[clang] [Clang] Instantiate constexpr function when they are needed. (PR #173537)

[Younan Zhang via cfe-commits]

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@@ -2958,3 +2970,21 @@ Attr *Sema::CreateAnnotationAttr(const ParsedAttr &AL) {
 
   return CreateAnnotationAttr(AL, Str, Args);
 }
+
+class SemaProxyImplementation final : public SemaProxy {
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zyn0217 wrote:

How about `SemaProxyForConstantEvaluator`?

https://github.com/llvm/llvm-project/pull/173537