Skip to content

GHCi segfaults on expression evaluation

Hello. 

I think I've come across a GHCi bug.

Using the following module, GHCi version 5.04.2 segfaults, apparently trying to compute a type using functional dependencies. The segfault
happens when I try to calculate (v1 .> v2). I tried the code on Hugs, and it answers

Main> v1 .> v2
V [] :: PSOp (Pop a Id)

as expected. I think the problem is occuring in the line

> instance Reverse a b c => CheckPS Id a b c

because if I remove the line

> instance Reverse a (Pop t b)  c => Reverse (Pop t a) b c

instead of segfaulting, GHCi rightfully complains:

<interactive>:1:
    No instance for (Reverse (Pop a Id) Id c)
    arising from use of `.>' at <interactive>:1
    In the definition of `it': v1 .> v2


GHC compiles the program just fine and runs it without any issues. I installed GHC 5.04.2 using the RedHat 8.0 RPM's. If there's any important information you may need from me, please,  contact me through my email (carlos.scheidegger@terra.com.br), I'd be glad to be of help.

Carlos
Trac metadata
Trac field Value
Version 5.04.2
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution ResolvedFixed
Component None
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information