Remove all unstable feature support in the missing_const_for_fn
lint
This commit is contained in:
parent
1b843896c8
commit
5d359db9cf
1 changed files with 25 additions and 97 deletions
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@ -3,7 +3,7 @@ use rustc_hir::def_id::DefId;
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use rustc_middle::mir::*;
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use rustc_middle::ty::subst::GenericArgKind;
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use rustc_middle::ty::{self, adjustment::PointerCast, Ty, TyCtxt};
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use rustc_span::symbol::{sym, Symbol};
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use rustc_span::symbol::{sym};
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use rustc_span::Span;
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use rustc_target::spec::abi::Abi::RustIntrinsic;
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use std::borrow::Cow;
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@ -11,14 +11,6 @@ use std::borrow::Cow;
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type McfResult = Result<(), (Span, Cow<'static, str>)>;
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pub fn is_min_const_fn(tcx: TyCtxt<'tcx>, def_id: DefId, body: &'a Body<'tcx>) -> McfResult {
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// Prevent const trait methods from being annotated as `stable`.
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if tcx.features().staged_api {
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let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
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if rustc_mir::const_eval::is_parent_const_impl_raw(tcx, hir_id) {
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return Err((body.span, "trait methods cannot be stable const fn".into()));
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}
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}
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let mut current = def_id;
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loop {
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let predicates = tcx.predicates_of(current);
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@ -40,19 +32,12 @@ pub fn is_min_const_fn(tcx: TyCtxt<'tcx>, def_id: DefId, body: &'a Body<'tcx>) -
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ty::PredicateAtom::Subtype(_) => {
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panic!("subtype predicate on function: {:#?}", predicate)
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}
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ty::PredicateAtom::Trait(pred, constness) => {
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ty::PredicateAtom::Trait(pred, _) => {
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if Some(pred.def_id()) == tcx.lang_items().sized_trait() {
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continue;
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}
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match pred.self_ty().kind() {
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ty::Param(ref p) => {
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// Allow `T: ?const Trait`
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if constness == hir::Constness::NotConst
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&& feature_allowed(tcx, def_id, sym::const_trait_bound_opt_out)
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{
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continue;
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}
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let generics = tcx.generics_of(current);
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let def = generics.type_param(p, tcx);
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let span = tcx.def_span(def.def_id);
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@ -77,18 +62,17 @@ pub fn is_min_const_fn(tcx: TyCtxt<'tcx>, def_id: DefId, body: &'a Body<'tcx>) -
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}
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for local in &body.local_decls {
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check_ty(tcx, local.ty, local.source_info.span, def_id)?;
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check_ty(tcx, local.ty, local.source_info.span)?;
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}
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// impl trait is gone in MIR, so check the return type manually
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check_ty(
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tcx,
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tcx.fn_sig(def_id).output().skip_binder(),
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body.local_decls.iter().next().unwrap().source_info.span,
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def_id,
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)?;
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for bb in body.basic_blocks() {
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check_terminator(tcx, body, def_id, bb.terminator())?;
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check_terminator(tcx, body, bb.terminator())?;
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for stmt in &bb.statements {
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check_statement(tcx, body, def_id, stmt)?;
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}
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@ -96,7 +80,7 @@ pub fn is_min_const_fn(tcx: TyCtxt<'tcx>, def_id: DefId, body: &'a Body<'tcx>) -
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Ok(())
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}
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fn check_ty(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, span: Span, fn_def_id: DefId) -> McfResult {
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fn check_ty(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, span: Span) -> McfResult {
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for arg in ty.walk() {
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let ty = match arg.unpack() {
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GenericArgKind::Type(ty) => ty,
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@ -108,16 +92,12 @@ fn check_ty(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, span: Span, fn_def_id: DefId) -> Mc
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match ty.kind() {
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ty::Ref(_, _, hir::Mutability::Mut) => {
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if !feature_allowed(tcx, fn_def_id, sym::const_mut_refs) {
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return Err((span, "mutable references in const fn are unstable".into()));
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}
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}
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ty::Opaque(..) => return Err((span, "`impl Trait` in const fn is unstable".into())),
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ty::FnPtr(..) => {
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if !tcx.const_fn_is_allowed_fn_ptr(fn_def_id) {
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return Err((span, "function pointers in const fn are unstable".into()));
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}
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}
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ty::Dynamic(preds, _) => {
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for pred in preds.iter() {
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match pred.skip_binder() {
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@ -161,12 +141,12 @@ fn check_rvalue(
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Err((span, "cannot access thread local storage in const fn".into()))
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}
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Rvalue::Repeat(operand, _) | Rvalue::Use(operand) => {
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check_operand(tcx, operand, span, def_id, body)
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check_operand(tcx, operand, span, body)
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}
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Rvalue::Len(place)
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| Rvalue::Discriminant(place)
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| Rvalue::Ref(_, _, place)
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| Rvalue::AddressOf(_, place) => check_place(tcx, *place, span, def_id, body),
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| Rvalue::AddressOf(_, place) => check_place(tcx, *place, span, body),
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Rvalue::Cast(CastKind::Misc, operand, cast_ty) => {
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use rustc_middle::ty::cast::CastTy;
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let cast_in = CastTy::from_ty(operand.ty(body, tcx)).expect("bad input type for cast");
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@ -175,14 +155,14 @@ fn check_rvalue(
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(CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Int(_)) => {
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Err((span, "casting pointers to ints is unstable in const fn".into()))
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}
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_ => check_operand(tcx, operand, span, def_id, body),
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_ => check_operand(tcx, operand, span, body),
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}
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}
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Rvalue::Cast(
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CastKind::Pointer(PointerCast::MutToConstPointer | PointerCast::ArrayToPointer),
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operand,
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_,
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) => check_operand(tcx, operand, span, def_id, body),
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) => check_operand(tcx, operand, span, body),
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Rvalue::Cast(
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CastKind::Pointer(
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PointerCast::UnsafeFnPointer
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@ -204,7 +184,7 @@ fn check_rvalue(
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};
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let unsized_ty = tcx.struct_tail_erasing_lifetimes(pointee_ty, tcx.param_env(def_id));
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if let ty::Slice(_) | ty::Str = unsized_ty.kind() {
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check_operand(tcx, op, span, def_id, body)?;
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check_operand(tcx, op, span, body)?;
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// Casting/coercing things to slices is fine.
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Ok(())
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} else {
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@ -214,8 +194,8 @@ fn check_rvalue(
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}
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// binops are fine on integers
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Rvalue::BinaryOp(_, lhs, rhs) | Rvalue::CheckedBinaryOp(_, lhs, rhs) => {
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check_operand(tcx, lhs, span, def_id, body)?;
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check_operand(tcx, rhs, span, def_id, body)?;
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check_operand(tcx, lhs, span, body)?;
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check_operand(tcx, rhs, span, body)?;
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let ty = lhs.ty(body, tcx);
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if ty.is_integral() || ty.is_bool() || ty.is_char() {
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Ok(())
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@ -230,14 +210,14 @@ fn check_rvalue(
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Rvalue::UnaryOp(_, operand) => {
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let ty = operand.ty(body, tcx);
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if ty.is_integral() || ty.is_bool() {
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check_operand(tcx, operand, span, def_id, body)
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check_operand(tcx, operand, span, body)
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} else {
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Err((span, "only int and `bool` operations are stable in const fn".into()))
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}
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}
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Rvalue::Aggregate(_, operands) => {
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for operand in operands {
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check_operand(tcx, operand, span, def_id, body)?;
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check_operand(tcx, operand, span, body)?;
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}
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Ok(())
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}
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@ -253,15 +233,15 @@ fn check_statement(
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let span = statement.source_info.span;
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match &statement.kind {
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StatementKind::Assign(box (place, rval)) => {
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check_place(tcx, *place, span, def_id, body)?;
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check_place(tcx, *place, span, body)?;
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check_rvalue(tcx, body, def_id, rval, span)
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}
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StatementKind::FakeRead(_, place) => check_place(tcx, **place, span, def_id, body),
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StatementKind::FakeRead(_, place) => check_place(tcx, **place, span, body),
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// just an assignment
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StatementKind::SetDiscriminant { place, .. } => {
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check_place(tcx, **place, span, def_id, body)
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check_place(tcx, **place, span, body)
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}
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StatementKind::LlvmInlineAsm { .. } => {
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@ -282,11 +262,10 @@ fn check_operand(
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tcx: TyCtxt<'tcx>,
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operand: &Operand<'tcx>,
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span: Span,
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def_id: DefId,
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body: &Body<'tcx>,
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) -> McfResult {
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match operand {
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Operand::Move(place) | Operand::Copy(place) => check_place(tcx, *place, span, def_id, body),
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Operand::Move(place) | Operand::Copy(place) => check_place(tcx, *place, span, body),
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Operand::Constant(c) => match c.check_static_ptr(tcx) {
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Some(_) => Err((span, "cannot access `static` items in const fn".into())),
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None => Ok(()),
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@ -298,7 +277,6 @@ fn check_place(
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tcx: TyCtxt<'tcx>,
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place: Place<'tcx>,
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span: Span,
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def_id: DefId,
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body: &Body<'tcx>,
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) -> McfResult {
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let mut cursor = place.projection.as_ref();
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@ -310,12 +288,10 @@ fn check_place(
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if let Some(def) = base_ty.ty_adt_def() {
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// No union field accesses in `const fn`
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if def.is_union() {
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if !feature_allowed(tcx, def_id, sym::const_fn_union) {
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return Err((span, "accessing union fields is unstable".into()));
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}
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}
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}
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}
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ProjectionElem::ConstantIndex { .. }
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| ProjectionElem::Downcast(..)
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| ProjectionElem::Subslice { .. }
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@ -327,48 +303,9 @@ fn check_place(
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Ok(())
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}
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/// Returns `true` if the given feature gate is allowed within the function with the given `DefId`.
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fn feature_allowed(tcx: TyCtxt<'tcx>, def_id: DefId, feature_gate: Symbol) -> bool {
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// All features require that the corresponding gate be enabled,
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// even if the function has `#[allow_internal_unstable(the_gate)]`.
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if !tcx.features().enabled(feature_gate) {
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return false;
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}
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// If this crate is not using stability attributes, or this function is not claiming to be a
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// stable `const fn`, that is all that is required.
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if !tcx.features().staged_api || tcx.has_attr(def_id, sym::rustc_const_unstable) {
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return true;
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}
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// However, we cannot allow stable `const fn`s to use unstable features without an explicit
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// opt-in via `allow_internal_unstable`.
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rustc_mir::transform::check_consts::allow_internal_unstable(tcx, def_id, feature_gate)
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}
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/// Returns `true` if the given library feature gate is allowed within the function with the given `DefId`.
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pub fn lib_feature_allowed(tcx: TyCtxt<'tcx>, def_id: DefId, feature_gate: Symbol) -> bool {
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// All features require that the corresponding gate be enabled,
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// even if the function has `#[allow_internal_unstable(the_gate)]`.
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if !tcx.features().declared_lib_features.iter().any(|&(sym, _)| sym == feature_gate) {
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return false;
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}
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// If this crate is not using stability attributes, or this function is not claiming to be a
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// stable `const fn`, that is all that is required.
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if !tcx.features().staged_api || tcx.has_attr(def_id, sym::rustc_const_unstable) {
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return true;
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}
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// However, we cannot allow stable `const fn`s to use unstable features without an explicit
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// opt-in via `allow_internal_unstable`.
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rustc_mir::transform::check_consts::allow_internal_unstable(tcx, def_id, feature_gate)
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}
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fn check_terminator(
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tcx: TyCtxt<'tcx>,
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body: &'a Body<'tcx>,
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def_id: DefId,
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terminator: &Terminator<'tcx>,
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) -> McfResult {
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let span = terminator.source_info.span;
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@ -380,14 +317,14 @@ fn check_terminator(
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| TerminatorKind::Resume
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| TerminatorKind::Unreachable => Ok(()),
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TerminatorKind::Drop { place, .. } => check_place(tcx, *place, span, def_id, body),
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TerminatorKind::Drop { place, .. } => check_place(tcx, *place, span, body),
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TerminatorKind::DropAndReplace { place, value, .. } => {
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check_place(tcx, *place, span, def_id, body)?;
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check_operand(tcx, value, span, def_id, body)
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check_place(tcx, *place, span, body)?;
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check_operand(tcx, value, span, body)
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}
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TerminatorKind::SwitchInt { discr, switch_ty: _, values: _, targets: _ } => {
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check_operand(tcx, discr, span, def_id, body)
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check_operand(tcx, discr, span, body)
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}
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TerminatorKind::Abort => Err((span, "abort is not stable in const fn".into())),
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@ -405,15 +342,7 @@ fn check_terminator(
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} => {
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let fn_ty = func.ty(body, tcx);
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if let ty::FnDef(fn_def_id, _) = *fn_ty.kind() {
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// Allow unstable const if we opt in by using #[allow_internal_unstable]
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// on function or macro declaration.
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if !rustc_mir::const_eval::is_min_const_fn(tcx, fn_def_id)
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&& !rustc_mir::const_eval::is_unstable_const_fn(tcx, fn_def_id)
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.map(|feature| {
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span.allows_unstable(feature)
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|| lib_feature_allowed(tcx, def_id, feature)
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})
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.unwrap_or(false)
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{
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return Err((
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span,
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@ -432,7 +361,6 @@ fn check_terminator(
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// transmutes in const fn before we add more hacks to this.
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if tcx.fn_sig(fn_def_id).abi() == RustIntrinsic
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&& tcx.item_name(fn_def_id) == sym::transmute
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&& !feature_allowed(tcx, def_id, sym::const_fn_transmute)
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{
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return Err((
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span,
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@ -440,10 +368,10 @@ fn check_terminator(
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));
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}
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check_operand(tcx, func, span, fn_def_id, body)?;
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check_operand(tcx, func, span, body)?;
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for arg in args {
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check_operand(tcx, arg, span, fn_def_id, body)?;
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check_operand(tcx, arg, span, body)?;
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}
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Ok(())
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} else {
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@ -452,7 +380,7 @@ fn check_terminator(
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}
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TerminatorKind::Assert { cond, expected: _, msg: _, target: _, cleanup: _ } => {
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check_operand(tcx, cond, span, def_id, body)
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check_operand(tcx, cond, span, body)
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}
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TerminatorKind::InlineAsm { .. } => {
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