[GHC] #13130: atomicModifyMutVar# has incorrect type

[GHC]

#13130: atomicModifyMutVar# has incorrect type
-------------------------------------+-------------------------------------
        Reporter:  carter            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"d91b10458885aede47ff17fa649b2c0fd9fdf3ca/ghc" d91b104/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d91b10458885aede47ff17fa649b2c0fd9fdf3ca"
 primops: Add comment describing type of atomicModifyMutVar#

 This resolves #13130. It's not entirely clear to me why we don't use an
 unboxed tuple here but this is at least better than the status quo.

 [skip ci]

 Test Plan: Read it

 Reviewers: simonmar, austin, dfeuer

 Reviewed By: dfeuer

 Subscribers: dfeuer, rwbarton, thomie

 Differential Revision: https://phabricator.haskell.org/D3288
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13130#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler