6667f90292
It's too easy to forget the `rust` tag to have a code example tested, and it's far more common to have testable code than untestable code. This alters rustdoc to have only two directives, `ignore` and `should_fail`. The `ignore` directive ignores the code block entirely, and the `should_fail` directive has been fixed to only fail the test if the code execution fails, not also compilation.