wlroots is a modular wayland compositor library to ease development of compositors, which is used by sway, cage and wayfire.
eweOS ships different version of wlroots library, as wlroots does not provide API compatibility.
Each version of wlroots is split into two packages, library and development package. For example, wlroots0.17 (library) and wlroots0.17-devel (development).
Library packages coexist, since there is only a dynamic library and soversion is bumped on a new release. Headers of different wlroots version are located at the same path, making coexistence of development packages require a lot of downstream work, so development packages are simply in conflict and cannot be installed at the same time.
wlroots version in PKGBUILD. wlroots is no longer provided.wlroots development package to makedepends in your PKGBUILD