Add an F_Delete flag

[• rafael]

Summary

For now this only changes the handle Access.

This is convenient to break the patches since we need DELETE access to change the LockFileManager implementation but if this were to set the file disposition we would need to squash all the patches.

[• rafael]

rebasde

[rnk]

lgtm

[• rafael]

r319121

include/llvm/Support/FileSystem.h

enum OpenFlags : unsigned {
   /// with F_Excl.
   F_Append = 2,
 
   /// The file should be opened in text mode on platforms that make this
   /// distinction.
   F_Text = 4,
 
   /// Open the file for read and write.
-  F_RW = 8
+  F_RW = 8,
+
+  /// The returned handle can be used for deleting the file. Only makes a
+  /// difference on windows.
+  F_Delete = 16
 };
 
 /// @brief Create a uniquely named file.
 ///
 /// Generates a unique path suitable for a temporary file and then opens it as a
 /// file. The name is based on \a model with '%' replaced by a random char in
 /// [0-9a-f]. If \a model is not an absolute path, the temporary file will be
 /// created in the current directory.

lib/Support/Windows/Path.inc

std::error_code openFileForWrite(const Twine &Name, int &ResultFD,
   else if (Flags & F_Append)
     CreationDisposition = OPEN_ALWAYS;
   else
     CreationDisposition = CREATE_ALWAYS;
 
   DWORD Access = GENERIC_WRITE;
   if (Flags & F_RW)
     Access |= GENERIC_READ;
+  if (Flags & F_Delete)
+    Access |= DELETE;
 
   HANDLE H =
       ::CreateFileW(PathUTF16.begin(), Access,
                     FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                     NULL, CreationDisposition, FILE_ATTRIBUTE_NORMAL, NULL);
 
   if (H == INVALID_HANDLE_VALUE) {
     DWORD LastError = ::GetLastError();