#649: better warning messages for why dependencies are missing / cannot be
selected
---------------------------------+------------------------------------------
Reporter: duncan | Owner: kosmikus
Type: enhancement | Status: closed
Priority: normal | Milestone: cabal-install-0.14
Component: cabal-install tool | Version: HEAD
Severity: normal | Resolution: fixed
Keywords: solver | Difficulty: unknown
Ghcversion: | Platform:
---------------------------------+------------------------------------------
Changes (by kosmikus):
* status: new => closed
* resolution: => fixed
Comment:
Here's the error message the modular solver reports in a similar
situation. I added a number of flags to prevent other solutions from being
found:
{{{
$ cabal install --global --package-db=local aeson-0.6.0.2 --constraint
="unordered-containers installed" --dry-run
cabal: Could not resolve dependencies:
trying: aeson-0.6.0.2 (user goal)
next goal: unordered-containers (dependency of aeson-0.6.0.2)
rejecting: unordered-containers-0.2.1.0/installed-171... (package is
broken)
rejecting: unordered-containers-0.2.1.0, 0.2.0.1, 0.2.0.0, 0.1.4.6,
0.1.4.5,
0.1.4.4, 0.1.4.3, 0.1.4.2, 0.1.4.1, 0.1.4.0, 0.1.3.0, 0.1.2.0, 0.1.1.0,
0.1.0.0 (global constraint requires installed instance)
}}}
The `unordered-containers-0.2.1.0` version is installed in the local
package DB, but depends on `hashable` which is installed in the user DB.
If we add the `--user` flag, it works:
{{{
$ cabal install --global --user --package-db=local aeson-0.6.0.2
--constraint="unordered-containers installed" --dry-run
Resolving dependencies...
In order, the following would be installed (use -v for more details):
blaze-builder-0.3.1.0
primitive-0.4.1
vector-0.9.1
aeson-0.6.0.2
}}}
The error message for the installed constraint is implicitly shown above
as well. Here's another example:
{{{
$ ~/.cabal/bin/cabal install repa-3.1.0.1 --dry-run
Resolving dependencies...
cabal: Could not resolve dependencies:
trying: repa-3.1.0.1 (user goal)
next goal: base (dependency of repa-3.1.0.1)
rejecting: base-3.0.3.2, 3.0.3.1 (global constraint requires installed
instance)
rejecting: base-4.3.1.0/installed-20f... (conflict: repa => base==4.5.*)
rejecting: base-4.5.0.0, 4.4.1.0, 4.4.0.0, 4.3.1.0, 4.3.0.0, 4.2.0.2,
4.2.0.1,
4.2.0.0, 4.1.0.0, 4.0.0.0 (global constraint requires installed instance)
}}}
This still lists all versions of `base`, but lists very clearly that we
can't use any version but 4.3.1.0 because they're not installed, and we
can't use 4.3.1.0 because repa requires 4.5.
Closing this bug.
--
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/649#comment:5>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects
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