[clang] [Clang] Preserve coroutine parameter referenced state (PR #70973)

[Chuanqi Xu via cfe-commits]

================
@@ -1965,9 +1965,15 @@ bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
     if (PD->getType()->isDependentType())
       continue;
 
+    // Preserve the referenced state for unused parameter diagnostics.
+    bool DeclReferenced = PD->isReferenced();
----------------
ChuanqiXu9 wrote:

Since we will construct the parameter moves at the very beginning of the coroutine function, I am wondering if it is really possible that `PD->isReferenced()` may be true now. And if it is not possible,
we should convert it to  `assert(!PD->isReferenced());`. Please changing this after  verifying this with some actual coroutine related workloads.

https://github.com/llvm/llvm-project/pull/70973