If extra-lib-dirs and/or extra-include-dirs are specified via either
command line or project files, they’re going to be added for each
package in the dendency graph. With enough long enough directories
the command-line length limits for gcc may be hit and calls to
the C compiler made from hsc2hs will start failing.

Ideally hsc2hs should be using repsonse files, but needlessly
specifying myriad of command-line parameters is redundant anyway.

Deduplicate hsc2hs args

Fix typo exsting

- Bump to hlint-3.10 in the gh-action

Fix typo in haddock comment

* Error messages are indented by 2 spaces
* 0:0 positions are never shown
* More attempts are made to remove extra newlines.

Bump to hlint-3.10

fix haskell#11073

CI: add GHC 8.6.5 to validate-old-ghcs

Replace cabal project parsing with Parsec

Typo in Makefile .PHONY target

Simply disabling the step causes all non-Windows to fail, so we
now skip it only on Windows.

Isolate the common logic between building and only downloading.

_Push the ifs up and the loops down_

More logging in ProjectBuilding

Determine packages to build in-place by their solver id, not their package id.

Cabal uses a peculiar c program to check if LD supports and should
use -x. To do this, it shells out to GHC to compiler the C file.
This however requires that GHC will not bail out, yet cabal does
not pass --package-db flags to this GHC invocation, and as such we
can run into situations where GHC bails out, especially during GHC
bootstrap phases where not all boot packages are available.

We however do not need GHC to compiler a c program, and can rely
on the C compiler.

Fundamentally cabal does not allow modelling program dependencies
in the program db, as such we must configure gcc first before using
it.

We make a small change to lib:Cabal (specifically the GHC module,
and it's Internal companion) to allow it to configure gcc first,
before trying to configure ld, and thus having gcc in scope while
configuring ld. This removes the need for the awkward ghc
invocation to compiler the test program.

…ectory after build

Split the function into multiple ones.

…tale cache

If a node has dangling edges, then the list of missing neighbours cannot be empty.

Exceptions are not nice but this is an obvious invariant. Graph should provide a better API to make this unnecessary.

Not really a fix. I do not know why this happens.

…iler id

It is duplicate information since we write the program invocation right after.