Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Avoid hardcoded assumed pointer types #384

Closed
wants to merge 1 commit into from

Conversation

ivan-aksamentov
Copy link

@ivan-aksamentov ivan-aksamentov commented Nov 11, 2024

Depends on blas-lapack-rs/lapack-sys#15

This replaces hardcoded platform-specific char* types with the opaque types from core::ffi. This is necessary when cross-compiling.

I believe when interacting with C and Fortran, both lax and lapack-sys should not assume integer and pointer types. Current setup is biased towards x86_64 platform, for the most part due to a bug in lapack-sys (see blas-lapack-rs/lapack-sys#15), and it could cause broken builds and undefined behavior on other platforms.

For example, cross compilation build could fail with:

error[E0308]: mismatched types
     --> /home/user/.cargo/registry/src/index.crates.io-6f17d22bba15001f/lax-0.16.0/src/cholesky.rs:30:26
      |
30    |                     $trf(uplo.as_ptr(), &n, AsPtr::as_mut_ptr(a), &n, &mut info);
      |                     ---- ^^^^^^^^^^^^^ expected `*const u8`, found `*const i8`
      |                     |
      |                     arguments to this function are incorrect
...
41    | impl_cholesky_!(c64, lapack_sys::zpotrf_);
      | ----------------------------------------- in this macro invocation
      |
      = note: expected raw pointer `*const u8`
                 found raw pointer `*const i8`
note: function defined here
     --> /workdir/.build/docker-aarch64-unknown-linux-gnu/aarch64-unknown-linux-gnu/release/build/lapack-sys-5fad11066d38a1a6/out/bindings.rs:12886:12

Full build log for aarch64-unknown-linux-gnu:
build.log.txt

In this PR I change i8 to core::ffi::c_char - this, for example, resolves to i8 on x86 and to u8 on ARM, but is also universal for any platform rust supports, removing bias towards x86.

Depends on blas-lapack-rs/lapack-sys#15

This replaces hardcoded platform-specific `char*` types with the opaque types from [`core::ffi`](https://doc.rust-lang.org/stable/core/ffi/type.c_char.html). This is necessary when cross-compiling.

I believe when interacting with C and Fortran, both `lax` and `lapack-sys` should not assume integer and pointer types. Current setup is biased towards x86_64 platform and it could cause broken builds and undefined behavior on other platforms.

For example, cross compilation build could fail with:

error[E0308]: mismatched types
     --> /home/user/.cargo/registry/src/index.crates.io-6f17d22bba15001f/lax-0.16.0/src/cholesky.rs:30:26
      |
30    |                     $trf(uplo.as_ptr(), &n, AsPtr::as_mut_ptr(a), &n, &mut info);
      |                     ---- ^^^^^^^^^^^^^ expected `*const u8`, found `*const i8`
      |                     |
      |                     arguments to this function are incorrect
...
41    | impl_cholesky_!(c64, lapack_sys::zpotrf_);
      | ----------------------------------------- in this macro invocation
      |
      = note: expected raw pointer `*const u8`
                 found raw pointer `*const i8`
note: function defined here
     --> /workdir/.build/docker-aarch64-unknown-linux-gnu/aarch64-unknown-linux-gnu/release/build/lapack-sys-5fad11066d38a1a6/out/bindings.rs:12886:12

Full build log for aarch64-unknown-linux-gnu:
[build.log.txt](https://github.com/user-attachments/files/17706011/build.log.txt)

In this PR I change `i8` to `core::ffi::c_char` - this, for example, resolves to `i8` on x86  and to `u8` on ARM, but is also universal for any platform rust supports, removing bias towards x86.
@ivan-aksamentov
Copy link
Author

Closing as duplicate to #354

@ivan-aksamentov
Copy link
Author

Reopening, because my version is better - it uses core::ffi::c_char not std.

Either way the root cause is blas-lapack-rs/lapack-sys#15 and it needs to be merged for the thing to not be UB.

@ivan-aksamentov
Copy link
Author

#354 now also uses core::. Closing

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

1 participant