When calling println! it currently causes a panic if stdout does not exist. Change this to ignore this specific error and simply void the output.


On Linux stdout almost always exists, so when people write games and turn off the terminal there is still an stdout that they write to. Then when getting the code to run on Windows, when the console is disabled, suddenly stdout doesn’t exist and println! panicks. This behavior difference is frustrating to developers trying to move to Windows.

There is also precedent with C and C++. On both Linux and Windows, if stdout is closed or doesn’t exist, neither platform will error when attempting to print to the console.

Detailed design

When using any of the convenience macros that write to either stdout or stderr, such as println! print! panic! and assert!, change the implementation to ignore the specific error of stdout or stderr not existing. The behavior of all other errors will be unaffected. This can be implemented by redirecting stdout and stderr to std::io::sink if the original handles do not exist.

Update the methods std::io::stdin std::io::stdout and std::io::stderr as follows:

  • If stdout or stderr does not exist, return the equivalent of std::io::sink.
  • If stdin does not exist, return the equivalent of std::io::empty.
  • For the raw versions, return a Result, and if the respective handle does not exist, return an Err.


  • Hides an error from the user which we may want to expose and may lead to people missing panicks occurring in threads.
  • Some languages, such as Ruby and Python, do throw an exception when stdout is missing.


  • Make println! print! panic! assert! return errors that the user has to handle. This would lose a large part of the convenience of these macros.
  • Continue with the status quo and panic if stdout or stderr doesn’t exist.
  • For std::io::stdin std::io::stdout and std::io::stderr, make them return a Result. This would be a breaking change to the signature, so if this is desired it should be done immediately before 1.0. ** Alternatively, make the objects returned by these methods error upon attempting to write to/read from them if their respective handle doesn’t exist.

Unresolved questions

  • Which is better? Breaking the signatures of those three methods in std::io, making them silently redirect to empty/sink, or erroring upon attempting to write to/read from the handle?