Could not obtain flags for: "Setup.hs"

[jneira]

• Opening a new specific issue from Could not obtain flags for test files with cabal-helper cradle using stack #1564, reported by:
  • 0xd34df00d in Could not obtain flags for test files with cabal-helper cradle using stack #1564 (comment)
  • Maybe @kirillFedorov1 in Could not obtain flags for test files with cabal-helper cradle using stack #1564 (comment) (pending on comfirm it is the same error)
• Citing @fendor:

We are currently not supporting diagnostics for Setup.hs. E.g. we can not load this into the IDE.

The workaround could be creating a implicit configuration with a hie.yaml file to make hie ignore Main.hs

More drastic one: if Setup.hs is the default one, like this:

import Distribution.Simple
main = defaultMain

and you build-type is simple (the default one) in your <pkgname>.cabal file, afaik you can delete it.

[fendor]

I dont think you may delete it. Cabal still needs it to build stuff, iirc.

Other work-around that got into my mind and I havent tested:
Direct arguments:

cradle:
  direct:
    arguments:
    - "-package Cabal-3.0.0.0"
    - "-package base-4.12.0.0"

[jneira]

I dont think you may delete it. Cabal still needs it to build stuff, iirc.

afaik cabal and stack(via cabal-simple i guess) generates a Setup.hs on the fly if the build-type is simple and there is no a real file (i've just tested deleting the Setup.hs in a cabal and stack projects and they build fine). But the file is regenerated under some circunstances (not always) so your workaround is better.

[fendor]

This work-around might not actually work, I did not try, yet :)

[jneira]

Finally the error was throwed cause hie was called without --lsp and it tries to load everything in the project, including Setup.hs.
So this error should not be showed if you start hie correctly and you dont open Setup.hs in the editor.

[fendor]

I mean, this issue can still be a feature request to load Setup.hs into the editor?

[jneira]

Uh, i thought abot that option but given it is handled by cabal in a exceptional way i guess it would be tricky: afaik cabal does not expose its build (or does it? dont know tbh) and we will have to replicate manually the ghc flags cabal uses to compile/interpret it, including the setup-config if the build-type is custom (see #1638)

Maybe cabal-helper could do that? But more important, does it worth the effort?

[jneira]

Maybe we should skip Main.hs when loading everything? At least until hie is able to handle it

[fendor]

Cabal-Helper could be able to do it (not yet, but maybe in the future), or at least, we should modify Cabal to expose an interface to load the Setup.hs

Problem with skipping Setup.hs:

• special case somewhere in hie/hls which I dislike.
• There can be files that are named Setup.hs.
  • Especially bad in a non-cabal project and this file just happens to be named Setup.hs

I think a custom hie.yaml for whoever is really bothered by it is the best work-around for now.

[mouse07410]

@fendor a stupidly naive question: can I put in in one hie.yaml file entries for both Cabal and Stack?

Something like

cradle:
  stack:
  cabal:

Or for a project that should support builds by both Stack and Cabal I need two files - cabal.project, and hie.yaml configured for Stack?

[fendor]

No, you can not add entries for both build tools, since hie would then not know what to use!
In this repo, we have hie.yaml.cbl and hie.yaml.stack which you rename to hie.yaml to use the appropriate build tool!

You only need a hie.yaml for cabal, the explicit cabal.project is optional and only used to determine, whether you should use stack or cabal if there is no hie.yaml.