[Modules] Don't prevent @import from ObjectiveC

Previously we forbiden the users to import named modules from clang header
modules. However, due to an oversight, the @import form of Objective C
got involved. This is not want and we fix that in this patch.

clang/lib/Sema/SemaModule.cpp

@@ -529,7 +529,8 @@ DeclResult Sema::ActOnModuleImport(SourceLocation StartLoc,
   if (!Mod)
     return true;
 
-  if (!Mod->isInterfaceOrPartition() && !ModuleName.empty()) {
+  if (!Mod->isInterfaceOrPartition() && !ModuleName.empty() &&
+      !getLangOpts().ObjC) {
     Diag(ImportLoc, diag::err_module_import_non_interface_nor_parition)
         << ModuleName;
     return true;

clang/test/Modules/pr64755.cppm

@@ -7,6 +7,11 @@
 // RUN: %clang_cc1 -std=c++20 %t/use.cpp -fmodule-file=a0=%t/a0.pcm -verify -fsyntax-only
 // RUN: %clang_cc1 -std=c++20 %t/use.cpp -fprebuilt-module-path=%t -verify -fsyntax-only
 
+// RUN: %clang_cc1 -std=c++20 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -I%t -fmodule-name=a0 -x objective-c++ -emit-module %t/module.modulemap -o %t/a0.pcm
+// RUN: %clang_cc1 -std=c++20 -x objective-c++ %t/use_obj.cpp -fmodule-file=%t/a0.pcm -verify -fsyntax-only
+// RUN: %clang_cc1 -std=c++20 -x objective-c++ %t/use_obj.cpp -fmodule-file=a0=%t/a0.pcm -verify -fsyntax-only
+// RUN: %clang_cc1 -std=c++20 -x objective-c++ %t/use_obj.cpp -fprebuilt-module-path=%t -verify -fsyntax-only
+
 //--- module.modulemap
 module a0 { header "a0.h" export * }
 
@@ -15,3 +20,7 @@ void a0() {}
 
 //--- use.cpp
 import a0; // expected-error {{import of module 'a0' imported non C++20 importable modules}}
+
+//--- use_obj.cpp
+// expected-no-diagnostics
+@import a0;