Clear raw_fd_ostream error string on success and explain behavior in

documentation.

Add C++ header marker.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57923 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 11 insertions, 7 deletions

diff --git a/include/llvm/Support/raw_ostream.h b/include/llvm/Support/raw_ostream.h
index 5ab0988d3e..af53477cea 100644
--- a/include/llvm/Support/raw_ostream.h
+++ b/include/llvm/Support/raw_ostream.h
@@ -1,4 +1,4 @@
-//===--- raw_ostream.h - Raw output stream --------------------------------===//
+//===--- raw_ostream.h - Raw output stream ----------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -152,9 +152,10 @@ class raw_fd_ostream : public raw_ostream {
   int FD;
   bool ShouldClose;
 public:
-  /// raw_fd_ostream - Open the specified file for writing.  If an error occurs,
-  /// information about the error is put into ErrorInfo, and the stream should
-  /// be immediately destroyed.
+  /// raw_fd_ostream - Open the specified file for writing. If an
+  /// error occurs, information about the error is put into ErrorInfo,
+  /// and the stream should be immediately destroyed; the string will
+  /// be empty if no error occurred.
   raw_fd_ostream(const char *Filename, std::string &ErrorInfo);
   
   /// raw_fd_ostream ctor - FD is the file descriptor that this writes to.  If
diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp
index 008f85603e..f3a53a5061 100644
--- a/lib/Support/raw_ostream.cpp
+++ b/lib/Support/raw_ostream.cpp
@@ -196,10 +196,13 @@ void format_object_base::home() {
 //  raw_fd_ostream
 //===----------------------------------------------------------------------===//
 
-/// raw_fd_ostream - Open the specified file for writing.  If an error occurs,
-/// information about the error is put into ErrorInfo, and the stream should
-/// be immediately destroyed.
+/// raw_fd_ostream - Open the specified file for writing. If an error
+/// occurs, information about the error is put into ErrorInfo, and the
+/// stream should be immediately destroyed; the string will be empty
+/// if no error occurred.
 raw_fd_ostream::raw_fd_ostream(const char *Filename, std::string &ErrorInfo) {
+  ErrorInfo.clear();
+
   // Handle "-" as stdout.
   if (Filename[0] == '-' && Filename[1] == 0) {
     FD = STDOUT_FILENO;