#788: Optionally exposed modules / APIs should be banned
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Reporter: duncan | 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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It is a deliberate decision that packages cannot depend on package + flag
combinations, only on packages. The point is that flags are not supposed
to change the API of a package.
This needs to be enforced.
Consider a real example (from Chart package:
http://hackage.haskell.org/packages/archive/Chart/0.14/Chart.cabal)
{{{
if flag(gtk)
build-depends: gtk >= 0.9.11
exposed-modules: Graphics.Rendering.Chart.Gtk
}}}
The criterion package depends on Chart and imports
`Graphics.Rendering.Chart.Gtk` meaning that it breaks if you build Chart
with the gtk flag turned off.
The solution is that Chart should be prevented from conditionally exposing
modules. We should add a QA check that looks for exposed modules that are
conditional on a flag. It is annoying but somewhat less bad for modules to
change between platforms.
Should it be a hard failure or just a warning?
--
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/788>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects
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