Rollup merge of #105624 - compiler-errors:cache-unsound, r=jyn514

Fix unsoundness in bootstrap cache code

Discovered via #105575, which showed that rustc was failing to build during a perf run.

Author: matthiaskrgr

src/bootstrap/cache.rs

@@ -89,16 +89,16 @@ impl<T: Internable + Hash> Hash for Interned<T> {
 
 impl<T: Internable + Deref> Deref for Interned<T> {
     type Target = T::Target;
-    fn deref(&self) -> &'static Self::Target {
+    fn deref(&self) -> &Self::Target {
         let l = T::intern_cache().lock().unwrap();
-        unsafe { mem::transmute::<&Self::Target, &'static Self::Target>(l.get(*self)) }
+        unsafe { mem::transmute::<&Self::Target, &Self::Target>(l.get(*self)) }
     }
 }
 
 impl<T: Internable + AsRef<U>, U: ?Sized> AsRef<U> for Interned<T> {
-    fn as_ref(&self) -> &'static U {
+    fn as_ref(&self) -> &U {
         let l = T::intern_cache().lock().unwrap();
-        unsafe { mem::transmute::<&U, &'static U>(l.get(*self).as_ref()) }
+        unsafe { mem::transmute::<&U, &U>(l.get(*self).as_ref()) }
     }
 }