Project that builds successfully in version 3.6.2.0 fails in version 3.8.1.0: "libcrypto-any, not found in the pkg-config database"

[clintonmead]

Describe the bug
Upon updating cabal from 3.6.2.0 to 3.8.1.0, I get this bizarre error:

[_10] rejecting: HsOpenSSL:-use-pkg-config (constraint from project config
/Users/clinton.mead/source/neph/brt/cabal.project requires opposite flag
selection)
[_10] rejecting: HsOpenSSL:+use-pkg-config (conflict: pkg-config package
libcrypto-any, not found in the pkg-config database)

I am intentionally using the +use-pkg-config flag, with the following in my cabal.project file:

constraints: HsOpenSSL +use-pkg-config

cabal version 3.6.2.0 happily builds though.

To Reproduce
Steps to reproduce the behavior:

$ cabal build all

I'm not sure what difference using v2-build makes, but cabal v2-build all produces the same error.

Expected behavior
The build working like it does for cabal 3.6.2.0

System information

• MacOS
• cabal 3.8.1.0
• GHC 9.2.2

Additional context
As this is propriety software it may be a bit tricky to give you a full reproducible example

[ulysses4ever]

Thanks for the report! I assume, it's due to #7621 /cc @gbaz.

[clintonmead]

@ulysses4ever I'm a bit confused, because it looks like #7621 is merged. Did it not make it into 3.8.1.0? Or was 3.6.2.0 doing some hack to get around this? Like was I actually falling back to a non-pkg-config flag and it was just working anyway?

[gbaz]

"Before, if there was no pkg-config that could be found, the solver would optimistically succeed"

So it would be due to that if this failure occurs because pkg-config is not present or perhaps finding the package in pkg-config fails due to the name not being exactly correct.

[clintonmead]

@gbaz I don't know much about pkg-config or even why we're using it in this project (I'm relatively new on this project) but is what you're saying that this our project is broken in some way, and 3.6.2.0 somehow worked around it, whereas 3.8.1.0 is more strict?

[clintonmead]

Sorry I'm quite dumb. It seems when making this report I accidentally hadn't entered a nix develop shell. I presume this sets up pkg-config appropriately for the build.

I guess 3.6.2.0 worked around this when doing dependency solving but 3.8.1.0 is probably CORRECTLY rejecting the build.

I'm happy to consider this closed.

[arrowd]

I bumped into similar problem on FreeBSD, except the rejection is incorrect. The error I get is

Resolving dependencies...
Error: cabal: Could not resolve dependencies:
[__0] next goal: gi-atk (user goal)
[__0] rejecting: gi-atk-2.0.24 (conflict: pkg-config package atk>=2.0 && <3,
not found in the pkg-config database)
[__0] fail (backjumping, conflict set: gi-atk)

However, pkg-config --modversion atk gives me 2.38.0. Running the same command with cabal-install 3.6 works too.

Running with -v3 reveals:

/usr/local/bin/pkg-config returned ExitFailure 1 with error message:
Package libevent-2.1.5 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libevent-2.1.5.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libevent-2.1.5', required by 'avahi-libevent', not found
Failed to query pkg-config, Cabal will continue without solving for pkg-config
constraints: dieVerbatim: user error (CallStack (from HasCallStack):
withMetadata, called at src/Distribution/Simple/Utils.hs:370:14 in
Cabal-3.8.1.0-6vwXxyy24tK3US19KEu6L5:Distribution.Simple.Utils
Error: cabal: '/usr/local/bin/pkg-config' exited with an error:
Package libevent-2.1.5 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libevent-2.1.5.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libevent-2.1.5', required by 'avahi-libevent', not found
)
Resolving dependencies...
...
[_82] fail (backjumping, conflict set: gi-atk)
CallStack (from HasCallStack):
  withMetadata, called at src/Distribution/Simple/Utils.hs:370:14 in Cabal-3.8.1.0-6vwXxyy24tK3US19KEu6L5:Distribution.Simple.Utils
Error: cabal: Could not resolve dependencies:
[__0] next goal: gi-atk (user goal)
[__0] rejecting: gi-atk-2.0.24 (conflict: pkg-config package atk>=2.0 && <3,
not found in the pkg-config database)

Removing the avahi-app system package makes Cabal happy. So, the outline is:

• Cabal queries all pkg-config packages currently present in the system.
• The avahi-app package contains broken .pc file, which is a packaging problem, not Cabal one.
• This makes Cabal fail even if avahi-libevent.pc isn't required by the Haskell package being built.
• Cabal will fail on any package containing pkg-config-depends if system has broken .pc files. I'd say this is a bug.

[gbaz]

It looks like cabal is trying to find libevent, and the broken avahi-app package prevents it from finding it?

I.e. the broken pc file breaks pkg-config-depends in general?

[arrowd]

avahi-libevent.pc has Requires: libevent-2.1.5 line, which hardcodes library version. It works when changed to Requires: libevent.

However, the library I'm building doesn't depend on libevent, nor on avahi. Cabal's error message is about atk and pkg-config return correct results for this package.

The problem is that Cabal somehow queries all pkg-config packages and if one of them is broken it thinks that nothing was found at all.

[arrowd]

Another problem with different Haskell package:

/usr/local/bin/pkg-config returned ExitFailure 1 with error message:
Package gtest was not found in the pkg-config search path.
Perhaps you should add the directory containing `gtest.pc'
to the PKG_CONFIG_PATH environment variable
Package 'gtest', required by 'libhwy-test', not found
Failed to query pkg-config, Cabal will continue without solving for pkg-config
constraints: dieVerbatim: user error (CallStack (from HasCallStack):
withMetadata, called at src/Distribution/Simple/Utils.hs:370:14 in
Cabal-3.8.1.0-6vwXxyy24tK3US19KEu6L5:Distribution.Simple.Utils
Error: cabal: '/usr/local/bin/pkg-config' exited with an error:
Package gtest was not found in the pkg-config search path.
Perhaps you should add the directory containing `gtest.pc'
to the PKG_CONFIG_PATH environment variable
Package 'gtest', required by 'libhwy-test', not found
)

The package doesn't use any of gtest and libhwy-test. It seems there are a lot of malformed .pc files around and Cabal chokes on all of them.

[gbaz]

Wait why does the first package succeed when there's still a broken pc for gtest apparently, and only the second package fail?

[arrowd]

These are different machines. The first one was building in a clean and isolated environment with only required dependencies installed.

The last one is on my laptop, which also has unrelated stuff installed.