Stdout panic

Signed-off-by: Peter Atashian <retep998@gmail.com>

0000-stdout-existential-crisis.md

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+- Feature Name: stdout_existential_crisis
+- Start Date: 2015-03-25
+- RFC PR: (leave this empty)
+- Rust Issue: (leave this empty)
+
+# Summary
+
+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.
+
+# Motivation
+
+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 printing to the console.
+
+# Detailed design
+
+Change the internal implementation of `println!` `print!` `panic!` and `assert!` to not `panic!` when `stdout` or `stderr` doesn't exist. When getting `stdout` or `stderr` through the `std::io` methods, those versions should continue to return an error if `stdout` or `stderr` doesn't exist.
+
+# Drawbacks
+
+Hides an error from the user which we may want to expose and may lead to people missing panicks occuring in threads.
+
+# Alternatives
+
+* Make `println!` `print!` `panic!` `assert!` return errors that the user has to handle.
+* Continue with the status quo and panic if `stdout` or `stderr` doesn't exist.
+
+# Unresolved questions
+
+* Should `std::io::stdout` return `Err` or `None` when there is no `stdout` instead of unconditionally returning `Stdout`?