Unrolled build for rust-lang#128453

Rollup merge of rust-lang#128453 - RalfJung:raw_eq, r=saethlin raw_eq: using it on bytes with provenance is not UB (outside const-eval) The current behavior of raw_eq violates provenance monotonicity. See rust-lang#124921 for an explanation of provenance monotonicity. It is violated in raw_eq because comparing bytes without provenance is well-defined, but adding provenance makes the operation UB. So remove the no-provenance requirement from raw_eq. However, the requirement stays in-place for compile-time invocations of raw_eq, that indeed cannot deal with provenance. Cc `@rust-lang/opsem`
rust-lang-ci · Aug 2, 2024 · afd4a8d · afd4a8d
2 parents 05e692a + f97aba2
commit afd4a8d
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Showing 7 changed files with 9 additions and 35 deletions.
diff --git a/compiler/rustc_const_eval/messages.ftl b/compiler/rustc_const_eval/messages.ftl
@@ -316,9 +316,6 @@ const_eval_range_upper = less or equal to {$hi}
 const_eval_range_wrapping = less or equal to {$hi}, or greater or equal to {$lo}
 const_eval_raw_bytes = the raw bytes of the constant (size: {$size}, align: {$align}) {"{"}{$bytes}{"}"}
 
-const_eval_raw_eq_with_provenance =
- `raw_eq` on bytes with provenance
-
 const_eval_raw_ptr_comparison =
  pointers cannot be reliably compared during const eval
  .note = see issue #53020 <https://github.com/rust-lang/rust/issues/53020> for more information

diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -690,9 +690,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
  // zero-sized access
  return Ok(&[]);
  };
- if alloc_ref.has_provenance() {
- throw_ub_custom!(fluent::const_eval_raw_eq_with_provenance);
- }
  alloc_ref.get_bytes_strip_provenance()
  };
 

diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
@@ -2436,11 +2436,13 @@ extern "rust-intrinsic" {
  ///
  /// # Safety
  ///
- /// It's UB to call this if any of the *bytes* in `*a` or `*b` are uninitialized or carry a
- /// pointer value.
+ /// It's UB to call this if any of the *bytes* in `*a` or `*b` are uninitialized.
  /// Note that this is a stricter criterion than just the *values* being
  /// fully-initialized: if `T` has padding, it's UB to call this intrinsic.
  ///
+ /// At compile-time, it is furthermore UB to call this if any of the bytes
+ /// in `*a` or `*b` have provenance.
+ ///
  /// (The implementation is allowed to branch on the results of comparisons,
  /// which is UB if any of their inputs are `undef`.)
  #[rustc_const_unstable(feature = "const_intrinsic_raw_eq", issue = "none")]

diff --git a/src/tools/miri/tests/fail/intrinsics/raw_eq_on_ptr.rs b/src/tools/miri/tests/fail/intrinsics/raw_eq_on_ptr.rs
diff --git a/src/tools/miri/tests/fail/intrinsics/raw_eq_on_ptr.stderr b/src/tools/miri/tests/fail/intrinsics/raw_eq_on_ptr.stderr
diff --git a/tests/ui/intrinsics/intrinsic-raw_eq-const-bad.rs b/tests/ui/intrinsics/intrinsic-raw_eq-const-bad.rs
@@ -10,7 +10,7 @@ const RAW_EQ_PADDING: bool = unsafe {
 const RAW_EQ_PTR: bool = unsafe {
  std::intrinsics::raw_eq(&(&0), &(&1))
 //~^ ERROR evaluation of constant value failed
-//~| `raw_eq` on bytes with provenance
+//~| unable to turn pointer into integer
 };
 
 pub fn main() {

diff --git a/tests/ui/intrinsics/intrinsic-raw_eq-const-bad.stderr b/tests/ui/intrinsics/intrinsic-raw_eq-const-bad.stderr
@@ -8,7 +8,10 @@ error[E0080]: evaluation of constant value failed
  --> $DIR/intrinsic-raw_eq-const-bad.rs:11:5
  |
 LL | std::intrinsics::raw_eq(&(&0), &(&1))
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `raw_eq` on bytes with provenance
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into integer
+ |
+ = help: this code performed an operation that depends on the underlying bytes representing a pointer
+ = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
 
 error: aborting due to 2 previous errors