Ctrl + C does not terminate hadrian build.
This is a known issue. See also:
- https://github.com/ndmitchell/shake/issues/169
- https://github.com/mintty/mintty/issues/684
- https://github.com/snowleopard/hadrian/issues/696#
The best workaround for this I found so far was to use winpty:
eg:
winpty -- hadrian/build.bat -j4
It's part of the msys distribution so can be installed using:
pacman -S winpty