[ ghc-Bugs-699225 ] GHCi segfaults on expression evaluation

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Bugs item #699225, was opened at 2003-03-07 03:21
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=108032&aid=699225&group_id=8032

Category: None
Group: 5.04.2
Status: Open
Resolution: None
Priority: 5
Submitted By: Carlos Eduardo Scheidegger (carlossch)
Assigned to: Nobody/Anonymous (nobody)
Summary: GHCi segfaults on expression evaluation

Initial Comment:
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 at terra.com.br), I'd be glad to be of help.

Carlos

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