Cargo Features

[dependencies]
futures-sink-preview = { version = "0.3.0-alpha.19", default-features = false, features = ["std", "alloc"] }
default = std

The std feature is set by default whenever futures-sink-preview is added without default-features = false somewhere in the dependency tree.

std default = alloc
alloc std

futures-sink-preview has 3 features without comments.