Auto merge of rust-lang#127442 - saethlin:alloc-decoding-lock, r=<try>

Try to fix ICE from re-interning an AllocId with different allocation contents

I'm trying to fix the ICE in rust-lang#126741 and just based on println-debugging this lock scoping looks strange.

r? `@ghost`

Author: bors

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -222,9 +222,8 @@ impl<'s> AllocDecodingSession<'s> {
 
         // Check the decoding state to see if it's already decoded or if we should
         // decode it here.
+        let mut entry = self.state.decoding_state[idx].lock();
         let alloc_id = {
-            let mut entry = self.state.decoding_state[idx].lock();
-
             match *entry {
                 State::Done(alloc_id) => {
                     return alloc_id;
@@ -317,9 +316,7 @@ impl<'s> AllocDecodingSession<'s> {
             }
         });
 
-        self.state.decoding_state[idx].with_lock(|entry| {
-            *entry = State::Done(alloc_id);
-        });
+        *entry = State::Done(alloc_id);
 
         alloc_id
     }