Install ninja via apt?

[Pesa]

INSTALL.md instructs the user to install ninja via pip. That seems unnecessary given that meson supports the version of ninja (1.8.2) available in Ubuntu 18.04.

The meson manual (1,2) also recommends using the version provided by the distro package manager, and never mentions installing ninja via pip. Moreover, when installing via pip and following pip's recommendation (specifically, --user), the ninja binary will be installed outside PATH, so in the common case the system-provided version will be used anyway, not the pip one.

[Pesa]

Moreover, when installing via pip and following pip's recommendation (specifically, --user), the ninja binary will be installed outside PATH, so in the common case the system-provided version will be used anyway, not the pip one.

And there's probably a similar problem with meson itself. So either tell people to use sudo pip3 ... (but that will trigger some warnings from pip) or link to upstream's installation doc (https://mesonbuild.com/Getting-meson.html#installing-meson-with-pip or similar) which mentions the PATH setting.

[yoursunny]

Updated in e1f05675a33f672bc1104253253f8849dfc31af9.

If you have installed ninja by pip, you should delete manually to avoid conflicts.