Cargo Features

[dependencies]
fixed_len_str = { version = "0.3.3", default-features = false, features = ["serde_support", "pattern_pred_support", "docs_hidden"] }
default = docs_hidden

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

serde_support = serde
pattern_pred_support
docs_hidden default

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.

serde serde_support?