cabal-3.14 v1-install expects Cabal file although not necessary

[amigalemming]

Describe the bug

I want to install many local packages at once, but cabal-3.14 refuses to do so, because there is no cabal description in the current package.

To Reproduce

This used to work:

/tmp$ cabal-3.12 v1-install pkg1/ pkg2/ pkg3/

But now I get:

/tmp$ cabal-3.14 v1-install pkg1/ pkg2/ pkg3/
...
Error: [Cabal-7654]
No cabal file found.
Please create a package description file <pkgname>.cabal
...

[ffaf1]

$ cabal v1-install --help
Install packages.

Usage: cabal v1-install [FLAGS]
   or: cabal v1-install [FLAGS] PACKAGES

Installs one or more packages. By default, the installed package will be
registered in the user's package database.
If PACKAGES are specified, downloads and installs those packages. Otherwise,
install the package in the current directory (and/or its dependencies) (there
must be exactly one .cabal file in the current directory).
⁝

So:

1. If packages are specified, download them and install them.
2. If not, install the package in current directory (or deops). There has to be one .cabal file in the current directory.

Am I correct in saying the behaviour you expect falls in neither of those two buckets?

[amigalemming]

On Sat, 5 Apr 2025, ffaf1 wrote: So: 1. If packages are specified, download them and install them. 2. If not, install the package in current directory (or deops). There has to be one .cabal file in the current directory.

In Cabal-3.12 and before, "PACKAGE" was allowed to be a local directory, indicated by a trailing slash. Was this feature removed in Cabal-3.14?

[Mikolaj]

From what you said, it was probably removed. If you can track the removal down, if it turns out it's easy to restore without complicating non-legacy code, I think we'll be open to a PR that does that. Note however, that v1- instructions will be gone sooner or later. Can your workflow we adjusted to v2- or, if not, to ./Setup foo (this one stays)?

[amigalemming]

On Sat, 5 Apr 2025, Mikolaj Konarski wrote: Note however, that v1- instructions will be gone sooner or later. Can your workflow we adjusted to v2- or, if not, to ./Setup foo (this one stays)?

I use "./Setup" stuff in the testsuites run by darcs in my packages. How would I install the imported packages with cabal-install if not with v1-install? I need to build against yet unpublished versions of imported packages. Darcs does a clean checkout of the repository and runs the tests in it. That is, it is not possible to pass a cabal.project.local to it, to make cabal v2-build work.

[amigalemming]

On Sat, 5 Apr 2025, Mikolaj Konarski wrote: From what you said, it was probably removed. If you can track the removal down, if it turns out it's easy to restore without complicating non-legacy code, I think we'll be open to a PR that does that. Note however, that v1- instructions will be gone sooner or later.

The funny thing is, that v1-install actually reads the Cabal files from the subdirectories and performs its dependency analysis. Only when the build plan is ready, it complains about the missing Cabal file.

[amigalemming]

On Sat, 5 Apr 2025, Mikolaj Konarski wrote: From what you said, it was probably removed. If you can track the removal down, if it turns out it's easy to restore without complicating non-legacy code, I think we'll be open to a PR that does that.

I investigated the issue with git-bisect and this identifies the commit 7b90583 as the one, that introduced the regression.

[ulysses4ever]

oh, #9718 strikes again. It was a substantial change, so it's understandable that it broke some things, including undocumented ones like the one discussed here. @sheaf @mpickering, any comments?

[mpickering]

I can investigate at some point soon but no immediate comments.