The fundamental difference between Cabal and cabal-install is that the former
deals with installed libraries, and -- in principle -- knows about _library_
dependencies only, whereas the latters deals with setup, executable, test-suite
and benchmark dependencies in addition to library dependencies. Currently we
classify all of these simply as 'dependencies' but that will change shortly.

In this commit we take a first step towards this by moving the PackageFixedDeps
class, which deals with dependencies of packages rather than installed
libraries, from Cabal to cabal-install.

The commit is pretty simple; we just move the type class and update import
statements where necessary.

Migrate the test suite to Tasty.

cabal-install.init: warn if the chosen package name is already registered to the source package index.

cabal-install.init: warn if the chosen package name is already registered to the source package index.

Fix test interface detailed-0.9 with GHC 7.10

Fixes #2476. Cabal could not build detailed-0.9 test suites with GHC
7.10 because the wrong package key was being used to build the test
suite library.

TODO: We should add real multi-library support to Cabal!

This reverts commit 1b930232.

This reverts commit e8d6e853.

Fixes #2475.

[ci skip]

fix HPC tests with GHC 7.10

Starting with version 7.10, GHC puts the module interface (.mix) files
for each project in a subdirectory of -hpcdir named for the package
key. We must adjust the search path accordingly when checking for the
.mix file.

Make sure to pass the package key to ghc

In https://github.com/haskell/cabal/pull/2439 the invocation of Haddock is
changed to use Haddock's new `--package-name` and `--package-version` flags,
necessary for GHC >= 7.10 (Cabal issue
https://github.com/haskell/cabal/issues/2297 / Haddock issue
https://github.com/haskell/haddock/issues/353). However, this commit also
removes the `-package-name` argument to GHC. This is incorrect, as it means
that GHC will end up calling the package `main` and we end up with Haddock link
environments such as

    (trans_H9c1w14lEUN3zdWCTsn8jG:Control.Monad.Trans.Error.strMsg, main:Control.Monad.Error.Class)

Note that before this commit we ended up with

    (trans_H9c1w14lEUN3zdWCTsn8jG:Control.Monad.Trans.Error.strMsg, mtl-2.1.1:Control.Monad.Error.Class)

which is equally wrong as it uses a package source ID rather than a package key
(Haddock issue https://github.com/haskell/haddock/issues/362). Instead, we need
to pass _both_ `--package-name` and `--package-version` to Haddock, and
`-package-name` or `-this-package-key` to GHC, depending on the version.
Thankfully the infrastructure for chosing between `-package-name` and
`-this-package-key` is already in place, so we just have to make sure to
populate the `ghcPackageKey` field. After this commit the link environment
looks like

    (trans_H9c1w14lEUN3zdWCTsn8jG:Control.Monad.Trans.Error.strMsg, mtl_Koly6qxRZLf86guywd4tkE:Control.Monad.Error.Class)

which is correct.

Fixes #2309, #1889.

Fixes #2461.

Say 16 days, rather than 16.3 days. The precision is quite unnecessary.