[clang] [clang][ASTImporter] Fix crash when template class static member imported to other translation unit. (PR #68774)

[via cfe-commits]

https://github.com/mzyKi updated https://github.com/llvm/llvm-project/pull/68774

>From e45c5e2792563ee8c7d84106fd6860656bac63bc Mon Sep 17 00:00:00 2001
From: miaozhiyuan <miaozhiyuan at feysh.com>
Date: Wed, 11 Oct 2023 15:45:36 +0800
Subject: [PATCH] [clang][ASTImporter] Fix crash when template class static
 member imported to other translation unit. Fixes: #68769

---
 clang/docs/ReleaseNotes.rst             |  4 +++
 clang/lib/AST/ASTImporter.cpp           | 11 +++++++++
 clang/unittests/AST/ASTImporterTest.cpp | 33 +++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 2d918967e7f0b02..3be9e60c82a18d0 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -497,6 +497,10 @@ Bug Fixes to C++ Support
   rather than prefer the non-templated constructor as specified in
   [standard.group]p3.
 
+- Fix crash when template class static member imported to other translation unit.
+  Fixes:
+  (`#68769 <https://github.com/llvm/llvm-project/issues/68769>`_)
+
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 - Fixed an import failure of recursive friend class template.
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 72e70427161bb0e..2a8add84f55dc3b 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -4475,6 +4475,17 @@ ExpectedDecl ASTNodeImporter::VisitVarDecl(VarDecl *D) {
     auto ToVTOrErr = import(D->getDescribedVarTemplate());
     if (!ToVTOrErr)
       return ToVTOrErr.takeError();
+  } else if (MemberSpecializationInfo *MSI = D->getMemberSpecializationInfo()) {
+    TemplateSpecializationKind SK = MSI->getTemplateSpecializationKind();
+    VarDecl *FromInst = D->getInstantiatedFromStaticDataMember();
+    if (Expected<VarDecl *> ToInstOrErr = import(FromInst))
+      ToVar->setInstantiationOfStaticDataMember(*ToInstOrErr, SK);
+    else
+      return ToInstOrErr.takeError();
+    if (ExpectedSLoc POIOrErr = import(MSI->getPointOfInstantiation()))
+      ToVar->getMemberSpecializationInfo()->setPointOfInstantiation(*POIOrErr);
+    else
+      return POIOrErr.takeError();
   }
 
   if (Error Err = ImportInitializer(D, ToVar))
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 393ed44de3f1831..f08befcc1f0db7e 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -1373,6 +1373,39 @@ TEST_P(ASTImporterOptionSpecificTestBase, ImportCorrectTemplatedDecl) {
   ASSERT_EQ(ToTemplated1, ToTemplated);
 }
 
+TEST_P(ASTImporterOptionSpecificTestBase, ImportTemplateSpecializationStaticMember) {
+  auto FromCode = R"(
+      template <typename H> class Test{
+      public:
+	      static const unsigned int length;
+      };
+
+      template<> const unsigned int Test<int>::length;
+      template<> const unsigned int Test<int>::length = 0;
+      )";
+  auto ToCode = R"(
+    template <typename H> class Test
+    {
+    public:
+	    static const unsigned int length;
+    };
+    template<> const unsigned int Test<int>::length;
+
+    void foo(){
+    int i = 1 / Test<int>::length;
+    }
+    )";
+  Decl *FromTU = getTuDecl(FromCode, Lang_CXX14);
+  auto FromDecl = FirstDeclMatcher<VarDecl>().match(
+      FromTU, varDecl(hasName("length"), isDefinition()));
+  Decl *ToTu = getToTuDecl(ToCode, Lang_CXX14);
+  auto ToX = Import(FromDecl, Lang_CXX03);
+  auto ToDecl = FirstDeclMatcher<VarDecl>().match(
+      ToTu, varDecl(hasName("length"), isDefinition()));
+  EXPECT_TRUE(ToX);
+  EXPECT_EQ(ToX, ToDecl);
+}
+
 TEST_P(ASTImporterOptionSpecificTestBase, ImportChooseExpr) {
   // This tests the import of isConditionTrue directly to make sure the importer
   // gets it right.