[C++20] [Modules] Don't complain about duplicated default template argument across modules

 See https://github.com/cplusplus/draft/pull/5204 for a detailed
 background.

 Simply, the test redundant-template-default-arg.cpp attached to this
 patch should be accepted instead of being complained about the
 redefinition.

 Reviewed By: urnathan, rsmith, ChuanqiXu

 Differential Revision: https://reviews.llvm.org/D118034

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index 3aa124d..e9a1ac17 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -935,3 +935,16 @@ void Sema::PopGlobalModuleFragment() {
          "left the wrong module scope, which is not global module fragment");
   ModuleScopes.pop_back();
 }
+
+bool Sema::isModuleUnitOfCurrentTU(const Module *M) const {
+  assert(M);
+
+  Module *CurrentModuleUnit = getCurrentModule();
+
+  // If we are not in a module currently, M must not be the module unit of
+  // current TU.
+  if (!CurrentModuleUnit)
+    return false;
+
+  return M->isSubModuleOf(CurrentModuleUnit->getTopLevelModule());
+}