[Frontend] Report Swift overlays loaded for indirect cland dependencies

Author: xymus

include/swift/AST/DiagnosticsSema.def

@@ -989,8 +989,9 @@ REMARK(cross_import_added,none,
        (Identifier, Identifier, Identifier))
 
 REMARK(module_loaded,none,
-       "loaded module at %0",
-       (StringRef))
+       "loaded module at %0"
+       "%select{|; overlay for a clang dependency}1",
+       (StringRef, unsigned))
 
 REMARK(explicit_interface_build_skipped,none,
        "Skipped rebuilding module at %0 - up-to-date",

lib/AST/ASTContext.cpp

@@ -2471,7 +2471,8 @@ ASTContext::getModule(ImportPath::Module ModulePath, bool AllowMemoryCached) {
       if (LangOpts.EnableModuleLoadingRemarks) {
         Diags.diagnose(ModulePath.getSourceRange().Start,
                        diag::module_loaded,
-                       M->getModuleFilename());
+                       M->getModuleFilename(),
+                       /*overlay=*/false);
       }
       return M;
     }
@@ -2499,8 +2500,15 @@ ModuleDecl *ASTContext::getOverlayModule(const FileUnit *FU) {
   for (auto &importer : getImpl().ModuleLoaders) {
     if (importer.get() == getClangModuleLoader())
       continue;
-    if (ModuleDecl *M = importer->loadModule(SourceLoc(), ModPath))
+    if (ModuleDecl *M = importer->loadModule(SourceLoc(), ModPath)) {
+      if (LangOpts.EnableModuleLoadingRemarks) {
+        Diags.diagnose(SourceLoc(),
+                       diag::module_loaded,
+                       M->getModuleFilename(),
+                       /*overlay=*/true);
+      }
       return M;
+    }
   }
 
   return nullptr;