Fix PR5633 by making the preprocessor handle the case where we can
stat a file but where mmaping it fails.  In this case, we emit an
error like:
t.c:1:10: fatal error: error opening file '../../foo.h'

instead of "cannot find file".



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@90110 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/DiagChecker.cpp b/lib/Frontend/DiagChecker.cpp
index 26bb6cc..e7a66b1 100644
--- a/lib/Frontend/DiagChecker.cpp
+++ b/lib/Frontend/DiagChecker.cpp
@@ -149,7 +149,8 @@
   FileID FID = PP.getSourceManager().getMainFileID();
 
   // Create a lexer to lex all the tokens of the main file in raw mode.
-  Lexer RawLex(FID, PP.getSourceManager(), PP.getLangOptions());
+  const llvm::MemoryBuffer *FromFile = PP.getSourceManager().getBuffer(FID);
+  Lexer RawLex(FID, FromFile, PP.getSourceManager(), PP.getLangOptions());
 
   // Return comments as tokens, this is how we find expected diagnostics.
   RawLex.SetCommentRetentionState(true);