[clang] [clang][ASTImporter] Fix import of variable template redeclarations. (PR #72841)

[Balázs Kéri via cfe-commits]

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@@ -5050,6 +5050,59 @@ TEST_P(ImportFriendClasses, RecordVarTemplateDecl) {
   EXPECT_EQ(ToTUX, ToX);
 }
 
+TEST_P(ASTImporterOptionSpecificTestBase, VarTemplateDeclConflict) {
+  getToTuDecl(
+      R"(
+      template <class U>
+      constexpr int X = 1;
+      )",
+      Lang_CXX14);
+
+  Decl *FromTU = getTuDecl(
+      R"(
+      template <class U>
+      constexpr int X = 2;
+      )",
+      Lang_CXX14, "input1.cc");
+  auto *FromX = FirstDeclMatcher<VarTemplateDecl>().match(
+      FromTU, varTemplateDecl(hasName("X")));
+  auto *ToX = Import(FromX, Lang_CXX11);
+  // FIXME: This import should fail.
+  EXPECT_TRUE(ToX);
+}
+
+TEST_P(ASTImporterOptionSpecificTestBase, VarTemplateStaticDefinition) {
+  Decl *ToTU = getToTuDecl(
+      R"(
+      struct A {
+        template <class U, class V>
+        static int X;
+      };
+      )",
+      Lang_CXX14);
+  auto *ToX = FirstDeclMatcher<VarTemplateDecl>().match(
+      ToTU, varTemplateDecl(hasName("X")));
+  ASSERT_FALSE(ToX->isThisDeclarationADefinition());
+
+  Decl *FromTU = getTuDecl(
+      R"(
+      struct A {
+        template <class U>
----------------
balazske wrote:

Yes, this code was incorrect. It is still a bug that the test did not fail, my next planned fixes should improve this situation.

https://github.com/llvm/llvm-project/pull/72841