Warning on “unstable” directive
Why does Rust gives me a warning when I add the #![allow(unstable)] directive? unknown allow attribute: unstable, #[warn(unknown_lints)] on by default Playpen example
The unstable lint was removed in a530cc9706324ad44dba464d541a807eb5afdb08.
As Steve points out, the unstable lint was removed. You can find more information in the Release Channels RFC, specifically the section Merging stability attributes and feature gates: As a simplifying measure stability attributes are unified with feature gates, and thus tied to release channels and Rust language versions. And With these modifications, new API surface area becomes a new "language feature" which is controlled via the #[feature] attribute just like other normal language features. The compiler will disallow all usage of #[staged_unstable(feature = "foo")] APIs unless the current crate declares #![feature(foo)]. This enables crates to declare what API features of the standard library they rely on without opting in to all unstable API features.
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