Make raw_fd_ostream consider itself the owner of STDOUT_FILENO when

constructed with an output filename of "-". In particular, allow the
file descriptor to be closed, and close the file descriptor in the
destructor if it hasn't been explicitly closed already, to ensure
that any write errors are detected.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111436 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/raw_ostream.h

@@ -353,8 +353,11 @@ public:
   /// be immediately destroyed; the string will be empty if no error occurred.
   /// This allows optional flags to control how the file will be opened.
   ///
-  /// \param Filename - The file to open. If this is "-" then the
-  /// stream will use stdout instead.
+  /// As a special case, if Filename is "-", then the stream will use
+  /// STDOUT_FILENO instead of opening a file. Note that it will still consider
+  /// itself to own the file descriptor. In particular, it will close the
+  /// file descriptor when it is done (this is necessary to detect
+  /// output errors).
   raw_fd_ostream(const char *Filename, std::string &ErrorInfo,
                  unsigned Flags = 0);
 

lib/Support/raw_ostream.cpp

@@ -377,14 +377,17 @@ raw_fd_ostream::raw_fd_ostream(const char *Filename, std::string &ErrorInfo,
 
   ErrorInfo.clear();
 
-  // Handle "-" as stdout.
+  // Handle "-" as stdout. Note that when we do this, we consider ourself
+  // the owner of stdout. This means that we can do things like close the
+  // file descriptor when we're done and set the "binary" flag globally.
   if (Filename[0] == '-' && Filename[1] == 0) {
     FD = STDOUT_FILENO;
     // If user requested binary then put stdout into binary mode if
     // possible.
     if (Flags & F_Binary)
       sys::Program::ChangeStdoutToBinary();
-    ShouldClose = false;
+    // Close stdout when we're done, to detect any output errors.
+    ShouldClose = true;
     return;
   }