Evaluate place expression in PlaceMention.

2022-11-24 19:09:27 +00:00
parent 409661936f
commit ddfa2463e2
13 changed files with 159 additions and 19 deletions
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -331,7 +331,8 @@ pub enum StatementKind<'tcx> {
    /// This is especially useful for `let _ = PLACE;` bindings that desugar to a single
    /// `PlaceMention(PLACE)`.
    ///
-    /// When executed at runtime this is a nop.
+    /// When executed at runtime, this computes the given place, but then discards
+    /// it without doing a load. It is UB if the place is not pointing to live memory.
    ///
    /// Disallowed after drop elaboration.
    PlaceMention(Box<Place<'tcx>>),