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"
         ^

llvm-svn: 90276

6 files changed, 22 insertions, 14 deletions

diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index 39123d9b371..cc06ab3a869 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -171,7 +171,7 @@ def err_pp_invalid_directive : Error<"invalid preprocessing directive">;
 def err_pp_hash_error : Error<"#error%0">;
 def err_pp_file_not_found : Error<"'%0' file not found">, DefaultFatal;
 def err_pp_error_opening_file : Error<
-  "error opening file '%0'">, DefaultFatal;
+  "error opening file '%0': %1">, DefaultFatal;
 def err_pp_empty_filename : Error<"empty filename">;
 def err_pp_include_too_deep : Error<"#include nested too deeply">;
 def err_pp_expects_filename : Error<"expected \"FILENAME\" or <FILENAME>">;
diff --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
index 7e9ac531017..67b3d500643 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/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.
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index edd34b71896..c8e4a0f2097 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -330,8 +330,9 @@ public:
 
   /// EnterSourceFile - Add a source file to the top of the include stack and
   /// start lexing tokens from it instead of the current buffer.  Return true
-  /// on failure.
-  bool EnterSourceFile(FileID CurFileID, const DirectoryLookup *Dir);
+  /// and fill in ErrorStr with the error information on failure.
+  bool EnterSourceFile(FileID CurFileID, const DirectoryLookup *Dir,
+                       std::string *ErrorStr = 0);
 
   /// EnterMacro - Add a Macro to the top of the include stack and start lexing
   /// tokens from it instead of the current buffer.  Args specifies the
diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index a85bef0f29e..394f493fa90 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -47,12 +47,12 @@ unsigned ContentCache::getSize() const {
   return Buffer ? Buffer->getBufferSize() : Entry->getSize();
 }
 
-const llvm::MemoryBuffer *ContentCache::getBuffer() const {
+const llvm::MemoryBuffer *ContentCache::getBuffer(std::string *ErrorStr) const {
   // Lazily create the Buffer for ContentCaches that wrap files.
   if (!Buffer && Entry) {
     // FIXME: Should we support a way to not have to do this check over
     //   and over if we cannot open the file?
-    Buffer = MemoryBuffer::getFile(Entry->getName(), 0, Entry->getSize());
+    Buffer = MemoryBuffer::getFile(Entry->getName(), ErrorStr,Entry->getSize());
     if (isTruncated())
       const_cast<ContentCache *>(this)->truncateAt(TruncateAtLine, 
                                                    TruncateAtColumn);
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 9caca339be3..028593f39c7 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -1112,9 +1112,10 @@ void Preprocessor::HandleIncludeDirective(Token &IncludeTok,
   }
 
   // Finally, if all is good, enter the new file!
-  if (EnterSourceFile(FID, CurDir))
+  std::string ErrorStr;
+  if (EnterSourceFile(FID, CurDir, &ErrorStr))
     Diag(FilenameTok, diag::err_pp_error_opening_file)
-      << std::string(SourceMgr.getFileEntryForID(FID)->getName());
+      << std::string(SourceMgr.getFileEntryForID(FID)->getName()) << ErrorStr;
 }
 
 /// HandleIncludeNextDirective - Implements #include_next.
diff --git a/clang/lib/Lex/PPLexerChange.cpp b/clang/lib/Lex/PPLexerChange.cpp
index 8a61d7b9c24..1580b87dac6 100644
--- a/clang/lib/Lex/PPLexerChange.cpp
+++ b/clang/lib/Lex/PPLexerChange.cpp
@@ -64,7 +64,8 @@ PreprocessorLexer *Preprocessor::getCurrentFileLexer() const {
 
 /// EnterSourceFile - Add a source file to the top of the include stack and
 /// start lexing tokens from it instead of the current buffer.
-bool Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir) {
+bool Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir,
+                                   std::string *ErrorStr) {
   assert(CurTokenLexer == 0 && "Cannot #include a file inside a macro!");
   ++NumEnteredSourceFiles;
 
@@ -79,7 +80,8 @@ bool Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir) {
   }
   
   // Get the MemoryBuffer for this FID, if it fails, we fail.
-  const llvm::MemoryBuffer *InputFile = getSourceManager().getBuffer(FID);
+  const llvm::MemoryBuffer *InputFile =
+    getSourceManager().getBuffer(FID, ErrorStr);
   if (InputFile == 0)
     return true;