Cargo Features

[dependencies]
proc-macro-api = { version = "0.1.5", default-features = false, features = ["deny_append", "deny_shadow", "auto_transform"] }
default = deny_shadow

The deny_shadow feature is set by default whenever proc-macro-api is added without default-features = false somewhere in the dependency tree.

deny_override deny_append
deny_shadow default
deny_group_attr auto_transform

proc-macro-api has 4 features without comments.