Ticket #7150 (closed bug: fixed)
unjustified overlapping instances error
| Reported by: | maeder | Owned by: | |
|---|---|---|---|
| Priority: | highest | Milestone: | 7.6.1 |
| Component: | Compiler | Version: | 7.6.1-rc1 |
| Keywords: | Cc: | ||
| Operating System: | Unknown/Multiple | Architecture: | Unknown/Multiple |
| Type of failure: | GHC rejects valid program | Difficulty: | Unknown |
| Test Case: | Blocked By: | ||
| Blocking: | Related Tickets: |
Description
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.
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