Unbreak and add test case for r90276, a situation in which getBuffer is expected to fail.

Also, update SourceManager.h doxyments for getBuffer() to reflect reality.

llvm-svn: 90701

clang/include/clang/Basic/SourceManager.h

@@ -70,8 +70,8 @@ namespace SrcMgr {
     unsigned NumLines;
 
     /// 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.
+    /// there is an error opening this buffer the first time, this manufactures
+    /// a temporary buffer and returns a non-empty error string.
     const llvm::MemoryBuffer *getBuffer(std::string *ErrorStr = 0) const;
 
     /// getSize - Returns the size of the content encapsulated by this
@@ -426,10 +426,9 @@ public:
   // FileID manipulation methods.
   //===--------------------------------------------------------------------===//
 
-  /// 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.
-  ///
+  /// getBuffer - Return the buffer for the specified FileID. If there is an
+  /// error opening this buffer the first time, this manufactures a temporary
+  /// buffer and returns a non-empty error string.
   const llvm::MemoryBuffer *getBuffer(FileID FID, std::string *Error = 0) const{
     return getSLocEntry(FID).getFile().getContentCache()->getBuffer(Error);
   }

clang/lib/Lex/PPLexerChange.cpp

@@ -81,8 +81,8 @@ bool Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir,
   
   // Get the MemoryBuffer for this FID, if it fails, we fail.
   const llvm::MemoryBuffer *InputFile =
-  if (InputFile == 0)
     getSourceManager().getBuffer(FID, &ErrorStr);
+  if (!ErrorStr.empty())
     return true;
   
   EnterSourceFileWithLexer(new Lexer(FID, InputFile, *this), CurDir);

clang/test/Preprocessor/open-failure.c

@@ -0,0 +1,11 @@
+// RUN: rm -rf %t.dir
+// RUN: mkdir %t.dir
+// RUN: echo 'void f0();' > %t.dir/t.h
+// RUN: chmod 000 %t.dir/t.h
+// RUN: clang-cc -verify -I %t.dir %s
+
+// FIXME: Is there a way to test this on Windows?
+// XFAIL: win32
+
+#include "t.h" // expected-error {{Permission denied}}
+int f0(void);