[GHC] #9243: Recompilation avoidance doesn't work for -fno-code/-fwrite-interface

[GHC]

#9243: Recompilation avoidance doesn't work for -fno-code/-fwrite-interface
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        Reporter:  ezyang            |                   Owner:  ezyang
            Type:  bug               |                  Status:  patch
        Priority:  high              |               Milestone:  7.10.1
       Component:  Compiler          |                 Version:  7.9
      Resolution:                    |                Keywords:  backpack
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D596
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Comment (by Edward Z. Yang <ezyang@…>):

 In [changeset:"2223e196b2dc5340d70e58be011c279d381b4319/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="2223e196b2dc5340d70e58be011c279d381b4319"
 Fix #9243 so recompilation avoidance works with -fno-code

 Summary:
 Where we track timestamps of object files, also track timestamps
 for interface files.  When -fno-code -fwrite-interface is enabled, use
 the interface file timestamp as an extra check to see if the files are
 up-to-date.  We had to apply this logic to one-shot and make modes.

 This fix would be good to merge into 7.10; it makes using -fno-code
 -fwrite-interface for flywheel type checking usable.

 Signed-off-by: Edward Z. Yang <ezyang at cs.stanford.edu>

 Test Plan: validate and new test cases

 Reviewers: austin

 Subscribers: carter, thomie

 Differential Revision: https://phabricator.haskell.org/D596

 GHC Trac Issues: #9243
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9243#comment:7>
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