[clang] [clang] Disable missing definition warning on pure virtual functions (PR #74510)

[Charalampos Mitrodimas via cfe-commits]

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@@ -18931,7 +18931,7 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
   //   constant evaluated
   bool NeededForConstantEvaluation =
       isPotentiallyConstantEvaluatedContext(*this) &&
-      isImplicitlyDefinableConstexprFunction(Func);
+      isImplicitlyDefinableConstexprFunction(Func) && !Func->isPure();
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charmitro wrote:

You're actually right. 

I don't really recall what I was entering back when I was developing it, but it should work now.

https://github.com/llvm/llvm-project/pull/74510