RFE: local plugins and build-tool-depends

[tseenshe]

This is a very ambituous request because it goes beyond #2965

I am the author of a compiler plugin and command line tool (both at https://gitlab.com/tseenshe/hsinspect) that are only useful for developers and not something anybody would ever want to export in their .cabal file.

I know of other plugins that are only useful for developers and not for the build itself, e.g. the removal of unused imports.

I would like for users to be able to install my plugin and command line tool via their cabal.project.local file.

[emilypi]

@phadej How difficult would it be to implement something like this? I have need, and I'd be happy to start putting in the effort if guidance is available.

@tseenshe I'd also add the RFE to define common stanzas in the toplevel cabal.project for multipackage builds. (Unless this is a huge problem for some problem I've missed in the lore)

[phadej]

@emilypi, tricky, yet not impossible. I see #2965 as a pre-requisite. (Then as follow-up from cabal.project one could be able to amend packages' plugin-depends)

[coot]

I found this way of doing it, unfortuantely it requires passing -package-db where the plugin is installed. That's a hack, because it requires that the plugin is installed globally.