cblas_dgemm returns incorrect results when the static feature of openblas-src is enabled on macOS

[maoe]

https://github.com/maoe/ndarray-dot-repro is a reproducer. It was minimized from code which used argmin + ndarrayl feature.

This reproducer uses the patched version of openblas-src from #65 so that static build works both on Linux and macOS Big Sur.

The expected output of the main is [1.0, 1.0, 1.0, 1.0] but it returns the zero matrix on macOS when the static feature of openblas-src is enabled.

% cargo run
   Compiling ndarray-dot-repro v0.1.0 (/Users/maoe/src/github.com/maoe/ndarray-dot-repro)
    Finished dev [unoptimized + debuginfo] target(s) in 0.49s
     Running `target/debug/ndarray-dot-repro`
[
    1.0,
    1.0,
    1.0,
    1.0,
]
% cargo run --features openblas-src/static
   Compiling ndarray-dot-repro v0.1.0 (/Users/maoe/src/github.com/maoe/ndarray-dot-repro)
    Finished dev [unoptimized + debuginfo] target(s) in 0.52s
     Running `target/debug/ndarray-dot-repro`
[
    0.0,
    0.0,
    0.0,
    0.0,
]

FWIW, I haven't been able to reproduce the issue in C on macOS:

% git clone https://github.com/xianyi/OpenBLAS.git
% cd OpenBLAS
% git checkout v0.3.14 # This is the commit #65 uses
% make
% wget -q https://gist.githubusercontent.com/maoe/953c4e863703be915928b0f8997fcc46/raw/e827d61ae2944a72a37d0784c0aab0026e1b6cdb/repro.c # See https://gist.github.com/maoe/953c4e863703be915928b0f8997fcc46
% cc -o repro repro.c libopenblas.a
% ./repro
1.000000
1.000000
1.000000
1.000000

[maoe]

OpenMathLib/OpenBLAS#1088 looks similar but I'm not sure if it's the same issue as I haven't reproduced it in C yet.

[maoe]

Removed the dependency on blas-src on current master of the reproducer.

[maoe]

FWIW this issue remains even with #65.

[maoe]

Updated the reproducer with #65 and a simpler matrix input and updated the description accordingly.

[maoe]

I managed to fix the issue with maoe/ndarray-dot-repro@4d94c73.

Apparently, at least on macOS, the static feature needs an empty extern block with #[link(name = "openblas")] attribute to work. I also tried putting the block in openblas-src's lib.rs but it didn't work. It seems that the block needs to be at the use site.

I guess the instructions on the wiki need updating.

[maoe]

Closing this because there's nothing to be done in this crate.