[clang] [Clang][Sema] Avoid crash in overload diagnostics for invalid static deducing-this (PR #177783)

[Luohao Wang via cfe-commits]

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@@ -11874,7 +11874,7 @@ static void DiagnoseBadConversion(Sema &S, OverloadCandidate *Cand,
       !isa<CXXConstructorDecl>(Fn)) {
     if (I == 0)
       isObjectArgument = true;
-    else if (!Fn->hasCXXExplicitFunctionObjectParameter())
+    else if (!cast<CXXMethodDecl>(Fn)->isExplicitObjectMemberFunction())
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Luohaothu wrote:

As the outer `if` states, this block handles the case where `Fn` is a CXXMethodDecl. Therefore, I think a cast is approprate.

https://github.com/llvm/llvm-project/pull/177783