[C++20] [Modules] Treat directly imported internal partition unit as reachable

Close https://github.com/llvm/llvm-project/issues/143788

See the discussion for details.

1 files changed, 7 insertions, 6 deletions

diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index 6c4df0a..9fcaad48 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -712,7 +712,13 @@ DeclResult Sema::ActOnModuleImport(SourceLocation StartLoc,
       Mod->Kind == Module::ModuleKind::ModulePartitionImplementation) {
     Diag(ExportLoc, diag::err_export_partition_impl)
         << SourceRange(ExportLoc, Path.back().getLoc());
-  } else if (!ModuleScopes.empty() && !currentModuleIsImplementation()) {
+  } else if (ExportLoc.isValid() &&
+             (ModuleScopes.empty() || currentModuleIsImplementation())) {
+    // [module.interface]p1:
+    // An export-declaration shall inhabit a namespace scope and appear in the
+    // purview of a module interface unit.
+    Diag(ExportLoc, diag::err_export_not_in_module_interface);
+  } else if (!ModuleScopes.empty()) {
     // Re-export the module if the imported module is exported.
     // Note that we don't need to add re-exported module to Imports field
     // since `Exports` implies the module is imported already.
@@ -720,11 +726,6 @@ DeclResult Sema::ActOnModuleImport(SourceLocation StartLoc,
       getCurrentModule()->Exports.emplace_back(Mod, false);
     else
       getCurrentModule()->Imports.insert(Mod);
-  } else if (ExportLoc.isValid()) {
-    // [module.interface]p1:
-    // An export-declaration shall inhabit a namespace scope and appear in the
-    // purview of a module interface unit.
-    Diag(ExportLoc, diag::err_export_not_in_module_interface);
   }
 
   return Import;