Address review comments

Author: tbaederr

clang/docs/ReleaseNotes.rst

@@ -76,6 +76,7 @@ C++20 Feature Support
 
 C++23 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
+- Removed the restriction to literal types in constexpr functions in C++23 mode.
 
 C++2c Feature Support
 ^^^^^^^^^^^^^^^^^^^^^

clang/lib/AST/ExprConstant.cpp

@@ -2401,10 +2401,11 @@ static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
 /// produce an appropriate diagnostic.
 static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
                              const LValue *This = nullptr) {
-  if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx))
+  // The restriction to literal types does not exist in C++23 anymore.
+  if (Info.getLangOpts().CPlusPlus23)
     return true;
 
-  if (Info.getLangOpts().CPlusPlus23)
+  if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx))
     return true;
 
   // C++1y: A constant initializer for an object o [...] may also invoke