Fix caller context on fused component<->component returns (bytecodealliance#12737)

In bytecodealliance#12718 I added a test for more cases but forgot to update the
`*.wast` to actually execute the test. Turns out all the cases were
failing, and so this commit properly enables the tests and then fixes
them.

Author: alexcrichton

crates/wasmtime/src/runtime/component/concurrent.rs

@@ -2507,6 +2507,14 @@ impl Instance {
                     if let ResultInfo::Heap { results } = &result_info {
                         my_src.push(ValRaw::u32(*results));
                     }
+
+                    // Execute the `return_` hook, generated by Wasmtime's FACT
+                    // compiler, in the context of the old thread. The old
+                    // thread, this thread's caller, may have `realloc`
+                    // callbacks invoked for example and those need the correct
+                    // context set for the current thread.
+                    let prev = store.0.set_thread(old_thread)?;
+
                     // SAFETY: `return_` is a valid `*mut VMFuncRef` from
                     // `wasmtime-cranelift`-generated fused adapter code.  Based
                     // on how it was constructed (see
@@ -2520,6 +2528,11 @@ impl Instance {
                             my_src.as_mut_slice().into(),
                         )?;
                     }
+
+                    // Restore the previous current thread after the
+                    // lifting/lowering has returned.
+                    store.0.set_thread(prev)?;
+
                     let state = store.0.concurrent_state_mut();
                     let thread = state.current_guest_thread()?;
                     if sync_caller {

tests/misc_testsuite/component-model/async/task-builtins.wast

@@ -381,9 +381,15 @@
   (instance $a (instantiate $A))
   (instance $b (instantiate $B (with "a" (instance $a))))
   (export "sync-to-sync" (func $b "sync-to-sync"))
+  (export "sync-to-async" (func $b "sync-to-async"))
+  (export "async-to-sync" (func $b "async-to-sync"))
+  (export "async-to-async" (func $b "async-to-async"))
 )
 
 (assert_return (invoke "sync-to-sync"))
+(assert_return (invoke "sync-to-async"))
+(assert_return (invoke "async-to-sync"))
+(assert_return (invoke "async-to-async"))
 
 ;; Same as above, but when calling the host.
 (component