is_wsl returns false negative when using WSL2

[mon]

Describe the bug
#8445 is hitting me again, where Windows EXEs attempt to be wrapped using mono. This is caused by is_wsl using the check:
'microsoft' in platform.version().lower()

Which fails on WSL2, as platform.version() in my case is #1 SMP Wed Oct 28 23:40:43 UTC 2020.

To Reproduce

project('test', 'c')

run_target('example',
    command : [find_program('/mnt/c/WINDOWS/system32/help.exe')]
)

Expected behavior
help.exe's default output is printed as meson runs the command, but instead it fails to find mono (which I do not have installed)

system parameters
Meson: 0.59.1
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal

[xclaesse]

Any suggestion how we can detect wsl2 then?

[mon]

Good question, it seems we're in luck!

I just checked, on another machine, running platform.uname():

WSL 1:
uname_result(system='Linux', node='smol', release='4.4.0-19041-Microsoft', version='#1151-Microsoft Thu Jul 22 21:05:00 PST 2021', machine='x86_64', processor='x86_64')

WSL 2:
uname_result(system='Linux', node='smol', release='4.19.104-microsoft-standard', version='#1 SMP Wed Feb 19 06:37:35 UTC 2020', machine='x86_64', processor='x86_64')

So it seems that 'microsoft' in platform.release().lower() will work for both WSL 1 and WSL2, and hopefully into the future. Should I make a PR, or would you be faster?

[xclaesse]

They even changed to remove the capital letter, to be sure they break as many script as possible, well done.

Here they suggest reading /proc/version: microsoft/WSL#4071, they even have a meson.build example :D

So it seems that 'microsoft' in platform.release().lower() will work for both WSL 1 and WSL2, and hopefully into the future. Should I make a PR, or would you be faster?

Yes, I think that should be fine until they change it again... I haven't found a formal documented way of doing it, so we can only hope. PR welcome :)

[eli-schwartz]

Fixed by linked PR.