1#![allow(internal_features)]
16#![doc(rust_logo)]
17#![feature(rustdoc_internals)]
18#![warn(unreachable_pub)]
19mod accepted;
22mod builtin_attrs;
23mod removed;
24mod unstable;
25
26#[cfg(test)]
27mod tests;
28
29use std::num::NonZero;
30
31use rustc_span::Symbol;
32
33#[derive(Debug, Clone)]
34pub struct Feature {
35 pub name: Symbol,
36 pub since: &'static str,
41 issue: Option<NonZero<u32>>,
42}
43
44#[derive(Copy, Clone, Debug)]
45pub enum Stability {
46 Unstable,
47 Deprecated(&'static str, Option<&'static str>),
50}
51
52#[derive(Clone, Copy, Debug, Hash)]
53pub enum UnstableFeatures {
54 Disallow,
56 Allow,
58 Cheat,
63}
64
65impl UnstableFeatures {
66 pub fn from_environment(krate: Option<&str>) -> Self {
71 Self::from_environment_value(krate, std::env::var("RUSTC_BOOTSTRAP"))
72 }
73
74 fn from_environment_value(
78 krate: Option<&str>,
79 env_var_rustc_bootstrap: Result<String, std::env::VarError>,
80 ) -> Self {
81 let disable_unstable_features =
83 option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some_and(|s| s != "0");
84 let is_unstable_crate =
86 |var: &str| krate.is_some_and(|name| var.split(',').any(|new_krate| new_krate == name));
87
88 let bootstrap = env_var_rustc_bootstrap.ok();
89 if let Some(val) = bootstrap.as_deref() {
90 match val {
91 val if val == "1" || is_unstable_crate(val) => return UnstableFeatures::Cheat,
92 "-1" => return UnstableFeatures::Disallow,
95 _ => {}
96 }
97 }
98
99 if disable_unstable_features { UnstableFeatures::Disallow } else { UnstableFeatures::Allow }
100 }
101
102 pub fn is_nightly_build(&self) -> bool {
103 match *self {
104 UnstableFeatures::Allow | UnstableFeatures::Cheat => true,
105 UnstableFeatures::Disallow => false,
106 }
107 }
108}
109
110fn find_lang_feature_issue(feature: Symbol) -> Option<NonZero<u32>> {
111 if let Some(f) = UNSTABLE_LANG_FEATURES.iter().find(|f| f.name == feature) {
113 return f.issue;
114 }
115 if let Some(f) = ACCEPTED_LANG_FEATURES.iter().find(|f| f.name == feature) {
116 return f.issue;
117 }
118 if let Some(f) = REMOVED_LANG_FEATURES.iter().find(|f| f.feature.name == feature) {
119 return f.feature.issue;
120 }
121 panic!("feature `{feature}` is not declared anywhere");
122}
123
124const fn to_nonzero(n: Option<u32>) -> Option<NonZero<u32>> {
125 match n {
128 None => None,
129 Some(n) => NonZero::new(n),
130 }
131}
132
133pub enum GateIssue {
134 Language,
135 Library(Option<NonZero<u32>>),
136}
137
138pub fn find_feature_issue(feature: Symbol, issue: GateIssue) -> Option<NonZero<u32>> {
139 match issue {
140 GateIssue::Language => find_lang_feature_issue(feature),
141 GateIssue::Library(lib) => lib,
142 }
143}
144
145pub use accepted::ACCEPTED_LANG_FEATURES;
146pub use builtin_attrs::{
147 AttributeDuplicates, AttributeGate, AttributeSafety, AttributeTemplate, AttributeType,
148 BUILTIN_ATTRIBUTE_MAP, BUILTIN_ATTRIBUTES, BuiltinAttribute, GatedCfg, deprecated_attributes,
149 encode_cross_crate, find_gated_cfg, is_builtin_attr_name, is_stable_diagnostic_attribute,
150 is_valid_for_get_attr,
151};
152pub use removed::REMOVED_LANG_FEATURES;
153pub use unstable::{
154 EnabledLangFeature, EnabledLibFeature, Features, INCOMPATIBLE_FEATURES, UNSTABLE_LANG_FEATURES,
155};