[clang] [HLSL] Implement output parameter (PR #101083)

[John McCall via cfe-commits]

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@@ -5915,6 +5916,16 @@ bool Sema::GatherArgumentsForCall(SourceLocation CallLoc, FunctionDecl *FDecl,
           ProtoArgType->isBlockPointerType())
         if (auto *BE = dyn_cast<BlockExpr>(Arg->IgnoreParenNoopCasts(Context)))
           BE->getBlockDecl()->setDoesNotEscape();
+      // During template instantiation it is possible that we already created
+      // the HLSLOutArgExpr if it was produced during tree transformation.
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rjmccall wrote:

Since you've fixed TreeTransform to look through the `HLSLOutArgExpr`, it should now no longer be possible to see an `HLSLOutArgExpr` here.

https://github.com/llvm/llvm-project/pull/101083