[Clang] Dispatch default overloads of TemplateArgumentVisitor to the implementation

[egorzhdan]

This fixes an issue where overriding clang::ConstTemplateArgumentVisitor::VisitTemplateArgument in an implementation visitor class did not have the desired effect: the overload was not invoked when one of the visitor methods (e.g. VisitDeclarationArgument) is not implemented, instead it dispatched to clang::ConstTemplateArgumentVisitor::VisitTemplateArgument itself and always returned a default-initialized result.

This makes TemplateArgumentVisitor and ConstTemplateArgumentVisitor follow the implicit convention that is followed elsewhere in Clang AST, in RecursiveASTVisitor and TypeVisitor.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Egor Zhdan (egorzhdan)

Changes

This fixes an issue where overriding clang::ConstTemplateArgumentVisitor::VisitTemplateArgument in an implementation visitor class did not have the desired effect: the overload was not invoked when one of the visitor methods (e.g. VisitDeclarationArgument) is not implemented, instead it dispatched to clang::ConstTemplateArgumentVisitor::VisitTemplateArgument itself and always returned a default-initialized result.

This makes TemplateArgumentVisitor and ConstTemplateArgumentVisitor follow the implicit convention that is followed elsewhere in Clang AST, in RecursiveASTVisitor and TypeVisitor.

---

Full diff: https://github.com/llvm/llvm-project/pull/115336.diff

1 Files Affected:

• (modified) clang/include/clang/AST/TemplateArgumentVisitor.h (+2-1)

diff --git a/clang/include/clang/AST/TemplateArgumentVisitor.h b/clang/include/clang/AST/TemplateArgumentVisitor.h
index cf0d3220158063..923f045a995703 100644
--- a/clang/include/clang/AST/TemplateArgumentVisitor.h
+++ b/clang/include/clang/AST/TemplateArgumentVisitor.h
@@ -52,7 +52,8 @@ class Base {
 #define VISIT_METHOD(CATEGORY)                                                 \
   RetTy Visit##CATEGORY##TemplateArgument(REF(TemplateArgument) TA,            \
                                           ParamTys... P) {                     \
-    return VisitTemplateArgument(TA, std::forward<ParamTys>(P)...);            \
+    return static_cast<ImplClass *>(this)->VisitTemplateArgument(              \
+        TA, std::forward<ParamTys>(P)...);                                     \
   }
 
   VISIT_METHOD(Null);