[GHC] #9049: Expose srcLoc from the assertion architecture to allow better error messages

[GHC]

#9049: Expose srcLoc from the assertion architecture to allow better error
messages
-------------------------------------+-------------------------------------
        Reporter:  nh2               |                   Owner:  gridaphobe
            Type:  feature request   |                  Status:  closed
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Compiler          |                 Version:  7.8.2
      Resolution:  fixed             |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:  Phab:D578
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Comment (by hvr):

 Replying to [comment:37 gridaphobe]:
 > Does it actually break any client packages? There was talk of building
 stackage with the backport to investigate.

 Yeah, one single package from Stackage seems to be affected by this:

 {{{
 [11 of 14] Compiling HsWalk           ( HsWalk.hs, dist/build/ide-backend-
 server/ide-backend-server-tmp/HsWalk.o )

 HsWalk.hs:136:35:
     Couldn't match expected type ‘SrcSpan’
                 with actual type ‘RealSrcSpan’
     In the first argument of ‘go’, namely ‘span’
     In the second argument of ‘($)’, namely ‘go span’
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9049#comment:38>
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