#4272: Typechecker loop with type families
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Reporter: NickSmallbone | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 6.13
Resolution: fixed | Keywords:
Testcase: indexed-types/should_fail/Ttttt4272 | Blockedby:
Difficulty: | Os: Linux
Blocking: | Architecture: x86_64
(amd64)
Failure: Compile-time crash |
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Changes (by simonpj):
* status: new => closed
* testcase: => indexed-types/should_fail/Ttttt4272
* resolution: => fixed
Comment:
The new type checker is coming to life. I've just tried it on your
program. Sure enough, it tickled a couple of easily-fixed bugs (thank
you) but once those were done it produced a decent error message in a
jiffy:
{{{
T4272.hs:11:26:
Occurs check: cannot construct the infinite type:
a = TermFamily a a
In the first argument of `terms', namely
`(undefined :: TermFamily a a)'
In the second argument of `prune', namely
`(terms (undefined :: TermFamily a a))'
In the expression: prune t (terms (undefined :: TermFamily a a))
}}}
So I declare this bug fixed. I've added a regression test, so you are
imortalised.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4272#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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