Add pkg-config to the shell

[zeme-iohk]

After integrating CHaP, nix develop stopped working on Darwin.
That is, running cabal build all would yield:

Error: cabal: Could not resolve dependencies:
[__0] trying: plutus-core-1.0.0.0 (user goal)
[__1] next goal: inline-r (dependency of plutus-core)
[__1] rejecting: inline-r-0.10.5, inline-r-0.10.4, inline-r-0.10.3,
inline-r-0.10.2, inline-r-0.10.1, inline-r-0.10, inline-r-0.9.2,
inline-r-0.9.1, inline-r-0.9.0.2, inline-r-0.9.0.1, inline-r-0.9.0.0,
inline-r-0.8.0.1, inline-r-0.8.0.0, inline-r-0.7.3.0, inline-r-0.7.2.0,
inline-r-0.7.1.2, inline-r-0.7.1.1, inline-r-0.7.1.0, inline-r-0.7.0.0
(conflict: pkg-config package libR>=3.0, not found in the pkg-config database)
[__1] fail (backjumping, conflict set: inline-r, plutus-core)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: inline-r, plutus-core

Turns out that when cabal.project contains no source-repository-package stanzas then haskell.nix does not include pkg-config in its devshell's buildInputs.

[michaelpj]

I guess this is being fixed by input-output-hk/haskell.nix#1751? Please add a note so we know to remove it when that's merged.

[jbgi]

No, input-output-hk/haskell.nix#1751 was for another issue, that occurred for shell with cross-compilation support.

[michaelpj]

Okay, could one of you make a haskell.nix issue for this? It seems like a bug in the devshell support: it should have the same things as the main haskell.nix shell, which seems to do the right thing.

[jbgi]

No the main haskell.nix shell had the same issue. pkg-config was removed from it. (hence removed from devshell as well).

[zeme-iohk]

Actually it's a little subtler no?

• nix develop .#x86_64-darwin.plutus.library.plutus-project.shell does not provide pkg-config
• nix develop .#x86_64-darwin.plutus.library.plutus-project.devshell does not provide pkg-config either
• but project.shellFor does, and it does so implicitly (it doesn't come from the added nativeBuildInputs)

[michaelpj]

Yes, my understanding was that it worked fine in the haskell.nix shell for @zeme-iohk ? Either way, this should definitely be fixed upstream -> need an issue.

[zeme-iohk]

I opened an issue here input-output-hk/haskell.nix#1753
And added a comment to the nix
@hamishmack @jbgi