[clang] [clang][ASTImporter] skip TemplateTypeParmDecl in VisitTypeAliasTemplateDecl (PR #74919)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Qizhi Hu (jcsxky)

<details>
<summary>Changes</summary>

Skip checking `TemplateTypeParmDecl ` in `VisitTypeAliasTemplateDecl`. [Fix this crash](https://github.com/llvm/llvm-project/issues/74765)

---
Full diff: https://github.com/llvm/llvm-project/pull/74919.diff


2 Files Affected:

- (modified) clang/lib/AST/ASTImporter.cpp (+2-1) 
- (modified) clang/unittests/AST/ASTImporterTest.cpp (+23) 


``````````diff
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index f1f335118f37a4..bfe9af648e603b 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -2769,7 +2769,8 @@ ASTNodeImporter::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
     unsigned IDNS = Decl::IDNS_Ordinary;
     auto FoundDecls = Importer.findDeclsInToCtx(DC, Name);
     for (auto *FoundDecl : FoundDecls) {
-      if (!FoundDecl->isInIdentifierNamespace(IDNS))
+      if (!FoundDecl->isInIdentifierNamespace(IDNS) ||
+          isa_and_nonnull<TemplateTypeParmDecl>(FoundDecl))
         continue;
       if (auto *FoundAlias = dyn_cast<TypeAliasTemplateDecl>(FoundDecl))
         return Importer.MapImported(D, FoundAlias);
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 4dd7510bf8ddf8..6f9aba2c867eea 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -9284,6 +9284,29 @@ TEST_P(ASTImporterOptionSpecificTestBase,
   // EXPECT_EQ(ToF1Imported->getPreviousDecl(), ToF1);
 }
 
+TEST_P(ASTImporterOptionSpecificTestBase, XXX) {
+  const char *Code =
+      R"(
+      struct S;
+      template <typename>
+      using Callable = S;
+      template <typename Callable>
+      int bindingFunctionVTable;
+      )";
+  Decl *FromTU = getTuDecl(Code, Lang_CXX17);
+
+  auto *FromCallable1 = FirstDeclMatcher<TypeAliasTemplateDecl>().match(
+      FromTU, typeAliasTemplateDecl(hasName("Callable")));
+
+  auto *FromCallable2 = FirstDeclMatcher<TemplateTypeParmDecl>().match(
+      FromTU, templateTypeParmDecl(hasName("Callable")));
+
+  auto *ToCallable2 = Import(FromCallable2, Lang_CXX17);
+  auto *ToCallable1 = Import(FromCallable1, Lang_CXX17);
+  EXPECT_TRUE(ToCallable1);
+  EXPECT_TRUE(ToCallable2);
+}
+
 INSTANTIATE_TEST_SUITE_P(ParameterizedTests, ASTImporterLookupTableTest,
                          DefaultTestValuesForRunOptions);
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/74919