[ASTImporter] Find previous friend function template

[martong]

Ping

[shafik]

LGTM, I just ran check-lldb and I don't see any regressions.

[a_sidorin]

Hi Gabor,
This patch LGTM with a minor nit.

unittests/AST/ASTImporterTest.cpp

5375

This deserves a FIXME, I think.

[martong]

• Add FIXME

[martong]

Rebase to master

lib/AST/ASTImporter.cpp

if (Error Err = ImportDeclParts(D, DC, LexicalDC, Name, ToD, Loc))
     return std::move(Err);
 
   if (ToD)
     return ToD;
 
   // Try to find a function in our own ("to") context with the same name, same
   // type, and in the same context as the function we're importing.
   if (!LexicalDC->isFunctionOrMethod()) {
-    unsigned IDNS = Decl::IDNS_Ordinary;
+    unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_OrdinaryFriend;
     auto FoundDecls = Importer.findDeclsInToCtx(DC, Name);
     for (auto *FoundDecl : FoundDecls) {
       if (!FoundDecl->isInIdentifierNamespace(IDNS))
         continue;
 
       if (auto *FoundFunction =
           dyn_cast<FunctionTemplateDecl>(FoundDecl)) {
         if (FoundFunction->hasExternalFormalLinkage() &&

unittests/AST/ASTImporterTest.cpp

Decl *FromTU = getTuDecl(
           int f;
         };
       }
       )",
       Lang_CXX);
   auto *FromFwd = FirstDeclMatcher<CXXRecordDecl>().match(
       FromTU, cxxRecordDecl(hasName("X"), unless(isImplicit())));
   auto *FromDef = LastDeclMatcher<CXXRecordDecl>().match(
       FromTU,
       cxxRecordDecl(hasName("X"), isDefinition(), unless(isImplicit())));
   ASSERT_NE(FromFwd, FromDef);
   ASSERT_FALSE(FromFwd->isThisDeclarationADefinition());
   ASSERT_TRUE(FromDef->isThisDeclarationADefinition());
   ASSERT_EQ(FromFwd->getCanonicalDecl(), FromDef->getCanonicalDecl());
 
   auto *ToDef = cast_or_null<CXXRecordDecl>(Import(FromDef, Lang_CXX));
   auto *ToFwd = cast_or_null<CXXRecordDecl>(Import(FromFwd, Lang_CXX));
   EXPECT_NE(ToFwd, ToDef);
   EXPECT_FALSE(ToFwd->isThisDeclarationADefinition());
   EXPECT_TRUE(ToDef->isThisDeclarationADefinition());
   EXPECT_EQ(ToFwd->getCanonicalDecl(), ToDef->getCanonicalDecl());
   auto *ToTU = ToAST->getASTContext().getTranslationUnitDecl();
   // We expect no (ODR) warning during the import.
   EXPECT_EQ(0u, ToTU->getASTContext().getDiagnostics().getNumWarnings());
 }
 
+struct ImportFriendFunctionTemplates : ASTImporterOptionSpecificTestBase {};
+
+TEST_P(ImportFriendFunctionTemplates, LookupShouldFindPreviousFriend) {
+  Decl *ToTU = getToTuDecl(
+      R"(
+      class X {
+        template <typename T> friend void foo();
+      };
+      )",
+      Lang_CXX);
+  auto *Friend = FirstDeclMatcher<FunctionTemplateDecl>().match(
+      ToTU, functionTemplateDecl(hasName("foo")));
+
+  Decl *FromTU = getTuDecl(
+      R"(
+      template <typename T> void foo();
+      )",
+      Lang_CXX);
+  auto *FromFoo = FirstDeclMatcher<FunctionTemplateDecl>().match(
+      FromTU, functionTemplateDecl(hasName("foo")));
+  auto *Imported = Import(FromFoo, Lang_CXX);
+
+  // FIXME Currently chains of FunctionTemplateDecls are not implemented.
+  //EXPECT_EQ(Imported->getPreviousDecl(), Friend);
+  EXPECT_EQ(Imported, Friend);
+}
+
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ASTImporterLookupTableTest,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportExpr,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportType,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportDecl,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ASTImporterOptionSpecificTestBase,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportFunctions,
                         DefaultTestValuesForRunOptions, );
 
+INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportFriendFunctionTemplates,
+                        DefaultTestValuesForRunOptions, );
+
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportClasses,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportFriendFunctions,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportFriendClasses,
                         DefaultTestValuesForRunOptions, );