[GHC] #16179: Mention DerivingStrategies in the warning when DeriveAnyClass and GeneralizedNewtypeDeriving are both enabled
GHC
ghc-devs at haskell.org
Mon Jan 14 16:58:07 UTC 2019
#16179: Mention DerivingStrategies in the warning when DeriveAnyClass and
GeneralizedNewtypeDeriving are both enabled
-------------------------------------+-------------------------------------
Reporter: ckoparkar | Owner: (none)
Type: feature | Status: new
request |
Priority: normal | Milestone: 8.10.1
Component: Compiler | Version:
Keywords: deriving | Operating System: Unknown/Multiple
Architecture: | Type of failure: None/Unknown
Unknown/Multiple |
Test Case: | Blocked By:
Blocking: | Related Tickets:
Differential Rev(s): | Wiki Page:
-------------------------------------+-------------------------------------
When {{{DeriveAnyClass}}} and {{{GeneralizedNewtypeDeriving}}} are both
enabled, GHC prints out the following warning for every {{{deriving C}}}:
{{{
#!haskell
warning:
• Both DeriveAnyClass and GeneralizedNewtypeDeriving are enabled
Defaulting to the DeriveAnyClass strategy for instantiating C
}}}
Would it be useful to point the users to {{{DerivingStrategies}}} ?
{{{Use DerivingStrategies to pick a different strategy}}}, or something
similar? I'm not sure if this was already discussed before, I couldn't
find any related tickets.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16179>
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