Auto merge of #111696 - lukas-code:offset-of-erase-regions-harder, r=compiler-errors

don't skip inference for type in `offset_of!`

Fixes rust-lang/rust#111678 by no longer skipping inference on the type in `offset_of!`. Simply erasing the regions the during writeback isn't enough and can cause ICEs. A test case for this is included.

This reverts rust-lang/rust#111661, because it becomes redundant, since inference already erases the regions.

Author: bors

core/tests/mem.rs

@@ -394,13 +394,18 @@ fn offset_of() {
         z: T
     }
 
+    trait Trait {}
+
     // Ensure that this type of generics works
     fn offs_of_z<T>() -> usize {
         offset_of!(Generic<T>, z)
     }
 
     assert_eq!(offset_of!(Generic<u8>, z), 8);
     assert_eq!(offs_of_z::<u8>(), 8);
+
+    // Ensure that it works with the implicit lifetime in `Box<dyn Trait + '_>`.
+    assert_eq!(offset_of!(Generic<Box<dyn Trait>>, z), 8);
 }
 
 #[test]