[GHC] #15167: DerivClause list is not populated for (TyConI (DataD ...))
GHC
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Sun May 20 01:01:12 UTC 2018
#15167: DerivClause list is not populated for (TyConI (DataD ...))
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Reporter: 0xd34df00d | Owner: (none)
Type: bug | Status: new
Priority: normal | Milestone: 8.6.1
Component: Template Haskell | Version: 8.4.2
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: |
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Changes (by RyanGlScott):
* cc: newcomer (added)
Comment:
Indeed, this is expected. Reified data declarations never have derived
instances attached to them, as they're only used when splicing a TH-
constructed data type into source code. (If you want to know a data type's
instances via TH, you should use `reifyInstances`.)
The Haddocks in `template-haskell` currently don't state that reified data
types lack derived instance information, however, so it would be good to
update the documentation to reflect this.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15167#comment:1>
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