Errors often exit with status 0

[cbiffle]

(Found at 6fc713d, consistent at least back through 0.9.18)

Bogus command line arguments given to idris --client print a usage message (good!) and then exit with status 0 (less good). This means that programs calling out to idris don't realize their command lines are formatted incorrectly.

I specifically noticed this with the idris-vim plugin, resulting in the issue idris-hackers/idris-vim#39.

Test case (note that idris requires quotes around the :l file.idr command):

$ idris --client :l file.idr
Usage is :l <string>
$ echo $?
0

[cbiffle]

Hm, it seems that all sorts of bad things exit with status 0.

$ idris --client ":l nonexist.idr"
Can't find import nonexist.idr
$ echo $?
0