Merge branch 'pr/DetectCyclesInSolver' of https://github.com/edsko/cabal into edsko-pr/DetectCyclesInSolver

Make configPrograms a bit more backward compatible

This implements the suggestion from
https://github.com/haskell/cabal/pull/3196#issuecomment-190285328

Replace Boilerplate Monoid/Semigroup instances with generics

See https://github.com/haskell/cabal/pull/3197#issuecomment-189839042.

This increases compile-time (until GHC becomes more clever) but the
generated code is expected to be at least as good (if not better) than
the manually generated code.

While at it, this removes -XCPP usage from all modules touched.

This addresses #3169

This increases compile-time (until GHC becomes more clever) but the
generated code is expected to be at least as good (if not better) than
the manually generated code.

This addresses #3169

This is preparatory work for implementing #3169
it's kept in a different commit in order to facilitate
comparing code-generation.

This is preparatory work for implementing #3169
it's kept in a different commit in order to facilitate
comparing code-generation.

Turn 'configPrograms' field into a 'Last'-monoid

This implements the suggestions mentioned at
https://github.com/haskell/cabal/issues/3169#issuecomment-189281916

The main benefit of this change is turning 'ConfigFlags' into a uniform
product-type suitable for generic derivation of pointwise
`Semigroup`/`Monoid` instances.

NB: This changes the `Binary` serialisation of `ConfigFlags` since there's
now an additional `Maybe` inserted in `configPrograms`'s type

Add `gmappend`/`gmempty` Generics-helpers (re #3169)

Since Cabal makes use of Maps and Sets we need them in place in our
Semigroups compat-layer.

Distribution.Simple.Setup: remove job cap

Fixes #3191.

See https://github.com/well-typed/hackage-security/pull/151.

Warn when 'cabal configure' cannot resolve dependencies.

Revert "Add warning about testing Cabal on Windows"

This reverts commit 727f4479.

This comment is unnecessary after #3180. [ci skip]

Unbreak the build on AppVeyor.

Update HACKING.md: Add --allow-newer=Cabal

Fix exitcode on `upload`ing failure

This reverts commit 5a1f8575.

Cabal should be buildable out of the box.

hackage-security doesn't know about Cabal 1.25.

Skip Cabal package tests that cannot run in the current environment

The functions 'testWhen' and 'testUnless' filter tests in the 'TestTreeM' monad.
The option '--enable-all-tests' ignores filtering.  This commit also applies
filtering to the existing package tests that cannot run on Windows.

This reverts commit f211508d.