[GHC] #15968: configure doesn't error out when --enable-dwarf-unwind is given but libdw cannot be found

[GHC]

#15968: configure doesn't error out when --enable-dwarf-unwind is given but libdw
cannot be found
-------------------------------------+-------------------------------------
        Reporter:  nh2               |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Build System      |              Version:  8.6.2
  (make)                             |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D5424
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"cb882fc993b4972f7f212b291229ef9e9ade0af9/ghc" cb882fc/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="cb882fc993b4972f7f212b291229ef9e9ade0af9"
 Require 'libdw' for '--enable-dwarf-unwind'

 This causes './configure --enable-dwarf-unwind' to exit with a helpful
 error message when 'libdw' cannot be found (compared to the previous
 behaviour of silently pretending the user hadn't requested DWARF support
 at all).

 Test Plan: ./configure --enable-dwarf-unwind # on systems with/without
 libdw

 Reviewers: bgamari, nh2

 Reviewed By: nh2

 Subscribers: nh2, rwbarton, erikd, carter

 GHC Trac Issues: #15968

 Differential Revision: https://phabricator.haskell.org/D5424
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15968#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler