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const validity checking: do not recurse to references inside MaybeDangling #154093

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Merged
rust-bors merged 1 commit into from
Mar 24, 2026
+9 −2
Merged

const validity checking: do not recurse to references inside MaybeDangling #154093

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7 changes: 5 additions & 2 deletions compiler/rustc_const_eval/src/interpret/validity.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -680,8 +680,11 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
format!("encountered a {ptr_kind} pointing to uninhabited type {ty}")
)
}
// Recursive checking
if let Some(ref_tracking) = self.ref_tracking.as_deref_mut() {

// Recursive checking (but not inside `MaybeDangling` of course).
if let Some(ref_tracking) = self.ref_tracking.as_deref_mut()
&& !self.may_dangle
{
// Proceed recursively even for ZST, no reason to skip them!
// `!` is a ZST and we want to validate it.
if let Some(ctfe_mode) = self.ctfe_mode {
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4 changes: 4 additions & 0 deletions tests/ui/consts/const-eval/valid-const.rs
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Original file line number Diff line number Diff line change
@@ -1,10 +1,12 @@
//@ check-pass
//
// Some constants that *are* valid
#![feature(maybe_dangling)]

use std::mem;
use std::ptr::NonNull;
use std::num::NonZero;
use std::mem::MaybeDangling;

const NON_NULL_PTR1: NonNull<u8> = unsafe { mem::transmute(1usize) };
const NON_NULL_PTR2: NonNull<u8> = unsafe { mem::transmute(&0) };
Expand All @@ -14,4 +16,6 @@ const NON_NULL_USIZE: NonZero<usize> = unsafe { mem::transmute(1usize) };

const UNIT: () = ();

const INVALID_INSIDE_MAYBE_DANGLING: MaybeDangling<&bool> = unsafe { std::mem::transmute(&5u8) };

fn main() {}
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