Some way to apply a constraint on the command line to build-tool-depends

[geekosaur]

Describe the feature request
--constraint only applies to libraries. There's no equivalent mechanism for build tools.

Additional context
happy-2.0 was just released, and breaks haskell-lib-parser and probably other things (and possibly is just straight-up broken). Until its constraint can be adjusted or a fixed happy is released, there needs to be some way to constrain it to avoid the breakage without making it a local source or editing cabal.project (which may be in CI, or you aren't doing an install within a project).

[grayjay]

I think that this issue is part of #3502. Is it possible to work around the specific issue with happy by using any.happy, or do you need to only constrain a specific use of the build tool?

[geekosaur]

I'm uncertain. It didn't attempt to build the library, whereas it did when I let it use happy-2.0, so I guess that's a good sign.