Teach the search for modules to consider modules described by a module
map, so long as they have an umbrella header. This makes it possible
to introduce a module map + umbrella header for a given set of
headers, to turn it into a module.

There are two major deficiencies here: first, we don't go hunting for
module map files when we just see a module import (so we won't know
about the modules described therein). Second, we don't yet have a way
to build modules that don't have umbrella headers, or have incomplete
umbrella headers.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144424 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/HeaderSearch.cpp b/lib/Lex/HeaderSearch.cpp
index 4522de5..3f50285 100644
--- a/lib/Lex/HeaderSearch.cpp
+++ b/lib/Lex/HeaderSearch.cpp
@@ -127,9 +127,19 @@
   if (!UmbrellaHeader)
     return 0;
   
+  // Look in the module map to determine if there is a module by this name
+  // that has an umbrella header.
+  // FIXME: Even if it doesn't have an umbrella header, we should be able to
+  // handle the module. However, the caller isn't ready for that yet.
+  if (ModuleMap::Module *Module = ModMap.findModule(ModuleName)) {
+    if (Module->UmbrellaHeader) {
+      *UmbrellaHeader = Module->UmbrellaHeader->getName();
+      return 0;
+    }
+  }
+  
   // Look in each of the framework directories for an umbrella header with
   // the same name as the module.
-  // FIXME: We need a way for non-frameworks to provide umbrella headers.
   llvm::SmallString<128> UmbrellaHeaderName;
   UmbrellaHeaderName = ModuleName;
   UmbrellaHeaderName += '/';