2 files changed, 14 insertions, 3 deletions
diff --git a/clang/lib/Frontend/DiagnosticRenderer.cpp b/clang/lib/Frontend/DiagnosticRenderer.cpp
index 4eee59548c8..b52f0103e6b 100644
--- a/clang/lib/Frontend/DiagnosticRenderer.cpp
+++ b/clang/lib/Frontend/DiagnosticRenderer.cpp
@@ -499,8 +499,11 @@ DiagnosticNoteRenderer::emitBuildingModuleLocation(SourceLocation Loc,
   // Generate a note indicating the include location.
   SmallString<200> MessageStorage;
   llvm::raw_svector_ostream Message(MessageStorage);
-  Message << "while building module '" << ModuleName << "' imported from "
-          << PLoc.getFilename() << ':' << PLoc.getLine() << ":";
+  if (PLoc.getFilename())
+    Message << "while building module '" << ModuleName << "' imported from "
+            << PLoc.getFilename() << ':' << PLoc.getLine() << ":";
+  else
+    Message << "while building module '" << ModuleName << ":";
   emitNote(Loc, Message.str(), &SM);
 }
 
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index f587d829b39..4ed2df3a25c 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -240,7 +240,15 @@ bool GenerateModuleAction::BeginSourceFileAction(CompilerInstance &CI,
     // map with a single module (the common case).
     return false;
   }
-  
+
+  // If we're being run from the command-line, the module build stack will not
+  // have been filled in yet, so complete it now in order to allow us to detect
+  // module cycles.
+  SourceManager &SourceMgr = CI.getSourceManager();
+  if (SourceMgr.getModuleBuildStack().empty())
+    SourceMgr.pushModuleBuildStack(CI.getLangOpts().CurrentModule,
+                                   FullSourceLoc(SourceLocation(), SourceMgr));
+
   // Dig out the module definition.
   Module = HS.lookupModule(CI.getLangOpts().CurrentModule, 
                            /*AllowSearch=*/false);