cabal file not found despite --cabal-file

[ghost]

Describe the bug
I expect to be able to use cabal files at an abnormal path by pointing Cabal at it with the --cabal-file argument.

To Reproduce
Steps to reproduce the behavior:

1. Set up a package that builds normally with Cabal.
2. Move [package name].cabal outside of the directory or change the extension.
3. Run cabal v2-build --cabal-file [new path].

Expected behavior
Cabal builds the package as if the Cabal file was at its original path.

Actual behavior
Cabal reports the following:

No cabal.project file or cabal file matching the default glob './*.cabal' was found.
Please create a package description file <pkgname>.cabal or a cabal.project file referencing the packages you want to build.

System information

• Operating system: NixOS 20.03
• cabal version: 3.2.0.0

[phadej]

--cabal-file is used for testing.

We should remove that flag from public interface.

cc @ezyang

[ezyang]

IIRC, --cabal-file does the right thing if you're using the Setup.hs interface. But it doesn't make any sense on the high level v2 interface. Agree it should be removed from there.

[jneira]

@hyperfekt as the decision was remove the flag and no "fix" it, I would close this one and open a new one tracking the flag deletion itself
will do if you don't disagree

[ulysses4ever]

Agree with @jneira's comment above. Let's act on it?

[ulysses4ever]

Same for #7225 (a dup).

[Mikolaj]

Agree with @jneira's comment above. Let's act on it?

Let's do it. :)

[ulysses4ever]

Done! #8395