Problems with gnu toolchain on windows

[stiv-yakovenko]

I have this dependency:

blas = "0.18.1"

During building this simple program (no types used de facto in the program):

extern crate blas;
use blas::c::*;

I get these errors:

error: linking with `gcc` failed: exit code: 1
  |
  = note: "gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-m64" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\crt2.o" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsbegin.o" "-L" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\rpolysolve-88ff07ef5c6657b1.0.o" "-o" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\rpolysolve-88ff07ef5c6657b1.exe" "-Wl,--gc-sections" "-nodefaultlibs" "-L" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps" "-L" "C:/Users/steve/Dropbox/Projects/rpolysolve/target/debug/build/openblas-src-d878051769a2d73f/out\\opt/OpenBLAS/lib" "-L" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-Wl,-Bstatic" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\libblas-b4aae95537d012fb.rlib" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\libblas_sys-e0d39b2df28e83ce.rlib" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\libopenblas_src-f69049297a7464c8.rlib" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\libnum_complex-f6dcb9467a42a2a8.rlib" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\liblibc-c8ae433ae4a960ed.rlib" "C:\\Users\\steve\\Dropbox\\Projects\\rpolysolve\\target\\debug\\deps\\libnum_traits-f34085513d19d5a6.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libstd-5a958d157a8d8d98.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libpanic_unwind-14e8bb7ca07ebf2c.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libunwind-a4bc20050f473f79.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\liblibc-892bd58ec617c3bd.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\librand-ce86047000b56785.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libcollections-b8b9a576d130e244.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\liballoc-b9c9173c47c20c41.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\liballoc_system-141f235246f01712.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libstd_unicode-9fbe5d3bbc85c563.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libcore-3a6338503b91076c.rlib" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libcompiler_builtins-e9e280acad4314a4.rlib" "-Wl,-Bdynamic" "-l" "gfortran" "-l" "openblas" "-l" "advapi32" "-l" "ws2_32" "-l" "userenv" "-l" "shell32" "-Wl,-Bstatic" "-l" "gcc_eh" "-l" "pthread" "-Wl,-Bdynamic" "-lmingwex" "-lmingw32" "-lgcc" "-lmsvcrt" "-luser32" "-lkernel32" "C:\\Users\\steve\\.rustup\\toolchains\\stable-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsend.o"
  = note: ld: cannot find -lgfortran
          C:/Users/steve/Dropbox/Projects/rpolysolve/target/debug/build/openblas-src-d878051769a2d73f/out\opt/OpenBLAS/lib/libopenblas.a: file not recognized: File format not recognized

My active toolchain is stable-x86_64-pc-windows-gnu. I want to keep it, because this is the only working approach for debug, which I've found (msvc toolchain doesn't allow to run dgb and thus debug in CLion).

What can I do? Are there any other connectors between rust and blas? More scpecially I need to call dsyev_. May be there are any other known stable methods of calculating real eigen values in rust?

[IvanUkhov]

Sorry, I have very little experience with Windows. If OpenBLAS supports Windows, there should be installation steps described somewhere in their repo. Then, perhaps, the build script of openblas-src should be adjusted in order to account for this scenario.

[mattico]

This works fine on windows if you follow the usual steps for C libraries. This is what I did:

1. Install MSYS2, open a MSYS2-mingw64 shell, go to project directory
2. rustup override add nightly-gnu (or stable-gnu, ...)
3. Install gcc, make, and fortran. I already had these so you can figure the commands out :)
4. Now you should be able to use openblas-src, and it'll build openblas from source. If you want to link to a prebuilt lib, continue on.
5. pacman -S mingw64/mingw-w64-x86_64-gcc-fortran mingw64/mingw-w64-x86_64-openblas Notice the libgfortran package doesn't actually contain libgfortran.a which is what we need.
6. Add "static" feature to openblas-src in Cargo.toml
7. Need to supply link paths so rustc can find the above libs. Can do this with build script, .cargo/config, or environment variables. E.g. RUSTFLAGS="-L/mingw64/lib -LC:/<PATH TO>/msys2/mingw64/lib/gcc/x86_64-w64-mingw32/7.2.0/" cargo build Notice the path to libgfortran.a is a windows path since that one didn't get expanded before it got to rustc for some reason. I didn't have that problem with /mingw64/lib.

It's possible I skipped some packages because I already had them installed. It should be straightforward to find them by searching with pacman -Ss.

[IvanUkhov]

@mattico, thanks for your answer! Could you please move or copy it to openblas-src/#22?

[IvanUkhov]

@stiv-yakovenko, I’ve closed this issue here and opened a new one there in order to keep it closer to where the actual problem is. I hope it’s OK with you.