[clang] [clang][Sema] fix crash on __type_pack_element with dependent packs (GH180307) (PR #180407)

[via cfe-commits]

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@@ -3406,6 +3406,10 @@ static QualType checkBuiltinTemplateIdType(
     Sema &SemaRef, ElaboratedTypeKeyword Keyword, BuiltinTemplateDecl *BTD,
     ArrayRef<TemplateArgument> Converted, SourceLocation TemplateLoc,
     TemplateArgumentListInfo &TemplateArgs) {
+  if (llvm::any_of(Converted,
+                   [](const TemplateArgument &A) { return A.isDependent(); }))
+    return QualType();
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Serosh-commits wrote:

> Oh huh, I wouldn't have thought of doing it this way. Good call.
> 
> Are we able to check that the minimum arg count is reached? e.g
> 
> ```c++
> __some_builtin_template<{some template parameter set}>(...)
> ```
> 
> is always invalid if there are insufficient template parameters (assuming no packs), e.g we can error out on incorrect/insufficient template parameters even if they are dependent

Thanks That's a great point. If the arity is already insufficient, the template is invalid regardless of dependency. I can update the top-level gatekeeper to also check Converted.size() against getMinRequiredArguments()
this would catch these cases early and ensure that the case-specific internal assertions are always safe. Does that sound good to you?

https://github.com/llvm/llvm-project/pull/180407