Meson: State corruption with multiple tasks running on same directory

[imirkin]

I ran ninja -C build after changing some options. At the middle, or towards the end, I hit ^Z to check on something. After checking, I totally forgot that the job was already running, and started it again. Realizing I had done that, I killed the new job, and resumed the old one. I got:

$ nice ninja -j4 -C armv7-build 
ninja: Entering directory `armv7-build'
[0/1] Regenerating build files.
Error during basic setup:

Something went terribly wrong. Please file a bug.
FAILED: build.ninja 
/usr/bin/python3.6 /home/ilia/src/meson/meson.py --internal regenerate /home/ilia/src/mesa-meson /home/ilia/src/mesa-meson/armv7-build --backend ninja
ninja: error: rebuilding 'build.ninja': subcommand failed

Do I now have to wipe the whole build directory and all the things that were already built in it?

[jpakkane]

We could maybe add a lock file in the meson-private directory to guard against these things.

[dcbaker]

I think this has been fixed, we do at least write a .lock file into the private directory.