[FileSystem] Split up the OpenFlags enumeration.

This breaks the OpenFlags enumeration into two separate
enumerations: OpenFlags and CreationDisposition.  The first
controls the behavior of the API depending on whether or not
the target file already exists, and is not a flags-based
enum.  The second controls more flags-like values.

This yields a more easy to understand API, while also allowing
flags to be passed to the openForRead api, where most of the
values didn't make sense before.  This also makes the apis more
testable as it becomes easy to enumerate all the configurations
which make sense, so I've added many new tests to exercise all
the different values.

llvm-svn: 334221

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Support/FileOutputBuffer.cpp b/llvm/lib/Support/FileOutputBuffer.cpp
index cd08b61d0d6..0a771682a2c 100644
--- a/llvm/lib/Support/FileOutputBuffer.cpp
+++ b/llvm/lib/Support/FileOutputBuffer.cpp
@@ -82,9 +82,10 @@ public:
   size_t getBufferSize() const override { return Buffer.size(); }
 
   Error commit() override {
+    using namespace sys::fs;
     int FD;
     std::error_code EC;
-    if (auto EC = openFileForWrite(FinalPath, FD, fs::F_None, Mode))
+    if (auto EC = openFileForWrite(FinalPath, FD, CD_CreateAlways, OF_None))
       return errorCodeToError(EC);
     raw_fd_ostream OS(FD, /*shouldClose=*/true, /*unbuffered=*/true);
     OS << StringRef((const char *)Buffer.base(), Buffer.size());