Cargo Features

[dependencies]
tracing-core = { version = "0.1.32", default-features = false, features = ["std", "valuable"] }
default = std

These default features are set whenever tracing-core is added without default-features = false somewhere in the dependency tree.

Enables std of valuable

valuable:

Provide impls for common standard library types like Vec<T> and HashMap<K, V>.

std default = once_cell

Affects dispatcher::DefaultGuard, dispatcher::with_default, dispatcher::set_default, dispatcher::get_default, dispatcher::get_current, field::Visit.record_error

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features.

once_cell std
valuable tracing_unstable default

Affects field::Visit.record_value, field::valuable