-o option is mostly ignored for libraries

[brson]

rustc`s -o command line option takes a filename but only uses the directory when creating libraries. This is surprising behavior that we should fix.

Not sure if there are other issues on this subject.

[brson]

Nominating for something.

[bstrie]

Related to #2401.

[graydon]

accepted for backwards-compatible milestone

[graydon]

given that #2401 was closed but this is still biting people, we need to change the behavior

[msullivan]

Perhaps we should disable -o for libraries, and maybe add a short version of --out-dir?