[clang] [clang] Fix self-capturing `__block` variables (PR #89475)

[via cfe-commits]

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@@ -2120,27 +2066,33 @@ void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
   // us from jumping into any of these scopes anyway.
   if (!HaveInsertPoint()) return;
 
-  const VarDecl &D = *emission.Variable;
+  // If we're initializing directly on the heap, _Block_object_destroy will
+  // handle destruction, so we don't need to perform cleanups directly.
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ille-apple wrote:

Indeed... and looking at this again, I put too much code inside the if statement.

Not only that, there's an existing bug here when combining `__attribute__((cleanup))` with `__block`: if the variable was copied to the heap, the cleanup function will be called after the byref allocation has already been freed.

Will fix.

https://github.com/llvm/llvm-project/pull/89475