Track license-file in ghc package database.

[bos]

(Imported from Trac #710, reported by elliottt on 2010-07-12)

ghc-pkg has supported (since 6.4) a license-file field in the package database. It would be useful to make this information available inside of Cabal, as guesses have to be made as to the location of the license file, currently.

[bos]

(Imported comment by elliottt on 2010-07-12)

Binary package parser changes

[bos]

(Imported comment by elliottt on 2010-07-13)

Thread license-file through Cabal

[bos]

(Imported comment by elliottt on 2010-07-13)

I've attached two patches for cabal and ghc, to support the tracking of the license-file field. Once a package is registered, ghc-pkg will now track the license-file field.

[bos]

(Imported comment by @dcoutts on 2010-07-13)

I have to admit, I'm slightly confused here. As far as I can see, ghc-pkg does not currently support any license-file field, but these patches add support to ghc-pkg (and Cabal) for it. Am I missing something?

If that's the case, then it changes the nature of the decision slightly, it's not just a matter of adding support for an existing feature, but of changing the standard Cabal-specified format that all compilers use for representing installed packages. That needs slightly more buy-in and support from the compiler authors.

It also touches on the issue of what information the package databases should actually track (especially when it comes to installed files like documentation files, see #674).

[bos]

(Imported comment by elliottt on 2010-08-09)

This page in the documentation states that ghc-pkg will deal with a license-file field, which it currently does not:

http://www.haskell.org/ghc/docs/6.12.2/html/users_guide/packages.html#installed-pkg-info

The patch addresses this by adding support for that field. Documentation since 6.4 has claimed that this field is managed, though no support has ever existed for it.