Fix v2-install ProgramDb confusion

Improve docs for html-location

Commit 273dacfd ("Extract installLibraries and InstallExes from
installAction") makes 'getInstalledPackages' get passed the
pre-configCompilerEx ProgramDb which will cause pattern match failures when
the code tries to lookup ghc-pkg in the progdb.

Someone mentioned this section was confusing in #haskell. I added an
example of command line usage so there is no confusion.

[ci skip]

Add changelog for #5977 amd #6134 fixes [ci skip]

Add cabal-version: 3.2

Depend on tagged to get Proxy

Pass `ld-options` through to GHC

parser: Clearly state that invalid fields are ignored

Ben Gamari authored 5 years ago and Oleg Grenrus committed 5 years ago

Previously we would issue a warning of the following form when
we encountered a field that isn't supported by the cabal-version
declared in the cabal file:

    Warning: ghc-heap.cabal:30:3: The field "cmm-sources" is available
    only since the Cabal specification version 3.0.

The message, however, doesn't tell the user the consequence of this
warning. Consequently a user could easily be confused when the build
subsequently fail.

Avoid this possibility by clearly stating that the field value will be
ignored.

Update to SPDX License List 3.6 2019-07-10

Parse list fields in cabal config file

Add FGSectionDescrs so cabal.project sections can be parsed using Fie…

runParseResult reutrns NonEmpty PError

Issue 5977

Bump version to 3.1.0.0

cabal run works with Literate Haskell file

Issue 5775 seems to be fixed, let's see

Improve CabalFileSearchFailure messages

The original error constructors had zero extra information (for
debugginng) when triggered. The error message "NoCabalFileFound"
is simply not useful without further context.

All of the existing CabalFileSearchFailure constructors now include
a FilePath field.