ghc panic in kindFunResult

[ifigueroap]

The compiler made me post this bug report. Unfortunately I don't have a minimal example to reproduce it...

ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for i386-apple-darwin):
	kindFunResult
    ( k_a2Yio{tv} [tau] :: ghc-prim:GHC.Prim.BOX{(w) tc 347} )

[goldfire]

Have you tried compiling with 7.6.1 or with HEAD? Some kindFunResult panics have been fixed since 7.4.1...

This may be related to #7368. Do you have a non-minimal example to reproduce the bug?

[simonpj]

Let's hope it's a duplicate of #7368. Still, it has served the useful purpose of reminding me about #7368, which I've just fixed. Validating now!

Meanwhile this ticket is stalled unless you can come up with a reproducible example. Probably the path of least resistance is to wait for the patch for #7368 to hit the repository, build GHC, and test to see if it fixes your problem.

Simon

[ifigueroap]

I'm sorry, I don't have a minimal reproducible example. The error ocurred when I was working in monadic code and I put a wrong type annotation, something like:

do current <- getCurrent :: m (M m)

the annotation was wrong because the type of getCurrent was actually

(AOT (MbT m)) (M m)

where AOT and MbT are some custom monad transformers

[ifigueroap]

Since then I modified my code to work correctly... If you think it is not a duplicate of #7368, I think I can search my svn history and provide the full project version that triggers the error.

Replying to ifigueroap:

I'm sorry, I don't have a minimal reproducible example. The error ocurred when I was working in monadic code and I put a wrong type annotation, something like: {{{ do current <- getCurrent :: m (M m) }}} the annotation was wrong because the type of getCurrent was actually {{{ (AOT (MbT m)) (M m) }}} where AOT and MbT are some custom monad transformers

[simonpj]

I'm guessing that it's the same, and it's fixed in HEAD, so I'll close this ticket. Reopen if you subsequently discover that HEAD doens't work for you. Thanks!

Simon