4 files changed, 21 insertions, 6 deletions
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 66238d0fc9f..12d368501ce 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1270,9 +1270,23 @@ Module *CompilerInstance::loadModule(SourceLocation ImportLoc,
   
   // Make the named module visible, if it's not already part of the module
   // we are parsing.
-  if (ModuleName != getLangOpts().CurrentModule)
+  if (ModuleName != getLangOpts().CurrentModule) {
+    if (!Module->IsFromModuleFile) {
+      // We have an umbrella header or directory that doesn't actually include
+      // all of the headers within the directory it covers. Complain about
+      // this missing submodule and recover by forgetting that we ever saw
+      // this submodule.
+      // FIXME: Should we detect this at module load time? It seems fairly
+      // expensive (and rare).
+      getDiagnostics().Report(ImportLoc, diag::warn_missing_submodule)
+        << Module->getFullModuleName()
+        << SourceRange(Path.front().second, Path.back().second);
+      
+      return 0;
+    }
     ModuleManager->makeModuleVisible(Module, Visibility);
-
+  }
+  
   // If this module import was due to an inclusion directive, create an 
   // implicit import declaration to capture it in the AST.
   if (IsInclusionDirective && hasASTContext()) {
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 7c8bfd7e7cd..4d700aef03b 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -1388,11 +1388,12 @@ void Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
     // If this was an #__include_macros directive, only make macros visible.
     Module::NameVisibilityKind Visibility 
       = (IncludeKind == 3)? Module::MacrosVisible : Module::AllVisible;
-    TheModuleLoader.loadModule(IncludeTok.getLocation(), Path, Visibility,
-                               /*IsIncludeDirective=*/true);
+    Module *Imported
+      = TheModuleLoader.loadModule(IncludeTok.getLocation(), Path, Visibility,
+                                   /*IsIncludeDirective=*/true);
     
     // If this header isn't part of the module we're building, we're done.
-    if (!BuildingImportedModule)
+    if (!BuildingImportedModule && Imported)
       return;
   }
   
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 1efc95408b3..9fc2962d27c 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3086,6 +3086,7 @@ ASTReader::ASTReadResult ASTReader::ReadSubmoduleBlock(ModuleFile &F) {
         return Failure;
       }
       
+      CurrentModule->IsFromModuleFile = true;
       CurrentModule->InferSubmodules = InferSubmodules;
       CurrentModule->InferExplicitSubmodules = InferExplicitSubmodules;
       CurrentModule->InferExportWildcard = InferExportWildcard;
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 1776b97bb03..6883dbe3294 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1877,7 +1877,6 @@ void ASTWriter::WriteSubmodules(Module *WritingModule) {
   for (ASTContext::import_iterator I = Context->local_import_begin(),
                                 IEnd = Context->local_import_end();
        I != IEnd; ++I) {
-    assert(SubmoduleIDs.find(I->getImportedModule()) != SubmoduleIDs.end());
     if (Module *ImportedFrom
           = ModMap.inferModuleFromLocation(FullSourceLoc(I->getLocation(), 
                                                          SrcMgr))) {