FAQ

Why does my program with colored output not have color under Ninja?

Because Ninja runs commands in parallel, it buffers their output to prevent it from interleaving. Commands will detect that their output is not directed to a terminal, assume they're going to a log file, and turn off their colored output. To fix this, pass flags to the subcommand (like -fcolor-diagnostics to clang) to force color on.

(Ninja could use pseudo ttys to work around this further, but different systems have different limits on the number of ptys available, and I also worry that commands like svn up would assume they can interact with the user.)