[clang] [clang-tools-extra] [Clang][Sema] Fix explicit specializations of member function templates with a deduced return type (PR #86817)

[Krystian Stasiowski via cfe-commits]

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@@ -12107,6 +12090,35 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
 
   CheckConstPureAttributesUsage(*this, NewFD);
 
+  // C++23 [dcl.spec.auto.general]p12:
+  //   Return type deduction for a templated function with a placeholder in its
+  //   declared type occurs when the definition is instantiated even if the
+  //   function body contains a return statement with a non-type-dependent
+  //   operand.
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sdkrystian wrote:

I changed both quotes to "C++"

https://github.com/llvm/llvm-project/pull/86817