[clang] [Clang] Propagate elide safe context through [[clang::coro_must_await]] (PR #108474)

[Yuxuan Chen via cfe-commits]

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@@ -249,7 +249,10 @@ Attribute Changes in Clang
   (#GH106864)
 
 - Introduced a new attribute ``[[clang::coro_await_elidable]]`` on coroutine return types
-  to express elideability at call sites where the coroutine is co_awaited as a prvalue.
+  to express elideability at call sites where the coroutine is invoked under a safe elide context.
+
+- Introduced a new attribute ``[[clang::coro_must_await]]`` on function parameters to
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yuxuanchen1997 wrote:

Or just`[[clang::coro_await_argument]]`? If some "coro_await_elidable" is an argument that's `[[clang::coro_await_argument]]`, it indicates elidability. 

https://github.com/llvm/llvm-project/pull/108474