From fd1ccbc68d759eef752ce1b626aca534dbf1f5a5 Mon Sep 17 00:00:00 2001 From: Evan Merlock Date: Wed, 20 Sep 2023 18:52:46 -0500 Subject: [PATCH 1/2] fix(const_eval): correctly check const type for function pointers - uses TypeReader for resolving local/return ty to support case where function pointer is before another type in a compound type --- .../src/transform/check_consts/check.rs | 38 +++++++++++-------- 1 file changed, 23 insertions(+), 15 deletions(-) diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs index 129e74425b6d7..32a7756dd39d0 100644 --- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs +++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs @@ -9,16 +9,17 @@ use rustc_infer::traits::{ImplSource, Obligation, ObligationCause}; use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor}; use rustc_middle::mir::*; use rustc_middle::traits::BuiltinImplSource; +use rustc_middle::ty::GenericArgs; use rustc_middle::ty::{self, adjustment::PointerCoercion, Instance, InstanceDef, Ty, TyCtxt}; -use rustc_middle::ty::{GenericArgKind, GenericArgs}; use rustc_middle::ty::{TraitRef, TypeVisitableExt}; use rustc_mir_dataflow::{self, Analysis}; use rustc_span::{sym, Span, Symbol}; use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _; use rustc_trait_selection::traits::{self, ObligationCauseCode, ObligationCtxt, SelectionContext}; +use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitor}; use std::mem; -use std::ops::Deref; +use std::ops::{ControlFlow, Deref}; use super::ops::{self, NonConstOp, Status}; use super::qualifs::{self, CustomEq, HasMutInterior, NeedsDrop}; @@ -188,6 +189,24 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> { } } +struct LocalReturnTyVisitor<'ck, 'mir, 'tcx> { + kind: LocalKind, + checker: &'ck mut Checker<'mir, 'tcx>, +} + +impl<'ck, 'mir, 'tcx> TypeVisitor> for LocalReturnTyVisitor<'ck, 'mir, 'tcx> { + fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow { + match t.kind() { + ty::FnPtr(_) => ControlFlow::Continue(()), + ty::Ref(_, _, hir::Mutability::Mut) => { + self.checker.check_op(ops::ty::MutRef(self.kind)); + t.super_visit_with(self) + } + _ => t.super_visit_with(self), + } + } +} + pub struct Checker<'mir, 'tcx> { ccx: &'mir ConstCx<'mir, 'tcx>, qualifs: Qualifs<'mir, 'tcx>, @@ -346,20 +365,9 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> { fn check_local_or_return_ty(&mut self, ty: Ty<'tcx>, local: Local) { let kind = self.body.local_kind(local); - for ty in ty.walk() { - let ty = match ty.unpack() { - GenericArgKind::Type(ty) => ty, - - // No constraints on lifetimes or constants, except potentially - // constants' types, but `walk` will get to them as well. - GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => continue, - }; + let mut visitor = LocalReturnTyVisitor { kind, checker: self }; - match *ty.kind() { - ty::Ref(_, _, hir::Mutability::Mut) => self.check_op(ops::ty::MutRef(kind)), - _ => {} - } - } + visitor.visit_ty(ty); } fn check_mut_borrow(&mut self, local: Local, kind: hir::BorrowKind) { From d975ae502749fa41d460588be39314f19b77db5d Mon Sep 17 00:00:00 2001 From: Evan Merlock Date: Wed, 20 Sep 2023 18:53:07 -0500 Subject: [PATCH 2/2] test(const_eval): add test cases for #114994 - add new testcase for TypeVisitor on const-eval mutable ref check --- .../ui/consts/const-eval/issue-114994-fail.rs | 14 +++++++++++++ .../const-eval/issue-114994-fail.stderr | 21 +++++++++++++++++++ tests/ui/consts/const-eval/issue-114994.rs | 18 ++++++++++++++++ 3 files changed, 53 insertions(+) create mode 100644 tests/ui/consts/const-eval/issue-114994-fail.rs create mode 100644 tests/ui/consts/const-eval/issue-114994-fail.stderr create mode 100644 tests/ui/consts/const-eval/issue-114994.rs diff --git a/tests/ui/consts/const-eval/issue-114994-fail.rs b/tests/ui/consts/const-eval/issue-114994-fail.rs new file mode 100644 index 0000000000000..7235046409191 --- /dev/null +++ b/tests/ui/consts/const-eval/issue-114994-fail.rs @@ -0,0 +1,14 @@ +// This checks that function pointer signatures that are referenced mutably +// but contain a &mut T parameter still fail in a constant context: see issue #114994. +// +// check-fail + +const fn use_mut_const_fn(_f: &mut fn(&mut String)) { //~ ERROR mutable references are not allowed in constant functions + () +} + +const fn use_mut_const_tuple_fn(_f: (fn(), &mut u32)) { //~ ERROR mutable references are not allowed in constant functions + +} + +fn main() {} diff --git a/tests/ui/consts/const-eval/issue-114994-fail.stderr b/tests/ui/consts/const-eval/issue-114994-fail.stderr new file mode 100644 index 0000000000000..4dae8ea9bcab3 --- /dev/null +++ b/tests/ui/consts/const-eval/issue-114994-fail.stderr @@ -0,0 +1,21 @@ +error[E0658]: mutable references are not allowed in constant functions + --> $DIR/issue-114994-fail.rs:6:27 + | +LL | const fn use_mut_const_fn(_f: &mut fn(&mut String)) { + | ^^ + | + = note: see issue #57349 for more information + = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable + +error[E0658]: mutable references are not allowed in constant functions + --> $DIR/issue-114994-fail.rs:10:33 + | +LL | const fn use_mut_const_tuple_fn(_f: (fn(), &mut u32)) { + | ^^ + | + = note: see issue #57349 for more information + = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0658`. diff --git a/tests/ui/consts/const-eval/issue-114994.rs b/tests/ui/consts/const-eval/issue-114994.rs new file mode 100644 index 0000000000000..a4cb2e61e5f6f --- /dev/null +++ b/tests/ui/consts/const-eval/issue-114994.rs @@ -0,0 +1,18 @@ +// This checks that function pointer signatures containing &mut T types +// work in a constant context: see issue #114994. +// +// check-pass + +const fn use_const_fn(_f: fn(&mut String)) { + () +} + +const fn get_some_fn() -> fn(&mut String) { + String::clear +} + +const fn some_const_fn() { + let _f: fn(&mut String) = String::clear; +} + +fn main() {}