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Make const_eval_select a real intrinsic

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This commit is contained in:
Deadbeef 2022-08-23 00:07:26 +00:00
parent 8521a8c92d
commit 075084f772
27 changed files with 432 additions and 287 deletions
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3
compiler/rustc_codegen_ssa/src/mir/block.rs
View file

@ -13,8 +13,7 @@ use rustc_ast as ast;
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_hir::lang_items::LangItem;
use rustc_index::vec::Idx;
use rustc_middle::mir::AssertKind;
use rustc_middle::mir::{self, SwitchTargets};
use rustc_middle::mir::{self, AssertKind, SwitchTargets};
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
use rustc_middle::ty::{self, Instance, Ty, TypeVisitable};

16
compiler/rustc_const_eval/src/const_eval/machine.rs
View file

@ -35,21 +35,7 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>> {
// All `#[rustc_do_not_const_check]` functions should be hooked here.
let def_id = instance.def_id();
if Some(def_id) == self.tcx.lang_items().const_eval_select() {
// redirect to const_eval_select_ct
if let Some(const_eval_select) = self.tcx.lang_items().const_eval_select_ct() {
return Ok(Some(
ty::Instance::resolve(
*self.tcx,
ty::ParamEnv::reveal_all(),
const_eval_select,
instance.substs,
)
.unwrap()
.unwrap(),
));
}
} else if Some(def_id) == self.tcx.lang_items().panic_display()
if Some(def_id) == self.tcx.lang_items().panic_display()
|| Some(def_id) == self.tcx.lang_items().begin_panic_fn()
{
// &str or &&str

2
compiler/rustc_hir/src/lang_items.rs
View file

@ -269,8 +269,6 @@ language_item_table! {
DropInPlace, sym::drop_in_place, drop_in_place_fn, Target::Fn, GenericRequirement::Minimum(1);
Oom, sym::oom, oom, Target::Fn, GenericRequirement::None;
AllocLayout, sym::alloc_layout, alloc_layout, Target::Struct, GenericRequirement::None;
ConstEvalSelect, sym::const_eval_select, const_eval_select, Target::Fn, GenericRequirement::Exact(4);
ConstConstEvalSelect, sym::const_eval_select_ct,const_eval_select_ct, Target::Fn, GenericRequirement::Exact(4);
Start, sym::start, start_fn, Target::Fn, GenericRequirement::Exact(1);

5
compiler/rustc_middle/src/ty/consts/valtree.rs
View file

@ -18,7 +18,7 @@ use rustc_macros::{HashStable, TyDecodable, TyEncodable};
/// `ValTree` does not have this problem with representation, as it only contains integers or
/// lists of (nested) `ValTree`.
pub enum ValTree<'tcx> {
/// ZSTs, integers, `bool`, `char` are represented as scalars.
/// integers, `bool`, `char` are represented as scalars.
/// See the `ScalarInt` documentation for how `ScalarInt` guarantees that equal values
/// of these types have the same representation.
Leaf(ScalarInt),
@ -27,8 +27,11 @@ pub enum ValTree<'tcx> {
// dont use SliceOrStr for now
/// The fields of any kind of aggregate. Structs, tuples and arrays are represented by
/// listing their fields' values in order.
///
/// Enums are represented by storing their discriminant as a field, followed by all
/// the fields of the variant.
///
/// ZST types are represented as an empty slice.
Branch(&'tcx [ValTree<'tcx>]),
}

175
compiler/rustc_middle/src/ty/layout.rs
View file

@ -263,6 +263,7 @@ fn layout_of<'tcx>(
Ok(layout)
}
#[derive(Clone, Copy)]
pub struct LayoutCx<'tcx, C> {
pub tcx: C,
pub param_env: ty::ParamEnv<'tcx>,
@ -3063,6 +3064,93 @@ fn fn_abi_of_instance<'tcx>(
)
}
// Handle safe Rust thin and fat pointers.
pub fn adjust_for_rust_scalar<'tcx>(
cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
attrs: &mut ArgAttributes,
scalar: Scalar,
layout: TyAndLayout<'tcx>,
offset: Size,
is_return: bool,
) {
// Booleans are always a noundef i1 that needs to be zero-extended.
if scalar.is_bool() {
attrs.ext(ArgExtension::Zext);
attrs.set(ArgAttribute::NoUndef);
return;
}
// Scalars which have invalid values cannot be undef.
if !scalar.is_always_valid(&cx) {
attrs.set(ArgAttribute::NoUndef);
}
// Only pointer types handled below.
let Scalar::Initialized { value: Pointer, valid_range} = scalar else { return };
if !valid_range.contains(0) {
attrs.set(ArgAttribute::NonNull);
}
if let Some(pointee) = layout.pointee_info_at(&cx, offset) {
if let Some(kind) = pointee.safe {
attrs.pointee_align = Some(pointee.align);
// `Box` (`UniqueBorrowed`) are not necessarily dereferenceable
// for the entire duration of the function as they can be deallocated
// at any time. Same for shared mutable references. If LLVM had a
// way to say "dereferenceable on entry" we could use it here.
attrs.pointee_size = match kind {
PointerKind::UniqueBorrowed
| PointerKind::UniqueBorrowedPinned
| PointerKind::Frozen => pointee.size,
PointerKind::SharedMutable | PointerKind::UniqueOwned => Size::ZERO,
};
// `Box`, `&T`, and `&mut T` cannot be undef.
// Note that this only applies to the value of the pointer itself;
// this attribute doesn't make it UB for the pointed-to data to be undef.
attrs.set(ArgAttribute::NoUndef);
// The aliasing rules for `Box<T>` are still not decided, but currently we emit
// `noalias` for it. This can be turned off using an unstable flag.
// See https://github.com/rust-lang/unsafe-code-guidelines/issues/326
let noalias_for_box = cx.tcx.sess.opts.unstable_opts.box_noalias.unwrap_or(true);
// `&mut` pointer parameters never alias other parameters,
// or mutable global data
//
// `&T` where `T` contains no `UnsafeCell<U>` is immutable,
// and can be marked as both `readonly` and `noalias`, as
// LLVM's definition of `noalias` is based solely on memory
// dependencies rather than pointer equality
//
// Due to past miscompiles in LLVM, we apply a separate NoAliasMutRef attribute
// for UniqueBorrowed arguments, so that the codegen backend can decide whether
// or not to actually emit the attribute. It can also be controlled with the
// `-Zmutable-noalias` debugging option.
let no_alias = match kind {
PointerKind::SharedMutable
| PointerKind::UniqueBorrowed
| PointerKind::UniqueBorrowedPinned => false,
PointerKind::UniqueOwned => noalias_for_box,
PointerKind::Frozen => !is_return,
};
if no_alias {
attrs.set(ArgAttribute::NoAlias);
}
if kind == PointerKind::Frozen && !is_return {
attrs.set(ArgAttribute::ReadOnly);
}
if kind == PointerKind::UniqueBorrowed && !is_return {
attrs.set(ArgAttribute::NoAliasMutRef);
}
}
}
}
impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
// FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
// arguments of this method, into a separate `struct`.
@ -3118,91 +3206,6 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
use SpecAbi::*;
let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall);
// Handle safe Rust thin and fat pointers.
let adjust_for_rust_scalar = |attrs: &mut ArgAttributes,
scalar: Scalar,
layout: TyAndLayout<'tcx>,
offset: Size,
is_return: bool| {
// Booleans are always a noundef i1 that needs to be zero-extended.
if scalar.is_bool() {
attrs.ext(ArgExtension::Zext);
attrs.set(ArgAttribute::NoUndef);
return;
}
// Scalars which have invalid values cannot be undef.
if !scalar.is_always_valid(self) {
attrs.set(ArgAttribute::NoUndef);
}
// Only pointer types handled below.
let Scalar::Initialized { value: Pointer, valid_range} = scalar else { return };
if !valid_range.contains(0) {
attrs.set(ArgAttribute::NonNull);
}
if let Some(pointee) = layout.pointee_info_at(self, offset) {
if let Some(kind) = pointee.safe {
attrs.pointee_align = Some(pointee.align);
// `Box` (`UniqueBorrowed`) are not necessarily dereferenceable
// for the entire duration of the function as they can be deallocated
// at any time. Same for shared mutable references. If LLVM had a
// way to say "dereferenceable on entry" we could use it here.
attrs.pointee_size = match kind {
PointerKind::UniqueBorrowed
| PointerKind::UniqueBorrowedPinned
| PointerKind::Frozen => pointee.size,
PointerKind::SharedMutable | PointerKind::UniqueOwned => Size::ZERO,
};
// `Box`, `&T`, and `&mut T` cannot be undef.
// Note that this only applies to the value of the pointer itself;
// this attribute doesn't make it UB for the pointed-to data to be undef.
attrs.set(ArgAttribute::NoUndef);
// The aliasing rules for `Box<T>` are still not decided, but currently we emit
// `noalias` for it. This can be turned off using an unstable flag.
// See https://github.com/rust-lang/unsafe-code-guidelines/issues/326
let noalias_for_box =
self.tcx().sess.opts.unstable_opts.box_noalias.unwrap_or(true);
// `&mut` pointer parameters never alias other parameters,
// or mutable global data
//
// `&T` where `T` contains no `UnsafeCell<U>` is immutable,
// and can be marked as both `readonly` and `noalias`, as
// LLVM's definition of `noalias` is based solely on memory
// dependencies rather than pointer equality
//
// Due to past miscompiles in LLVM, we apply a separate NoAliasMutRef attribute
// for UniqueBorrowed arguments, so that the codegen backend can decide whether
// or not to actually emit the attribute. It can also be controlled with the
// `-Zmutable-noalias` debugging option.
let no_alias = match kind {
PointerKind::SharedMutable
| PointerKind::UniqueBorrowed
| PointerKind::UniqueBorrowedPinned => false,
PointerKind::UniqueOwned => noalias_for_box,
PointerKind::Frozen => !is_return,
};
if no_alias {
attrs.set(ArgAttribute::NoAlias);
}
if kind == PointerKind::Frozen && !is_return {
attrs.set(ArgAttribute::ReadOnly);
}
if kind == PointerKind::UniqueBorrowed && !is_return {
attrs.set(ArgAttribute::NoAliasMutRef);
}
}
}
};
let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, FnAbiError<'tcx>> {
let is_return = arg_idx.is_none();
@ -3218,7 +3221,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
let mut arg = ArgAbi::new(self, layout, |layout, scalar, offset| {
let mut attrs = ArgAttributes::new();
adjust_for_rust_scalar(&mut attrs, scalar, *layout, offset, is_return);
adjust_for_rust_scalar(*self, &mut attrs, scalar, *layout, offset, is_return);
attrs
});

68
compiler/rustc_mir_transform/src/lib.rs
View file

@ -10,6 +10,7 @@
#![feature(trusted_step)]
#![feature(try_blocks)]
#![feature(yeet_expr)]
#![feature(if_let_guard)]
#![recursion_limit = "256"]
#[macro_use]
@ -27,10 +28,13 @@ use rustc_hir::intravisit::{self, Visitor};
use rustc_index::vec::IndexVec;
use rustc_middle::mir::visit::Visitor as _;
use rustc_middle::mir::{
traversal, AnalysisPhase, Body, ConstQualifs, MirPass, MirPhase, Promoted, RuntimePhase,
traversal, AnalysisPhase, Body, ConstQualifs, Constant, LocalDecl, MirPass, MirPhase, Operand,
Place, ProjectionElem, Promoted, RuntimePhase, Rvalue, SourceInfo, Statement, StatementKind,
TerminatorKind,
};
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, TyCtxt, TypeVisitable};
use rustc_span::sym;
#[macro_use]
mod pass_manager;
@ -140,6 +144,64 @@ pub fn provide(providers: &mut Providers) {
};
}
fn remap_mir_for_const_eval_select<'tcx>(
tcx: TyCtxt<'tcx>,
mut body: Body<'tcx>,
context: hir::Constness,
) -> Body<'tcx> {
for bb in body.basic_blocks.as_mut().iter_mut() {
let terminator = bb.terminator.as_mut().expect("invalid terminator");
match terminator.kind {
TerminatorKind::Call {
func: Operand::Constant(box Constant { ref literal, .. }),
ref mut args,
destination,
target,
cleanup,
fn_span,
..
} if let ty::FnDef(def_id, _) = *literal.ty().kind()
&& tcx.item_name(def_id) == sym::const_eval_select
&& tcx.is_intrinsic(def_id) =>
{
let [tupled_args, called_in_const, called_at_rt]: [_; 3] = std::mem::take(args).try_into().unwrap();
let ty = tupled_args.ty(&body.local_decls, tcx);
let fields = ty.tuple_fields();
let num_args = fields.len();
let func = if context == hir::Constness::Const { called_in_const } else { called_at_rt };
let (method, place): (fn(Place<'tcx>) -> Operand<'tcx>, Place<'tcx>) = match tupled_args {
Operand::Constant(_) => {
// there is no good way of extracting a tuple arg from a constant (const generic stuff)
// so we just create a temporary and deconstruct that.
let local = body.local_decls.push(LocalDecl::new(ty, fn_span));
bb.statements.push(Statement {
source_info: SourceInfo::outermost(fn_span),
kind: StatementKind::Assign(Box::new((local.into(), Rvalue::Use(tupled_args.clone())))),
});
(Operand::Move, local.into())
}
Operand::Move(place) => (Operand::Move, place),
Operand::Copy(place) => (Operand::Copy, place),
};
let place_elems = place.projection;
let arguments = (0..num_args).map(|x| {
let mut place_elems = place_elems.to_vec();
place_elems.push(ProjectionElem::Field(x.into(), fields[x]));
let projection = tcx.intern_place_elems(&place_elems);
let place = Place {
local: place.local,
projection,
};
method(place)
}).collect();
terminator.kind = TerminatorKind::Call { func, args: arguments, destination, target, cleanup, from_hir_call: false, fn_span };
}
_ => {}
}
}
body
}
fn is_mir_available(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
let def_id = def_id.expect_local();
tcx.mir_keys(()).contains(&def_id)
@ -354,7 +416,7 @@ fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -
debug_assert!(!body.has_free_regions(), "Free regions in MIR for CTFE");
body
remap_mir_for_const_eval_select(tcx, body, hir::Constness::Const)
}
/// Obtain just the main MIR (no promoteds) and run some cleanups on it. This also runs
@ -565,7 +627,7 @@ fn inner_optimized_mir(tcx: TyCtxt<'_>, did: LocalDefId) -> Body<'_> {
debug_assert!(!body.has_free_regions(), "Free regions in optimized MIR");
body
remap_mir_for_const_eval_select(tcx, body, hir::Constness::NotConst)
}
/// Fetch all the promoteds of an item and prepare their MIR bodies to be ready for

8
compiler/rustc_monomorphize/src/collector.rs
View file

@ -112,12 +112,6 @@
//! method in operand position, we treat it as a neighbor of the current
//! mono item. Calls are just a special case of that.
//!
//! #### Closures
//! In a way, closures are a simple case. Since every closure object needs to be
//! constructed somewhere, we can reliably discover them by observing
//! `RValue::Aggregate` expressions with `AggregateKind::Closure`. This is also
//! true for closures inlined from other crates.
//!
//! #### Drop glue
//! Drop glue mono items are introduced by MIR drop-statements. The
//! generated mono item will again have drop-glue item neighbors if the
@ -835,7 +829,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
mir::TerminatorKind::Call { ref func, .. } => {
let callee_ty = func.ty(self.body, tcx);
let callee_ty = self.monomorphize(callee_ty);
visit_fn_use(self.tcx, callee_ty, true, source, &mut self.output);
visit_fn_use(self.tcx, callee_ty, true, source, &mut self.output)
}
mir::TerminatorKind::Drop { ref place, .. }
| mir::TerminatorKind::DropAndReplace { ref place, .. } => {

1
compiler/rustc_span/src/symbol.rs
View file

@ -510,7 +510,6 @@ symbols! {
const_deallocate,
const_eval_limit,
const_eval_select,
const_eval_select_ct,
const_evaluatable_checked,
const_extern_fn,
const_fn,

33
compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
View file

@ -31,7 +31,7 @@ use rustc_middle::ty::visit::TypeVisitable;
use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty, TypeSuperVisitable, TypeVisitor};
use rustc_session::Session;
use rustc_span::symbol::Ident;
use rustc_span::{self, Span};
use rustc_span::{self, sym, Span};
use rustc_trait_selection::traits::{self, ObligationCauseCode, SelectionContext};
use std::iter;
@ -224,6 +224,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let minimum_input_count = expected_input_tys.len();
let provided_arg_count = provided_args.len();
let is_const_eval_select = matches!(fn_def_id, Some(def_id) if
self.tcx.def_kind(def_id) == hir::def::DefKind::Fn
&& self.tcx.is_intrinsic(def_id)
&& self.tcx.item_name(def_id) == sym::const_eval_select);
// We introduce a helper function to demand that a given argument satisfy a given input
// This is more complicated than just checking type equality, as arguments could be coerced
// This version writes those types back so further type checking uses the narrowed types
@ -259,6 +264,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
return Compatibility::Incompatible(coerce_error);
}
// Check that second and third argument of `const_eval_select` must be `FnDef`, and additionally that
// the second argument must be `const fn`. The first argument must be a tuple, but this is already expressed
// in the function signature (`F: FnOnce<ARG>`), so I did not bother to add another check here.
//
// This check is here because there is currently no way to express a trait bound for `FnDef` types only.
if is_const_eval_select && (1..=2).contains(&idx) {
if let ty::FnDef(def_id, _) = checked_ty.kind() {
if idx == 1 && !self.tcx.is_const_fn_raw(*def_id) {
self.tcx
.sess
.struct_span_err(provided_arg.span, "this argument must be a `const fn`")
.help("consult the documentation on `const_eval_select` for more information")
.emit();
}
} else {
self.tcx
.sess
.struct_span_err(provided_arg.span, "this argument must be a function item")
.note(format!("expected a function item, found {checked_ty}"))
.help(
"consult the documentation on `const_eval_select` for more information",
)
.emit();
}
}
// 3. Check if the formal type is a supertype of the checked one
// and register any such obligations for future type checks
let supertype_error = self

143
library/core/src/intrinsics.rs
View file

@ -54,7 +54,9 @@
)]
#![allow(missing_docs)]
use crate::marker::{Destruct, DiscriminantKind};
#[cfg(bootstrap)]
use crate::marker::Destruct;
use crate::marker::DiscriminantKind;
use crate::mem;
// These imports are used for simplifying intra-doc links
@ -2085,6 +2087,65 @@ extern "rust-intrinsic" {
/// `ptr` must point to a vtable.
/// The intrinsic will return the alignment stored in that vtable.
pub fn vtable_align(ptr: *const ()) -> usize;
/// Selects which function to call depending on the context.
///
/// If this function is evaluated at compile-time, then a call to this
/// intrinsic will be replaced with a call to `called_in_const`. It gets
/// replaced with a call to `called_at_rt` otherwise.
///
/// # Type Requirements
///
/// The two functions must be both function items. They cannot be function
/// pointers or closures. The first function must be a `const fn`.
///
/// `arg` will be the tupled arguments that will be passed to either one of
/// the two functions, therefore, both functions must accept the same type of
/// arguments. Both functions must return RET.
///
/// # Safety
///
/// The two functions must behave observably equivalent. Safe code in other
/// crates may assume that calling a `const fn` at compile-time and at run-time
/// produces the same result. A function that produces a different result when
/// evaluated at run-time, or has any other observable side-effects, is
/// *unsound*.
///
/// Here is an example of how this could cause a problem:
/// ```no_run
/// #![feature(const_eval_select)]
/// #![feature(core_intrinsics)]
/// use std::hint::unreachable_unchecked;
/// use std::intrinsics::const_eval_select;
///
/// // Crate A
/// pub const fn inconsistent() -> i32 {
/// fn runtime() -> i32 { 1 }
/// const fn compiletime() -> i32 { 2 }
///
/// unsafe {
// // ⚠ This code violates the required equivalence of `compiletime`
/// // and `runtime`.
/// const_eval_select((), compiletime, runtime)
/// }
/// }
///
/// // Crate B
/// const X: i32 = inconsistent();
/// let x = inconsistent();
/// if x != X { unsafe { unreachable_unchecked(); }}
/// ```
///
/// This code causes Undefined Behavior when being run, since the
/// `unreachable_unchecked` is actually being reached. The bug is in *crate A*,
/// which violates the principle that a `const fn` must behave the same at
/// compile-time and at run-time. The unsafe code in crate B is fine.
#[cfg(not(bootstrap))]
#[rustc_const_unstable(feature = "const_eval_select", issue = "none")]
pub fn const_eval_select<ARG, F, G, RET>(arg: ARG, called_in_const: F, called_at_rt: G) -> RET
where
G: FnOnce<ARG, Output = RET>,
F: FnOnce<ARG, Output = RET>;
}
// Some functions are defined here because they accidentally got made
@ -2095,6 +2156,11 @@ extern "rust-intrinsic" {
/// Check that the preconditions of an unsafe function are followed, if debug_assertions are on,
/// and only at runtime.
///
/// This macro should be called as `assert_unsafe_precondition!([Generics](name: Type) => Expression)`
/// where the names specified will be moved into the macro as captured variables, and defines an item
/// to call `const_eval_select` on. The tokens inside the square brackets are used to denote generics
/// for the function declaractions and can be omitted if there is no generics.
///
/// # Safety
///
/// Invoking this macro is only sound if the following code is already UB when the passed
@ -2109,18 +2175,20 @@ extern "rust-intrinsic" {
/// the occasional mistake, and this check should help them figure things out.
#[allow_internal_unstable(const_eval_select)] // permit this to be called in stably-const fn
macro_rules! assert_unsafe_precondition {
($e:expr) => {
($([$($tt:tt)*])?($($i:ident:$ty:ty),*$(,)?) => $e:expr) => {
if cfg!(debug_assertions) {
// Use a closure so that we can capture arbitrary expressions from the invocation
let runtime = || {
// allow non_snake_case to allow capturing const generics
#[allow(non_snake_case)]
fn runtime$(<$($tt)*>)?($($i:$ty),*) {
if !$e {
// abort instead of panicking to reduce impact on code size
::core::intrinsics::abort();
}
};
const fn comptime() {}
}
#[allow(non_snake_case)]
const fn comptime$(<$($tt)*>)?($(_:$ty),*) {}
::core::intrinsics::const_eval_select((), comptime, runtime);
::core::intrinsics::const_eval_select(($($i,)*), comptime, runtime);
}
};
}
@ -2243,7 +2311,7 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
// SAFETY: the safety contract for `copy_nonoverlapping` must be
// upheld by the caller.
unsafe {
assert_unsafe_precondition!(
assert_unsafe_precondition!([T](src: *const T, dst: *mut T, count: usize) =>
is_aligned_and_not_null(src)
&& is_aligned_and_not_null(dst)
&& is_nonoverlapping(src, dst, count)
@ -2329,7 +2397,8 @@ pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
// SAFETY: the safety contract for `copy` must be upheld by the caller.
unsafe {
assert_unsafe_precondition!(is_aligned_and_not_null(src) && is_aligned_and_not_null(dst));
assert_unsafe_precondition!([T](src: *const T, dst: *mut T) =>
is_aligned_and_not_null(src) && is_aligned_and_not_null(dst));
copy(src, dst, count)
}
}
@ -2397,63 +2466,12 @@ pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
// SAFETY: the safety contract for `write_bytes` must be upheld by the caller.
unsafe {
assert_unsafe_precondition!(is_aligned_and_not_null(dst));
assert_unsafe_precondition!([T](dst: *mut T) => is_aligned_and_not_null(dst));
write_bytes(dst, val, count)
}
}
/// Selects which function to call depending on the context.
///
/// If this function is evaluated at compile-time, then a call to this
/// intrinsic will be replaced with a call to `called_in_const`. It gets
/// replaced with a call to `called_at_rt` otherwise.
///
/// # Type Requirements
///
/// The two functions must be both function items. They cannot be function
/// pointers or closures.
///
/// `arg` will be the arguments that will be passed to either one of the
/// two functions, therefore, both functions must accept the same type of
/// arguments. Both functions must return RET.
///
/// # Safety
///
/// The two functions must behave observably equivalent. Safe code in other
/// crates may assume that calling a `const fn` at compile-time and at run-time
/// produces the same result. A function that produces a different result when
/// evaluated at run-time, or has any other observable side-effects, is
/// *unsound*.
///
/// Here is an example of how this could cause a problem:
/// ```no_run
/// #![feature(const_eval_select)]
/// #![feature(core_intrinsics)]
/// use std::hint::unreachable_unchecked;
/// use std::intrinsics::const_eval_select;
///
/// // Crate A
/// pub const fn inconsistent() -> i32 {
/// fn runtime() -> i32 { 1 }
/// const fn compiletime() -> i32 { 2 }
///
/// unsafe {
// // ⚠ This code violates the required equivalence of `compiletime`
/// // and `runtime`.
/// const_eval_select((), compiletime, runtime)
/// }
/// }
///
/// // Crate B
/// const X: i32 = inconsistent();
/// let x = inconsistent();
/// if x != X { unsafe { unreachable_unchecked(); }}
/// ```
///
/// This code causes Undefined Behavior when being run, since the
/// `unreachable_unchecked` is actually being reached. The bug is in *crate A*,
/// which violates the principle that a `const fn` must behave the same at
/// compile-time and at run-time. The unsafe code in crate B is fine.
#[cfg(bootstrap)]
#[unstable(
feature = "const_eval_select",
issue = "none",
@ -2475,6 +2493,7 @@ where
called_at_rt.call_once(arg)
}
#[cfg(bootstrap)]
#[unstable(
feature = "const_eval_select",
issue = "none",

2
library/core/src/mem/valid_align.rs
View file

@ -28,7 +28,7 @@ impl ValidAlign {
#[inline]
pub(crate) const unsafe fn new_unchecked(align: usize) -> Self {
// SAFETY: Precondition passed to the caller.
unsafe { assert_unsafe_precondition!(align.is_power_of_two()) };
unsafe { assert_unsafe_precondition!((align: usize) => align.is_power_of_two()) };
// SAFETY: By precondition, this must be a power of two, and
// our variants encompass all possible powers of two.

22
library/core/src/num/f32.rs
View file

@ -1033,10 +1033,13 @@ impl f32 {
}
}
}
// SAFETY: `u32` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
let rt_f32_to_u32 = |rt| unsafe { mem::transmute::<f32, u32>(rt) };
fn rt_f32_to_u32(x: f32) -> u32 {
// SAFETY: `u32` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
unsafe { mem::transmute(x) }
}
// SAFETY: We use internal implementations that either always work or fail at compile time.
unsafe { intrinsics::const_eval_select((self,), ct_f32_to_u32, rt_f32_to_u32) }
}
@ -1121,10 +1124,13 @@ impl f32 {
}
}
}
// SAFETY: `u32` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
let rt_u32_to_f32 = |rt| unsafe { mem::transmute::<u32, f32>(rt) };
fn rt_u32_to_f32(x: u32) -> f32 {
// SAFETY: `u32` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
unsafe { mem::transmute(x) }
}
// SAFETY: We use internal implementations that either always work or fail at compile time.
unsafe { intrinsics::const_eval_select((v,), ct_u32_to_f32, rt_u32_to_f32) }
}

22
library/core/src/num/f64.rs
View file

@ -1026,10 +1026,13 @@ impl f64 {
}
}
}
// SAFETY: `u64` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
let rt_f64_to_u64 = |rt| unsafe { mem::transmute::<f64, u64>(rt) };
fn rt_f64_to_u64(rt: f64) -> u64 {
// SAFETY: `u64` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
unsafe { mem::transmute::<f64, u64>(rt) }
}
// SAFETY: We use internal implementations that either always work or fail at compile time.
unsafe { intrinsics::const_eval_select((self,), ct_f64_to_u64, rt_f64_to_u64) }
}
@ -1119,10 +1122,13 @@ impl f64 {
}
}
}
// SAFETY: `u64` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
let rt_u64_to_f64 = |rt| unsafe { mem::transmute::<u64, f64>(rt) };
fn rt_u64_to_f64(rt: u64) -> f64 {
// SAFETY: `u64` is a plain old datatype so we can always... uh...
// ...look, just pretend you forgot what you just read.
// Stability concerns.
unsafe { mem::transmute::<u64, f64>(rt) }
}
// SAFETY: We use internal implementations that either always work or fail at compile time.
unsafe { intrinsics::const_eval_select((v,), ct_u64_to_f64, rt_u64_to_f64) }
}

2
library/core/src/num/nonzero.rs
View file

@ -56,7 +56,7 @@ macro_rules! nonzero_integers {
pub const unsafe fn new_unchecked(n: $Int) -> Self {
// SAFETY: this is guaranteed to be safe by the caller.
unsafe {
core::intrinsics::assert_unsafe_precondition!(n != 0);
core::intrinsics::assert_unsafe_precondition!((n: $Int) => n != 0);
Self(n)
}
}

5
library/core/src/ptr/const_ptr.rs
View file

@ -755,9 +755,12 @@ impl<T: ?Sized> *const T {
where
T: Sized,
{
let this = self;
// SAFETY: The comparison has no side-effects, and the intrinsic
// does this check internally in the CTFE implementation.
unsafe { assert_unsafe_precondition!(self >= origin) };
unsafe {
assert_unsafe_precondition!([T](this: *const T, origin: *const T) => this >= origin)
};
let pointee_size = mem::size_of::<T>();
assert!(0 < pointee_size && pointee_size <= isize::MAX as usize);

8
library/core/src/ptr/mod.rs
View file

@ -886,7 +886,7 @@ pub const unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
// SAFETY: the caller must guarantee that `x` and `y` are
// valid for writes and properly aligned.
unsafe {
assert_unsafe_precondition!(
assert_unsafe_precondition!([T](x: *mut T, y: *mut T, count: usize) =>
is_aligned_and_not_null(x)
&& is_aligned_and_not_null(y)
&& is_nonoverlapping(x, y, count)
@ -983,7 +983,7 @@ pub const unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
// and cannot overlap `src` since `dst` must point to a distinct
// allocated object.
unsafe {
assert_unsafe_precondition!(is_aligned_and_not_null(dst));
assert_unsafe_precondition!([T](dst: *mut T) => is_aligned_and_not_null(dst));
mem::swap(&mut *dst, &mut src); // cannot overlap
}
src
@ -1470,7 +1470,7 @@ pub const unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
pub unsafe fn read_volatile<T>(src: *const T) -> T {
// SAFETY: the caller must uphold the safety contract for `volatile_load`.
unsafe {
assert_unsafe_precondition!(is_aligned_and_not_null(src));
assert_unsafe_precondition!([T](src: *const T) => is_aligned_and_not_null(src));
intrinsics::volatile_load(src)
}
}
@ -1541,7 +1541,7 @@ pub unsafe fn read_volatile<T>(src: *const T) -> T {
pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
// SAFETY: the caller must uphold the safety contract for `volatile_store`.
unsafe {
assert_unsafe_precondition!(is_aligned_and_not_null(dst));
assert_unsafe_precondition!([T](dst: *mut T) => is_aligned_and_not_null(dst));
intrinsics::volatile_store(dst, src);
}
}

20
library/core/src/slice/index.rs
View file

@ -48,10 +48,12 @@ const fn slice_start_index_len_fail(index: usize, len: usize) -> ! {
}
// FIXME const-hack
#[track_caller]
fn slice_start_index_len_fail_rt(index: usize, len: usize) -> ! {
panic!("range start index {index} out of range for slice of length {len}");
}
#[track_caller]
const fn slice_start_index_len_fail_ct(_: usize, _: usize) -> ! {
panic!("slice start index is out of range for slice");
}
@ -69,10 +71,12 @@ const fn slice_end_index_len_fail(index: usize, len: usize) -> ! {
}
// FIXME const-hack
#[track_caller]
fn slice_end_index_len_fail_rt(index: usize, len: usize) -> ! {
panic!("range end index {index} out of range for slice of length {len}");
}
#[track_caller]
const fn slice_end_index_len_fail_ct(_: usize, _: usize) -> ! {
panic!("slice end index is out of range for slice");
}
@ -88,10 +92,12 @@ const fn slice_index_order_fail(index: usize, end: usize) -> ! {
}
// FIXME const-hack
#[track_caller]
fn slice_index_order_fail_rt(index: usize, end: usize) -> ! {
panic!("slice index starts at {index} but ends at {end}");
}
#[track_caller]
const fn slice_index_order_fail_ct(_: usize, _: usize) -> ! {
panic!("slice index start is larger than end");
}
@ -217,21 +223,23 @@ unsafe impl<T> const SliceIndex<[T]> for usize {
#[inline]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const T {
let this = self;
// SAFETY: the caller guarantees that `slice` is not dangling, so it
// cannot be longer than `isize::MAX`. They also guarantee that
// `self` is in bounds of `slice` so `self` cannot overflow an `isize`,
// so the call to `add` is safe.
unsafe {
assert_unsafe_precondition!(self < slice.len());
assert_unsafe_precondition!([T](this: usize, slice: *const [T]) => this < slice.len());
slice.as_ptr().add(self)
}
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut T {
let this = self;
// SAFETY: see comments for `get_unchecked` above.
unsafe {
assert_unsafe_precondition!(self < slice.len());
assert_unsafe_precondition!([T](this: usize, slice: *mut [T]) => this < slice.len());
slice.as_mut_ptr().add(self)
}
}
@ -276,22 +284,26 @@ unsafe impl<T> const SliceIndex<[T]> for ops::Range<usize> {
#[inline]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] {
let this = ops::Range { start: self.start, end: self.end };
// SAFETY: the caller guarantees that `slice` is not dangling, so it
// cannot be longer than `isize::MAX`. They also guarantee that
// `self` is in bounds of `slice` so `self` cannot overflow an `isize`,
// so the call to `add` is safe.
unsafe {
assert_unsafe_precondition!(self.end >= self.start && self.end <= slice.len());
assert_unsafe_precondition!([T](this: ops::Range<usize>, slice: *const [T]) =>
this.end >= this.start && this.end <= slice.len());
ptr::slice_from_raw_parts(slice.as_ptr().add(self.start), self.end - self.start)
}
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] {
let this = ops::Range { start: self.start, end: self.end };
// SAFETY: see comments for `get_unchecked` above.
unsafe {
assert_unsafe_precondition!(self.end >= self.start && self.end <= slice.len());
assert_unsafe_precondition!([T](this: ops::Range<usize>, slice: *mut [T]) =>
this.end >= this.start && this.end <= slice.len());
ptr::slice_from_raw_parts_mut(slice.as_mut_ptr().add(self.start), self.end - self.start)
}
}

15
library/core/src/slice/mod.rs
View file

@ -656,10 +656,11 @@ impl<T> [T] {
#[unstable(feature = "slice_swap_unchecked", issue = "88539")]
#[rustc_const_unstable(feature = "const_swap", issue = "83163")]
pub const unsafe fn swap_unchecked(&mut self, a: usize, b: usize) {
let ptr = self.as_mut_ptr();
let this = self;
let ptr = this.as_mut_ptr();
// SAFETY: caller has to guarantee that `a < self.len()` and `b < self.len()`
unsafe {
assert_unsafe_precondition!(a < self.len() && b < self.len());
assert_unsafe_precondition!([T](a: usize, b: usize, this: &mut [T]) => a < this.len() && b < this.len());
ptr::swap(ptr.add(a), ptr.add(b));
}
}
@ -972,9 +973,10 @@ impl<T> [T] {
#[inline]
#[must_use]
pub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]] {
let this = self;
// SAFETY: Caller must guarantee that `N` is nonzero and exactly divides the slice length
let new_len = unsafe {
assert_unsafe_precondition!(N != 0 && self.len() % N == 0);
assert_unsafe_precondition!([T](this: &[T], N: usize) => N != 0 && this.len() % N == 0);
exact_div(self.len(), N)
};
// SAFETY: We cast a slice of `new_len * N` elements into
@ -1111,10 +1113,11 @@ impl<T> [T] {
#[inline]
#[must_use]
pub unsafe fn as_chunks_unchecked_mut<const N: usize>(&mut self) -> &mut [[T; N]] {
let this = &*self;
// SAFETY: Caller must guarantee that `N` is nonzero and exactly divides the slice length
let new_len = unsafe {
assert_unsafe_precondition!(N != 0 && self.len() % N == 0);
exact_div(self.len(), N)
assert_unsafe_precondition!([T](this: &[T], N: usize) => N != 0 && this.len() % N == 0);
exact_div(this.len(), N)
};
// SAFETY: We cast a slice of `new_len * N` elements into
// a slice of `new_len` many `N` elements chunks.
@ -1687,7 +1690,7 @@ impl<T> [T] {
// `[ptr; mid]` and `[mid; len]` are not overlapping, so returning a mutable reference
// is fine.
unsafe {
assert_unsafe_precondition!(mid <= len);
assert_unsafe_precondition!((mid: usize, len: usize) => mid <= len);
(from_raw_parts_mut(ptr, mid), from_raw_parts_mut(ptr.add(mid), len - mid))
}
}

4
library/core/src/slice/raw.rs
View file

@ -90,7 +90,7 @@ use crate::ptr;
pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
// SAFETY: the caller must uphold the safety contract for `from_raw_parts`.
unsafe {
assert_unsafe_precondition!(
assert_unsafe_precondition!([T](data: *const T, len: usize) =>
is_aligned_and_not_null(data)
&& crate::mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize
);
@ -134,7 +134,7 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
// SAFETY: the caller must uphold the safety contract for `from_raw_parts_mut`.
unsafe {
assert_unsafe_precondition!(
assert_unsafe_precondition!([T](data: *mut T, len: usize) =>
is_aligned_and_not_null(data)
&& crate::mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize
);

2
library/core/src/str/mod.rs
View file

@ -91,10 +91,12 @@ const fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
}
}
#[track_caller]
const fn slice_error_fail_ct(_: &str, _: usize, _: usize) -> ! {
panic!("failed to slice string");
}
#[track_caller]
fn slice_error_fail_rt(s: &str, begin: usize, end: usize) -> ! {
const MAX_DISPLAY_LENGTH: usize = 256;
let trunc_len = s.floor_char_boundary(MAX_DISPLAY_LENGTH);

40
src/test/ui/consts/const-float-bits-reject-conv.stderr
View file

@ -10,16 +10,6 @@ LL | panic!("const-eval error: cannot use f32::to_bits on a
LL | unsafe { intrinsics::const_eval_select((self,), ct_f32_to_u32, rt_f32_to_u32) }
| -------------------------------------------------------------------- inside `core::f32::<impl f32>::to_bits` at $SRC_DIR/core/src/num/f32.rs:LL:COL
|
::: $SRC_DIR/core/src/ops/function.rs:LL:COL
|
LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
| ------------------------------------------------------------------ inside `<fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32} as FnOnce<(f32,)>>::call_once - shim(fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32})` at $SRC_DIR/core/src/ops/function.rs:LL:COL
|
::: $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | called_in_const.call_once(arg)
| ------------------------------ inside `const_eval_select::<(f32,), fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32}, [closure@core::f32::<impl f32>::to_bits::{closure#0}], u32>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
::: $DIR/const-float-bits-reject-conv.rs:27:30
|
LL | const MASKED_NAN1: u32 = f32::NAN.to_bits() ^ 0x002A_AAAA;
@ -39,16 +29,6 @@ LL | panic!("const-eval error: cannot use f32::to_bits on a
LL | unsafe { intrinsics::const_eval_select((self,), ct_f32_to_u32, rt_f32_to_u32) }
| -------------------------------------------------------------------- inside `core::f32::<impl f32>::to_bits` at $SRC_DIR/core/src/num/f32.rs:LL:COL
|
::: $SRC_DIR/core/src/ops/function.rs:LL:COL
|
LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
| ------------------------------------------------------------------ inside `<fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32} as FnOnce<(f32,)>>::call_once - shim(fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32})` at $SRC_DIR/core/src/ops/function.rs:LL:COL
|
::: $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | called_in_const.call_once(arg)
| ------------------------------ inside `const_eval_select::<(f32,), fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32}, [closure@core::f32::<impl f32>::to_bits::{closure#0}], u32>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
::: $DIR/const-float-bits-reject-conv.rs:28:30
|
LL | const MASKED_NAN2: u32 = f32::NAN.to_bits() ^ 0x0055_5555;
@ -117,16 +97,6 @@ LL | panic!("const-eval error: cannot use f64::to_bits on a
LL | unsafe { intrinsics::const_eval_select((self,), ct_f64_to_u64, rt_f64_to_u64) }
| -------------------------------------------------------------------- inside `core::f64::<impl f64>::to_bits` at $SRC_DIR/core/src/num/f64.rs:LL:COL
|
::: $SRC_DIR/core/src/ops/function.rs:LL:COL
|
LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
| ------------------------------------------------------------------ inside `<fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64} as FnOnce<(f64,)>>::call_once - shim(fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64})` at $SRC_DIR/core/src/ops/function.rs:LL:COL
|
::: $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | called_in_const.call_once(arg)
| ------------------------------ inside `const_eval_select::<(f64,), fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64}, [closure@core::f64::<impl f64>::to_bits::{closure#0}], u64>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
::: $DIR/const-float-bits-reject-conv.rs:54:30
|
LL | const MASKED_NAN1: u64 = f64::NAN.to_bits() ^ 0x000A_AAAA_AAAA_AAAA;
@ -146,16 +116,6 @@ LL | panic!("const-eval error: cannot use f64::to_bits on a
LL | unsafe { intrinsics::const_eval_select((self,), ct_f64_to_u64, rt_f64_to_u64) }
| -------------------------------------------------------------------- inside `core::f64::<impl f64>::to_bits` at $SRC_DIR/core/src/num/f64.rs:LL:COL
|
::: $SRC_DIR/core/src/ops/function.rs:LL:COL
|
LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
| ------------------------------------------------------------------ inside `<fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64} as FnOnce<(f64,)>>::call_once - shim(fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64})` at $SRC_DIR/core/src/ops/function.rs:LL:COL
|
::: $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | called_in_const.call_once(arg)
| ------------------------------ inside `const_eval_select::<(f64,), fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64}, [closure@core::f64::<impl f64>::to_bits::{closure#0}], u64>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
::: $DIR/const-float-bits-reject-conv.rs:55:30
|
LL | const MASKED_NAN2: u64 = f64::NAN.to_bits() ^ 0x0005_5555_5555_5555;

6
src/test/ui/intrinsics/const-eval-select-backtrace-std.rs Normal file
View file

@ -0,0 +1,6 @@
// See issue #100696.
// run-fail
// check-run-results
fn main() {
&""[1..];
}

2
src/test/ui/intrinsics/const-eval-select-backtrace-std.run.stderr Normal file
View file

@ -0,0 +1,2 @@
thread 'main' panicked at 'byte index 1 is out of bounds of ``', $DIR/const-eval-select-backtrace-std.rs:5:6
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

18
src/test/ui/intrinsics/const-eval-select-backtrace.rs Normal file
View file

@ -0,0 +1,18 @@
#![feature(core_intrinsics)]
// See issue #100696.
// run-fail
// check-run-results
#[track_caller]
fn uhoh() {
panic!("Aaah!")
}
const fn c() {}
fn main() {
// safety: this is unsound and just used to test
unsafe {
std::intrinsics::const_eval_select((), c, uhoh);
}
}

2
src/test/ui/intrinsics/const-eval-select-backtrace.run.stderr Normal file
View file

@ -0,0 +1,2 @@
thread 'main' panicked at 'Aaah!', $DIR/const-eval-select-backtrace.rs:16:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

12
src/test/ui/intrinsics/const-eval-select-bad.rs
View file

@ -5,10 +5,13 @@ use std::intrinsics::const_eval_select;
const fn not_fn_items() {
const_eval_select((), || {}, || {});
//~^ ERROR the trait bound
//~^ ERROR this argument must be a function item
//~| ERROR this argument must be a function item
const_eval_select((), 42, 0xDEADBEEF);
//~^ ERROR the trait bound
//~^ ERROR expected a `FnOnce<()>` closure
//~| ERROR expected a `FnOnce<()>` closure
//~| ERROR this argument must be a function item
//~| ERROR this argument must be a function item
}
const fn foo(n: i32) -> i32 {
@ -35,4 +38,9 @@ const fn args_ty_mismatch() {
//~^ ERROR type mismatch
}
const fn non_const_fn() {
const_eval_select((1,), bar, bar);
//~^ ERROR this argument must be a `const fn`
}
fn main() {}

83
src/test/ui/intrinsics/const-eval-select-bad.stderr
View file

@ -1,42 +1,57 @@
error[E0277]: the trait bound `[closure@$DIR/const-eval-select-bad.rs:7:27: 7:29]: FnOnce<()>` is not satisfied
--> $DIR/const-eval-select-bad.rs:7:27
|
LL | const_eval_select((), || {}, || {});
| ----------------- ^^^^^ expected an `FnOnce<()>` closure, found `[closure@$DIR/const-eval-select-bad.rs:7:27: 7:29]`
| |
| required by a bound introduced by this call
|
= help: the trait `~const FnOnce<()>` is not implemented for closure `[closure@$DIR/const-eval-select-bad.rs:7:27: 7:29]`
note: the trait `FnOnce<()>` is implemented for `[closure@$DIR/const-eval-select-bad.rs:7:27: 7:29]`, but that implementation is not `const`
error: this argument must be a function item
--> $DIR/const-eval-select-bad.rs:7:27
|
LL | const_eval_select((), || {}, || {});
| ^^^^^
= note: wrap the `[closure@$DIR/const-eval-select-bad.rs:7:27: 7:29]` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `const_eval_select`
--> $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | F: ~const FnOnce<ARG, Output = RET>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `const_eval_select`
= note: expected a function item, found [closure@$DIR/const-eval-select-bad.rs:7:27: 7:29]
= help: consult the documentation on `const_eval_select` for more information
error[E0277]: the trait bound `{integer}: FnOnce<()>` is not satisfied
--> $DIR/const-eval-select-bad.rs:9:27
error: this argument must be a function item
--> $DIR/const-eval-select-bad.rs:7:34
|
LL | const_eval_select((), || {}, || {});
| ^^^^^
|
= note: expected a function item, found [closure@$DIR/const-eval-select-bad.rs:7:34: 7:36]
= help: consult the documentation on `const_eval_select` for more information
error: this argument must be a function item
--> $DIR/const-eval-select-bad.rs:10:27
|
LL | const_eval_select((), 42, 0xDEADBEEF);
| ^^
|
= note: expected a function item, found {integer}
= help: consult the documentation on `const_eval_select` for more information
error[E0277]: expected a `FnOnce<()>` closure, found `{integer}`
--> $DIR/const-eval-select-bad.rs:10:27
|
LL | const_eval_select((), 42, 0xDEADBEEF);
| ----------------- ^^ expected an `FnOnce<()>` closure, found `{integer}`
| |
| required by a bound introduced by this call
|
= help: the trait `~const FnOnce<()>` is not implemented for `{integer}`
= help: the trait `FnOnce<()>` is not implemented for `{integer}`
= note: wrap the `{integer}` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `const_eval_select`
--> $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | F: ~const FnOnce<ARG, Output = RET>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `const_eval_select`
LL | F: FnOnce<ARG, Output = RET>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `const_eval_select`
error: this argument must be a function item
--> $DIR/const-eval-select-bad.rs:10:31
|
LL | const_eval_select((), 42, 0xDEADBEEF);
| ^^^^^^^^^^
|
= note: expected a function item, found {integer}
= help: consult the documentation on `const_eval_select` for more information
error[E0277]: expected a `FnOnce<()>` closure, found `{integer}`
--> $DIR/const-eval-select-bad.rs:9:31
--> $DIR/const-eval-select-bad.rs:10:31
|
LL | const_eval_select((), 42, 0xDEADBEEF);
| ----------------- ^^^^^^^^^^ expected an `FnOnce<()>` closure, found `{integer}`
@ -48,11 +63,11 @@ LL | const_eval_select((), 42, 0xDEADBEEF);
note: required by a bound in `const_eval_select`
--> $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | G: FnOnce<ARG, Output = RET> + ~const Destruct,
| ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `const_eval_select`
LL | G: FnOnce<ARG, Output = RET>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `const_eval_select`
error[E0271]: expected `fn(i32) -> bool {bar}` to be a fn item that returns `i32`, but it returns `bool`
--> $DIR/const-eval-select-bad.rs:29:34
--> $DIR/const-eval-select-bad.rs:32:34
|
LL | const_eval_select((1,), foo, bar);
| ----------------- ^^^ expected `i32`, found `bool`
@ -62,11 +77,11 @@ LL | const_eval_select((1,), foo, bar);
note: required by a bound in `const_eval_select`
--> $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | G: FnOnce<ARG, Output = RET> + ~const Destruct,
| ^^^^^^^^^^^^ required by this bound in `const_eval_select`
LL | G: FnOnce<ARG, Output = RET>,
| ^^^^^^^^^^^^ required by this bound in `const_eval_select`
error[E0631]: type mismatch in function arguments
--> $DIR/const-eval-select-bad.rs:34:32
--> $DIR/const-eval-select-bad.rs:37:32
|
LL | const fn foo(n: i32) -> i32 {
| --------------------------- found signature defined here
@ -81,10 +96,18 @@ LL | const_eval_select((true,), foo, baz);
note: required by a bound in `const_eval_select`
--> $SRC_DIR/core/src/intrinsics.rs:LL:COL
|
LL | F: ~const FnOnce<ARG, Output = RET>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `const_eval_select`
LL | F: FnOnce<ARG, Output = RET>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `const_eval_select`
error: aborting due to 5 previous errors
error: this argument must be a `const fn`
--> $DIR/const-eval-select-bad.rs:42:29
|
LL | const_eval_select((1,), bar, bar);
| ^^^
|
= help: consult the documentation on `const_eval_select` for more information
error: aborting due to 9 previous errors
Some errors have detailed explanations: E0271, E0277, E0631.
For more information about an error, try `rustc --explain E0271`.