tracing = "0.1.28"
tracing-subscriber = { version = "0.3.3", default-features = false, features = ["fmt", "env-filter", "smallvec", "parking_lot", "ansi"] }
tracing-tree = "0.2.0"
+tracing-core = "0.1.28"
[dev-dependencies]
rustc_span = { path = "../rustc_span" }