[clang] Enable matrices in HLSL (PR #111415)

[Florian Hahn via cfe-commits]

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@@ -459,8 +459,81 @@ void HLSLExternalSemaSource::defineHLSLVectorAlias() {
   HLSLNamespace->addDecl(Template);
 }
 
+void HLSLExternalSemaSource::defineHLSLMatrixAlias() {
+  ASTContext &AST = SemaPtr->getASTContext();
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fhahn wrote:

Could you add a comment here explaining what alias is added?

https://github.com/llvm/llvm-project/pull/111415