[GHC] #14817: GHC 8.4.1 pretty-prints data family instances with redundant kind signatures using -ddump-splices
GHC
ghc-devs at haskell.org
Fri Mar 2 21:07:31 UTC 2018
#14817: GHC 8.4.1 pretty-prints data family instances with redundant kind
signatures using -ddump-splices
-------------------------------------+-------------------------------------
Reporter: RyanGlScott | Owner: (none)
Type: bug | Status: patch
Priority: normal | Milestone:
Component: Compiler | Version: 8.4.1-alpha3
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:D4418
Wiki Page: |
-------------------------------------+-------------------------------------
Comment (by Ben Gamari <ben@…>):
In [changeset:"aef2b429072e3d3bbdbcb9e4082a0d86ba329d9e/ghc"
aef2b429/ghc]:
{{{
#!CommitTicketReference repository="ghc"
revision="aef2b429072e3d3bbdbcb9e4082a0d86ba329d9e"
Fix #14817 by not double-printing data family instance kind signatures
Within `pprDataFamInstDecl`, we were invoking `pprFamInstLHS` to
pretty-print a data family instance header, and we were passing `Just` a
kind signature to `pprFamInstLHS` to make it pretty-print the kind
signature alongside it (this is a consequence of commit
d1ef223cfebd23c25489a4b0c67fbaa2f91c1ec6). But this is silly, because
then invoke `pp_data_defn`, which //also// pretty-prints the kind
signature, resulting in the kind signature being printed twice by
mistake.
This fix is simple—pass `Nothing` to `pprFamInstLHS` instead.
Test Plan: make test TEST=T14817
Reviewers: alanz, bgamari, mpickering
Reviewed By: mpickering
Subscribers: mpickering, rwbarton, thomie, carter
GHC Trac Issues: #14817
Differential Revision: https://phabricator.haskell.org/D4418
}}}
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14817#comment:2>
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