Cabal cradle matches only exposed-modules to component

[fendor]

Upstream issue haskell/cabal#6622

Explanation in hie-bios:

Assume project setup:

$ cabal init -p example --libandexe --tests --main-is=Main.hs --source-dir=src --application-dir=app --test-dir=test

and hie.yaml:

cradle:
  cabal:

then we can observe the following behaviour:

$ hie-bios flags src/MyLib.hs
Options: [...]
Dependencies: [...]

$ hie-bios flags app/Main.hs
Failed to show flags for "./app/Main.hs": ["Failed to parse result of calling cabal","","cabal.exe: Unknown target './app/Main.hs'.\nThe package example has no file target 'app/Main.hs'.\n\n\n",""]

However, the invocation hie-bios flags app/Main.hs should work just as well.

[expipiplus1]

Adding Main to other-modules seems to allow hie to work, however it's complained about by hie and probably breaks other tools

2020-04-02 14:08:32.123114596 [ThreadId 14] - Warning: Enabling workaround for Main module 'Main' listed in 'other-modules'
2020-04-02 14:08:32.12318556 [ThreadId 14] - illegally!

[expipiplus1]

I have no idea why, but this configuration allows src/Main.hs to work

cradle:
  multi:
    - path: "./src"
      config:
        cradle:
          cabal:
    - path: "./src/Main.hs"
      config:
        cradle:
          none:

[fendor]

Closing as upstream ticket is fixed.