[Hackage] #773: Default value for flag ignored, but explicit flag assignment is honored
Hackage
cvs-ghc at haskell.org
Fri Dec 3 12:19:18 CET 2010
#773: Default value for flag ignored, but explicit flag assignment is honored
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Reporter: guest | Owner:
Type: defect | Status: new
Priority: normal | Milestone:
Component: Cabal library | Version: 1.8.0.6
Severity: normal | Keywords:
Difficulty: unknown | Ghcversion:
Platform: |
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Comment(by malcolm.wallace@…):
This is not a bug, it is a design feature. The "default" value of a flag
is only a hint to the constraint solver that it should try using that flag
value first, before trying other values. If the constraint solver was
unable to find a valid solution to the dependencies using your default
value of "True", then it continues looking with the value "False", and
then apparently does find a valid solution respecting all dependencies
listed there.
However, if you specify a flag value on the command-line, the constraint
solver will not try using other values for flags: it trusts that the user
really wants what they explicitly asked for. In your case, I think if you
specify True for the value of the flag on the commandline, the solver will
probably fail to find a solution, and tell you why.
--
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/773#comment:1>
Hackage <http://haskell.org/cabal/>
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