#4174: Jumbled error message from type family operator
------------------------------------------------+---------------------------
Reporter: lilac | Owner:
Type: bug | Status: closed
Priority: normal | Milestone: 7.0.1
Component: Compiler (Type checker) | Version: 6.12.1
Resolution: fixed | Keywords:
Testcase: indexed-types/should_fail/T4174 | Blockedby:
Difficulty: | Os:
Unknown/Multiple
Blocking: | Architecture:
Unknown/Multiple
Failure: Incorrect warning at compile-time |
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Changes (by simonpj):
* status: new => closed
* testcase: => indexed-types/should_fail/T4174
* resolution: => fixed
Comment:
This bug is fixed by the latest wave of typechecker fixes (I'm not sure
exactly which one). Now we get these errors:
{{{
T4174.hs:42:12:
Couldn't match type `False' with `True'
Expected type: True
Actual type: GHC6'10 Minor1 :<=: GHCVersion (WayOf m)
In the expression: sync_large_objects
In an equation for `testcase': testcase = sync_large_objects
T4174.hs:42:12:
Could not deduce (a ~ SmStep) from the context (Monad m)
`a' is a rigid type variable bound by
the type signature for `testcase' at T4174.hs:41:60
In the expression: sync_large_objects
In an equation for `testcase': testcase = sync_large_objects
T4174.hs:42:12:
Could not deduce (b ~ RtsSpinLock) from the context (Monad m)
`b' is a rigid type variable bound by
the type signature for `testcase' at T4174.hs:41:62
In the expression: sync_large_objects
In an equation for `testcase': testcase = sync_large_objects
T4174.hs:42:12:
Could not deduce (p ~ True) from the context (Monad m)
`p' is a rigid type variable bound by
the type signature for `testcase' at T4174.hs:41:57
Expected type: True
Actual type: Threaded (WayOf m)
In the expression: sync_large_objects
In an equation for `testcase': testcase = sync_large_objects
}}}
The first of these is the one you were after, and looks quite reasonable.
I've added a regression test.
Thanks for reporting it!
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4174#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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