_required_obligations(&self, span: Span, def_id: DefId, substs: &SubstsRef<'tcx>) { + let (bounds, spans) = self.instantiate_bounds(span, def_id, &substs); + + for (i, mut obligation) in traits::predicates_for_generics( + traits::ObligationCause::new(span, self.body_id, traits::ItemObligation(def_id)), + self.param_env, + bounds, + ) + .enumerate() + { + // This makes the error point at the bound, but we want to point at the argument + if let Some(span) = spans.get(i) { + obligation.cause.make_mut().code = traits::BindingObligation(def_id, *span); + } + self.register_predicate(obligation); + } + } + + fn check_rustc_args_require_const(&self, def_id: DefId, hir_id: hir::HirId, span: Span) { + // We're only interested in functions tagged with + // #[rustc_args_required_const], so ignore anything that's not. + if !self.tcx.has_attr(def_id, sym::rustc_args_required_const) { + return; + } + + // If our calling expression is indeed the function itself, we're good! + // If not, generate an error that this can only be called directly. + if let Node::Expr(expr) = self.tcx.hir().get(self.tcx.hir().get_parent_node(hir_id)) { + if let ExprKind::Call(ref callee, ..) = expr.kind { + if callee.hir_id == hir_id { + return; + } + } + } + + self.tcx.sess.span_err( + span, + "this function can only be invoked directly, not through a function pointer", + ); + } + + /// Resolves `typ` by a single level if `typ` is a type variable. + /// If no resolution is possible, then an error is reported. + /// Numeric inference variables may be left unresolved. + pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> { + let ty = self.resolve_vars_with_obligations(ty); + if !ty.is_ty_var() { + ty + } else { + if !self.is_tainted_by_errors() { + self.need_type_info_err((**self).body_id, sp, ty, E0282) + .note("type must be known at this point") + .emit(); + } + let err = self.tcx.ty_error(); + self.demand_suptype(sp, err, ty); + err + } + } + + pub(super) fn with_breakable_ctxt R, R>( + &self, + id: hir::HirId, + ctxt: BreakableCtxt<'tcx>, + f: F, + ) -> (BreakableCtxt<'tcx>, R) { + let index; + { + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + index = enclosing_breakables.stack.len(); + enclosing_breakables.by_id.insert(id, index); + enclosing_breakables.stack.push(ctxt); + } + let result = f(); + let ctxt = { + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + debug_assert!(enclosing_breakables.stack.len() == index + 1); + enclosing_breakables.by_id.remove(&id).expect("missing breakable context"); + enclosing_breakables.stack.pop().expect("missing breakable context") + }; + (ctxt, result) + } + + /// Instantiate a QueryResponse in a probe context, without a + /// good ObligationCause. + pub(super) fn probe_instantiate_query_response( + &self, + span: Span, + original_values: &OriginalQueryValues<'tcx>, + query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, + ) -> InferResult<'tcx, Ty<'tcx>> { + self.instantiate_query_response_and_region_obligations( + &traits::ObligationCause::misc(span, self.body_id), + self.param_env, + original_values, + query_result, + ) + } + + /// Returns `true` if an expression is contained inside the LHS of an assignment expression. + pub(super) fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool { + let mut contained_in_place = false; + + while let hir::Node::Expr(parent_expr) = + self.tcx.hir().get(self.tcx.hir().get_parent_node(expr_id)) + { + match &parent_expr.kind { + hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => { + if lhs.hir_id == expr_id { + contained_in_place = true; + break; + } + } + _ => (), + } + expr_id = parent_expr.hir_id; + } + + contained_in_place + } +} +impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> { + type Target = Inherited<'a, 'tcx>; + fn deref(&self) -> &Self::Target { + &self.inh + } +} + +impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn item_def_id(&self) -> Option { + None + } + + fn default_constness_for_trait_bounds(&self) -> hir::Constness { + // FIXME: refactor this into a method + let node = self.tcx.hir().get(self.body_id); + if let Some(fn_like) = FnLikeNode::from_node(node) { + fn_like.constness() + } else { + hir::Constness::NotConst + } + } + + fn get_type_parameter_bounds(&self, _: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> { + let tcx = self.tcx; + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); + let item_id = tcx.hir().ty_param_owner(hir_id); + let item_def_id = tcx.hir().local_def_id(item_id); + let generics = tcx.generics_of(item_def_id); + let index = generics.param_def_id_to_index[&def_id]; + ty::GenericPredicates { + parent: None, + predicates: tcx.arena.alloc_from_iter( + self.param_env.caller_bounds().iter().filter_map(|predicate| { + match predicate.skip_binders() { + ty::PredicateAtom::Trait(data, _) if data.self_ty().is_param(index) => { + // HACK(eddyb) should get the original `Span`. + let span = tcx.def_span(def_id); + Some((predicate, span)) + } + _ => None, + } + }), + ), + } + } + + fn re_infer(&self, def: Option<&ty::GenericParamDef>, span: Span) -> Option> { + let v = match def { + Some(def) => infer::EarlyBoundRegion(span, def.name), + None => infer::MiscVariable(span), + }; + Some(self.next_region_var(v)) + } + + fn allow_ty_infer(&self) -> bool { + true + } + + fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> { + if let Some(param) = param { + if let GenericArgKind::Type(ty) = self.var_for_def(span, param).unpack() { + return ty; + } + unreachable!() + } else { + self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::TypeInference, + span, + }) + } + } + + fn ct_infer( + &self, + ty: Ty<'tcx>, + param: Option<&ty::GenericParamDef>, + span: Span, + ) -> &'tcx Const<'tcx> { + if let Some(param) = param { + if let GenericArgKind::Const(ct) = self.var_for_def(span, param).unpack() { + return ct; + } + unreachable!() + } else { + self.next_const_var( + ty, + ConstVariableOrigin { kind: ConstVariableOriginKind::ConstInference, span }, + ) + } + } + + fn projected_ty_from_poly_trait_ref( + &self, + span: Span, + item_def_id: DefId, + item_segment: &hir::PathSegment<'_>, + poly_trait_ref: ty::PolyTraitRef<'tcx>, + ) -> Ty<'tcx> { + let (trait_ref, _) = self.replace_bound_vars_with_fresh_vars( + span, + infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id), + &poly_trait_ref, + ); + + let item_substs = >::create_substs_for_associated_item( + self, + self.tcx, + span, + item_def_id, + item_segment, + trait_ref.substs, + ); + + self.tcx().mk_projection(item_def_id, item_substs) + } + + fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx> { + if ty.has_escaping_bound_vars() { + ty // FIXME: normalization and escaping regions + } else { + self.normalize_associated_types_in(span, &ty) + } + } + + fn set_tainted_by_errors(&self) { + self.infcx.set_tainted_by_errors() + } + + fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, _span: Span) { + self.write_ty(hir_id, ty) + } +} diff --git a/compiler/rustc_typeck/src/check/mod.rs b/compiler/rustc_typeck/src/check/mod.rs index 2b8940f1813..5ef718c98ee 100644 --- a/compiler/rustc_typeck/src/check/mod.rs +++ b/compiler/rustc_typeck/src/check/mod.rs @@ -72,6 +72,7 @@ mod compare_method; pub mod demand; pub mod dropck; mod expr; +mod fn_ctxt; mod gather_locals; mod generator_interior; pub mod intrinsic; @@ -85,71 +86,49 @@ mod util; mod wfcheck; pub mod writeback; -use crate::astconv::{ - AstConv, ExplicitLateBound, GenericArgCountMismatch, GenericArgCountResult, PathSeg, -}; +pub use fn_ctxt::FnCtxt; + +use crate::astconv::AstConv; use crate::check::gather_locals::GatherLocalsVisitor; use crate::check::util::MaybeInProgressTables; -use rustc_ast as ast; -use rustc_ast::util::parser::ExprPrecedence; use rustc_attr as attr; -use rustc_data_structures::captures::Captures; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; -use rustc_errors::ErrorReported; -use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder, DiagnosticId}; +use rustc_errors::{pluralize, struct_span_err, Applicability}; use rustc_hir as hir; -use rustc_hir::def::{CtorOf, DefKind, Res}; +use rustc_hir::def::Res; use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId, LOCAL_CRATE}; use rustc_hir::intravisit::Visitor; use rustc_hir::lang_items::LangItem; -use rustc_hir::{ExprKind, GenericArg, HirIdMap, ItemKind, Node, QPath}; +use rustc_hir::{HirIdMap, ItemKind, Node}; use rustc_index::bit_set::BitSet; use rustc_index::vec::Idx; use rustc_infer::infer; -use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse}; -use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282; use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; -use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind}; -use rustc_infer::infer::{InferCtxt, InferOk, InferResult, RegionVariableOrigin, TyCtxtInferExt}; -use rustc_middle::hir::map::blocks::FnLikeNode; -use rustc_middle::ty::adjustment::{ - Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, -}; +use rustc_infer::infer::{InferCtxt, InferOk, RegionVariableOrigin, TyCtxtInferExt}; use rustc_middle::ty::fold::{TypeFoldable, TypeFolder}; use rustc_middle::ty::query::Providers; -use rustc_middle::ty::subst::{self, InternalSubsts, Subst, SubstsRef}; -use rustc_middle::ty::subst::{GenericArgKind, UserSelfTy, UserSubsts}; +use rustc_middle::ty::subst::GenericArgKind; +use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef}; use rustc_middle::ty::util::{Discr, IntTypeExt, Representability}; use rustc_middle::ty::WithConstness; -use rustc_middle::ty::{self, AdtKind, CanonicalUserType, Const, DefIdTree, GenericParamDefKind}; -use rustc_middle::ty::{RegionKind, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, UserType}; +use rustc_middle::ty::{self, RegionKind, ToPredicate, Ty, TyCtxt, UserType}; use rustc_session::config::{self, EntryFnType}; -use rustc_session::lint; use rustc_session::parse::feature_err; use rustc_session::Session; -use rustc_span::hygiene::DesugaringKind; -use rustc_span::source_map::{original_sp, DUMMY_SP}; +use rustc_span::source_map::DUMMY_SP; use rustc_span::symbol::{kw, sym, Ident}; use rustc_span::{self, BytePos, MultiSpan, Span}; use rustc_target::abi::VariantIdx; use rustc_target::spec::abi::Abi; use rustc_trait_selection::infer::InferCtxtExt as _; -use rustc_trait_selection::opaque_types::{InferCtxtExt as _, OpaqueTypeDecl}; +use rustc_trait_selection::opaque_types::OpaqueTypeDecl; use rustc_trait_selection::traits::error_reporting::recursive_type_with_infinite_size_error; use rustc_trait_selection::traits::error_reporting::suggestions::ReturnsVisitor; -use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _; -use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; -use rustc_trait_selection::traits::{ - self, ObligationCause, ObligationCauseCode, TraitEngine, TraitEngineExt, -}; +use rustc_trait_selection::traits::{self, ObligationCauseCode, TraitEngine, TraitEngineExt}; -use std::cell::{Cell, RefCell}; +use std::cell::RefCell; use std::cmp; -use std::collections::hash_map::Entry; -use std::iter; -use std::mem::replace; use std::ops::{self, Deref}; -use std::slice; use crate::require_c_abi_if_c_variadic; use crate::util::common::indenter; @@ -157,9 +136,7 @@ use crate::util::common::indenter; use self::callee::DeferredCallResolution; use self::coercion::{CoerceMany, DynamicCoerceMany}; use self::compare_method::{compare_const_impl, compare_impl_method, compare_ty_impl}; -use self::method::{MethodCallee, SelfSource}; pub use self::Expectation::*; -use self::TupleArgumentsFlag::*; #[macro_export] macro_rules! type_error_struct { @@ -513,100 +490,6 @@ impl<'tcx> EnclosingBreakables<'tcx> { } } -pub struct FnCtxt<'a, 'tcx> { - body_id: hir::HirId, - - /// The parameter environment used for proving trait obligations - /// in this function. This can change when we descend into - /// closures (as they bring new things into scope), hence it is - /// not part of `Inherited` (as of the time of this writing, - /// closures do not yet change the environment, but they will - /// eventually). - param_env: ty::ParamEnv<'tcx>, - - /// Number of errors that had been reported when we started - /// checking this function. On exit, if we find that *more* errors - /// have been reported, we will skip regionck and other work that - /// expects the types within the function to be consistent. - // FIXME(matthewjasper) This should not exist, and it's not correct - // if type checking is run in parallel. - err_count_on_creation: usize, - - /// If `Some`, this stores coercion information for returned - /// expressions. If `None`, this is in a context where return is - /// inappropriate, such as a const expression. - /// - /// This is a `RefCell`, which means that we - /// can track all the return expressions and then use them to - /// compute a useful coercion from the set, similar to a match - /// expression or other branching context. You can use methods - /// like `expected_ty` to access the declared return type (if - /// any). - ret_coercion: Option>>, - - ret_coercion_impl_trait: Option>, - - ret_type_span: Option, - - /// Used exclusively to reduce cost of advanced evaluation used for - /// more helpful diagnostics. - in_tail_expr: bool, - - /// First span of a return site that we find. Used in error messages. - ret_coercion_span: RefCell>, - - resume_yield_tys: Option<(Ty<'tcx>, Ty<'tcx>)>, - - ps: RefCell, - - /// Whether the last checked node generates a divergence (e.g., - /// `return` will set this to `Always`). In general, when entering - /// an expression or other node in the tree, the initial value - /// indicates whether prior parts of the containing expression may - /// have diverged. It is then typically set to `Maybe` (and the - /// old value remembered) for processing the subparts of the - /// current expression. As each subpart is processed, they may set - /// the flag to `Always`, etc. Finally, at the end, we take the - /// result and "union" it with the original value, so that when we - /// return the flag indicates if any subpart of the parent - /// expression (up to and including this part) has diverged. So, - /// if you read it after evaluating a subexpression `X`, the value - /// you get indicates whether any subexpression that was - /// evaluating up to and including `X` diverged. - /// - /// We currently use this flag only for diagnostic purposes: - /// - /// - To warn about unreachable code: if, after processing a - /// sub-expression but before we have applied the effects of the - /// current node, we see that the flag is set to `Always`, we - /// can issue a warning. This corresponds to something like - /// `foo(return)`; we warn on the `foo()` expression. (We then - /// update the flag to `WarnedAlways` to suppress duplicate - /// reports.) Similarly, if we traverse to a fresh statement (or - /// tail expression) from a `Always` setting, we will issue a - /// warning. This corresponds to something like `{return; - /// foo();}` or `{return; 22}`, where we would warn on the - /// `foo()` or `22`. - /// - /// An expression represents dead code if, after checking it, - /// the diverges flag is set to something other than `Maybe`. - diverges: Cell, - - /// Whether any child nodes have any type errors. - has_errors: Cell, - - enclosing_breakables: RefCell>, - - inh: &'a Inherited<'a, 'tcx>, -} - -impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> { - type Target = Inherited<'a, 'tcx>; - fn deref(&self) -> &Self::Target { - &self.inh - } -} - /// Helper type of a temporary returned by `Inherited::build(...)`. /// Necessary because we can't write the following bound: /// `F: for<'b, 'tcx> where 'tcx FnOnce(Inherited<'b, 'tcx>)`. @@ -2760,136 +2643,6 @@ fn report_unexpected_variant_res(tcx: TyCtxt<'_>, res: Res, span: Span) { .emit(); } -impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> { - fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { - self.tcx - } - - fn item_def_id(&self) -> Option { - None - } - - fn default_constness_for_trait_bounds(&self) -> hir::Constness { - // FIXME: refactor this into a method - let node = self.tcx.hir().get(self.body_id); - if let Some(fn_like) = FnLikeNode::from_node(node) { - fn_like.constness() - } else { - hir::Constness::NotConst - } - } - - fn get_type_parameter_bounds(&self, _: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> { - let tcx = self.tcx; - let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); - let item_id = tcx.hir().ty_param_owner(hir_id); - let item_def_id = tcx.hir().local_def_id(item_id); - let generics = tcx.generics_of(item_def_id); - let index = generics.param_def_id_to_index[&def_id]; - ty::GenericPredicates { - parent: None, - predicates: tcx.arena.alloc_from_iter( - self.param_env.caller_bounds().iter().filter_map(|predicate| { - match predicate.skip_binders() { - ty::PredicateAtom::Trait(data, _) if data.self_ty().is_param(index) => { - // HACK(eddyb) should get the original `Span`. - let span = tcx.def_span(def_id); - Some((predicate, span)) - } - _ => None, - } - }), - ), - } - } - - fn re_infer(&self, def: Option<&ty::GenericParamDef>, span: Span) -> Option> { - let v = match def { - Some(def) => infer::EarlyBoundRegion(span, def.name), - None => infer::MiscVariable(span), - }; - Some(self.next_region_var(v)) - } - - fn allow_ty_infer(&self) -> bool { - true - } - - fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> { - if let Some(param) = param { - if let GenericArgKind::Type(ty) = self.var_for_def(span, param).unpack() { - return ty; - } - unreachable!() - } else { - self.next_ty_var(TypeVariableOrigin { - kind: TypeVariableOriginKind::TypeInference, - span, - }) - } - } - - fn ct_infer( - &self, - ty: Ty<'tcx>, - param: Option<&ty::GenericParamDef>, - span: Span, - ) -> &'tcx Const<'tcx> { - if let Some(param) = param { - if let GenericArgKind::Const(ct) = self.var_for_def(span, param).unpack() { - return ct; - } - unreachable!() - } else { - self.next_const_var( - ty, - ConstVariableOrigin { kind: ConstVariableOriginKind::ConstInference, span }, - ) - } - } - - fn projected_ty_from_poly_trait_ref( - &self, - span: Span, - item_def_id: DefId, - item_segment: &hir::PathSegment<'_>, - poly_trait_ref: ty::PolyTraitRef<'tcx>, - ) -> Ty<'tcx> { - let (trait_ref, _) = self.replace_bound_vars_with_fresh_vars( - span, - infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id), - &poly_trait_ref, - ); - - let item_substs = >::create_substs_for_associated_item( - self, - self.tcx, - span, - item_def_id, - item_segment, - trait_ref.substs, - ); - - self.tcx().mk_projection(item_def_id, item_substs) - } - - fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx> { - if ty.has_escaping_bound_vars() { - ty // FIXME: normalization and escaping regions - } else { - self.normalize_associated_types_in(span, &ty) - } - } - - fn set_tainted_by_errors(&self) { - self.infcx.set_tainted_by_errors() - } - - fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, _span: Span) { - self.write_ty(hir_id, ty) - } -} - /// Controls whether the arguments are tupled. This is used for the call /// operator. /// @@ -2922,2911 +2675,6 @@ enum FallbackMode { All, } -impl<'a, 'tcx> FnCtxt<'a, 'tcx> { - pub fn new( - inh: &'a Inherited<'a, 'tcx>, - param_env: ty::ParamEnv<'tcx>, - body_id: hir::HirId, - ) -> FnCtxt<'a, 'tcx> { - FnCtxt { - body_id, - param_env, - err_count_on_creation: inh.tcx.sess.err_count(), - ret_coercion: None, - ret_coercion_impl_trait: None, - ret_type_span: None, - in_tail_expr: false, - ret_coercion_span: RefCell::new(None), - resume_yield_tys: None, - ps: RefCell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)), - diverges: Cell::new(Diverges::Maybe), - has_errors: Cell::new(false), - enclosing_breakables: RefCell::new(EnclosingBreakables { - stack: Vec::new(), - by_id: Default::default(), - }), - inh, - } - } - - pub fn sess(&self) -> &Session { - &self.tcx.sess - } - - pub fn errors_reported_since_creation(&self) -> bool { - self.tcx.sess.err_count() > self.err_count_on_creation - } - - /// Produces warning on the given node, if the current point in the - /// function is unreachable, and there hasn't been another warning. - fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) { - // FIXME: Combine these two 'if' expressions into one once - // let chains are implemented - if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() { - // If span arose from a desugaring of `if` or `while`, then it is the condition itself, - // which diverges, that we are about to lint on. This gives suboptimal diagnostics. - // Instead, stop here so that the `if`- or `while`-expression's block is linted instead. - if !span.is_desugaring(DesugaringKind::CondTemporary) - && !span.is_desugaring(DesugaringKind::Async) - && !orig_span.is_desugaring(DesugaringKind::Await) - { - self.diverges.set(Diverges::WarnedAlways); - - debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind); - - self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, |lint| { - let msg = format!("unreachable {}", kind); - lint.build(&msg) - .span_label(span, &msg) - .span_label( - orig_span, - custom_note - .unwrap_or("any code following this expression is unreachable"), - ) - .emit(); - }) - } - } - } - - pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> { - ObligationCause::new(span, self.body_id, code) - } - - pub fn misc(&self, span: Span) -> ObligationCause<'tcx> { - self.cause(span, ObligationCauseCode::MiscObligation) - } - - /// Resolves type and const variables in `ty` if possible. Unlike the infcx - /// version (resolve_vars_if_possible), this version will - /// also select obligations if it seems useful, in an effort - /// to get more type information. - fn resolve_vars_with_obligations(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> { - debug!("resolve_vars_with_obligations(ty={:?})", ty); - - // No Infer()? Nothing needs doing. - if !ty.has_infer_types_or_consts() { - debug!("resolve_vars_with_obligations: ty={:?}", ty); - return ty; - } - - // If `ty` is a type variable, see whether we already know what it is. - ty = self.resolve_vars_if_possible(&ty); - if !ty.has_infer_types_or_consts() { - debug!("resolve_vars_with_obligations: ty={:?}", ty); - return ty; - } - - // If not, try resolving pending obligations as much as - // possible. This can help substantially when there are - // indirect dependencies that don't seem worth tracking - // precisely. - self.select_obligations_where_possible(false, |_| {}); - ty = self.resolve_vars_if_possible(&ty); - - debug!("resolve_vars_with_obligations: ty={:?}", ty); - ty - } - - fn record_deferred_call_resolution( - &self, - closure_def_id: DefId, - r: DeferredCallResolution<'tcx>, - ) { - let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); - deferred_call_resolutions.entry(closure_def_id).or_default().push(r); - } - - fn remove_deferred_call_resolutions( - &self, - closure_def_id: DefId, - ) -> Vec> { - let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); - deferred_call_resolutions.remove(&closure_def_id).unwrap_or(vec![]) - } - - pub fn tag(&self) -> String { - format!("{:p}", self) - } - - pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> { - self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| { - span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid)) - }) - } - - #[inline] - pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) { - debug!( - "write_ty({:?}, {:?}) in fcx {}", - id, - self.resolve_vars_if_possible(&ty), - self.tag() - ); - self.typeck_results.borrow_mut().node_types_mut().insert(id, ty); - - if ty.references_error() { - self.has_errors.set(true); - self.set_tainted_by_errors(); - } - } - - pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) { - self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index); - } - - fn write_resolution(&self, hir_id: hir::HirId, r: Result<(DefKind, DefId), ErrorReported>) { - self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r); - } - - pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) { - debug!("write_method_call(hir_id={:?}, method={:?})", hir_id, method); - self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id))); - self.write_substs(hir_id, method.substs); - - // When the method is confirmed, the `method.substs` includes - // parameters from not just the method, but also the impl of - // the method -- in particular, the `Self` type will be fully - // resolved. However, those are not something that the "user - // specified" -- i.e., those types come from the inferred type - // of the receiver, not something the user wrote. So when we - // create the user-substs, we want to replace those earlier - // types with just the types that the user actually wrote -- - // that is, those that appear on the *method itself*. - // - // As an example, if the user wrote something like - // `foo.bar::(...)` -- the `Self` type here will be the - // type of `foo` (possibly adjusted), but we don't want to - // include that. We want just the `[_, u32]` part. - if !method.substs.is_noop() { - let method_generics = self.tcx.generics_of(method.def_id); - if !method_generics.params.is_empty() { - let user_type_annotation = self.infcx.probe(|_| { - let user_substs = UserSubsts { - substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| { - let i = param.index as usize; - if i < method_generics.parent_count { - self.infcx.var_for_def(DUMMY_SP, param) - } else { - method.substs[i] - } - }), - user_self_ty: None, // not relevant here - }; - - self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf( - method.def_id, - user_substs, - )) - }); - - debug!("write_method_call: user_type_annotation={:?}", user_type_annotation); - self.write_user_type_annotation(hir_id, user_type_annotation); - } - } - } - - pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) { - if !substs.is_noop() { - debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag()); - - self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs); - } - } - - /// Given the substs that we just converted from the HIR, try to - /// canonicalize them and store them as user-given substitutions - /// (i.e., substitutions that must be respected by the NLL check). - /// - /// This should be invoked **before any unifications have - /// occurred**, so that annotations like `Vec<_>` are preserved - /// properly. - pub fn write_user_type_annotation_from_substs( - &self, - hir_id: hir::HirId, - def_id: DefId, - substs: SubstsRef<'tcx>, - user_self_ty: Option>, - ) { - debug!( - "write_user_type_annotation_from_substs: hir_id={:?} def_id={:?} substs={:?} \ - user_self_ty={:?} in fcx {}", - hir_id, - def_id, - substs, - user_self_ty, - self.tag(), - ); - - if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) { - let canonicalized = self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf( - def_id, - UserSubsts { substs, user_self_ty }, - )); - debug!("write_user_type_annotation_from_substs: canonicalized={:?}", canonicalized); - self.write_user_type_annotation(hir_id, canonicalized); - } - } - - pub fn write_user_type_annotation( - &self, - hir_id: hir::HirId, - canonical_user_type_annotation: CanonicalUserType<'tcx>, - ) { - debug!( - "write_user_type_annotation: hir_id={:?} canonical_user_type_annotation={:?} tag={}", - hir_id, - canonical_user_type_annotation, - self.tag(), - ); - - if !canonical_user_type_annotation.is_identity() { - self.typeck_results - .borrow_mut() - .user_provided_types_mut() - .insert(hir_id, canonical_user_type_annotation); - } else { - debug!("write_user_type_annotation: skipping identity substs"); - } - } - - pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec>) { - debug!("apply_adjustments(expr={:?}, adj={:?})", expr, adj); - - if adj.is_empty() { - return; - } - - let autoborrow_mut = adj.iter().any(|adj| { - matches!(adj, &Adjustment { - kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })), - .. - }) - }); - - match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) { - Entry::Vacant(entry) => { - entry.insert(adj); - } - Entry::Occupied(mut entry) => { - debug!(" - composing on top of {:?}", entry.get()); - match (&entry.get()[..], &adj[..]) { - // Applying any adjustment on top of a NeverToAny - // is a valid NeverToAny adjustment, because it can't - // be reached. - (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return, - (&[ - Adjustment { kind: Adjust::Deref(_), .. }, - Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. }, - ], &[ - Adjustment { kind: Adjust::Deref(_), .. }, - .. // Any following adjustments are allowed. - ]) => { - // A reborrow has no effect before a dereference. - } - // FIXME: currently we never try to compose autoderefs - // and ReifyFnPointer/UnsafeFnPointer, but we could. - _ => - bug!("while adjusting {:?}, can't compose {:?} and {:?}", - expr, entry.get(), adj) - }; - *entry.get_mut() = adj; - } - } - - // If there is an mutable auto-borrow, it is equivalent to `&mut `. - // In this case implicit use of `Deref` and `Index` within `` should - // instead be `DerefMut` and `IndexMut`, so fix those up. - if autoborrow_mut { - self.convert_place_derefs_to_mutable(expr); - } - } - - /// Basically whenever we are converting from a type scheme into - /// the fn body space, we always want to normalize associated - /// types as well. This function combines the two. - fn instantiate_type_scheme(&self, span: Span, substs: SubstsRef<'tcx>, value: &T) -> T - where - T: TypeFoldable<'tcx>, - { - let value = value.subst(self.tcx, substs); - let result = self.normalize_associated_types_in(span, &value); - debug!("instantiate_type_scheme(value={:?}, substs={:?}) = {:?}", value, substs, result); - result - } - - /// As `instantiate_type_scheme`, but for the bounds found in a - /// generic type scheme. - fn instantiate_bounds( - &self, - span: Span, - def_id: DefId, - substs: SubstsRef<'tcx>, - ) -> (ty::InstantiatedPredicates<'tcx>, Vec) { - let bounds = self.tcx.predicates_of(def_id); - let spans: Vec = bounds.predicates.iter().map(|(_, span)| *span).collect(); - let result = bounds.instantiate(self.tcx, substs); - let result = self.normalize_associated_types_in(span, &result); - debug!( - "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}", - bounds, substs, result, spans, - ); - (result, spans) - } - - /// Replaces the opaque types from the given value with type variables, - /// and records the `OpaqueTypeMap` for later use during writeback. See - /// `InferCtxt::instantiate_opaque_types` for more details. - fn instantiate_opaque_types_from_value>( - &self, - parent_id: hir::HirId, - value: &T, - value_span: Span, - ) -> T { - let parent_def_id = self.tcx.hir().local_def_id(parent_id); - debug!( - "instantiate_opaque_types_from_value(parent_def_id={:?}, value={:?})", - parent_def_id, value - ); - - let (value, opaque_type_map) = - self.register_infer_ok_obligations(self.instantiate_opaque_types( - parent_def_id, - self.body_id, - self.param_env, - value, - value_span, - )); - - let mut opaque_types = self.opaque_types.borrow_mut(); - let mut opaque_types_vars = self.opaque_types_vars.borrow_mut(); - for (ty, decl) in opaque_type_map { - let _ = opaque_types.insert(ty, decl); - let _ = opaque_types_vars.insert(decl.concrete_ty, decl.opaque_type); - } - - value - } - - fn normalize_associated_types_in(&self, span: Span, value: &T) -> T - where - T: TypeFoldable<'tcx>, - { - self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value) - } - - fn normalize_associated_types_in_as_infer_ok( - &self, - span: Span, - value: &T, - ) -> InferOk<'tcx, T> - where - T: TypeFoldable<'tcx>, - { - self.inh.partially_normalize_associated_types_in(span, self.body_id, self.param_env, value) - } - - pub fn require_type_meets( - &self, - ty: Ty<'tcx>, - span: Span, - code: traits::ObligationCauseCode<'tcx>, - def_id: DefId, - ) { - self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code)); - } - - pub fn require_type_is_sized( - &self, - ty: Ty<'tcx>, - span: Span, - code: traits::ObligationCauseCode<'tcx>, - ) { - if !ty.references_error() { - let lang_item = self.tcx.require_lang_item(LangItem::Sized, None); - self.require_type_meets(ty, span, code, lang_item); - } - } - - pub fn require_type_is_sized_deferred( - &self, - ty: Ty<'tcx>, - span: Span, - code: traits::ObligationCauseCode<'tcx>, - ) { - if !ty.references_error() { - self.deferred_sized_obligations.borrow_mut().push((ty, span, code)); - } - } - - pub fn register_bound( - &self, - ty: Ty<'tcx>, - def_id: DefId, - cause: traits::ObligationCause<'tcx>, - ) { - if !ty.references_error() { - self.fulfillment_cx.borrow_mut().register_bound( - self, - self.param_env, - ty, - def_id, - cause, - ); - } - } - - pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> { - let t = AstConv::ast_ty_to_ty(self, ast_t); - self.register_wf_obligation(t.into(), ast_t.span, traits::MiscObligation); - t - } - - pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> { - let ty = self.to_ty(ast_ty); - debug!("to_ty_saving_user_provided_ty: ty={:?}", ty); - - if Self::can_contain_user_lifetime_bounds(ty) { - let c_ty = self.infcx.canonicalize_response(&UserType::Ty(ty)); - debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty); - self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty); - } - - ty - } - - pub fn to_const(&self, ast_c: &hir::AnonConst) -> &'tcx ty::Const<'tcx> { - let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id); - let c = ty::Const::from_anon_const(self.tcx, const_def_id); - self.register_wf_obligation( - c.into(), - self.tcx.hir().span(ast_c.hir_id), - ObligationCauseCode::MiscObligation, - ); - c - } - - pub fn const_arg_to_const( - &self, - ast_c: &hir::AnonConst, - param_def_id: DefId, - ) -> &'tcx ty::Const<'tcx> { - let const_def = ty::WithOptConstParam { - did: self.tcx.hir().local_def_id(ast_c.hir_id), - const_param_did: Some(param_def_id), - }; - let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def); - self.register_wf_obligation( - c.into(), - self.tcx.hir().span(ast_c.hir_id), - ObligationCauseCode::MiscObligation, - ); - c - } - - // If the type given by the user has free regions, save it for later, since - // NLL would like to enforce those. Also pass in types that involve - // projections, since those can resolve to `'static` bounds (modulo #54940, - // which hopefully will be fixed by the time you see this comment, dear - // reader, although I have my doubts). Also pass in types with inference - // types, because they may be repeated. Other sorts of things are already - // sufficiently enforced with erased regions. =) - fn can_contain_user_lifetime_bounds(t: T) -> bool - where - T: TypeFoldable<'tcx>, - { - t.has_free_regions() || t.has_projections() || t.has_infer_types() - } - - pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> { - match self.typeck_results.borrow().node_types().get(id) { - Some(&t) => t, - None if self.is_tainted_by_errors() => self.tcx.ty_error(), - None => { - bug!( - "no type for node {}: {} in fcx {}", - id, - self.tcx.hir().node_to_string(id), - self.tag() - ); - } - } - } - - /// Registers an obligation for checking later, during regionck, that `arg` is well-formed. - pub fn register_wf_obligation( - &self, - arg: subst::GenericArg<'tcx>, - span: Span, - code: traits::ObligationCauseCode<'tcx>, - ) { - // WF obligations never themselves fail, so no real need to give a detailed cause: - let cause = traits::ObligationCause::new(span, self.body_id, code); - self.register_predicate(traits::Obligation::new( - cause, - self.param_env, - ty::PredicateAtom::WellFormed(arg).to_predicate(self.tcx), - )); - } - - /// Registers obligations that all `substs` are well-formed. - pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) { - for arg in substs.iter().filter(|arg| { - matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..)) - }) { - self.register_wf_obligation(arg, expr.span, traits::MiscObligation); - } - } - - /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each - /// type/region parameter was instantiated (`substs`), creates and registers suitable - /// trait/region obligations. - /// - /// For example, if there is a function: - /// - /// ``` - /// fn foo<'a,T:'a>(...) - /// ``` - /// - /// and a reference: - /// - /// ``` - /// let f = foo; - /// ``` - /// - /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a` - /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally. - pub fn add_obligations_for_parameters( - &self, - cause: traits::ObligationCause<'tcx>, - predicates: ty::InstantiatedPredicates<'tcx>, - ) { - assert!(!predicates.has_escaping_bound_vars()); - - debug!("add_obligations_for_parameters(predicates={:?})", predicates); - - for obligation in traits::predicates_for_generics(cause, self.param_env, predicates) { - self.register_predicate(obligation); - } - } - - // FIXME(arielb1): use this instead of field.ty everywhere - // Only for fields! Returns for methods> - // Indifferent to privacy flags - pub fn field_ty( - &self, - span: Span, - field: &'tcx ty::FieldDef, - substs: SubstsRef<'tcx>, - ) -> Ty<'tcx> { - self.normalize_associated_types_in(span, &field.ty(self.tcx, substs)) - } - - fn check_casts(&self) { - let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut(); - for cast in deferred_cast_checks.drain(..) { - cast.check(self); - } - } - - fn resolve_generator_interiors(&self, def_id: DefId) { - let mut generators = self.deferred_generator_interiors.borrow_mut(); - for (body_id, interior, kind) in generators.drain(..) { - self.select_obligations_where_possible(false, |_| {}); - generator_interior::resolve_interior(self, def_id, body_id, interior, kind); - } - } - - // Tries to apply a fallback to `ty` if it is an unsolved variable. - // - // - Unconstrained ints are replaced with `i32`. - // - // - Unconstrained floats are replaced with with `f64`. - // - // - Non-numerics get replaced with `!` when `#![feature(never_type_fallback)]` - // is enabled. Otherwise, they are replaced with `()`. - // - // Fallback becomes very dubious if we have encountered type-checking errors. - // In that case, fallback to Error. - // The return value indicates whether fallback has occurred. - fn fallback_if_possible(&self, ty: Ty<'tcx>, mode: FallbackMode) -> bool { - use rustc_middle::ty::error::UnconstrainedNumeric::Neither; - use rustc_middle::ty::error::UnconstrainedNumeric::{UnconstrainedFloat, UnconstrainedInt}; - - assert!(ty.is_ty_infer()); - let fallback = match self.type_is_unconstrained_numeric(ty) { - _ if self.is_tainted_by_errors() => self.tcx().ty_error(), - UnconstrainedInt => self.tcx.types.i32, - UnconstrainedFloat => self.tcx.types.f64, - Neither if self.type_var_diverges(ty) => self.tcx.mk_diverging_default(), - Neither => { - // This type variable was created from the instantiation of an opaque - // type. The fact that we're attempting to perform fallback for it - // means that the function neither constrained it to a concrete - // type, nor to the opaque type itself. - // - // For example, in this code: - // - //``` - // type MyType = impl Copy; - // fn defining_use() -> MyType { true } - // fn other_use() -> MyType { defining_use() } - // ``` - // - // `defining_use` will constrain the instantiated inference - // variable to `bool`, while `other_use` will constrain - // the instantiated inference variable to `MyType`. - // - // When we process opaque types during writeback, we - // will handle cases like `other_use`, and not count - // them as defining usages - // - // However, we also need to handle cases like this: - // - // ```rust - // pub type Foo = impl Copy; - // fn produce() -> Option { - // None - // } - // ``` - // - // In the above snippet, the inference variable created by - // instantiating `Option` will be completely unconstrained. - // We treat this as a non-defining use by making the inference - // variable fall back to the opaque type itself. - if let FallbackMode::All = mode { - if let Some(opaque_ty) = self.opaque_types_vars.borrow().get(ty) { - debug!( - "fallback_if_possible: falling back opaque type var {:?} to {:?}", - ty, opaque_ty - ); - *opaque_ty - } else { - return false; - } - } else { - return false; - } - } - }; - debug!("fallback_if_possible: defaulting `{:?}` to `{:?}`", ty, fallback); - self.demand_eqtype(rustc_span::DUMMY_SP, ty, fallback); - true - } - - fn select_all_obligations_or_error(&self) { - debug!("select_all_obligations_or_error"); - if let Err(errors) = self.fulfillment_cx.borrow_mut().select_all_or_error(&self) { - self.report_fulfillment_errors(&errors, self.inh.body_id, false); - } - } - - /// Select as many obligations as we can at present. - fn select_obligations_where_possible( - &self, - fallback_has_occurred: bool, - mutate_fullfillment_errors: impl Fn(&mut Vec>), - ) { - let result = self.fulfillment_cx.borrow_mut().select_where_possible(self); - if let Err(mut errors) = result { - mutate_fullfillment_errors(&mut errors); - self.report_fulfillment_errors(&errors, self.inh.body_id, fallback_has_occurred); - } - } - - /// For the overloaded place expressions (`*x`, `x[3]`), the trait - /// returns a type of `&T`, but the actual type we assign to the - /// *expression* is `T`. So this function just peels off the return - /// type by one layer to yield `T`. - fn make_overloaded_place_return_type( - &self, - method: MethodCallee<'tcx>, - ) -> ty::TypeAndMut<'tcx> { - // extract method return type, which will be &T; - let ret_ty = method.sig.output(); - - // method returns &T, but the type as visible to user is T, so deref - ret_ty.builtin_deref(true).unwrap() - } - - fn check_method_argument_types( - &self, - sp: Span, - expr: &'tcx hir::Expr<'tcx>, - method: Result, ()>, - args_no_rcvr: &'tcx [hir::Expr<'tcx>], - tuple_arguments: TupleArgumentsFlag, - expected: Expectation<'tcx>, - ) -> Ty<'tcx> { - let has_error = match method { - Ok(method) => method.substs.references_error() || method.sig.references_error(), - Err(_) => true, - }; - if has_error { - let err_inputs = self.err_args(args_no_rcvr.len()); - - let err_inputs = match tuple_arguments { - DontTupleArguments => err_inputs, - TupleArguments => vec![self.tcx.intern_tup(&err_inputs[..])], - }; - - self.check_argument_types( - sp, - expr, - &err_inputs[..], - &[], - args_no_rcvr, - false, - tuple_arguments, - None, - ); - return self.tcx.ty_error(); - } - - let method = method.unwrap(); - // HACK(eddyb) ignore self in the definition (see above). - let expected_arg_tys = self.expected_inputs_for_expected_output( - sp, - expected, - method.sig.output(), - &method.sig.inputs()[1..], - ); - self.check_argument_types( - sp, - expr, - &method.sig.inputs()[1..], - &expected_arg_tys[..], - args_no_rcvr, - method.sig.c_variadic, - tuple_arguments, - self.tcx.hir().span_if_local(method.def_id), - ); - method.sig.output() - } - - fn self_type_matches_expected_vid( - &self, - trait_ref: ty::PolyTraitRef<'tcx>, - expected_vid: ty::TyVid, - ) -> bool { - let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty()); - debug!( - "self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?}, expected_vid={:?})", - trait_ref, self_ty, expected_vid - ); - match *self_ty.kind() { - ty::Infer(ty::TyVar(found_vid)) => { - // FIXME: consider using `sub_root_var` here so we - // can see through subtyping. - let found_vid = self.root_var(found_vid); - debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid); - expected_vid == found_vid - } - _ => false, - } - } - - fn obligations_for_self_ty<'b>( - &'b self, - self_ty: ty::TyVid, - ) -> impl Iterator, traits::PredicateObligation<'tcx>)> - + Captures<'tcx> - + 'b { - // FIXME: consider using `sub_root_var` here so we - // can see through subtyping. - let ty_var_root = self.root_var(self_ty); - debug!( - "obligations_for_self_ty: self_ty={:?} ty_var_root={:?} pending_obligations={:?}", - self_ty, - ty_var_root, - self.fulfillment_cx.borrow().pending_obligations() - ); - - self.fulfillment_cx - .borrow() - .pending_obligations() - .into_iter() - .filter_map(move |obligation| { - match obligation.predicate.skip_binders() { - ty::PredicateAtom::Projection(data) => { - Some((ty::Binder::bind(data).to_poly_trait_ref(self.tcx), obligation)) - } - ty::PredicateAtom::Trait(data, _) => { - Some((ty::Binder::bind(data).to_poly_trait_ref(), obligation)) - } - ty::PredicateAtom::Subtype(..) => None, - ty::PredicateAtom::RegionOutlives(..) => None, - ty::PredicateAtom::TypeOutlives(..) => None, - ty::PredicateAtom::WellFormed(..) => None, - ty::PredicateAtom::ObjectSafe(..) => None, - ty::PredicateAtom::ConstEvaluatable(..) => None, - ty::PredicateAtom::ConstEquate(..) => None, - // N.B., this predicate is created by breaking down a - // `ClosureType: FnFoo()` predicate, where - // `ClosureType` represents some `Closure`. It can't - // possibly be referring to the current closure, - // because we haven't produced the `Closure` for - // this closure yet; this is exactly why the other - // code is looking for a self type of a unresolved - // inference variable. - ty::PredicateAtom::ClosureKind(..) => None, - ty::PredicateAtom::TypeWellFormedFromEnv(..) => None, - } - }) - .filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root)) - } - - fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool { - self.obligations_for_self_ty(self_ty) - .any(|(tr, _)| Some(tr.def_id()) == self.tcx.lang_items().sized_trait()) - } - - /// Generic function that factors out common logic from function calls, - /// method calls and overloaded operators. - fn check_argument_types( - &self, - sp: Span, - expr: &'tcx hir::Expr<'tcx>, - fn_inputs: &[Ty<'tcx>], - expected_arg_tys: &[Ty<'tcx>], - args: &'tcx [hir::Expr<'tcx>], - c_variadic: bool, - tuple_arguments: TupleArgumentsFlag, - def_span: Option, - ) { - let tcx = self.tcx; - // Grab the argument types, supplying fresh type variables - // if the wrong number of arguments were supplied - let supplied_arg_count = if tuple_arguments == DontTupleArguments { args.len() } else { 1 }; - - // All the input types from the fn signature must outlive the call - // so as to validate implied bounds. - for (&fn_input_ty, arg_expr) in fn_inputs.iter().zip(args.iter()) { - self.register_wf_obligation(fn_input_ty.into(), arg_expr.span, traits::MiscObligation); - } - - let expected_arg_count = fn_inputs.len(); - - let param_count_error = |expected_count: usize, - arg_count: usize, - error_code: &str, - c_variadic: bool, - sugg_unit: bool| { - let (span, start_span, args) = match &expr.kind { - hir::ExprKind::Call(hir::Expr { span, .. }, args) => (*span, *span, &args[..]), - hir::ExprKind::MethodCall(path_segment, span, args, _) => ( - *span, - // `sp` doesn't point at the whole `foo.bar()`, only at `bar`. - path_segment - .args - .and_then(|args| args.args.iter().last()) - // Account for `foo.bar::()`. - .map(|arg| { - // Skip the closing `>`. - tcx.sess - .source_map() - .next_point(tcx.sess.source_map().next_point(arg.span())) - }) - .unwrap_or(*span), - &args[1..], // Skip the receiver. - ), - k => span_bug!(sp, "checking argument types on a non-call: `{:?}`", k), - }; - let arg_spans = if args.is_empty() { - // foo() - // ^^^-- supplied 0 arguments - // | - // expected 2 arguments - vec![tcx.sess.source_map().next_point(start_span).with_hi(sp.hi())] - } else { - // foo(1, 2, 3) - // ^^^ - - - supplied 3 arguments - // | - // expected 2 arguments - args.iter().map(|arg| arg.span).collect::>() - }; - - let mut err = tcx.sess.struct_span_err_with_code( - span, - &format!( - "this function takes {}{} but {} {} supplied", - if c_variadic { "at least " } else { "" }, - potentially_plural_count(expected_count, "argument"), - potentially_plural_count(arg_count, "argument"), - if arg_count == 1 { "was" } else { "were" } - ), - DiagnosticId::Error(error_code.to_owned()), - ); - let label = format!("supplied {}", potentially_plural_count(arg_count, "argument")); - for (i, span) in arg_spans.into_iter().enumerate() { - err.span_label( - span, - if arg_count == 0 || i + 1 == arg_count { &label } else { "" }, - ); - } - - if let Some(def_s) = def_span.map(|sp| tcx.sess.source_map().guess_head_span(sp)) { - err.span_label(def_s, "defined here"); - } - if sugg_unit { - let sugg_span = tcx.sess.source_map().end_point(expr.span); - // remove closing `)` from the span - let sugg_span = sugg_span.shrink_to_lo(); - err.span_suggestion( - sugg_span, - "expected the unit value `()`; create it with empty parentheses", - String::from("()"), - Applicability::MachineApplicable, - ); - } else { - err.span_label( - span, - format!( - "expected {}{}", - if c_variadic { "at least " } else { "" }, - potentially_plural_count(expected_count, "argument") - ), - ); - } - err.emit(); - }; - - let mut expected_arg_tys = expected_arg_tys.to_vec(); - - let formal_tys = if tuple_arguments == TupleArguments { - let tuple_type = self.structurally_resolved_type(sp, fn_inputs[0]); - match tuple_type.kind() { - ty::Tuple(arg_types) if arg_types.len() != args.len() => { - param_count_error(arg_types.len(), args.len(), "E0057", false, false); - expected_arg_tys = vec![]; - self.err_args(args.len()) - } - ty::Tuple(arg_types) => { - expected_arg_tys = match expected_arg_tys.get(0) { - Some(&ty) => match ty.kind() { - ty::Tuple(ref tys) => tys.iter().map(|k| k.expect_ty()).collect(), - _ => vec![], - }, - None => vec![], - }; - arg_types.iter().map(|k| k.expect_ty()).collect() - } - _ => { - struct_span_err!( - tcx.sess, - sp, - E0059, - "cannot use call notation; the first type parameter \ - for the function trait is neither a tuple nor unit" - ) - .emit(); - expected_arg_tys = vec![]; - self.err_args(args.len()) - } - } - } else if expected_arg_count == supplied_arg_count { - fn_inputs.to_vec() - } else if c_variadic { - if supplied_arg_count >= expected_arg_count { - fn_inputs.to_vec() - } else { - param_count_error(expected_arg_count, supplied_arg_count, "E0060", true, false); - expected_arg_tys = vec![]; - self.err_args(supplied_arg_count) - } - } else { - // is the missing argument of type `()`? - let sugg_unit = if expected_arg_tys.len() == 1 && supplied_arg_count == 0 { - self.resolve_vars_if_possible(&expected_arg_tys[0]).is_unit() - } else if fn_inputs.len() == 1 && supplied_arg_count == 0 { - self.resolve_vars_if_possible(&fn_inputs[0]).is_unit() - } else { - false - }; - param_count_error(expected_arg_count, supplied_arg_count, "E0061", false, sugg_unit); - - expected_arg_tys = vec![]; - self.err_args(supplied_arg_count) - }; - - debug!( - "check_argument_types: formal_tys={:?}", - formal_tys.iter().map(|t| self.ty_to_string(*t)).collect::>() - ); - - // If there is no expectation, expect formal_tys. - let expected_arg_tys = - if !expected_arg_tys.is_empty() { expected_arg_tys } else { formal_tys.clone() }; - - let mut final_arg_types: Vec<(usize, Ty<'_>, Ty<'_>)> = vec![]; - - // Check the arguments. - // We do this in a pretty awful way: first we type-check any arguments - // that are not closures, then we type-check the closures. This is so - // that we have more information about the types of arguments when we - // type-check the functions. This isn't really the right way to do this. - for &check_closures in &[false, true] { - debug!("check_closures={}", check_closures); - - // More awful hacks: before we check argument types, try to do - // an "opportunistic" trait resolution of any trait bounds on - // the call. This helps coercions. - if check_closures { - self.select_obligations_where_possible(false, |errors| { - self.point_at_type_arg_instead_of_call_if_possible(errors, expr); - self.point_at_arg_instead_of_call_if_possible( - errors, - &final_arg_types[..], - sp, - &args, - ); - }) - } - - // For C-variadic functions, we don't have a declared type for all of - // the arguments hence we only do our usual type checking with - // the arguments who's types we do know. - let t = if c_variadic { - expected_arg_count - } else if tuple_arguments == TupleArguments { - args.len() - } else { - supplied_arg_count - }; - for (i, arg) in args.iter().take(t).enumerate() { - // Warn only for the first loop (the "no closures" one). - // Closure arguments themselves can't be diverging, but - // a previous argument can, e.g., `foo(panic!(), || {})`. - if !check_closures { - self.warn_if_unreachable(arg.hir_id, arg.span, "expression"); - } - - let is_closure = match arg.kind { - ExprKind::Closure(..) => true, - _ => false, - }; - - if is_closure != check_closures { - continue; - } - - debug!("checking the argument"); - let formal_ty = formal_tys[i]; - - // The special-cased logic below has three functions: - // 1. Provide as good of an expected type as possible. - let expected = Expectation::rvalue_hint(self, expected_arg_tys[i]); - - let checked_ty = self.check_expr_with_expectation(&arg, expected); - - // 2. Coerce to the most detailed type that could be coerced - // to, which is `expected_ty` if `rvalue_hint` returns an - // `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise. - let coerce_ty = expected.only_has_type(self).unwrap_or(formal_ty); - // We're processing function arguments so we definitely want to use - // two-phase borrows. - self.demand_coerce(&arg, checked_ty, coerce_ty, None, AllowTwoPhase::Yes); - final_arg_types.push((i, checked_ty, coerce_ty)); - - // 3. Relate the expected type and the formal one, - // if the expected type was used for the coercion. - self.demand_suptype(arg.span, formal_ty, coerce_ty); - } - } - - // We also need to make sure we at least write the ty of the other - // arguments which we skipped above. - if c_variadic { - fn variadic_error<'tcx>(s: &Session, span: Span, t: Ty<'tcx>, cast_ty: &str) { - use crate::structured_errors::{StructuredDiagnostic, VariadicError}; - VariadicError::new(s, span, t, cast_ty).diagnostic().emit(); - } - - for arg in args.iter().skip(expected_arg_count) { - let arg_ty = self.check_expr(&arg); - - // There are a few types which get autopromoted when passed via varargs - // in C but we just error out instead and require explicit casts. - let arg_ty = self.structurally_resolved_type(arg.span, arg_ty); - match arg_ty.kind() { - ty::Float(ast::FloatTy::F32) => { - variadic_error(tcx.sess, arg.span, arg_ty, "c_double"); - } - ty::Int(ast::IntTy::I8 | ast::IntTy::I16) | ty::Bool => { - variadic_error(tcx.sess, arg.span, arg_ty, "c_int"); - } - ty::Uint(ast::UintTy::U8 | ast::UintTy::U16) => { - variadic_error(tcx.sess, arg.span, arg_ty, "c_uint"); - } - ty::FnDef(..) => { - let ptr_ty = self.tcx.mk_fn_ptr(arg_ty.fn_sig(self.tcx)); - let ptr_ty = self.resolve_vars_if_possible(&ptr_ty); - variadic_error(tcx.sess, arg.span, arg_ty, &ptr_ty.to_string()); - } - _ => {} - } - } - } - } - - fn err_args(&self, len: usize) -> Vec> { - vec![self.tcx.ty_error(); len] - } - - /// Given a vec of evaluated `FulfillmentError`s and an `fn` call argument expressions, we walk - /// the checked and coerced types for each argument to see if any of the `FulfillmentError`s - /// reference a type argument. The reason to walk also the checked type is that the coerced type - /// can be not easily comparable with predicate type (because of coercion). If the types match - /// for either checked or coerced type, and there's only *one* argument that does, we point at - /// the corresponding argument's expression span instead of the `fn` call path span. - fn point_at_arg_instead_of_call_if_possible( - &self, - errors: &mut Vec>, - final_arg_types: &[(usize, Ty<'tcx>, Ty<'tcx>)], - call_sp: Span, - args: &'tcx [hir::Expr<'tcx>], - ) { - // We *do not* do this for desugared call spans to keep good diagnostics when involving - // the `?` operator. - if call_sp.desugaring_kind().is_some() { - return; - } - - for error in errors { - // Only if the cause is somewhere inside the expression we want try to point at arg. - // Otherwise, it means that the cause is somewhere else and we should not change - // anything because we can break the correct span. - if !call_sp.contains(error.obligation.cause.span) { - continue; - } - - if let ty::PredicateAtom::Trait(predicate, _) = - error.obligation.predicate.skip_binders() - { - // Collect the argument position for all arguments that could have caused this - // `FulfillmentError`. - let mut referenced_in = final_arg_types - .iter() - .map(|&(i, checked_ty, _)| (i, checked_ty)) - .chain(final_arg_types.iter().map(|&(i, _, coerced_ty)| (i, coerced_ty))) - .flat_map(|(i, ty)| { - let ty = self.resolve_vars_if_possible(&ty); - // We walk the argument type because the argument's type could have - // been `Option`, but the `FulfillmentError` references `T`. - if ty.walk().any(|arg| arg == predicate.self_ty().into()) { - Some(i) - } else { - None - } - }) - .collect::>(); - - // Both checked and coerced types could have matched, thus we need to remove - // duplicates. - - // We sort primitive type usize here and can use unstable sort - referenced_in.sort_unstable(); - referenced_in.dedup(); - - if let (Some(ref_in), None) = (referenced_in.pop(), referenced_in.pop()) { - // We make sure that only *one* argument matches the obligation failure - // and we assign the obligation's span to its expression's. - error.obligation.cause.make_mut().span = args[ref_in].span; - error.points_at_arg_span = true; - } - } - } - } - - /// Given a vec of evaluated `FulfillmentError`s and an `fn` call expression, we walk the - /// `PathSegment`s and resolve their type parameters to see if any of the `FulfillmentError`s - /// were caused by them. If they were, we point at the corresponding type argument's span - /// instead of the `fn` call path span. - fn point_at_type_arg_instead_of_call_if_possible( - &self, - errors: &mut Vec>, - call_expr: &'tcx hir::Expr<'tcx>, - ) { - if let hir::ExprKind::Call(path, _) = &call_expr.kind { - if let hir::ExprKind::Path(qpath) = &path.kind { - if let hir::QPath::Resolved(_, path) = &qpath { - for error in errors { - if let ty::PredicateAtom::Trait(predicate, _) = - error.obligation.predicate.skip_binders() - { - // If any of the type arguments in this path segment caused the - // `FullfillmentError`, point at its span (#61860). - for arg in path - .segments - .iter() - .filter_map(|seg| seg.args.as_ref()) - .flat_map(|a| a.args.iter()) - { - if let hir::GenericArg::Type(hir_ty) = &arg { - if let hir::TyKind::Path(hir::QPath::TypeRelative(..)) = - &hir_ty.kind - { - // Avoid ICE with associated types. As this is best - // effort only, it's ok to ignore the case. It - // would trigger in `is_send::();` - // from `typeck-default-trait-impl-assoc-type.rs`. - } else { - let ty = AstConv::ast_ty_to_ty(self, hir_ty); - let ty = self.resolve_vars_if_possible(&ty); - if ty == predicate.self_ty() { - error.obligation.cause.make_mut().span = hir_ty.span; - } - } - } - } - } - } - } - } - } - } - - // AST fragment checking - fn check_lit(&self, lit: &hir::Lit, expected: Expectation<'tcx>) -> Ty<'tcx> { - let tcx = self.tcx; - - match lit.node { - ast::LitKind::Str(..) => tcx.mk_static_str(), - ast::LitKind::ByteStr(ref v) => { - tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.u8, v.len() as u64)) - } - ast::LitKind::Byte(_) => tcx.types.u8, - ast::LitKind::Char(_) => tcx.types.char, - ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(t), - ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(t), - ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => { - let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() { - ty::Int(_) | ty::Uint(_) => Some(ty), - ty::Char => Some(tcx.types.u8), - ty::RawPtr(..) => Some(tcx.types.usize), - ty::FnDef(..) | ty::FnPtr(_) => Some(tcx.types.usize), - _ => None, - }); - opt_ty.unwrap_or_else(|| self.next_int_var()) - } - ast::LitKind::Float(_, ast::LitFloatType::Suffixed(t)) => tcx.mk_mach_float(t), - ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) => { - let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() { - ty::Float(_) => Some(ty), - _ => None, - }); - opt_ty.unwrap_or_else(|| self.next_float_var()) - } - ast::LitKind::Bool(_) => tcx.types.bool, - ast::LitKind::Err(_) => tcx.ty_error(), - } - } - - /// Unifies the output type with the expected type early, for more coercions - /// and forward type information on the input expressions. - fn expected_inputs_for_expected_output( - &self, - call_span: Span, - expected_ret: Expectation<'tcx>, - formal_ret: Ty<'tcx>, - formal_args: &[Ty<'tcx>], - ) -> Vec> { - let formal_ret = self.resolve_vars_with_obligations(formal_ret); - let ret_ty = match expected_ret.only_has_type(self) { - Some(ret) => ret, - None => return Vec::new(), - }; - let expect_args = self - .fudge_inference_if_ok(|| { - // Attempt to apply a subtyping relationship between the formal - // return type (likely containing type variables if the function - // is polymorphic) and the expected return type. - // No argument expectations are produced if unification fails. - let origin = self.misc(call_span); - let ures = self.at(&origin, self.param_env).sup(ret_ty, &formal_ret); - - // FIXME(#27336) can't use ? here, Try::from_error doesn't default - // to identity so the resulting type is not constrained. - match ures { - Ok(ok) => { - // Process any obligations locally as much as - // we can. We don't care if some things turn - // out unconstrained or ambiguous, as we're - // just trying to get hints here. - self.save_and_restore_in_snapshot_flag(|_| { - let mut fulfill = TraitEngine::new(self.tcx); - for obligation in ok.obligations { - fulfill.register_predicate_obligation(self, obligation); - } - fulfill.select_where_possible(self) - }) - .map_err(|_| ())?; - } - Err(_) => return Err(()), - } - - // Record all the argument types, with the substitutions - // produced from the above subtyping unification. - Ok(formal_args.iter().map(|ty| self.resolve_vars_if_possible(ty)).collect()) - }) - .unwrap_or_default(); - debug!( - "expected_inputs_for_expected_output(formal={:?} -> {:?}, expected={:?} -> {:?})", - formal_args, formal_ret, expect_args, expected_ret - ); - expect_args - } - - pub fn check_struct_path( - &self, - qpath: &QPath<'_>, - hir_id: hir::HirId, - ) -> Option<(&'tcx ty::VariantDef, Ty<'tcx>)> { - let path_span = qpath.qself_span(); - let (def, ty) = self.finish_resolving_struct_path(qpath, path_span, hir_id); - let variant = match def { - Res::Err => { - self.set_tainted_by_errors(); - return None; - } - Res::Def(DefKind::Variant, _) => match ty.kind() { - ty::Adt(adt, substs) => Some((adt.variant_of_res(def), adt.did, substs)), - _ => bug!("unexpected type: {:?}", ty), - }, - Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _) - | Res::SelfTy(..) => match ty.kind() { - ty::Adt(adt, substs) if !adt.is_enum() => { - Some((adt.non_enum_variant(), adt.did, substs)) - } - _ => None, - }, - _ => bug!("unexpected definition: {:?}", def), - }; - - if let Some((variant, did, substs)) = variant { - debug!("check_struct_path: did={:?} substs={:?}", did, substs); - self.write_user_type_annotation_from_substs(hir_id, did, substs, None); - - // Check bounds on type arguments used in the path. - let (bounds, _) = self.instantiate_bounds(path_span, did, substs); - let cause = - traits::ObligationCause::new(path_span, self.body_id, traits::ItemObligation(did)); - self.add_obligations_for_parameters(cause, bounds); - - Some((variant, ty)) - } else { - struct_span_err!( - self.tcx.sess, - path_span, - E0071, - "expected struct, variant or union type, found {}", - ty.sort_string(self.tcx) - ) - .span_label(path_span, "not a struct") - .emit(); - None - } - } - - // Finish resolving a path in a struct expression or pattern `S::A { .. }` if necessary. - // The newly resolved definition is written into `type_dependent_defs`. - fn finish_resolving_struct_path( - &self, - qpath: &QPath<'_>, - path_span: Span, - hir_id: hir::HirId, - ) -> (Res, Ty<'tcx>) { - match *qpath { - QPath::Resolved(ref maybe_qself, ref path) => { - let self_ty = maybe_qself.as_ref().map(|qself| self.to_ty(qself)); - let ty = AstConv::res_to_ty(self, self_ty, path, true); - (path.res, ty) - } - QPath::TypeRelative(ref qself, ref segment) => { - let ty = self.to_ty(qself); - - let res = if let hir::TyKind::Path(QPath::Resolved(_, ref path)) = qself.kind { - path.res - } else { - Res::Err - }; - let result = - AstConv::associated_path_to_ty(self, hir_id, path_span, ty, res, segment, true); - let ty = result.map(|(ty, _, _)| ty).unwrap_or_else(|_| self.tcx().ty_error()); - let result = result.map(|(_, kind, def_id)| (kind, def_id)); - - // Write back the new resolution. - self.write_resolution(hir_id, result); - - (result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), ty) - } - QPath::LangItem(lang_item, span) => { - self.resolve_lang_item_path(lang_item, span, hir_id) - } - } - } - - fn resolve_lang_item_path( - &self, - lang_item: hir::LangItem, - span: Span, - hir_id: hir::HirId, - ) -> (Res, Ty<'tcx>) { - let def_id = self.tcx.require_lang_item(lang_item, Some(span)); - let def_kind = self.tcx.def_kind(def_id); - - let item_ty = if let DefKind::Variant = def_kind { - self.tcx.type_of(self.tcx.parent(def_id).expect("variant w/out parent")) - } else { - self.tcx.type_of(def_id) - }; - let substs = self.infcx.fresh_substs_for_item(span, def_id); - let ty = item_ty.subst(self.tcx, substs); - - self.write_resolution(hir_id, Ok((def_kind, def_id))); - self.add_required_obligations(span, def_id, &substs); - (Res::Def(def_kind, def_id), ty) - } - - /// Resolves an associated value path into a base type and associated constant, or method - /// resolution. The newly resolved definition is written into `type_dependent_defs`. - pub fn resolve_ty_and_res_ufcs<'b>( - &self, - qpath: &'b QPath<'b>, - hir_id: hir::HirId, - span: Span, - ) -> (Res, Option>, &'b [hir::PathSegment<'b>]) { - debug!("resolve_ty_and_res_ufcs: qpath={:?} hir_id={:?} span={:?}", qpath, hir_id, span); - let (ty, qself, item_segment) = match *qpath { - QPath::Resolved(ref opt_qself, ref path) => { - return ( - path.res, - opt_qself.as_ref().map(|qself| self.to_ty(qself)), - &path.segments[..], - ); - } - QPath::TypeRelative(ref qself, ref segment) => (self.to_ty(qself), qself, segment), - QPath::LangItem(..) => bug!("`resolve_ty_and_res_ufcs` called on `LangItem`"), - }; - if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id) - { - // Return directly on cache hit. This is useful to avoid doubly reporting - // errors with default match binding modes. See #44614. - let def = - cached_result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err); - return (def, Some(ty), slice::from_ref(&**item_segment)); - } - let item_name = item_segment.ident; - let result = self.resolve_ufcs(span, item_name, ty, hir_id).or_else(|error| { - let result = match error { - method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)), - _ => Err(ErrorReported), - }; - if item_name.name != kw::Invalid { - if let Some(mut e) = self.report_method_error( - span, - ty, - item_name, - SelfSource::QPath(qself), - error, - None, - ) { - e.emit(); - } - } - result - }); - - // Write back the new resolution. - self.write_resolution(hir_id, result); - ( - result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), - Some(ty), - slice::from_ref(&**item_segment), - ) - } - - pub fn check_decl_initializer( - &self, - local: &'tcx hir::Local<'tcx>, - init: &'tcx hir::Expr<'tcx>, - ) -> Ty<'tcx> { - // FIXME(tschottdorf): `contains_explicit_ref_binding()` must be removed - // for #42640 (default match binding modes). - // - // See #44848. - let ref_bindings = local.pat.contains_explicit_ref_binding(); - - let local_ty = self.local_ty(init.span, local.hir_id).revealed_ty; - if let Some(m) = ref_bindings { - // Somewhat subtle: if we have a `ref` binding in the pattern, - // we want to avoid introducing coercions for the RHS. This is - // both because it helps preserve sanity and, in the case of - // ref mut, for soundness (issue #23116). In particular, in - // the latter case, we need to be clear that the type of the - // referent for the reference that results is *equal to* the - // type of the place it is referencing, and not some - // supertype thereof. - let init_ty = self.check_expr_with_needs(init, Needs::maybe_mut_place(m)); - self.demand_eqtype(init.span, local_ty, init_ty); - init_ty - } else { - self.check_expr_coercable_to_type(init, local_ty, None) - } - } - - /// Type check a `let` statement. - pub fn check_decl_local(&self, local: &'tcx hir::Local<'tcx>) { - // Determine and write the type which we'll check the pattern against. - let ty = self.local_ty(local.span, local.hir_id).decl_ty; - self.write_ty(local.hir_id, ty); - - // Type check the initializer. - if let Some(ref init) = local.init { - let init_ty = self.check_decl_initializer(local, &init); - self.overwrite_local_ty_if_err(local, ty, init_ty); - } - - // Does the expected pattern type originate from an expression and what is the span? - let (origin_expr, ty_span) = match (local.ty, local.init) { - (Some(ty), _) => (false, Some(ty.span)), // Bias towards the explicit user type. - (_, Some(init)) => (true, Some(init.span)), // No explicit type; so use the scrutinee. - _ => (false, None), // We have `let $pat;`, so the expected type is unconstrained. - }; - - // Type check the pattern. Override if necessary to avoid knock-on errors. - self.check_pat_top(&local.pat, ty, ty_span, origin_expr); - let pat_ty = self.node_ty(local.pat.hir_id); - self.overwrite_local_ty_if_err(local, ty, pat_ty); - } - - fn overwrite_local_ty_if_err( - &self, - local: &'tcx hir::Local<'tcx>, - decl_ty: Ty<'tcx>, - ty: Ty<'tcx>, - ) { - if ty.references_error() { - // Override the types everywhere with `err()` to avoid knock on errors. - self.write_ty(local.hir_id, ty); - self.write_ty(local.pat.hir_id, ty); - let local_ty = LocalTy { decl_ty, revealed_ty: ty }; - self.locals.borrow_mut().insert(local.hir_id, local_ty); - self.locals.borrow_mut().insert(local.pat.hir_id, local_ty); - } - } - - fn suggest_semicolon_at_end(&self, span: Span, err: &mut DiagnosticBuilder<'_>) { - err.span_suggestion_short( - span.shrink_to_hi(), - "consider using a semicolon here", - ";".to_string(), - Applicability::MachineApplicable, - ); - } - - pub fn check_stmt(&self, stmt: &'tcx hir::Stmt<'tcx>) { - // Don't do all the complex logic below for `DeclItem`. - match stmt.kind { - hir::StmtKind::Item(..) => return, - hir::StmtKind::Local(..) | hir::StmtKind::Expr(..) | hir::StmtKind::Semi(..) => {} - } - - self.warn_if_unreachable(stmt.hir_id, stmt.span, "statement"); - - // Hide the outer diverging and `has_errors` flags. - let old_diverges = self.diverges.replace(Diverges::Maybe); - let old_has_errors = self.has_errors.replace(false); - - match stmt.kind { - hir::StmtKind::Local(ref l) => { - self.check_decl_local(&l); - } - // Ignore for now. - hir::StmtKind::Item(_) => {} - hir::StmtKind::Expr(ref expr) => { - // Check with expected type of `()`. - self.check_expr_has_type_or_error(&expr, self.tcx.mk_unit(), |err| { - self.suggest_semicolon_at_end(expr.span, err); - }); - } - hir::StmtKind::Semi(ref expr) => { - self.check_expr(&expr); - } - } - - // Combine the diverging and `has_error` flags. - self.diverges.set(self.diverges.get() | old_diverges); - self.has_errors.set(self.has_errors.get() | old_has_errors); - } - - pub fn check_block_no_value(&self, blk: &'tcx hir::Block<'tcx>) { - let unit = self.tcx.mk_unit(); - let ty = self.check_block_with_expected(blk, ExpectHasType(unit)); - - // if the block produces a `!` value, that can always be - // (effectively) coerced to unit. - if !ty.is_never() { - self.demand_suptype(blk.span, unit, ty); - } - } - - /// If `expr` is a `match` expression that has only one non-`!` arm, use that arm's tail - /// expression's `Span`, otherwise return `expr.span`. This is done to give better errors - /// when given code like the following: - /// ```text - /// if false { return 0i32; } else { 1u32 } - /// // ^^^^ point at this instead of the whole `if` expression - /// ``` - fn get_expr_coercion_span(&self, expr: &hir::Expr<'_>) -> rustc_span::Span { - if let hir::ExprKind::Match(_, arms, _) = &expr.kind { - let arm_spans: Vec = arms - .iter() - .filter_map(|arm| { - self.in_progress_typeck_results - .and_then(|typeck_results| { - typeck_results.borrow().node_type_opt(arm.body.hir_id) - }) - .and_then(|arm_ty| { - if arm_ty.is_never() { - None - } else { - Some(match &arm.body.kind { - // Point at the tail expression when possible. - hir::ExprKind::Block(block, _) => { - block.expr.as_ref().map(|e| e.span).unwrap_or(block.span) - } - _ => arm.body.span, - }) - } - }) - }) - .collect(); - if arm_spans.len() == 1 { - return arm_spans[0]; - } - } - expr.span - } - - fn check_block_with_expected( - &self, - blk: &'tcx hir::Block<'tcx>, - expected: Expectation<'tcx>, - ) -> Ty<'tcx> { - let prev = { - let mut fcx_ps = self.ps.borrow_mut(); - let unsafety_state = fcx_ps.recurse(blk); - replace(&mut *fcx_ps, unsafety_state) - }; - - // In some cases, blocks have just one exit, but other blocks - // can be targeted by multiple breaks. This can happen both - // with labeled blocks as well as when we desugar - // a `try { ... }` expression. - // - // Example 1: - // - // 'a: { if true { break 'a Err(()); } Ok(()) } - // - // Here we would wind up with two coercions, one from - // `Err(())` and the other from the tail expression - // `Ok(())`. If the tail expression is omitted, that's a - // "forced unit" -- unless the block diverges, in which - // case we can ignore the tail expression (e.g., `'a: { - // break 'a 22; }` would not force the type of the block - // to be `()`). - let tail_expr = blk.expr.as_ref(); - let coerce_to_ty = expected.coercion_target_type(self, blk.span); - let coerce = if blk.targeted_by_break { - CoerceMany::new(coerce_to_ty) - } else { - let tail_expr: &[&hir::Expr<'_>] = match tail_expr { - Some(e) => slice::from_ref(e), - None => &[], - }; - CoerceMany::with_coercion_sites(coerce_to_ty, tail_expr) - }; - - let prev_diverges = self.diverges.get(); - let ctxt = BreakableCtxt { coerce: Some(coerce), may_break: false }; - - let (ctxt, ()) = self.with_breakable_ctxt(blk.hir_id, ctxt, || { - for s in blk.stmts { - self.check_stmt(s); - } - - // check the tail expression **without** holding the - // `enclosing_breakables` lock below. - let tail_expr_ty = tail_expr.map(|t| self.check_expr_with_expectation(t, expected)); - - let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); - let ctxt = enclosing_breakables.find_breakable(blk.hir_id); - let coerce = ctxt.coerce.as_mut().unwrap(); - if let Some(tail_expr_ty) = tail_expr_ty { - let tail_expr = tail_expr.unwrap(); - let span = self.get_expr_coercion_span(tail_expr); - let cause = self.cause(span, ObligationCauseCode::BlockTailExpression(blk.hir_id)); - coerce.coerce(self, &cause, tail_expr, tail_expr_ty); - } else { - // Subtle: if there is no explicit tail expression, - // that is typically equivalent to a tail expression - // of `()` -- except if the block diverges. In that - // case, there is no value supplied from the tail - // expression (assuming there are no other breaks, - // this implies that the type of the block will be - // `!`). - // - // #41425 -- label the implicit `()` as being the - // "found type" here, rather than the "expected type". - if !self.diverges.get().is_always() { - // #50009 -- Do not point at the entire fn block span, point at the return type - // span, as it is the cause of the requirement, and - // `consider_hint_about_removing_semicolon` will point at the last expression - // if it were a relevant part of the error. This improves usability in editors - // that highlight errors inline. - let mut sp = blk.span; - let mut fn_span = None; - if let Some((decl, ident)) = self.get_parent_fn_decl(blk.hir_id) { - let ret_sp = decl.output.span(); - if let Some(block_sp) = self.parent_item_span(blk.hir_id) { - // HACK: on some cases (`ui/liveness/liveness-issue-2163.rs`) the - // output would otherwise be incorrect and even misleading. Make sure - // the span we're aiming at correspond to a `fn` body. - if block_sp == blk.span { - sp = ret_sp; - fn_span = Some(ident.span); - } - } - } - coerce.coerce_forced_unit( - self, - &self.misc(sp), - &mut |err| { - if let Some(expected_ty) = expected.only_has_type(self) { - self.consider_hint_about_removing_semicolon(blk, expected_ty, err); - } - if let Some(fn_span) = fn_span { - err.span_label( - fn_span, - "implicitly returns `()` as its body has no tail or `return` \ - expression", - ); - } - }, - false, - ); - } - } - }); - - if ctxt.may_break { - // If we can break from the block, then the block's exit is always reachable - // (... as long as the entry is reachable) - regardless of the tail of the block. - self.diverges.set(prev_diverges); - } - - let mut ty = ctxt.coerce.unwrap().complete(self); - - if self.has_errors.get() || ty.references_error() { - ty = self.tcx.ty_error() - } - - self.write_ty(blk.hir_id, ty); - - *self.ps.borrow_mut() = prev; - ty - } - - fn parent_item_span(&self, id: hir::HirId) -> Option { - let node = self.tcx.hir().get(self.tcx.hir().get_parent_item(id)); - match node { - Node::Item(&hir::Item { kind: hir::ItemKind::Fn(_, _, body_id), .. }) - | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(_, body_id), .. }) => { - let body = self.tcx.hir().body(body_id); - if let ExprKind::Block(block, _) = &body.value.kind { - return Some(block.span); - } - } - _ => {} - } - None - } - - /// Given a function block's `HirId`, returns its `FnDecl` if it exists, or `None` otherwise. - fn get_parent_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident)> { - let parent = self.tcx.hir().get(self.tcx.hir().get_parent_item(blk_id)); - self.get_node_fn_decl(parent).map(|(fn_decl, ident, _)| (fn_decl, ident)) - } - - /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise. - fn get_node_fn_decl(&self, node: Node<'tcx>) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> { - match node { - Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => { - // This is less than ideal, it will not suggest a return type span on any - // method called `main`, regardless of whether it is actually the entry point, - // but it will still present it as the reason for the expected type. - Some((&sig.decl, ident, ident.name != sym::main)) - } - Node::TraitItem(&hir::TraitItem { - ident, - kind: hir::TraitItemKind::Fn(ref sig, ..), - .. - }) => Some((&sig.decl, ident, true)), - Node::ImplItem(&hir::ImplItem { - ident, - kind: hir::ImplItemKind::Fn(ref sig, ..), - .. - }) => Some((&sig.decl, ident, false)), - _ => None, - } - } - - /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a - /// suggestion can be made, `None` otherwise. - pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> { - // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or - // `while` before reaching it, as block tail returns are not available in them. - self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| { - let parent = self.tcx.hir().get(blk_id); - self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main)) - }) - } - - /// On implicit return expressions with mismatched types, provides the following suggestions: - /// - /// - Points out the method's return type as the reason for the expected type. - /// - Possible missing semicolon. - /// - Possible missing return type if the return type is the default, and not `fn main()`. - pub fn suggest_mismatched_types_on_tail( - &self, - err: &mut DiagnosticBuilder<'_>, - expr: &'tcx hir::Expr<'tcx>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - cause_span: Span, - blk_id: hir::HirId, - ) -> bool { - let expr = expr.peel_drop_temps(); - self.suggest_missing_semicolon(err, expr, expected, cause_span); - let mut pointing_at_return_type = false; - if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) { - pointing_at_return_type = - self.suggest_missing_return_type(err, &fn_decl, expected, found, can_suggest); - } - pointing_at_return_type - } - - /// When encountering an fn-like ctor that needs to unify with a value, check whether calling - /// the ctor would successfully solve the type mismatch and if so, suggest it: - /// ``` - /// fn foo(x: usize) -> usize { x } - /// let x: usize = foo; // suggest calling the `foo` function: `foo(42)` - /// ``` - fn suggest_fn_call( - &self, - err: &mut DiagnosticBuilder<'_>, - expr: &hir::Expr<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - ) -> bool { - let hir = self.tcx.hir(); - let (def_id, sig) = match *found.kind() { - ty::FnDef(def_id, _) => (def_id, found.fn_sig(self.tcx)), - ty::Closure(def_id, substs) => (def_id, substs.as_closure().sig()), - _ => return false, - }; - - let sig = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, &sig).0; - let sig = self.normalize_associated_types_in(expr.span, &sig); - if self.can_coerce(sig.output(), expected) { - let (mut sugg_call, applicability) = if sig.inputs().is_empty() { - (String::new(), Applicability::MachineApplicable) - } else { - ("...".to_string(), Applicability::HasPlaceholders) - }; - let mut msg = "call this function"; - match hir.get_if_local(def_id) { - Some( - Node::Item(hir::Item { kind: ItemKind::Fn(.., body_id), .. }) - | Node::ImplItem(hir::ImplItem { - kind: hir::ImplItemKind::Fn(_, body_id), .. - }) - | Node::TraitItem(hir::TraitItem { - kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Provided(body_id)), - .. - }), - ) => { - let body = hir.body(*body_id); - sugg_call = body - .params - .iter() - .map(|param| match ¶m.pat.kind { - hir::PatKind::Binding(_, _, ident, None) - if ident.name != kw::SelfLower => - { - ident.to_string() - } - _ => "_".to_string(), - }) - .collect::>() - .join(", "); - } - Some(Node::Expr(hir::Expr { - kind: ExprKind::Closure(_, _, body_id, _, _), - span: full_closure_span, - .. - })) => { - if *full_closure_span == expr.span { - return false; - } - msg = "call this closure"; - let body = hir.body(*body_id); - sugg_call = body - .params - .iter() - .map(|param| match ¶m.pat.kind { - hir::PatKind::Binding(_, _, ident, None) - if ident.name != kw::SelfLower => - { - ident.to_string() - } - _ => "_".to_string(), - }) - .collect::>() - .join(", "); - } - Some(Node::Ctor(hir::VariantData::Tuple(fields, _))) => { - sugg_call = fields.iter().map(|_| "_").collect::>().join(", "); - match def_id.as_local().map(|def_id| hir.def_kind(def_id)) { - Some(DefKind::Ctor(hir::def::CtorOf::Variant, _)) => { - msg = "instantiate this tuple variant"; - } - Some(DefKind::Ctor(CtorOf::Struct, _)) => { - msg = "instantiate this tuple struct"; - } - _ => {} - } - } - Some(Node::ForeignItem(hir::ForeignItem { - kind: hir::ForeignItemKind::Fn(_, idents, _), - .. - })) => { - sugg_call = idents - .iter() - .map(|ident| { - if ident.name != kw::SelfLower { - ident.to_string() - } else { - "_".to_string() - } - }) - .collect::>() - .join(", ") - } - Some(Node::TraitItem(hir::TraitItem { - kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Required(idents)), - .. - })) => { - sugg_call = idents - .iter() - .map(|ident| { - if ident.name != kw::SelfLower { - ident.to_string() - } else { - "_".to_string() - } - }) - .collect::>() - .join(", ") - } - _ => {} - } - err.span_suggestion_verbose( - expr.span.shrink_to_hi(), - &format!("use parentheses to {}", msg), - format!("({})", sugg_call), - applicability, - ); - return true; - } - false - } - - pub fn suggest_deref_ref_or_into( - &self, - err: &mut DiagnosticBuilder<'_>, - expr: &hir::Expr<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, - ) { - if let Some((sp, msg, suggestion, applicability)) = self.check_ref(expr, found, expected) { - err.span_suggestion(sp, msg, suggestion, applicability); - } else if let (ty::FnDef(def_id, ..), true) = - (&found.kind(), self.suggest_fn_call(err, expr, expected, found)) - { - if let Some(sp) = self.tcx.hir().span_if_local(*def_id) { - let sp = self.sess().source_map().guess_head_span(sp); - err.span_label(sp, &format!("{} defined here", found)); - } - } else if !self.check_for_cast(err, expr, found, expected, expected_ty_expr) { - let is_struct_pat_shorthand_field = - self.is_hir_id_from_struct_pattern_shorthand_field(expr.hir_id, expr.span); - let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id); - if let Ok(expr_text) = self.sess().source_map().span_to_snippet(expr.span) { - let mut suggestions = iter::repeat(&expr_text) - .zip(methods.iter()) - .filter_map(|(receiver, method)| { - let method_call = format!(".{}()", method.ident); - if receiver.ends_with(&method_call) { - None // do not suggest code that is already there (#53348) - } else { - let method_call_list = [".to_vec()", ".to_string()"]; - let sugg = if receiver.ends_with(".clone()") - && method_call_list.contains(&method_call.as_str()) - { - let max_len = receiver.rfind('.').unwrap(); - format!("{}{}", &receiver[..max_len], method_call) - } else { - if expr.precedence().order() < ExprPrecedence::MethodCall.order() { - format!("({}){}", receiver, method_call) - } else { - format!("{}{}", receiver, method_call) - } - }; - Some(if is_struct_pat_shorthand_field { - format!("{}: {}", receiver, sugg) - } else { - sugg - }) - } - }) - .peekable(); - if suggestions.peek().is_some() { - err.span_suggestions( - expr.span, - "try using a conversion method", - suggestions, - Applicability::MaybeIncorrect, - ); - } - } - } - } - - /// When encountering the expected boxed value allocated in the stack, suggest allocating it - /// in the heap by calling `Box::new()`. - fn suggest_boxing_when_appropriate( - &self, - err: &mut DiagnosticBuilder<'_>, - expr: &hir::Expr<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - ) { - if self.tcx.hir().is_inside_const_context(expr.hir_id) { - // Do not suggest `Box::new` in const context. - return; - } - if !expected.is_box() || found.is_box() { - return; - } - let boxed_found = self.tcx.mk_box(found); - if let (true, Ok(snippet)) = ( - self.can_coerce(boxed_found, expected), - self.sess().source_map().span_to_snippet(expr.span), - ) { - err.span_suggestion( - expr.span, - "store this in the heap by calling `Box::new`", - format!("Box::new({})", snippet), - Applicability::MachineApplicable, - ); - err.note( - "for more on the distinction between the stack and the heap, read \ - https://doc.rust-lang.org/book/ch15-01-box.html, \ - https://doc.rust-lang.org/rust-by-example/std/box.html, and \ - https://doc.rust-lang.org/std/boxed/index.html", - ); - } - } - - fn note_internal_mutation_in_method( - &self, - err: &mut DiagnosticBuilder<'_>, - expr: &hir::Expr<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - ) { - if found != self.tcx.types.unit { - return; - } - if let ExprKind::MethodCall(path_segment, _, [rcvr, ..], _) = expr.kind { - if self - .typeck_results - .borrow() - .expr_ty_adjusted_opt(rcvr) - .map_or(true, |ty| expected.peel_refs() != ty.peel_refs()) - { - return; - } - let mut sp = MultiSpan::from_span(path_segment.ident.span); - sp.push_span_label( - path_segment.ident.span, - format!( - "this call modifies {} in-place", - match rcvr.kind { - ExprKind::Path(QPath::Resolved( - None, - hir::Path { segments: [segment], .. }, - )) => format!("`{}`", segment.ident), - _ => "its receiver".to_string(), - } - ), - ); - sp.push_span_label( - rcvr.span, - "you probably want to use this value after calling the method...".to_string(), - ); - err.span_note( - sp, - &format!("method `{}` modifies its receiver in-place", path_segment.ident), - ); - err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident)); - } - } - - /// When encountering an `impl Future` where `BoxFuture` is expected, suggest `Box::pin`. - fn suggest_calling_boxed_future_when_appropriate( - &self, - err: &mut DiagnosticBuilder<'_>, - expr: &hir::Expr<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - ) -> bool { - // Handle #68197. - - if self.tcx.hir().is_inside_const_context(expr.hir_id) { - // Do not suggest `Box::new` in const context. - return false; - } - let pin_did = self.tcx.lang_items().pin_type(); - match expected.kind() { - ty::Adt(def, _) if Some(def.did) != pin_did => return false, - // This guards the `unwrap` and `mk_box` below. - _ if pin_did.is_none() || self.tcx.lang_items().owned_box().is_none() => return false, - _ => {} - } - let boxed_found = self.tcx.mk_box(found); - let new_found = self.tcx.mk_lang_item(boxed_found, LangItem::Pin).unwrap(); - if let (true, Ok(snippet)) = ( - self.can_coerce(new_found, expected), - self.sess().source_map().span_to_snippet(expr.span), - ) { - match found.kind() { - ty::Adt(def, _) if def.is_box() => { - err.help("use `Box::pin`"); - } - _ => { - err.span_suggestion( - expr.span, - "you need to pin and box this expression", - format!("Box::pin({})", snippet), - Applicability::MachineApplicable, - ); - } - } - true - } else { - false - } - } - - /// A common error is to forget to add a semicolon at the end of a block, e.g., - /// - /// ``` - /// fn foo() { - /// bar_that_returns_u32() - /// } - /// ``` - /// - /// This routine checks if the return expression in a block would make sense on its own as a - /// statement and the return type has been left as default or has been specified as `()`. If so, - /// it suggests adding a semicolon. - fn suggest_missing_semicolon( - &self, - err: &mut DiagnosticBuilder<'_>, - expression: &'tcx hir::Expr<'tcx>, - expected: Ty<'tcx>, - cause_span: Span, - ) { - if expected.is_unit() { - // `BlockTailExpression` only relevant if the tail expr would be - // useful on its own. - match expression.kind { - ExprKind::Call(..) - | ExprKind::MethodCall(..) - | ExprKind::Loop(..) - | ExprKind::Match(..) - | ExprKind::Block(..) => { - err.span_suggestion( - cause_span.shrink_to_hi(), - "try adding a semicolon", - ";".to_string(), - Applicability::MachineApplicable, - ); - } - _ => (), - } - } - } - - /// A possible error is to forget to add a return type that is needed: - /// - /// ``` - /// fn foo() { - /// bar_that_returns_u32() - /// } - /// ``` - /// - /// This routine checks if the return type is left as default, the method is not part of an - /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return - /// type. - fn suggest_missing_return_type( - &self, - err: &mut DiagnosticBuilder<'_>, - fn_decl: &hir::FnDecl<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - can_suggest: bool, - ) -> bool { - // Only suggest changing the return type for methods that - // haven't set a return type at all (and aren't `fn main()` or an impl). - match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) { - (&hir::FnRetTy::DefaultReturn(span), true, true, true) => { - err.span_suggestion( - span, - "try adding a return type", - format!("-> {} ", self.resolve_vars_with_obligations(found)), - Applicability::MachineApplicable, - ); - true - } - (&hir::FnRetTy::DefaultReturn(span), false, true, true) => { - err.span_label(span, "possibly return type missing here?"); - true - } - (&hir::FnRetTy::DefaultReturn(span), _, false, true) => { - // `fn main()` must return `()`, do not suggest changing return type - err.span_label(span, "expected `()` because of default return type"); - true - } - // expectation was caused by something else, not the default return - (&hir::FnRetTy::DefaultReturn(_), _, _, false) => false, - (&hir::FnRetTy::Return(ref ty), _, _, _) => { - // Only point to return type if the expected type is the return type, as if they - // are not, the expectation must have been caused by something else. - debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind); - let sp = ty.span; - let ty = AstConv::ast_ty_to_ty(self, ty); - debug!("suggest_missing_return_type: return type {:?}", ty); - debug!("suggest_missing_return_type: expected type {:?}", ty); - if ty.kind() == expected.kind() { - err.span_label(sp, format!("expected `{}` because of return type", expected)); - return true; - } - false - } - } - } - - /// A possible error is to forget to add `.await` when using futures: - /// - /// ``` - /// async fn make_u32() -> u32 { - /// 22 - /// } - /// - /// fn take_u32(x: u32) {} - /// - /// async fn foo() { - /// let x = make_u32(); - /// take_u32(x); - /// } - /// ``` - /// - /// This routine checks if the found type `T` implements `Future` where `U` is the - /// expected type. If this is the case, and we are inside of an async body, it suggests adding - /// `.await` to the tail of the expression. - fn suggest_missing_await( - &self, - err: &mut DiagnosticBuilder<'_>, - expr: &hir::Expr<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - ) { - debug!("suggest_missing_await: expr={:?} expected={:?}, found={:?}", expr, expected, found); - // `.await` is not permitted outside of `async` bodies, so don't bother to suggest if the - // body isn't `async`. - let item_id = self.tcx().hir().get_parent_node(self.body_id); - if let Some(body_id) = self.tcx().hir().maybe_body_owned_by(item_id) { - let body = self.tcx().hir().body(body_id); - if let Some(hir::GeneratorKind::Async(_)) = body.generator_kind { - let sp = expr.span; - // Check for `Future` implementations by constructing a predicate to - // prove: `::Output == U` - let future_trait = self.tcx.require_lang_item(LangItem::Future, Some(sp)); - let item_def_id = self - .tcx - .associated_items(future_trait) - .in_definition_order() - .next() - .unwrap() - .def_id; - // `::Output` - let projection_ty = ty::ProjectionTy { - // `T` - substs: self - .tcx - .mk_substs_trait(found, self.fresh_substs_for_item(sp, item_def_id)), - // `Future::Output` - item_def_id, - }; - - let predicate = ty::PredicateAtom::Projection(ty::ProjectionPredicate { - projection_ty, - ty: expected, - }) - .potentially_quantified(self.tcx, ty::PredicateKind::ForAll); - let obligation = traits::Obligation::new(self.misc(sp), self.param_env, predicate); - - debug!("suggest_missing_await: trying obligation {:?}", obligation); - - if self.infcx.predicate_may_hold(&obligation) { - debug!("suggest_missing_await: obligation held: {:?}", obligation); - if let Ok(code) = self.sess().source_map().span_to_snippet(sp) { - err.span_suggestion( - sp, - "consider using `.await` here", - format!("{}.await", code), - Applicability::MaybeIncorrect, - ); - } else { - debug!("suggest_missing_await: no snippet for {:?}", sp); - } - } else { - debug!("suggest_missing_await: obligation did not hold: {:?}", obligation) - } - } - } - } - - fn suggest_missing_parentheses(&self, err: &mut DiagnosticBuilder<'_>, expr: &hir::Expr<'_>) { - let sp = self.tcx.sess.source_map().start_point(expr.span); - if let Some(sp) = self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) { - // `{ 42 } &&x` (#61475) or `{ 42 } && if x { 1 } else { 0 }` - self.tcx.sess.parse_sess.expr_parentheses_needed(err, *sp, None); - } - } - - fn note_need_for_fn_pointer( - &self, - err: &mut DiagnosticBuilder<'_>, - expected: Ty<'tcx>, - found: Ty<'tcx>, - ) { - let (sig, did, substs) = match (&expected.kind(), &found.kind()) { - (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => { - let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1); - let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2); - if sig1 != sig2 { - return; - } - err.note( - "different `fn` items always have unique types, even if their signatures are \ - the same", - ); - (sig1, *did1, substs1) - } - (ty::FnDef(did, substs), ty::FnPtr(sig2)) => { - let sig1 = self.tcx.fn_sig(*did).subst(self.tcx, substs); - if sig1 != *sig2 { - return; - } - (sig1, *did, substs) - } - _ => return, - }; - err.help(&format!("change the expected type to be function pointer `{}`", sig)); - err.help(&format!( - "if the expected type is due to type inference, cast the expected `fn` to a function \ - pointer: `{} as {}`", - self.tcx.def_path_str_with_substs(did, substs), - sig - )); - } - - /// A common error is to add an extra semicolon: - /// - /// ``` - /// fn foo() -> usize { - /// 22; - /// } - /// ``` - /// - /// This routine checks if the final statement in a block is an - /// expression with an explicit semicolon whose type is compatible - /// with `expected_ty`. If so, it suggests removing the semicolon. - fn consider_hint_about_removing_semicolon( - &self, - blk: &'tcx hir::Block<'tcx>, - expected_ty: Ty<'tcx>, - err: &mut DiagnosticBuilder<'_>, - ) { - if let Some(span_semi) = self.could_remove_semicolon(blk, expected_ty) { - err.span_suggestion( - span_semi, - "consider removing this semicolon", - String::new(), - Applicability::MachineApplicable, - ); - } - } - - fn could_remove_semicolon( - &self, - blk: &'tcx hir::Block<'tcx>, - expected_ty: Ty<'tcx>, - ) -> Option { - // Be helpful when the user wrote `{... expr;}` and - // taking the `;` off is enough to fix the error. - let last_stmt = blk.stmts.last()?; - let last_expr = match last_stmt.kind { - hir::StmtKind::Semi(ref e) => e, - _ => return None, - }; - let last_expr_ty = self.node_ty(last_expr.hir_id); - if matches!(last_expr_ty.kind(), ty::Error(_)) - || self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err() - { - return None; - } - let original_span = original_sp(last_stmt.span, blk.span); - Some(original_span.with_lo(original_span.hi() - BytePos(1))) - } - - // Instantiates the given path, which must refer to an item with the given - // number of type parameters and type. - pub fn instantiate_value_path( - &self, - segments: &[hir::PathSegment<'_>], - self_ty: Option>, - res: Res, - span: Span, - hir_id: hir::HirId, - ) -> (Ty<'tcx>, Res) { - debug!( - "instantiate_value_path(segments={:?}, self_ty={:?}, res={:?}, hir_id={})", - segments, self_ty, res, hir_id, - ); - - let tcx = self.tcx; - - let path_segs = match res { - Res::Local(_) | Res::SelfCtor(_) => vec![], - Res::Def(kind, def_id) => { - AstConv::def_ids_for_value_path_segments(self, segments, self_ty, kind, def_id) - } - _ => bug!("instantiate_value_path on {:?}", res), - }; - - let mut user_self_ty = None; - let mut is_alias_variant_ctor = false; - match res { - Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) => { - if let Some(self_ty) = self_ty { - let adt_def = self_ty.ty_adt_def().unwrap(); - user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did, self_ty }); - is_alias_variant_ctor = true; - } - } - Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => { - let container = tcx.associated_item(def_id).container; - debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container); - match container { - ty::TraitContainer(trait_did) => { - callee::check_legal_trait_for_method_call(tcx, span, None, trait_did) - } - ty::ImplContainer(impl_def_id) => { - if segments.len() == 1 { - // `::assoc` will end up here, and so - // can `T::assoc`. It this came from an - // inherent impl, we need to record the - // `T` for posterity (see `UserSelfTy` for - // details). - let self_ty = self_ty.expect("UFCS sugared assoc missing Self"); - user_self_ty = Some(UserSelfTy { impl_def_id, self_ty }); - } - } - } - } - _ => {} - } - - // Now that we have categorized what space the parameters for each - // segment belong to, let's sort out the parameters that the user - // provided (if any) into their appropriate spaces. We'll also report - // errors if type parameters are provided in an inappropriate place. - - let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect(); - let generics_has_err = AstConv::prohibit_generics( - self, - segments.iter().enumerate().filter_map(|(index, seg)| { - if !generic_segs.contains(&index) || is_alias_variant_ctor { - Some(seg) - } else { - None - } - }), - ); - - if let Res::Local(hid) = res { - let ty = self.local_ty(span, hid).decl_ty; - let ty = self.normalize_associated_types_in(span, &ty); - self.write_ty(hir_id, ty); - return (ty, res); - } - - if generics_has_err { - // Don't try to infer type parameters when prohibited generic arguments were given. - user_self_ty = None; - } - - // Now we have to compare the types that the user *actually* - // provided against the types that were *expected*. If the user - // did not provide any types, then we want to substitute inference - // variables. If the user provided some types, we may still need - // to add defaults. If the user provided *too many* types, that's - // a problem. - - let mut infer_args_for_err = FxHashSet::default(); - for &PathSeg(def_id, index) in &path_segs { - let seg = &segments[index]; - let generics = tcx.generics_of(def_id); - // Argument-position `impl Trait` is treated as a normal generic - // parameter internally, but we don't allow users to specify the - // parameter's value explicitly, so we have to do some error- - // checking here. - if let GenericArgCountResult { - correct: Err(GenericArgCountMismatch { reported: Some(ErrorReported), .. }), - .. - } = AstConv::check_generic_arg_count_for_call( - tcx, span, &generics, &seg, false, // `is_method_call` - ) { - infer_args_for_err.insert(index); - self.set_tainted_by_errors(); // See issue #53251. - } - } - - let has_self = path_segs - .last() - .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self) - .unwrap_or(false); - - let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res { - let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id)); - match *ty.kind() { - ty::Adt(adt_def, substs) if adt_def.has_ctor() => { - let variant = adt_def.non_enum_variant(); - let ctor_def_id = variant.ctor_def_id.unwrap(); - ( - Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id), - Some(substs), - ) - } - _ => { - let mut err = tcx.sess.struct_span_err( - span, - "the `Self` constructor can only be used with tuple or unit structs", - ); - if let Some(adt_def) = ty.ty_adt_def() { - match adt_def.adt_kind() { - AdtKind::Enum => { - err.help("did you mean to use one of the enum's variants?"); - } - AdtKind::Struct | AdtKind::Union => { - err.span_suggestion( - span, - "use curly brackets", - String::from("Self { /* fields */ }"), - Applicability::HasPlaceholders, - ); - } - } - } - err.emit(); - - return (tcx.ty_error(), res); - } - } - } else { - (res, None) - }; - let def_id = res.def_id(); - - // The things we are substituting into the type should not contain - // escaping late-bound regions, and nor should the base type scheme. - let ty = tcx.type_of(def_id); - - let arg_count = GenericArgCountResult { - explicit_late_bound: ExplicitLateBound::No, - correct: if infer_args_for_err.is_empty() { - Ok(()) - } else { - Err(GenericArgCountMismatch::default()) - }, - }; - - let substs = self_ctor_substs.unwrap_or_else(|| { - AstConv::create_substs_for_generic_args( - tcx, - def_id, - &[][..], - has_self, - self_ty, - arg_count, - // Provide the generic args, and whether types should be inferred. - |def_id| { - if let Some(&PathSeg(_, index)) = - path_segs.iter().find(|&PathSeg(did, _)| *did == def_id) - { - // If we've encountered an `impl Trait`-related error, we're just - // going to infer the arguments for better error messages. - if !infer_args_for_err.contains(&index) { - // Check whether the user has provided generic arguments. - if let Some(ref data) = segments[index].args { - return (Some(data), segments[index].infer_args); - } - } - return (None, segments[index].infer_args); - } - - (None, true) - }, - // Provide substitutions for parameters for which (valid) arguments have been provided. - |param, arg| match (¶m.kind, arg) { - (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => { - AstConv::ast_region_to_region(self, lt, Some(param)).into() - } - (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => { - self.to_ty(ty).into() - } - (GenericParamDefKind::Const, GenericArg::Const(ct)) => { - self.const_arg_to_const(&ct.value, param.def_id).into() - } - _ => unreachable!(), - }, - // Provide substitutions for parameters for which arguments are inferred. - |substs, param, infer_args| { - match param.kind { - GenericParamDefKind::Lifetime => { - self.re_infer(Some(param), span).unwrap().into() - } - GenericParamDefKind::Type { has_default, .. } => { - if !infer_args && has_default { - // If we have a default, then we it doesn't matter that we're not - // inferring the type arguments: we provide the default where any - // is missing. - let default = tcx.type_of(param.def_id); - self.normalize_ty( - span, - default.subst_spanned(tcx, substs.unwrap(), Some(span)), - ) - .into() - } else { - // If no type arguments were provided, we have to infer them. - // This case also occurs as a result of some malformed input, e.g. - // a lifetime argument being given instead of a type parameter. - // Using inference instead of `Error` gives better error messages. - self.var_for_def(span, param) - } - } - GenericParamDefKind::Const => { - // FIXME(const_generics:defaults) - // No const parameters were provided, we have to infer them. - self.var_for_def(span, param) - } - } - }, - ) - }); - assert!(!substs.has_escaping_bound_vars()); - assert!(!ty.has_escaping_bound_vars()); - - // First, store the "user substs" for later. - self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty); - - self.add_required_obligations(span, def_id, &substs); - - // Substitute the values for the type parameters into the type of - // the referenced item. - let ty_substituted = self.instantiate_type_scheme(span, &substs, &ty); - - if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty { - // In the case of `Foo::method` and `>::method`, if `method` - // is inherent, there is no `Self` parameter; instead, the impl needs - // type parameters, which we can infer by unifying the provided `Self` - // with the substituted impl type. - // This also occurs for an enum variant on a type alias. - let ty = tcx.type_of(impl_def_id); - - let impl_ty = self.instantiate_type_scheme(span, &substs, &ty); - match self.at(&self.misc(span), self.param_env).sup(impl_ty, self_ty) { - Ok(ok) => self.register_infer_ok_obligations(ok), - Err(_) => { - self.tcx.sess.delay_span_bug( - span, - &format!( - "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?", - self_ty, - impl_ty, - ), - ); - } - } - } - - self.check_rustc_args_require_const(def_id, hir_id, span); - - debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted); - self.write_substs(hir_id, substs); - - (ty_substituted, res) - } - - /// Add all the obligations that are required, substituting and normalized appropriately. - fn add_required_obligations(&self, span: Span, def_id: DefId, substs: &SubstsRef<'tcx>) { - let (bounds, spans) = self.instantiate_bounds(span, def_id, &substs); - - for (i, mut obligation) in traits::predicates_for_generics( - traits::ObligationCause::new(span, self.body_id, traits::ItemObligation(def_id)), - self.param_env, - bounds, - ) - .enumerate() - { - // This makes the error point at the bound, but we want to point at the argument - if let Some(span) = spans.get(i) { - obligation.cause.make_mut().code = traits::BindingObligation(def_id, *span); - } - self.register_predicate(obligation); - } - } - - fn check_rustc_args_require_const(&self, def_id: DefId, hir_id: hir::HirId, span: Span) { - // We're only interested in functions tagged with - // #[rustc_args_required_const], so ignore anything that's not. - if !self.tcx.has_attr(def_id, sym::rustc_args_required_const) { - return; - } - - // If our calling expression is indeed the function itself, we're good! - // If not, generate an error that this can only be called directly. - if let Node::Expr(expr) = self.tcx.hir().get(self.tcx.hir().get_parent_node(hir_id)) { - if let ExprKind::Call(ref callee, ..) = expr.kind { - if callee.hir_id == hir_id { - return; - } - } - } - - self.tcx.sess.span_err( - span, - "this function can only be invoked directly, not through a function pointer", - ); - } - - /// Resolves `typ` by a single level if `typ` is a type variable. - /// If no resolution is possible, then an error is reported. - /// Numeric inference variables may be left unresolved. - pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> { - let ty = self.resolve_vars_with_obligations(ty); - if !ty.is_ty_var() { - ty - } else { - if !self.is_tainted_by_errors() { - self.need_type_info_err((**self).body_id, sp, ty, E0282) - .note("type must be known at this point") - .emit(); - } - let err = self.tcx.ty_error(); - self.demand_suptype(sp, err, ty); - err - } - } - - fn with_breakable_ctxt R, R>( - &self, - id: hir::HirId, - ctxt: BreakableCtxt<'tcx>, - f: F, - ) -> (BreakableCtxt<'tcx>, R) { - let index; - { - let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); - index = enclosing_breakables.stack.len(); - enclosing_breakables.by_id.insert(id, index); - enclosing_breakables.stack.push(ctxt); - } - let result = f(); - let ctxt = { - let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); - debug_assert!(enclosing_breakables.stack.len() == index + 1); - enclosing_breakables.by_id.remove(&id).expect("missing breakable context"); - enclosing_breakables.stack.pop().expect("missing breakable context") - }; - (ctxt, result) - } - - /// Instantiate a QueryResponse in a probe context, without a - /// good ObligationCause. - fn probe_instantiate_query_response( - &self, - span: Span, - original_values: &OriginalQueryValues<'tcx>, - query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, - ) -> InferResult<'tcx, Ty<'tcx>> { - self.instantiate_query_response_and_region_obligations( - &traits::ObligationCause::misc(span, self.body_id), - self.param_env, - original_values, - query_result, - ) - } - - /// Returns `true` if an expression is contained inside the LHS of an assignment expression. - fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool { - let mut contained_in_place = false; - - while let hir::Node::Expr(parent_expr) = - self.tcx.hir().get(self.tcx.hir().get_parent_node(expr_id)) - { - match &parent_expr.kind { - hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => { - if lhs.hir_id == expr_id { - contained_in_place = true; - break; - } - } - _ => (), - } - expr_id = parent_expr.hir_id; - } - - contained_in_place - } -} - fn check_type_params_are_used<'tcx>(tcx: TyCtxt<'tcx>, generics: &ty::Generics, ty: Ty<'tcx>) { debug!("check_type_params_are_used(generics={:?}, ty={:?})", generics, ty);