So I'm sure as anyone who uses qutebrowser knows, it relies on qtwebengine to function, which already took forever and a day to compile unless you had a pretty fast computer with plenty of RAM to spare.
I've not seen much discussion over the issue with trying to compile qtwebengine 5.15.2, in which OOM reaper kills the compile after a while, in my case that's half a day wasted trying to compile this because I'm not compiling this on a fast computer, yet I had been able to compile it on the same hardware before.
Emerge does not show an actual error when the compile dies, because the compile itself hasn't failed, but dmesg shows that it's been killed because it ran out of memory, which even though the hardware isn't that fast did not make sense that it could fail with 8gb available.
The problem is that qtwebengine is bundling the ninja build system in it, and ninja has been the cause of OOM even on systems with a lot of memory because ninja will detect how many cores you have, and add 2 to the parallel jobs option, disregarding your MAKEOPTS argument.
I have seen no workaround to this ninja build system steathily killing the compile halfway through beyond actually disabling all but 1 core so that it doesn't exhaust memory by trying to allocate for {cores}+2 threads by running:
# chcpu --disable 1-3
I'll be compiling this garbage for the next few days thanks to this crap.