[C++20] [Modules] Prevent to accept clang modules

Close https://github.com/llvm/llvm-project/issues/64755

This wouldn't affect the form @import as the test shows. The two
affected test case `diag-flags.cpp` and `diag-pragma.cpp` are old test
cases in 2017 and 2018, when we're not so clear about the direction of
modules. And the things that these 2 tests tested can be covered by
clang modules naturally. So I change the them into clang modules to
not block this patch.

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index cd38cd4..9b8af60 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -531,6 +531,12 @@ DeclResult Sema::ActOnModuleImport(SourceLocation StartLoc,
   if (!Mod)
     return true;
 
+  if (!Mod->isInterfaceOrPartition() && !ModuleName.empty()) {
+    Diag(ImportLoc, diag::err_module_import_non_interface_nor_parition)
+        << ModuleName;
+    return true;
+  }
+
   return ActOnModuleImport(StartLoc, ExportLoc, ImportLoc, Mod, Path);
 }