Cargo Features

tantivy-fst = { version = "0.5.0", default-features = false, features = ["regex"] }
default = regex

The regex feature is set by default whenever tantivy-fst is added without default-features = false somewhere in the dependency tree.

regex default = regex-syntax

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.

regex-syntax regex