[GHC] #15475: Plugin recompilation check still panics

[GHC]

#15475: Plugin recompilation check still panics
-------------------------------------+-------------------------------------
        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  highest           |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D5048
       Wiki Page:                    |
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Comment (by Krzysztof Gogolewski <krz.gogolewski@…>):

 In [changeset:"b324c5624432f2c3d5b0a689fdff75a1ccc563f5/ghc"
 b324c562/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="b324c5624432f2c3d5b0a689fdff75a1ccc563f5"
 Filter plugin dylib locations

 Summary:
 Previously we just created a cartesian product of the library
 paths of the plugin package and the libraries of the package.
 Of course, some of these combinations result in a filepath of
 a file doesn't exists, leading to #15475.

 Instead of making `haskFile` return Nothing in case a file
 doesn't exist (which would hide errors), we look at all the
 possible dylib locations and ensure that at least one of those
 locations is an existing file. If the list turns out to be
 empty however, we panic.

 Reviewers: mpickering, bgamari

 Reviewed By: mpickering

 Subscribers: monoidal, rwbarton, carter

 GHC Trac Issues: #15475

 Differential Revision: https://phabricator.haskell.org/D5048
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15475#comment:3>
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