Merging upstream version 1.69.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/tests/mir-opt/dataflow-const-prop/sibling_ptr.rs b/tests/mir-opt/dataflow-const-prop/sibling_ptr.rs
index 87ef00d18..6dfb3a4ed 100644
--- a/tests/mir-opt/dataflow-const-prop/sibling_ptr.rs
+++ b/tests/mir-opt/dataflow-const-prop/sibling_ptr.rs
@@ -1,3 +1,10 @@
+// This attempts to modify `x.1` via a pointer derived from `addr_of_mut!(x.0)`.
+// According to Miri, that is UB. However, T-opsem has not finalized that
+// decision and as such we cannot rely on it in optimizations. Consequently,
+// DataflowConstProp must treat the `addr_of_mut!(x.0)` as potentially being
+// used to modify `x.1` - if it did not, then it might incorrectly assume that it
+// can infer the value of `x.1` at the end of this function.
+
 // unit-test: DataflowConstProp
 
 // EMIT_MIR sibling_ptr.main.DataflowConstProp.diff
@@ -7,5 +14,5 @@ fn main() {
         let p = std::ptr::addr_of_mut!(x.0);
         *p.add(1) = 1;
     }
-    let x1 = x.1;  // should not be propagated
+    let x1 = x.1; // should not be propagated
 }