[ASTImporter] Extend lookup logic in class templates
During import of a class template, lookup may find a forward
declaration and structural match falsely reports equivalency
between a forward decl and a definition. The result is that
some definitions are not imported if we had imported a forward
decl previously. This patch gives a fix.
Patch by Gabor Marton!
Differential Revision: https://reviews.llvm.org/D46353
llvm-svn: 332338
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 57d4585..d8c2259 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -4108,8 +4108,14 @@
if (auto *FoundTemplate = dyn_cast<ClassTemplateDecl>(Found)) {
if (IsStructuralMatch(D, FoundTemplate)) {
// The class templates structurally match; call it the same template.
- // FIXME: We may be filling in a forward declaration here. Handle
- // this case!
+
+ // We found a forward declaration but the class to be imported has a
+ // definition.
+ // FIXME Add this forward declaration to the redeclaration chain.
+ if (D->isThisDeclarationADefinition() &&
+ !FoundTemplate->isThisDeclarationADefinition())
+ continue;
+
Importer.Imported(D->getTemplatedDecl(),
FoundTemplate->getTemplatedDecl());
return Importer.Imported(D, FoundTemplate);
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index debcfe6..9eec1d2 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -1431,6 +1431,39 @@
MatchVerifier<Decl>{}.match(To->getTranslationUnitDecl(), Pattern));
}
+TEST_P(ASTImporterTestBase, ImportDefinitionOfClassTemplateAfterFwdDecl) {
+ {
+ Decl *FromTU = getTuDecl(
+ R"(
+ template <typename T>
+ struct B;
+ )",
+ Lang_CXX, "input0.cc");
+ auto *FromD = FirstDeclMatcher<ClassTemplateDecl>().match(
+ FromTU, classTemplateDecl(hasName("B")));
+
+ Import(FromD, Lang_CXX);
+ }
+
+ {
+ Decl *FromTU = getTuDecl(
+ R"(
+ template <typename T>
+ struct B {
+ void f();
+ };
+ )",
+ Lang_CXX, "input1.cc");
+ FunctionDecl *FromD = FirstDeclMatcher<FunctionDecl>().match(
+ FromTU, functionDecl(hasName("f")));
+ Import(FromD, Lang_CXX);
+ auto *FromCTD = FirstDeclMatcher<ClassTemplateDecl>().match(
+ FromTU, classTemplateDecl(hasName("B")));
+ auto *ToCTD = cast<ClassTemplateDecl>(Import(FromCTD, Lang_CXX));
+ EXPECT_TRUE(ToCTD->isThisDeclarationADefinition());
+ }
+}
+
INSTANTIATE_TEST_CASE_P(
ParameterizedTests, ASTImporterTestBase,
::testing::Values(ArgVector(), ArgVector{"-fdelayed-template-parsing"}),);