Rollup merge of #92704 - 5225225:std_mem_transmute_ref_t_mut_t, r=michaelwoerister

[rust.git] / compiler / rustc_lint / src / builtin.rs

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 66a89492abd84323134090d364b3bfdee2311f37..38e1669d331977ed5207eba26218ed452f1008dd 100644 (file)
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -1247,7 +1247,7 @@ fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
     /// [`UnsafeCell`]: https://doc.rust-lang.org/std/cell/struct.UnsafeCell.html
     MUTABLE_TRANSMUTES,
     Deny,
-    "mutating transmuted &mut T from &T may cause undefined behavior"
+    "transmuting &T to &mut T is undefined behavior, even if the reference is unused"
 }
 
 declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
@@ -1259,8 +1259,8 @@ fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
             get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (ty1.kind(), ty2.kind()))
         {
             if to_mt == hir::Mutability::Mut && from_mt == hir::Mutability::Not {
-                let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
-                               consider instead using an UnsafeCell";
+                let msg = "transmuting &T to &mut T is undefined behavior, \
+                    even if the reference is unused, consider instead using an UnsafeCell";
                 cx.struct_span_lint(MUTABLE_TRANSMUTES, expr.span, |lint| lint.build(msg).emit());
             }
         }