This replicates GHC's normalization logic so that Cabal's built in parsers can
be used. This should ensure maximum compatibility with how the Cabal file will
actually be evaluated during the build.

Additionally, this adds support for passing in the full LLVM style platform
triple/quadruple (e.g. x86_64-unknown-linux-gnu) instead of just the short Nix
style (x86_64-linux). This will make it possible for the ABI to treated as part
of the OS where applicable (e.g. linux-android). We can then change
`make-package-set.nix` to use `hostPlatform.config` instead of
`hostPlatform.system` to get the full information.

Support all architectures and OSs that GHC and Cabal support

The vendored library causes build errors, i.e.:

  yesodweb/persistent#803

… later

gdk-x11-3.0: point to the gtk3 package

fetchOrFromDB: Show which source failed when calling `fail`

homepage will be set to Hackage by the generic builder.

The hackage page is always there, and supports a TLS connection.

hackage2nix: clear homepage

It also has a dependency on gtk3 which is not being picked up.

Fix dbusmenu-gtk3

Fixes #354.

NixOS/nixpkgs#41939
haskell/cabal#5391

…estedSpec

A record update on defaultComponentRequestedSpec is no safer than just
constructing an instance of the type directly, because there is a mysterious
second constructor, OneComponentRequestedSpec, that our record update won't
match if defaultComponentRequestedSpec turns out to be such a thing for some
reason. Curiously enough, we have helper functions that can query the state of
the ComponentRequestedSpec type, but we cannot easily manipulate it.

…ce again

…utable

When that value is set, it means that the --no-haddock options was not given on
the command line. That is not the same thing as meaning that Haddock generation
should be enabled.

…bot-irc-plugins

Refactor cabal2nix lib api

We've had an API change.

Closes #359.

If we need a library and build tool from the same package, we should
keep both deps.

See comment in code for more details.

Fixes #356

Add hack for common erroneous missing build-tool-depends, and keep duplicate deps for cross

Fixes NixOS/nixpkgs#43574.

This is because in a nomal workflow, you would generate the .cabal
every now and then from the package.yaml file.

If you forget to do this generation and you have an old .cabal file
in your tree (common because for users of hpack, .cabal files are
usually in .gitignore), then until now nix would pick up the outdated
cabal file and you would accidentally be running against outdated cabal
contents.

So in this commit we change the logic from

  "if *.cabal doens't exist, check if package.yaml exist, if so use hpack"

to

  "if package.ymal exists, use hpack, otherwise use *.cabal"