Cargo Features

imgui-sys has no features set by default.

[dependencies]
imgui-sys = { version = "0.12.0", features = ["wasm", "docking", "freetype", "use-vcpkg"] }
wasm
docking
freetype = pkg-config
use-vcpkg = vcpkg

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

pkg-config build freetype?
vcpkg build use-vcpkg?