[clang] [Clang] Ignore invalid base classes (PR #147213)

[Shafik Yaghmour via cfe-commits]

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@@ -2252,7 +2252,7 @@ void Parser::ParseBaseClause(Decl *ClassDecl) {
   while (true) {
     // Parse a base-specifier.
     BaseResult Result = ParseBaseSpecifier(ClassDecl);
-    if (Result.isInvalid()) {
+    if (!Result.isUsable()) {
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shafik wrote:

I am a bit surprised we still don't want the `BaseInfo.push_back(Result.get())` in the else branch in the good case. Why does not having this not change behavior?

https://github.com/llvm/llvm-project/pull/147213