[clang] [clang-tools-extra] [clang] Improved canonicalization for template specialization types (PR #135119)

[Matheus Izvekov via cfe-commits]

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@@ -3250,8 +3251,7 @@ checkBuiltinTemplateIdType(Sema &SemaRef, BuiltinTemplateDecl *BTD,
 
     TemplateArgument NumArgsArg = Converted[2];
     if (NumArgsArg.isDependent())
-      return Context.getCanonicalTemplateSpecializationType(TemplateName(BTD),
-                                                            Converted);
+      return QualType();
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mizvekov wrote:

This just feeds into the CanonType / UnderlyingType of the TemplateSpecializationType created within CheckTemplateId, and returning a null qualtype here has the same effect; it will create a canonical TST with this name and arguments, but is less error prone and there is better sanity checking.

https://github.com/llvm/llvm-project/pull/135119