[ASTImporter] Implicitly declare parameters for imported ObjCMethodDecls

[teemperor]

Summary

When Sema encounters a ObjCMethodDecl definition it declares the implicit parameters for the ObjCMethodDecl.
When importing such a method with the ASTImporter we need to do the same for the imported method
otherwise we will crash when generating code (where CodeGen expects that this was called by Sema).

Note I had to implement Objective-C[++] support in Language.cpp as this is the first test for Objective-C and this
would otherwise just hit this 'not implemented' assert when running the unit test.

[martong]

Thanks for addressing this, I just have some minor comments.

clang/unittests/AST/ASTImporterTest.cpp

5603

You could use a raw string literal for the code, that way we could get rid of the '\n's and the trailing " characters.

[teemperor]

• Put code in raw string (Thanks Gabor!)

[martong]

clang/unittests/AST/Language.cpp

47

I think, we should keep the "Not implemented yet!" message here. Perhaps you wanted "-std=objc++" to put next to -x objective-c++ in line 41?

[teemperor]

clang/unittests/AST/Language.cpp

47

Whoops, yes that should have stayed "Not implemented"...

[teemperor]

• Reverted unintentional change to unreachable error message.

clang/lib/AST/ASTImporter.cpp

ExpectedDecl ASTNodeImporter::VisitObjCMethodDecl(ObjCMethodDecl *D) {
   SmallVector<SourceLocation, 12> ToSelLocs(FromSelLocs.size());
   if (Error Err = ImportContainerChecked(FromSelLocs, ToSelLocs))
     return std::move(Err);
 
   ToMethod->setMethodParams(Importer.getToContext(), ToParams, ToSelLocs);
 
   ToMethod->setLexicalDeclContext(LexicalDC);
   LexicalDC->addDeclInternal(ToMethod);
+
+  // Implicit params are declared when Sema encounters the definition but this
+  // never happens when the method is imported. Manually declare the implicit
+  // params now that the MethodDecl knows its class interface.
+  if (D->getSelfDecl())
+    ToMethod->createImplicitParams(Importer.getToContext(),
+                                   ToMethod->getClassInterface());
+
   return ToMethod;
 }
 
 ExpectedDecl ASTNodeImporter::VisitObjCTypeParamDecl(ObjCTypeParamDecl *D) {
   // Import the major distinguishing characteristics of a category.
   DeclContext *DC, *LexicalDC;
   DeclarationName Name;
   SourceLocation Loc;

clang/unittests/AST/ASTImporterTest.cpp

TEST_P(ASTImporterOptionSpecificTestBase, ImportDefaultConstructibleLambdas) {
   FunctionDecl *ToF = Import(FromF, Lang_CXX2a);
   EXPECT_TRUE(ToF);
   TranslationUnitDecl *ToTU = ToAST->getASTContext().getTranslationUnitDecl();
   // We have two lambda classes after the import.
   EXPECT_EQ(DeclCounter<CXXRecordDecl>().match(ToTU, cxxRecordDecl(isLambda())),
             2u);
 }
 
+TEST_P(ASTImporterOptionSpecificTestBase, ImplicitlyDeclareSelf) {
+  Decl *FromTU = getTuDecl(R"(
+                           __attribute__((objc_root_class))
+                           @interface Root
+                           @end
+                           @interface C : Root
+                             -(void)method;
+                           @end
+                           @implementation C
+                             -(void)method {}
+                           @end
+                           )",
+                           Lang_OBJCXX, "input.mm");
+  auto *FromMethod = LastDeclMatcher<ObjCMethodDecl>().match(
+      FromTU, namedDecl(hasName("method")));
+  ASSERT_TRUE(FromMethod);
+  auto ToMethod = Import(FromMethod, Lang_OBJCXX);
+  ASSERT_TRUE(ToMethod);
+
+  // Both methods should have their implicit parameters.
+  EXPECT_TRUE(FromMethod->getSelfDecl() != nullptr);
+  EXPECT_TRUE(ToMethod->getSelfDecl() != nullptr);
+}
+
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ASTImporterLookupTableTest,
                         DefaultTestValuesForRunOptions, );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportPath,
                         ::testing::Values(ArgVector()), );
 
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ImportExpr,
                         DefaultTestValuesForRunOptions, );

clang/unittests/AST/Language.cpp

case Lang_CXX11:
     BasicArgs = {"-std=c++11", "-frtti"};
     break;
   case Lang_CXX14:
     BasicArgs = {"-std=c++14", "-frtti"};
     break;
   case Lang_CXX2a:
     BasicArgs = {"-std=c++2a", "-frtti"};
     break;
-  case Lang_OpenCL:
   case Lang_OBJCXX:
+    BasicArgs = {"-x", "objective-c++", "-frtti"};
+    break;
+  case Lang_OpenCL:
     llvm_unreachable("Not implemented yet!");
   }
   return BasicArgs;
 }
 
 } // end namespace ast_matchers
 } // end namespace clang