[tor-bugs] #19161 [Core Tor/Tor]: test for libscrypt_scrypt() fails

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#19161: test for libscrypt_scrypt() fails
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 Reporter:  isis               |          Owner:  nickm
     Type:  defect             |         Status:  needs_review
 Priority:  Medium             |      Milestone:  Tor: 0.2.8.x-final
Component:  Core Tor/Tor       |        Version:
 Severity:  Normal             |     Resolution:
 Keywords:  TorCoreTeam201605  |  Actual Points:  0.1
Parent ID:                     |         Points:  0
 Reviewer:  isis               |        Sponsor:
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Comment (by isis):

 Replying to [comment:11 isis]:
 > Replying to [comment:10 nickm]:
 > > uggggggggggggggg. starting around line 7617 is where we see the
 problem: linking doesn't work because we try to include '-libscrypt' but
 not '-lm'.
 > >
 > > `bug19161_028` now has an extra fix to search for libm even harder.
 >
 > All the `AC_CHECK_SIZEOF` checks are still failing due to not adding
 `-lm`, see attached
 [https://trac.torproject.org/projects/tor/attachment/ticket/19161/config.log.2.tar.xz
 config.log.2.tar.xz].

 And fourteen pages of GNU Autoconf documentation later… I think I have a
 patch which fixes this so that libscript is linked in when available, and
 when it is linked in, if we do need `-lm`, then `-lm` is also added where
 needed. It's available in my `bug19161_028`
 [https://gitweb.torproject.org/user/isis/tor.git/log/?h=bug19161_028
 branch], which is based on nickm's branch of the same name.

 My patch works for me, but it'd be nice to know that it doesn't break
 things for anyone else.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19161#comment:15>
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