pass the reason for failure up from MemoryBuffer and report it

in diagnostics when we fail to open a file.  This allows us to
report things like:

$ clang test.c -I.
test.c:2:10: fatal error: error opening file './foo.h': Permission denied
#include "foo.h"
         ^



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@90276 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 5 deletions

diff --git a/include/clang/Basic/SourceManager.h b/include/clang/Basic/SourceManager.h
index 7e9ac53101..67b3d50064 100644
--- a/include/clang/Basic/SourceManager.h
+++ b/include/clang/Basic/SourceManager.h
@@ -77,8 +77,10 @@ namespace SrcMgr {
     /// ContentCache.
     mutable FileID FirstFID;
 
-    /// getBuffer - Returns the memory buffer for the associated content.
-    const llvm::MemoryBuffer *getBuffer() const;
+    /// getBuffer - Returns the memory buffer for the associated content.  If
+    /// there is an error opening this buffer the first time, this returns null
+    /// and fills in the ErrorStr with a reason.
+    const llvm::MemoryBuffer *getBuffer(std::string *ErrorStr = 0) const;
 
     /// getSize - Returns the size of the content encapsulated by this
     ///  ContentCache. This can be the size of the source file or the size of an
@@ -432,10 +434,12 @@ public:
   // FileID manipulation methods.
   //===--------------------------------------------------------------------===//
 
-  /// getBuffer - Return the buffer for the specified FileID.
+  /// getBuffer - Return the buffer for the specified FileID.  If there is an
+  /// error opening this buffer the first time, this returns null and fills in
+  /// the ErrorStr with a reason.
   ///
-  const llvm::MemoryBuffer *getBuffer(FileID FID) const {
-    return getSLocEntry(FID).getFile().getContentCache()->getBuffer();
+  const llvm::MemoryBuffer *getBuffer(FileID FID, std::string *Error = 0) const{
+    return getSLocEntry(FID).getFile().getContentCache()->getBuffer(Error);
   }
 
   /// getFileEntryForID - Returns the FileEntry record for the provided FileID.