3 files changed, 68 insertions, 15 deletions
diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index f87a635420..150f99578c 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -762,6 +762,7 @@ static void doCompileMapModule(void *UserData) {
 /// \brief Compile a module file for the given module, using the options 
 /// provided by the importing compiler instance.
 static void compileModule(CompilerInstance &ImportingInstance,
+                          SourceLocation ImportLoc,
                           Module *Module,
                           StringRef ModuleFileName) {
   llvm::LockFileManager Locked(ModuleFileName);
@@ -797,10 +798,6 @@ static void compileModule(CompilerInstance &ImportingInstance,
   // Note the name of the module we're building.
   Invocation->getLangOpts()->CurrentModule = Module->getTopLevelModuleName();
 
-  // Note that this module is part of the module build path, so that we
-  // can detect cycles in the module graph.
-  PPOpts.ModuleBuildPath.push_back(Module->getTopLevelModuleName());
-
   // Make sure that the failed-module structure has been allocated in
   // the importing instance, and propagate the pointer to the newly-created
   // instance.
@@ -861,7 +858,18 @@ static void compileModule(CompilerInstance &ImportingInstance,
                              &ImportingInstance.getDiagnosticClient(),
                              /*ShouldOwnClient=*/true,
                              /*ShouldCloneClient=*/true);
-  
+
+  // Note that this module is part of the module build path, so that we
+  // can detect cycles in the module graph.
+  Instance.createFileManager(); // FIXME: Adopt file manager from importer?
+  Instance.createSourceManager(Instance.getFileManager());
+  SourceManager &SourceMgr = Instance.getSourceManager();
+  SourceMgr.setModuleBuildPath(
+    ImportingInstance.getSourceManager().getModuleBuildPath());
+  SourceMgr.appendModuleBuildPath(Module->getTopLevelModuleName(),
+    FullSourceLoc(ImportLoc, ImportingInstance.getSourceManager()));
+
+
   // Construct a module-generating action.
   GenerateModuleAction CreateModuleAction;
   
@@ -939,14 +947,17 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
       // build the module.
 
       // Check whether there is a cycle in the module graph.
-      SmallVectorImpl<std::string> &ModuleBuildPath
-        = getPreprocessorOpts().ModuleBuildPath;
-      SmallVectorImpl<std::string>::iterator Pos
-        = std::find(ModuleBuildPath.begin(), ModuleBuildPath.end(), ModuleName);
-      if (Pos != ModuleBuildPath.end()) {
+      ModuleBuildPath Path = getSourceManager().getModuleBuildPath();
+      ModuleBuildPath::iterator Pos = Path.begin(), PosEnd = Path.end();
+      for (; Pos != PosEnd; ++Pos) {
+        if (Pos->first == ModuleName)
+          break;
+      }
+
+      if (Pos != PosEnd) {
         SmallString<256> CyclePath;
-        for (; Pos != ModuleBuildPath.end(); ++Pos) {
-          CyclePath += *Pos;
+        for (; Pos != PosEnd; ++Pos) {
+          CyclePath += Pos->first;
           CyclePath += " -> ";
         }
         CyclePath += ModuleName;
@@ -970,7 +981,7 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
       getDiagnostics().Report(ModuleNameLoc, diag::warn_module_build)
         << ModuleName;
       BuildingModule = true;
-      compileModule(*this, Module, ModuleFileName);
+      compileModule(*this, ModuleNameLoc, Module, ModuleFileName);
       ModuleFile = FileMgr->getFile(ModuleFileName);
 
       if (!ModuleFile)
@@ -1040,7 +1051,7 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
         return ModuleLoadResult();
       }
 
-      compileModule(*this, Module, ModuleFileName);
+      compileModule(*this, ModuleNameLoc, Module, ModuleFileName);
 
       // Try loading the module again.
       ModuleFile = FileMgr->getFile(ModuleFileName);
diff --git a/lib/Frontend/DiagnosticRenderer.cpp b/lib/Frontend/DiagnosticRenderer.cpp
index 3143cc7b32..3599df82c7 100644
--- a/lib/Frontend/DiagnosticRenderer.cpp
+++ b/lib/Frontend/DiagnosticRenderer.cpp
@@ -205,8 +205,10 @@ void DiagnosticRenderer::emitIncludeStack(SourceLocation Loc,
 /// on the way back down.
 void DiagnosticRenderer::emitIncludeStackRecursively(SourceLocation Loc,
                                                      const SourceManager &SM) {
-  if (Loc.isInvalid())
+  if (Loc.isInvalid()) {
+    emitModuleBuildPath(SM);
     return;
+  }
   
   PresumedLoc PLoc = SM.getPresumedLoc(Loc, DiagOpts->ShowPresumedLoc);
   if (PLoc.isInvalid())
@@ -219,6 +221,21 @@ void DiagnosticRenderer::emitIncludeStackRecursively(SourceLocation Loc,
   emitIncludeLocation(Loc, PLoc, SM);
 }
 
+/// \brief Emit the module build path, for cases where a module is (re-)built
+/// on demand.
+void DiagnosticRenderer::emitModuleBuildPath(const SourceManager &SM) {
+  ModuleBuildPath Path = SM.getModuleBuildPath();
+  for (unsigned I = 0, N = Path.size(); I != N; ++I) {
+    const SourceManager &CurSM = Path[I].second.getManager();
+    SourceLocation CurLoc = Path[I].second;
+    emitBuildingModuleLocation(CurLoc,
+                               CurSM.getPresumedLoc(CurLoc,
+                                                    DiagOpts->ShowPresumedLoc),
+                               Path[I].first,
+                               CurSM);
+  }
+}
+
 // Helper function to fix up source ranges.  It takes in an array of ranges,
 // and outputs an array of ranges where we want to draw the range highlighting
 // around the location specified by CaretLoc.
@@ -390,6 +407,20 @@ void DiagnosticNoteRenderer::emitIncludeLocation(SourceLocation Loc,
   emitNote(Loc, Message.str(), &SM);
 }
 
+void
+DiagnosticNoteRenderer::emitBuildingModuleLocation(SourceLocation Loc,
+                                                   PresumedLoc PLoc,
+                                                   StringRef ModuleName,
+                                                   const SourceManager &SM) {
+  // 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() << ":";
+  emitNote(Loc, Message.str(), &SM);
+}
+
+
 void DiagnosticNoteRenderer::emitBasicNote(StringRef Message) {
   emitNote(SourceLocation(), Message, 0);  
 }
diff --git a/lib/Frontend/TextDiagnostic.cpp b/lib/Frontend/TextDiagnostic.cpp
index 35dabad606..65df875aea 100644
--- a/lib/Frontend/TextDiagnostic.cpp
+++ b/lib/Frontend/TextDiagnostic.cpp
@@ -884,6 +884,17 @@ void TextDiagnostic::emitIncludeLocation(SourceLocation Loc,
     OS << "In included file:\n"; 
 }
 
+void TextDiagnostic::emitBuildingModuleLocation(SourceLocation Loc,
+                                                PresumedLoc PLoc,
+                                                StringRef ModuleName,
+                                                const SourceManager &SM) {
+  if (DiagOpts->ShowLocation)
+    OS << "While building module '" << ModuleName << "' imported from "
+      << PLoc.getFilename() << ':' << PLoc.getLine() << ":\n";
+  else
+    OS << "While building module '" << ModuleName << "':\n";
+}
+
 /// \brief Emit a code snippet and caret line.
 ///
 /// This routine emits a single line's code snippet and caret line..