[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

5109

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

 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, DeclContextTest,
                         ::testing::Values(ArgVector()), );
 
 INSTANTIATE_TEST_CASE_P(
     ParameterizedTests, CanonicalRedeclChain,
     ::testing::Values(ArgVector()),);
 
+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);
+
+  // 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, ImportClassTemplates,
                         DefaultTestValuesForRunOptions, );