Cargo Features

qiniu-ng has no features set by default.

[dependencies]
qiniu-ng = { version = "0.0.4", features = ["use-libcurl"] }
use-libcurl = qiniu-with-libcurl

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.

qiniu-with-libcurl use-libcurl?