[ASTImporter] Typedef import brings in the complete type

Summary:
When we already have an incomplete underlying type of a typedef in the
"To" context, and the "From" context has the same typedef, but the
underlying type is complete, then the imported type should be complete.

Fixes an assertion in CTU analysis of Xerces:
Assertion `DD && "queried property of class with no definition"' failed.
This assert is happening in the analyzer engine, because that attempts
to query an underlying type of a typedef, which happens to be
incomplete.

Reviewers: a_sidorin, a.sidorin

Subscribers: rnkovacs, dkrupp, Szelethus, cfe-commits

Differential Revision: https://reviews.llvm.org/D53693

llvm-svn: 347648

1 files changed, 32 insertions, 0 deletions

diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 3a0ee5d129c5..0450cb41a408 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -3764,6 +3764,38 @@ TEST_P(ASTImporterTestBase,
   }
 }
 
+TEST_P(ASTImporterTestBase, ImportingTypedefShouldImportTheCompleteType) {
+  // We already have an incomplete underlying type in the "To" context.
+  auto Code =
+      R"(
+      template <typename T>
+      struct S {
+        void foo();
+      };
+      using U = S<int>;
+      )";
+  Decl *ToTU = getToTuDecl(Code, Lang_CXX11);
+  auto *ToD = FirstDeclMatcher<TypedefNameDecl>().match(ToTU,
+      typedefNameDecl(hasName("U")));
+  ASSERT_TRUE(ToD->getUnderlyingType()->isIncompleteType());
+
+  // The "From" context has the same typedef, but the underlying type is
+  // complete this time.
+  Decl *FromTU = getTuDecl(std::string(Code) +
+      R"(
+      void foo(U* u) {
+        u->foo();
+      }
+      )", Lang_CXX11);
+  auto *FromD = FirstDeclMatcher<TypedefNameDecl>().match(FromTU,
+      typedefNameDecl(hasName("U")));
+  ASSERT_FALSE(FromD->getUnderlyingType()->isIncompleteType());
+
+  // The imported type should be complete.
+  auto *ImportedD = cast<TypedefNameDecl>(Import(FromD, Lang_CXX11));
+  EXPECT_FALSE(ImportedD->getUnderlyingType()->isIncompleteType());
+}
+
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, DeclContextTest,
                         ::testing::Values(ArgVector()), );