Cabal 3.8 expects `pkg-config --libs --static` to always work.

[hamishmack]

See bf32602 and input-output-hk/haskell.nix#1642

I think it is unreasonable for cabal to expect pkg-config --libs --static to work when only dynamic libraries may be installed on a system.

To Reproduce

$ cabal --version
cabal-install version 3.9
compiled using version 3.9.0.0 of the Cabal library
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.10.7
$ cabal v2-install haskell-gi-base -v3
...

In setup configure for haskell-gi-base you will see it has both:

Running: SOME_PATH/pkg-config --libs gobject-2.0 glib-2.0
Running: SOME_PATH/pkg-config --libs --static gobject-2.0 glib-2.0

On nix you can run something like this to see the second one fail:

nix-shell -E 'let pkgs = import <nixpkgs> {}; in pkgs.mkShell { buildInputs = [ pkgs.gtk4.dev pkgs.pkgconfig ]; }' --run 'cabal v2-install haskell-gi-base -v3'

Expected behavior
Perhaps cabal could store the error and replay it when the linker arguments are actually needed.

[Mikolaj]

@hamishmack: thank you for the report. Did it work fine with cabal 3.6.2 (I assume it's failing with 3.8.1?)?

[hamishmack]

Yes, 3.6.2 worked fine (I think because it does not include bf32602)

[gbaz]

associated ticket for the original change: #7536

cc @nh2 @alexbiehl

[nh2]

The issue description doesn't say what the error message is. Is it like this?

% nix-shell -E 'let pkgs = import <nixpkgs> {}; in pkgs.mkShell { buildInputs = with pkgs; [ gtk4.dev pkgconfig haskellPackages.cabal-install ghc ]; }' --run 'pkg-config --libs --static gobject-2.0 glib-2.0'

Package libpcre was not found in the pkg-config search path.
Perhaps you should add the directory containing `libpcre.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libpcre', required by 'glib-2.0', not found

An alternative to

Perhaps cabal could store the error and replay it when the linker arguments are actually needed.

would be to do what I did before this commit, conditionally passing the flag on configure with ["--static" | fullyStatic]:

bf32602#diff-fff9e57c2727835086925d886619deb3fafd33a06e1af760d60d485ae07cec68L1647

Edit: This alternative cannot work, see #8455 (comment)

[sternenseemann]

I can reproduce this as well and it is probably going to break a lot of packages in nixpkgs with no nice way of fixing them. When we have a Haskell package pkg, that depends on liba which in turn depends on libb, we'd just place liba's pc files in PKG_CONFIG_PATH. This means that --libs --static will fail, since pkg-config would lookup liba's (private) dependencies for this (in the dynamic case this is unnecessary thanks to dynamic linking).

When we actually link the (system) libs statically, we propagate liba's dependencies, so that they'd be available. We don't do it in the dynamic case, because it is not necessary.

Accomodating Cabal here is hard, since it pertains how packaging of non-Haskell packages is done, so I'd prefer it if we could get rid of this requirement.

[Mikolaj]

@hamishmack: could you respond to #8455 (comment)? Thank you.

@sternenseemann: I lack context, so I'd need more explanation of your proposal. Could you elaborate on "if we could get rid of this requirement"? What requirement? In which code the change would be done?