unjustified overlapping instances error
When compiling hets (http://trac.informatik.uni-bremen.de:8080/hets/wiki/HetsForDevelopers) using ghc-7.6.0.20120810 I get the following error
[489 of 664] Compiling Comorphisms.HasCASL2IsabelleHOL ( Comorphisms/HasCASL2IsabelleHOL.hs, Comorphisms/HasCASL2IsabelleHOL.o )
Comorphisms/HasCASL2IsabelleHOL.hs:61:44:
Overlapping instances for Category Env Morphism
arising from a use of `sourceSublogic'
Matching instances:
instance [incoherent] Category Env Morphism
-- Defined at HasCASL/Logic_HasCASL.hs:74:10
There exists a (perhaps superclass) match:
(The choice depends on the instantiation of `'
To pick the first instance above, use -XIncoherentInstances
when compiling the other instance declarations)
In the second argument of `isSubElem', namely `sourceSublogic cid'
In the expression: sl `isSubElem` sourceSublogic cid
In the expression:
if sl `isSubElem` sourceSublogic cid then Just () else Nothing
Note, that only a single instance is listed and that the choice is empty. Adding -XIncoherentInstances does also not help to get it compiled.
Trac metadata
Trac field | Value |
---|---|
Version | 7.6.1-rc1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | Solaris |
Architecture | x86 |