[clang] [clang][ASTImporter] Fix crash when import `VarTemplateDecl` in record (PR #67522)

[Qizhi Hu via cfe-commits]

https://github.com/jcsxky updated https://github.com/llvm/llvm-project/pull/67522

>From 9dc31bfb012c32da7a1bf511db04df9c6c480a78 Mon Sep 17 00:00:00 2001
From: huqizhi <huqizhi at feysh.com>
Date: Wed, 27 Sep 2023 15:32:10 +0800
Subject: [PATCH] [clang][ASTImporter] fix clash when import `VarTemplateDecl`
 in record

---
 clang/lib/AST/ASTImporter.cpp           |  3 +++
 clang/unittests/AST/ASTImporterTest.cpp | 33 +++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index c7c2aecc8b179a4..a8ce1c469b6329c 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -6240,6 +6240,9 @@ ExpectedDecl ASTNodeImporter::VisitVarTemplateDecl(VarTemplateDecl *D) {
           // FIXME Check for ODR error if the two definitions have
           // different initializers?
           return Importer.MapImported(D, FoundDef);
+        if (FoundTemplate->getDeclContext()->isRecord() &&
+            D->getDeclContext()->isRecord())
+          return Importer.MapImported(D, FoundTemplate);
 
         FoundByLookup = FoundTemplate;
         break;
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index c90b5aaeb624306..8cbd5436c7093ae 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -4988,6 +4988,39 @@ TEST_P(ASTImporterOptionSpecificTestBase,
   }
 }
 
+TEST_P(ImportFriendClasses, RecordVarTemplateDecl) {
+  Decl *ToTU = getToTuDecl(
+      R"(
+      template <class T>
+      class A {
+      public:
+        template <class U>
+        static constexpr bool X = true;
+      };
+      )",
+      Lang_CXX14);
+
+  auto *Fwd = FirstDeclMatcher<VarTemplateDecl>().match(
+      ToTU, varTemplateDecl(hasName("X")));
+  Decl *FromTU = getTuDecl(
+      R"(
+      template <class T>
+      class A {
+      public:
+        template <class U>
+        static constexpr bool X = true;
+      };
+      )",
+      Lang_CXX14, "input1.cc");
+  auto *FromA = FirstDeclMatcher<VarTemplateDecl>().match(
+      FromTU, varTemplateDecl(hasName("X")));
+  auto *ToA = Import(FromA, Lang_CXX11);
+  EXPECT_TRUE(ToA);
+  EXPECT_EQ(Fwd->getTemplatedDecl(), ToA->getTemplatedDecl());
+  EXPECT_EQ(Fwd->getTemplatedDecl()->getDefinition(),
+            ToA->getTemplatedDecl()->getDefinition());
+}
+
 TEST_P(ASTImporterOptionSpecificTestBase, VarTemplateParameterDeclContext) {
   constexpr auto Code =
       R"(