Cargo Features

[dependencies]
libmosquitto-sys = { version = "0.2.3", default-features = false, features = ["vendored-mosquitto", "vendored-openssl"] }
default = openssl-sys, vendored-mosquitto

These default features are set whenever libmosquitto-sys is added without default-features = false somewhere in the dependency tree.

vendored-mosquitto default
vendored-openssl = openssl-sys

Enables vendored of openssl-sys

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.

openssl-sys default vendored-openssl?