[GHC] #14118: Strangeness regarding STG alternative types and linter

[GHC]

#14118: Strangeness regarding STG alternative types and linter
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3889
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"a36b34c4821653e3db3ff24b903265a7750a3397/ghc" a36b34c/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a36b34c4821653e3db3ff24b903265a7750a3397"
 StgLint: Enforce MultiValAlt liveness invariant only after unariser

 The unariser ensures that we never use case binders that are void,
 unboxed sums, or unboxed tuples. However, previously StgLint was
 enforcing this invariant even before the unariser was running, giving
 rise to spurious lint failures.  Fix this. Following CoreLint, we
 introduce a LintFlags environment to the linter monad, allowing for
 additional flags to be easily accomodated in the future.

 See #14118.

 Test Plan: Build GHC with -dstg-lint

 Reviewers: simonpj, austin

 Subscribers: rwbarton, thomie

 GHC Trac Issues: #14118

 Differential Revision: https://phabricator.haskell.org/D3889
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14118#comment:9>
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