Module use declarations (II)

Review: http://llvm-reviews.chandlerc.com/D1546.

I have picked up this patch form Lawrence
(http://llvm-reviews.chandlerc.com/D1063) and did a few changes.

From the original change description (updated as appropriate):
This patch adds a check that ensures that modules only use modules they
have so declared. To this end, it adds a statement on intended module
use to the module.map grammar:

  use module-id

A module can then only use headers from other modules if it 'uses' them.
This enforcement is off by default, but may be turned on with the new
option -fmodules-decluse.

When enforcing the module semantics, we also need to consider a source
file part of a module. This is achieved with a compiler option

-fmodule-name=<module-id>.

The compiler at present only applies restrictions to the module directly
being built.

llvm-svn: 191283

clang/lib/Basic/Module.cpp

@@ -362,6 +362,20 @@ void Module::print(raw_ostream &OS, unsigned Indent) const {
     OS << "\n";
   }
 
+  for (unsigned I = 0, N = DirectUses.size(); I != N; ++I) {
+    OS.indent(Indent + 2);
+    OS << "use ";
+    OS << DirectUses[I]->getFullModuleName();
+    OS << "\n";
+  }
+
+  for (unsigned I = 0, N = UnresolvedDirectUses.size(); I != N; ++I) {
+    OS.indent(Indent + 2);
+    OS << "use ";
+    printModuleId(OS, UnresolvedDirectUses[I]);
+    OS << "\n";
+  }
+
   for (unsigned I = 0, N = LinkLibraries.size(); I != N; ++I) {
     OS.indent(Indent + 2);
     OS << "link ";