3 files changed, 47 insertions, 34 deletions

diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index 29594994ff6..287ee146c6b 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -865,50 +865,44 @@ void ModuleMap::dump() {
 }
 
 bool ModuleMap::resolveExports(Module *Mod, bool Complain) {
-  bool HadError = false;
-  for (unsigned I = 0, N = Mod->UnresolvedExports.size(); I != N; ++I) {
-    Module::ExportDecl Export = resolveExport(Mod, Mod->UnresolvedExports[I], 
-                                              Complain);
+  auto Unresolved = std::move(Mod->UnresolvedExports);
+  Mod->UnresolvedExports.clear();
+  for (auto &UE : Unresolved) {
+    Module::ExportDecl Export = resolveExport(Mod, UE, Complain);
     if (Export.getPointer() || Export.getInt())
       Mod->Exports.push_back(Export);
     else
-      HadError = true;
+      Mod->UnresolvedExports.push_back(UE);
   }
-  Mod->UnresolvedExports.clear();
-  return HadError;
+  return !Mod->UnresolvedExports.empty();
 }
 
 bool ModuleMap::resolveUses(Module *Mod, bool Complain) {
-  bool HadError = false;
-  for (unsigned I = 0, N = Mod->UnresolvedDirectUses.size(); I != N; ++I) {
-    Module *DirectUse =
-        resolveModuleId(Mod->UnresolvedDirectUses[I], Mod, Complain);
+  auto Unresolved = std::move(Mod->UnresolvedDirectUses);
+  Mod->UnresolvedDirectUses.clear();
+  for (auto &UDU : Unresolved) {
+    Module *DirectUse = resolveModuleId(UDU, Mod, Complain);
     if (DirectUse)
       Mod->DirectUses.push_back(DirectUse);
     else
-      HadError = true;
+      Mod->UnresolvedDirectUses.push_back(UDU);
   }
-  Mod->UnresolvedDirectUses.clear();
-  return HadError;
+  return !Mod->UnresolvedDirectUses.empty();
 }
 
 bool ModuleMap::resolveConflicts(Module *Mod, bool Complain) {
-  bool HadError = false;
-  for (unsigned I = 0, N = Mod->UnresolvedConflicts.size(); I != N; ++I) {
-    Module *OtherMod = resolveModuleId(Mod->UnresolvedConflicts[I].Id,
-                                       Mod, Complain);
-    if (!OtherMod) {
-      HadError = true;
-      continue;
-    }
-
-    Module::Conflict Conflict;
-    Conflict.Other = OtherMod;
-    Conflict.Message = Mod->UnresolvedConflicts[I].Message;
-    Mod->Conflicts.push_back(Conflict);
-  }
+  auto Unresolved = std::move(Mod->UnresolvedConflicts);
   Mod->UnresolvedConflicts.clear();
-  return HadError;
+  for (auto &UC : Unresolved) {
+    if (Module *OtherMod = resolveModuleId(UC.Id, Mod, Complain)) {
+      Module::Conflict Conflict;
+      Conflict.Other = OtherMod;
+      Conflict.Message = UC.Message;
+      Mod->Conflicts.push_back(Conflict);
+    } else
+      Mod->UnresolvedConflicts.push_back(UC);
+  }
+  return !Mod->UnresolvedConflicts.empty();
 }
 
 Module *ModuleMap::inferModuleFromLocation(FullSourceLoc Loc) {
@@ -1759,7 +1753,13 @@ void ModuleMapParser::parseHeaderDecl(MMToken::TokenKind LeadingToken,
         // If Clang supplies this header but the underlying system does not,
         // just silently swap in our builtin version. Otherwise, we'll end
         // up adding both (later).
-        if (!File && BuiltinFile) {
+        //
+        // For local visibility, entirely replace the system file with our
+        // one and textually include the system one. We need to pass macros
+        // from our header to the system one if we #include_next it.
+        //
+        // FIXME: Can we do this in all cases?
+        if (BuiltinFile && (!File || Map.LangOpts.ModulesLocalVisibility)) {
           File = BuiltinFile;
           RelativePathName = BuiltinPathName;
           BuiltinFile = nullptr;
diff --git a/clang/lib/Lex/PPLexerChange.cpp b/clang/lib/Lex/PPLexerChange.cpp
index 4af68b0b80a..ddc3fa646b9 100644
--- a/clang/lib/Lex/PPLexerChange.cpp
+++ b/clang/lib/Lex/PPLexerChange.cpp
@@ -615,9 +615,21 @@ void Preprocessor::EnterSubmodule(Module *M, SourceLocation ImportLoc) {
   auto &Info = BuildingSubmoduleStack.back();
   Info.Macros.swap(Macros);
   // Save our visible modules set. This is guaranteed to clear the set.
-  if (getLangOpts().ModulesLocalVisibility)
+  if (getLangOpts().ModulesLocalVisibility) {
     Info.VisibleModules = std::move(VisibleModules);
 
+    // Resolve as much of the module definition as we can now, before we enter
+    // one if its headers.
+    // FIXME: Can we enable Complain here?
+    ModuleMap &ModMap = getHeaderSearchInfo().getModuleMap();
+    ModMap.resolveExports(M, /*Complain=*/false);
+    ModMap.resolveUses(M, /*Complain=*/false);
+    ModMap.resolveConflicts(M, /*Complain=*/false);
+
+    // This module is visible to itself.
+    makeModuleVisible(M, ImportLoc);
+  }
+
   // Determine the set of starting macros for this submodule.
   // FIXME: If we re-enter a submodule, should we restore its MacroDirectives?
   auto &StartingMacros = getLangOpts().ModulesLocalVisibility
@@ -628,7 +640,7 @@ void Preprocessor::EnterSubmodule(Module *M, SourceLocation ImportLoc) {
   // FIXME: Do this lazily, when each macro name is first referenced.
   for (auto &Macro : StartingMacros) {
     MacroState MS(Macro.second.getLatest());
-    MS.setOverriddenMacros(*this, MS.getOverriddenMacros());
+    MS.setOverriddenMacros(*this, Macro.second.getOverriddenMacros());
     Macros.insert(std::make_pair(Macro.first, std::move(MS)));
   }
 }
@@ -712,6 +724,7 @@ void Preprocessor::LeaveSubmodule() {
   BuildingSubmoduleStack.pop_back();
 
   // A nested #include makes the included submodule visible.
-  if (!BuildingSubmoduleStack.empty() || !getLangOpts().ModulesLocalVisibility)
+  if (!BuildingSubmoduleStack.empty() ||
+      !getLangOpts().ModulesLocalVisibility)
     makeModuleVisible(LeavingMod, ImportLoc);
 }
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 7121578c8fb..aa4e8b67644 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -238,7 +238,7 @@ void Preprocessor::dumpMacroInfo(const IdentifierInfo *II) {
       llvm::errs() << " active";
     else if (!VisibleModules.isVisible(MM->getOwningModule()))
       llvm::errs() << " hidden";
-    else
+    else if (MM->getMacroInfo())
       llvm::errs() << " overridden";
 
     if (!MM->overrides().empty()) {