error: const-stable function cannot use `#[feature(const_fn_floating_point_arithmetic)]` --> $DIR/internal-unstable-const.rs:10:5 | LL | 1.0 + 1.0 | ^^^^^^^^^ | help: if it is not part of the public API, make this function unstably const | LL + #[rustc_const_unstable(feature = "...", issue = "...")] LL | pub const fn foo() -> f32 { | help: otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks | LL + #[rustc_allow_const_fn_unstable(const_fn_floating_point_arithmetic)] LL | pub const fn foo() -> f32 { | error: aborting due to 1 previous error