Inscrutable error message if cabal.project has no packages field

[Boarders]

If I create a project with a cabal.project file that does not list the packages field then I get the error:

cabal: There is no <pkgname>.cabal package file or cabal.project file. To
build packages locally you need at minimum a <pkgname>.cabal file. You can use
'cabal init' to create one.

For non-trivial projects you will also want a cabal.project file in the root
directory of your project. This file lists the packages in your project and
all other build configuration. See the Cabal user guide for full details.

I think this is not a very helpful message for the problem at hand.

[mitchellwrosen]

I believe it also does this if you write

packages:
  my-package

EDIT: Played with a parser a bit. It's this that fails with the above error message:

packages:
  .

However, this works fine:

packages: .

As does

packages:
  ./

[Boarders]

To be clear, this behavior occurs if I do have a <pkgname>.cabal file and a cabal.project but fail to list the packages field in the cabal.project file.

[23Skidoo]

Yep, bumped into this too.

[phadej]

Related: #6144