[clang] [clang][ASTImporter] Fix import of template parameter default values. (PR #100100)

[Donát Nagy via cfe-commits]

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@@ -359,6 +359,31 @@ namespace clang {
           Params, Importer.getToContext().getTranslationUnitDecl());
     }
 
+    template <typename TemplateParmDeclT>
+    void tryUpdateTemplateParmDeclInheritedFrom(NamedDecl *RecentParm,
+                                                NamedDecl *NewParm) {
+      if (auto *ParmT = dyn_cast<TemplateParmDeclT>(RecentParm)) {
+        if (ParmT->hasDefaultArgument()) {
+          auto *P = cast<TemplateParmDeclT>(NewParm);
+          P->removeDefaultArgument();
+          P->setInheritedDefaultArgument(Importer.ToContext, ParmT);
+        }
+      }
+    }
+
+    void updateTemplateParametersInheritedFrom(
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NagyDonat wrote:

Thanks for the clarifications!

https://github.com/llvm/llvm-project/pull/100100