this massive patch introduces a simple new abstraction: it makes
"FileID" a concept that is now enforced by the compiler's type checker
instead of yet-another-random-unsigned floating around.

This is an important distinction from the "FileID" currently tracked by
SourceLocation.  *That* FileID may refer to the start of a file or to a
chunk within it.  The new FileID *only* refers to the file (and its 
#include stack and eventually #line data), it cannot refer to a chunk.

FileID is a completely opaque datatype to all clients, only SourceManager
is allowed to poke and prod it.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62407 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Driver/RewriteBlocks.cpp b/Driver/RewriteBlocks.cpp
index e4e470a..c729a90 100644
--- a/Driver/RewriteBlocks.cpp
+++ b/Driver/RewriteBlocks.cpp
@@ -37,7 +37,7 @@
 
   ASTContext *Context;
   SourceManager *SM;
-  unsigned MainFileID;
+  FileID MainFileID;
   const char *MainFileStart, *MainFileEnd;
 
   // Block expressions.
@@ -223,7 +223,7 @@
   Preamble += "__OBJC_RW_EXTERN void *_NSConcreteStackBlock;\n";
   Preamble += "#endif\n";
   
-  InsertText(SourceLocation::getFileLoc(MainFileID, 0), 
+  InsertText(SM->getLocForStartOfFile(MainFileID), 
              Preamble.c_str(), Preamble.size());
 }