Build and tests fail on MINGW platform

[thomasfire]

Affected Operating Systems

• Windows - MSYS2/MINGW64

Affected py-lmdb Version

1.4.1

py-lmdb Installation Method

See PKGBUILD file

Using bundled or distribution-provided LMDB library?

Bundled

Distribution name and LMDB library version

Both built from this package and using latest available from system.

Describe Your Problem

Build fails as setup.py script assumes that everything built on windows is built with MSVC, which is not true in case of MINGW setup.
env_test.py tests segfault on opening temp files.
See patch file for details and potential solution.

Related issues

Affects msys2/MINGW-packages#17025

Potential solution

See the patch above. I would suggest adding compilations flags specifically for mingw compilers on windows and either skip or fix segfault in tests.

[sbourdeauducq]

either skip or fix segfault in tests.

Why would skipping be a good idea at all?

[thomasfire]

Why would skipping be a good idea at all?

If the temporary files are not supported by mingw for example (I am not sure though, it looks like it would work fine with MSVC), then probably it would be better to skip and mark as not supported features

[sbourdeauducq]

Why would temporary files not being supported cause a segfault?

[thomasfire]

Well the true issue appears to be in these lines:
https://github.com/LMDB/lmdb/blob/3947014aed7ffe39a79991fa7fb5b234da47ad1a/libraries/liblmdb/mdb.c#L1737-L1745
The same code is in this repo.
Looks like I'll need to change C API a bit to handle these strings properly

[sbourdeauducq]

Haha this is such garbage code. Can you just do something like static char buf[MSGSIZE]? It's not thread-safe, but I'm not sure if the current code is any better...

[sbourdeauducq]

And Python doesn't have real threads due to the GIL so it probably doesn't matter here.

[thomasfire]

Updated patch with segfault fix: msys2/MINGW-packages#17095