[pacman-dev] Is there an architectural document for pacman

[Martin Kühne]

Your question is basically about the difference between depends and makedepends.
When you installed parity, pacman just downloaded the finished package
as *.pkg.tar.xz for you and installed (runtime-) dependencies as you
need them.
If you set up abs [0] for you, you can build the package yourself,
just update the abs tree, copy /var/abs/*/parity to ~/abs/parity and
type makepkg -s. if you add -i to the makepkg command, it also tries
to run pacman -U the_finished_package.pkg.tar.xz as root. In that
order of doing things, makepkg (as told by the -s flag) will install
cargo, because it needs the (make-) dependency to build the package.

So uh, yeah, read up how ABS works and how you can create, maintain
and fix archlinux packages for personal use/learning experience [1].

cheers!
mar77i

[0] https://wiki.archlinux.org/index.php/Arch_Build_System
[1] https://wiki.archlinux.org/index.php/Makepkg