Opened 13 years ago

Closed 13 years ago

Last modified 46 years ago

#124 closed bug (Fixed)

GHCi segfaults on expression evaluation

Reported by: carlossch Owned by: simonpj
Priority: normal Milestone:
Component: None Version: 5.04.2
Keywords: Cc:
Operating System: Architecture:
Type of failure: Test Case:
Blocked By: Blocking:
Related Tickets: Differential Rev(s):
Wiki Page:



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:

    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 ([email protected]), I'd be glad to be of help.


Attachments (1)

Test.2.hs (1.5 KB) - added by carlossch 13 years ago.

Download all attachments as: .zip

Change History (3)

Changed 13 years ago by carlossch

comment:1 Changed 13 years ago by carlossch

Logged In: YES 

I have just noticed that I mistakenly uploaded the file Test.hs without uncommenting the line

> instance Reverse a (Pop t b) ... 

GHCi only crashes with this line uncommented. I am sorry for the confusion

comment:2 Changed 13 years ago by simonmar

  • Status changed from assigned to closed
Logged In: YES 

This one is now fixed.
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