ncal: Error out if writing to stdout failed.

[des]

Summary

MFC after: 1 week
Sponsored by: Klara, Inc.

[imp]

seems ok, but why?

[kevans]

In D39958#909666, @imp wrote:

seems ok, but why?

Yeah, suggest adding something like: "UNIX conformance requires command-line utilities to detect errors writing to stdout, emit an error message and exit accordingly."

Technically we could check every write, but that seems too invasive and not really any better than just catching it at the end.

[kevans]

In D39958#909684, @kevans wrote:

In D39958#909666, @imp wrote:

seems ok, but why?

Yeah, suggest adding something like: "UNIX conformance requires command-line utilities to detect errors writing to stdout, emit an error message and exit accordingly."

Technically we could check every write, but that seems too invasive and not really any better than just catching it at the end.

In fact, that seems like it'd be worse. We shouldn't mask other logical errors just because stdout was somehow borked.