[clang] [Clang] [Sema] Handle placeholders in '.*' expressions (PR #83103)

[Aaron Ballman via cfe-commits]

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@@ -14474,6 +14474,23 @@ ExprResult Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
                                        CurFPFeatureOverrides());
   }
 
+  // If this is the .* operator, which is not overloadable, just
+  // create a built-in binary operator.
+  if (Opc == BO_PtrMemD) {
+    auto CheckPlaceholder = [&](Expr *&Arg) {
+      ExprResult Res = CheckPlaceholderExpr(Arg);
+      if (!Res.isInvalid())
+        Arg = Res.get();
+      return Res.isInvalid();
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AaronBallman wrote:

Do we perhaps want to use `!Res.isUsable()` because `CreateBuiltinBinOp()` expects the `Expr *`s to be nonnull?

https://github.com/llvm/llvm-project/pull/83103