use std::iter::{self, once};

use rustc_ast as ast;

use rustc_attr::{ConstStability, StabilityLevel};

use rustc_attr::{ConstStability, StabilityLevel, StableSince};

use rustc_data_structures::captures::Captures;

use rustc_data_structures::fx::FxHashSet;

use rustc_hir as hir;

pub(crate) fn print_constness_with_space(

c: &hir::Constness,

s: Option<ConstStability>,

overall_stab: Option<StableSince>,

const_stab: Option<ConstStability>,

) -> &'static str {

match (c, s) {

// const stable or when feature(staged_api) is not set

(

hir::Constness::Const,

Some(ConstStability { level: StabilityLevel::Stable { .. }, .. }),

)

| (hir::Constness::Const, None) => "const ",

// const unstable or not const

_ => "",

match c {

hir::Constness::Const => match (overall_stab, const_stab) {

// const stable...

(_, Some(ConstStability { level: StabilityLevel::Stable { .. }, .. }))

// ...or when feature(staged_api) is not set...

| (_, None)

// ...or when const unstable, but overall unstable too

| (None, Some(ConstStability { level: StabilityLevel::Unstable { .. }, .. })) => {

"const "

}

// const unstable (and overall stable)

(Some(_), Some(ConstStability { level: StabilityLevel::Unstable { .. }, .. })) => "",

},

// not const

hir::Constness::NotConst => "",

}

}