Cargo Features

[dependencies]
cargo-manifest-proc-macros = { version = "0.3.3", default-features = false, features = ["nightly", "proc-macro"] }
default = proc-macro

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

nightly
proc-macro default

Enables proc-macro of syn

cargo-manifest-proc-macros has 3 features without comments.