Library tests fail

[khazaddum]

Hello,

This library has been incredibly useful for a couple of apps I've developed. I'm currently working on implementing Nix Flakes for my apps to ease distribution and I have run into an interesting issue, running cabal test inside a Nix shell fails with this error:

$ cabal test
Resolving dependencies...
Build profile: -w ghc-9.6.5 -O1
In order, the following will be built (use -v for more details):
 - foreign-rust-0.2.0 (lib) (configuration changed)
 - foreign-rust-0.2.0 (test:test-foreign-rust) (configuration changed)
Configuring library for foreign-rust-0.2.0...
Preprocessing library for foreign-rust-0.2.0...
Building library for foreign-rust-0.2.0...
Configuring test suite 'test-foreign-rust' for foreign-rust-0.2.0...
Preprocessing test suite 'test-foreign-rust' for foreign-rust-0.2.0...
Building test suite 'test-foreign-rust' for foreign-rust-0.2.0...
[1 of 8] Compiling Test.Serialisation.Types ( test/Test/Serialisation/Types.hs, dist-newstyle/build/x86_64-linux/ghc-9.6.5/foreign-rust-0.2.0/t/test-foreign-rust/build/test-foreign-rust/test-foreign-rust-tmp/Test/Serialisation/Types.o, dist-newstyle/build/x86_64-linux/ghc-9.6.5/foreign-rust-0.2.0/t/test-foreign-rust/build/test-foreign-rust/test-foreign-rust-tmp/Test/Serialisation/Types.dyn_o ) [Flags changed]

<no location info>: error:
    /home/rav/Documents/programs/haskell-foreign-rust/dist-newstyle/build/x86_64-linux/ghc-9.6.5/foreign-rust-0.2.0/build/libHSforeign-rust-0.2.0-inplace-ghc9.6.5.so: undefined symbol: haskell_ffi_external_ptr

The library builds fine and I can use it on other Nix Flakes (if I disable the default run of the test suites). This "undefined symbol" issue also happens when using cabal repl inside the Nix shell.

It's clear that it is looking for the companion Rust library, but when I use cabal test outside of the Nix shell, the tests compile and succeed. I suspect that I need to explicitly tell Nix where to look for this symbol, but it's not clear to me where does cabal find it in the first place.

Any pointers would be greatly appreciated.

[Eiko-Tokura]

I'm encountering the same error saying that

undefined symbol: haskell_ffi_external_ptr

This is used in src/Foreign/Rust/Marshall/External.hs as we have a foreign import ccall unsafe "haskell_ffi_external_ptr", but I'm unable to find this function anywhere.

I guess this is supposed to be generated somewhere before we can run?

[khazaddum]

Yes, this library is the Haskell side of a Haskell-Rust bridge and thus, it depends on some of the C functions that the Rust side of the bridge would create if applied.

To fix this problem, I implemented a minimal Rust FFI inside my flake that forces the compilation of the C bindings and makes them available for the tests in the Nix shell.

The code is in https://code.vergara.tech/Vergara_Tech/haskell-foreign-rust , the relevant changes are in the rustbits folder and in the flake.nix file.

[Eiko-Tokura]

Thanks for your response, I havn't check that yet but I got an update:

It seems if you downgrade the compiler, in my case switch to ghc-9.4.8, the problem of undefined symbol disappeared. I don't know why though