[GHC] #7766: equality constraints exposed by patterns mess up constraint inference
GHC
cvs-ghc at haskell.org
Wed Mar 13 13:47:54 CET 2013
#7766: equality constraints exposed by patterns mess up constraint inference
--------------------------------------+-------------------------------------
Reporter: heisenbug | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.7 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: GHC rejects valid program | Blockedby:
Blocking: | Related:
--------------------------------------+-------------------------------------
When patterns bring (equality) constraints into scope, the inference
mechanism for other (unrelated) constraints breaks down.
This is a new problem that appeared between
* ghc-7.7.20121025 and
* ghc-7.7.20121114
I can try to track down the commit if that helps.
Testcase against HEAD attached.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7766>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
More information about the ghc-tickets
mailing list