Cargo Features
proc-macro3 has no features set by default.
[dependencies]
proc-macro3 = { version = "0.1.1", features = ["span-locations"] }- span-locations
-
Enables span-locations of proc-macro2
*do not* enable the proc-macro2 feature in a proc-macro context
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.