Cargo Features

[dependencies]
quincy = { version = "0.15.1", default-features = false, features = ["offload", "jemalloc"] }
default = offload

The offload feature is set by default whenever quincy is added without default-features = false somewhere in the dependency tree.

offload default
jemalloc = jemallocator

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.

jemallocator unix jemalloc?