Back out my heinous hack that tricked the module generation mechanism

into using non-absolute system includes (<foo>)...

... and introduce another hack that is simultaneously more heineous
and more effective. We whitelist Clang-supplied headers that augment
or override system headers (such as float.h, stdarg.h, and
tgmath.h). For these headers, Clang does not provide a module
mapping. Instead, a system-supplied module map can refer to these
headers in a system module, and Clang will look both in its own
include directory and wherever the system-supplied module map
suggests, then adds either or both headers. The end result is that
Clang-supplied headers get merged into the system-supplied module for
the C standard library.

As a drive-by, fix up a few dependencies in the _Builtin_instrinsics
module.

llvm-svn: 149611

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/Frontend/InitHeaderSearch.cpp b/clang/lib/Frontend/InitHeaderSearch.cpp
index ee75e6921d9..9faa1267553 100644
--- a/clang/lib/Frontend/InitHeaderSearch.cpp
+++ b/clang/lib/Frontend/InitHeaderSearch.cpp
@@ -666,5 +666,13 @@ void clang::ApplyHeaderSearchOptions(HeaderSearch &HS,
 
   Init.AddDefaultIncludePaths(Lang, Triple, HSOpts);
 
+  if (HSOpts.UseBuiltinIncludes) {
+    // Set up the builtin include directory in the module map.
+    llvm::sys::Path P(HSOpts.ResourceDir);
+    P.appendComponent("include");
+    if (const DirectoryEntry *Dir = HS.getFileMgr().getDirectory(P.str()))
+      HS.getModuleMap().setBuiltinIncludeDir(Dir);
+  }
+
   Init.Realize(Lang);
 }