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| author | León Orell Valerian Liehr <me@fmease.dev> | 2025-06-10 16:54:50 +0200 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2025-06-10 16:54:50 +0200 |
| commit | e8be230f1ff21e00d54dd45f4f3119ca35ec2196 (patch) | |
| tree | 998b3f7fe5125aa4e19680723911bcbb637ec16b | |
| parent | 590f630ec6affc51dee868ad968743fe4b7251fc (diff) | |
| parent | c677dc26b4d9d5e742ff860ace924a270a2266b6 (diff) | |
| download | rust-e8be230f1ff21e00d54dd45f4f3119ca35ec2196.tar.gz rust-e8be230f1ff21e00d54dd45f4f3119ca35ec2196.zip | |
Rollup merge of #142124 - oli-obk:transmute-cast, r=scottmcm
Allow transmute casts in pre-runtime-MIR r? ``@scottmcm`` cc ``@BoxyUwU`` turns out in https://github.com/rust-lang/rust/pull/138393 I erroneously used transmute casts in https://github.com/rust-lang/rust/blob/fd3da4bebdff63b7529483ff7025986ef16bf463/compiler/rustc_mir_build/src/builder/matches/test.rs#L209 I don't think they have any issues using them before runtime, we just checked for them because we didn't have code exercising those code paths
| -rw-r--r-- | compiler/rustc_middle/src/mir/syntax.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/validate.rs | 48 | ||||
| -rw-r--r-- | tests/ui/type/pattern_types/matching.rs | 1 |
3 files changed, 20 insertions, 31 deletions
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs index bb068f3821d..f2f975a6968 100644 --- a/compiler/rustc_middle/src/mir/syntax.rs +++ b/compiler/rustc_middle/src/mir/syntax.rs @@ -1531,8 +1531,6 @@ pub enum CastKind { /// /// MIR is well-formed if the input and output types have different sizes, /// but running a transmute between differently-sized types is UB. - /// - /// Allowed only in [`MirPhase::Runtime`]; Earlier it's a [`TerminatorKind::Call`]. Transmute, } diff --git a/compiler/rustc_mir_transform/src/validate.rs b/compiler/rustc_mir_transform/src/validate.rs index fd91508cc11..7dcdd7999f2 100644 --- a/compiler/rustc_mir_transform/src/validate.rs +++ b/compiler/rustc_mir_transform/src/validate.rs @@ -1308,37 +1308,27 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> { } } CastKind::Transmute => { - if let MirPhase::Runtime(..) = self.body.phase { - // Unlike `mem::transmute`, a MIR `Transmute` is well-formed - // for any two `Sized` types, just potentially UB to run. - - if !self - .tcx - .normalize_erasing_regions(self.typing_env, op_ty) - .is_sized(self.tcx, self.typing_env) - { - self.fail( - location, - format!("Cannot transmute from non-`Sized` type {op_ty}"), - ); - } - if !self - .tcx - .normalize_erasing_regions(self.typing_env, *target_type) - .is_sized(self.tcx, self.typing_env) - { - self.fail( - location, - format!("Cannot transmute to non-`Sized` type {target_type:?}"), - ); - } - } else { + // Unlike `mem::transmute`, a MIR `Transmute` is well-formed + // for any two `Sized` types, just potentially UB to run. + + if !self + .tcx + .normalize_erasing_regions(self.typing_env, op_ty) + .is_sized(self.tcx, self.typing_env) + { self.fail( location, - format!( - "Transmute is not supported in non-runtime phase {:?}.", - self.body.phase - ), + format!("Cannot transmute from non-`Sized` type {op_ty}"), + ); + } + if !self + .tcx + .normalize_erasing_regions(self.typing_env, *target_type) + .is_sized(self.tcx, self.typing_env) + { + self.fail( + location, + format!("Cannot transmute to non-`Sized` type {target_type:?}"), ); } } diff --git a/tests/ui/type/pattern_types/matching.rs b/tests/ui/type/pattern_types/matching.rs index b8463a8e822..21f89b3b673 100644 --- a/tests/ui/type/pattern_types/matching.rs +++ b/tests/ui/type/pattern_types/matching.rs @@ -1,6 +1,7 @@ #![feature(pattern_types, pattern_type_macro, structural_match)] //@ check-pass +//@ compile-flags: -Zvalidate-mir use std::marker::StructuralPartialEq; use std::pat::pattern_type; |