#3297: Compiler panic on incorrect code (TcTyFuns.flattenType: synonym family
in a
rank-n type)
----------------------------------------+-----------------------------------
Reporter: hesselink | Owner: chak
Type: bug | Status: new
Priority: low | Milestone: 7.2.1
Component: Compiler (Type checker) | Version: 6.11
Keywords: | Testcase:
Blockedby: | Difficulty: Unknown
Os: Linux | Blocking:
Architecture: x86 | Failure: None/Unknown
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Comment(by hesselink):
I just tested this with GHC 7.0.2, and the compiler panic is gone. I now
get two type errors instead, which is much better. The errors are below.
{{{
Temp.hs:13:9:
Occurs check: cannot construct the infinite type:
uf0
=
Es (PF (forall n. uf0 n) (Es (forall n. uf0 n)) (forall n. uf0 n))
Expected type: forall n. Es a n
Actual type: forall n. uf0 n
Expected type: (forall n. Es a n) -> a
Actual type: (forall n. uf0 n)
-> PF (forall n. uf0 n) (Es (forall n. uf0 n)) (forall
n. uf0 n)
In the expression: from
In an equation for `crash': crash = from
Temp.hs:13:9:
Couldn't match type `a'
with `PF
(forall n. uf0 n) (Es (forall n. uf0 n))
(forall n. uf0 n)'
`a' is a rigid type variable bound by
the type signature for crash :: (forall n. Es a n) -> a
at Temp.hs:13:1
Expected type: (forall n. Es a n) -> a
Actual type: (forall n. uf0 n)
-> PF (forall n. uf0 n) (Es (forall n. uf0 n)) (forall
n. uf0 n)
In the expression: from
In an equation for `crash': crash = from
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3297#comment:9>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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