[GHC] #14174: GHC panic with TypeInType and type family
GHC
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Mon Mar 5 08:51:01 UTC 2018
#14174: GHC panic with TypeInType and type family
-------------------------------------+-------------------------------------
Reporter: dfeuer | Owner: (none)
Type: bug | Status: closed
Priority: normal | Milestone: 8.2.3
Component: Compiler (Type | Version: 8.2.1
checker) |
Resolution: fixed | Keywords: TypeInType
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: Compile-time | Test Case:
crash or panic | polykinds/T14174.hs, T14174a
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
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Comment (by Simon Peyton Jones <simonpj@…>):
In [changeset:"3d252037234ce48f9bdada7d5c9b1d8eba470829/ghc"
3d252037/ghc]:
{{{
#!CommitTicketReference repository="ghc"
revision="3d252037234ce48f9bdada7d5c9b1d8eba470829"
Respect Note [The tcType invariant]
I tried to do this with
commit 0a12d92a8f65d374f9317af2759af2b46267ad5c
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date: Wed Dec 13 12:53:26 2017 +0000
Further improvements to well-kinded types
The typechecker has the invariant that every type should be well-
kinded
as it stands, without zonking. See Note [The well-kinded type
invariant]
in TcType.
That invariant was not being upheld, which led to Trac #14174. I
fixed
part of it, but T14174a showed that there was more. This patch
finishes
the job.
But I didn't get it quite right as Trac #14873 showed.
This patch fixes the problem; although I am still a bit unhappy.
(See "A worry" in the HsApp case of tc_infer_hs_type.)
}}}
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14174#comment:10>
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