[modules] Add local submodule visibility support for declarations.

With this change, enabling -fmodules-local-submodule-visibility results in name
visibility rules being applied to submodules of the current module in addition
to imported modules (that is, names no longer "leak" between submodules of the
same top-level module). This also makes it much safer to textually include a
non-modular library into a module: each submodule that textually includes that
library will get its own "copy" of that library, and so the library becomes
visible no matter which including submodule you import.

llvm-svn: 237473

1 files changed, 30 insertions, 30 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;