Functions missing in libjulia.so.1.7, no longer able to generate FFI bindings due to missing headers

[Taaitaaiger]

Today I tried to migrate jlrs, a crate that provides bindings to the Julia C API for Rust, to Julia 1.7.0-beta2. I've run into two problems.

The first is related to how the low-level bindings are created: this uses bindgen which automatically generates Rust FFI bindings to C and C++ libraries. Previously this worked without any problems in combination with Julia, but now causes an error because the support directory and its contents are not available in the include directory. This can be solved relatively easily by creating a symlink to the support directory.

The second, larger issue, is that some functions that should be exported aren't actually exported by libjulia.so. Both jl_get_pgcstack and jl_field_index are marked as JL_DLLEXPORT. I can find the latter if I inspect libjulia.so.1.6 with nm, but I can't find either in libjulia.so.1.7. Compilation of tests eventually fails due to a linker error because it can't find these functions. If I redefine these two functions to just call exit(1) in a custom C library everything compiles and the tests run until jl_get_pgcstack is called "outside" Julia.

My code can be found here if that's useful: https://github.com/Taaitaaiger/jlrs/tree/dev-1.7

[giordano]

jl_get_pgcstack has been exported by #41320

[fingolfin]

The header problems were fixed in #41308 so that will be fine in beta3

that leaves jl_field_index

[fingolfin]

In general I wonder what the relation between functions marked with JL_DLLEXPORT and functions listed in src/jl_exported_funcs.inc is -- I would have expected the two to coincide, but that's clearly not the case, tons more things are in the former category compared to the later.

[fingolfin]

I've submitted PR #41466. @Taaitaaiger if you apply the patches we pointed to and rebuild Julia, does it then work? Would be good to discover if there are other issues so that they can be resolved with beta3.

[Taaitaaiger]

Thanks for the quick replies and patches, I should be able to test this later today.

[Taaitaaiger]

I've applied the changes from the three PRs and rebuilt Julia, this solves all my issues. Everything compiles and the tests succeed.