[clang] [HLSL] Handle init list with OpaqueValueExprs in CGExprScalar (PR #138541)

[Chris B via cfe-commits]

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@@ -2095,6 +2096,17 @@ Value *ScalarExprEmitter::VisitInitListExpr(InitListExpr *E) {
   assert (Ignore == false && "init list ignored");
   unsigned NumInitElements = E->getNumInits();
 
+  // HLSL initialization lists in the AST are an expansion which can contain
+  // side-effecting expressions wrapped in opaque value expressions. To properly
+  // emit these we need to emit the opaque values before we emit the argument
+  // expressions themselves. This is a little hacky, but it prevents us needing
+  // to do a bigger AST-level change for a language feature that we need
+  // deprecate in the near future. See related HLSL language proposals:
+  // * 0005-strict-initializer-lists.md
+  // * https://github.com/microsoft/hlsl-specs/pull/325
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llvm-beanz wrote:

This looks an awful lot like a comment I wrote... minor suggested update:
```suggestion
  // deprecate in the near future. See related HLSL language proposals in the
  // proposals (https://github.com/microsoft/hlsl-specs/blob/main/proposals):
  // * 0005-strict-initializer-lists.md
  // * 0032-constructors.md
```

https://github.com/llvm/llvm-project/pull/138541