Ben Gamari authored 7 years ago and Ben Gamari committed 7 years ago

FP_PROG_AR_ARGS appears to be probing for what flags to use to build an
archive with an index. However, none of the flags that it probed
previously were valid as they all started with `c`, which isn't a mode
character. This went unnoticed until someone attempted to use LLVM ar
since we have a special case for gnu ar.

Additionally, we work around a bug in llvm-ar 5.0 where ar will exit
with code 0 even if it fails to parse the command line. Silliness.

I believe these should rather all be mode `q` however I'll need to test
this on a few platforms to be certain.

Test Plan: Validate on OS X, BSD, and Linux with binutils and llvm ar

Reviewers: hvr

Subscribers: rwbarton, thomie, erikd

Differential Revision: https://phabricator.haskell.org/D4214