[llvm-commits] [llvm] r111643 - /llvm/trunk/lib/Support/raw_ostream.cpp

[Chris Lattner]

On Aug 20, 2010, at 9:44 AM, Dan Gohman wrote:

> Author: djg
> Date: Fri Aug 20 11:44:56 2010
> New Revision: 111643
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=111643&view=rev
> Log:
> Make outs() close its file when its stream is destructed, so that
> pending output errors are detected.

I don't get this.  This means that any evaluation (e.g. in a library) of outs() will dramatically change the behavior of the program it is embedded into.  This is non-obvious and seems really really dangerous.

-Chris

> 
> Modified:
>    llvm/trunk/lib/Support/raw_ostream.cpp
> 
> Modified: llvm/trunk/lib/Support/raw_ostream.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=111643&r1=111642&r2=111643&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Support/raw_ostream.cpp (original)
> +++ llvm/trunk/lib/Support/raw_ostream.cpp Fri Aug 20 11:44:56 2010
> @@ -540,14 +540,16 @@
> }
> 
> //===----------------------------------------------------------------------===//
> -//  raw_stdout/err_ostream
> +//  outs(), errs(), nulls()
> //===----------------------------------------------------------------------===//
> 
> /// outs() - This returns a reference to a raw_ostream for standard output.
> /// Use it like: outs() << "foo" << "bar";
> raw_ostream &llvm::outs() {
>   // Set buffer settings to model stdout behavior.
> -  static raw_fd_ostream S(STDOUT_FILENO, false);
> +  // Delete the file descriptor when the program exists, forcing error
> +  // detection. If you don't want this behavior, don't use outs().
> +  static raw_fd_ostream S(STDOUT_FILENO, true);
>   return S;
> }
> 
> 
> 
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