[llvm] [clang] [Coroutines] Introduce [[clang::coro_only_destroy_when_complete]] (PR #71014)

[via cfe-commits]

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@@ -1775,6 +1775,17 @@ CoroCleanup
 This pass runs late to lower all coroutine related intrinsics not replaced by
 earlier passes.
 
+Attributes
+==========
+
+coro_only_destroy_when_done
+---------------------------
+
+When the coroutine are marked with coro_only_destroy_when_done, it indicates
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h-vetinari wrote:

still `_done` not `_complete`

https://github.com/llvm/llvm-project/pull/71014