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Commit | Line | Data |
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0731742a | 1 | // Detecting lib features (i.e., features that are not lang features). |
b7449926 | 2 | // |
0731742a | 3 | // These are declared using stability attributes (e.g., `#[stable (..)]` |
b7449926 XL |
4 | // and `#[unstable (..)]`), but are not declared in one single location |
5 | // (unlike lang features), which means we need to collect them instead. | |
6 | ||
3dfed10e | 7 | use rustc_ast::{Attribute, MetaItem, MetaItemKind}; |
dfeec247 | 8 | use rustc_errors::struct_span_err; |
dfeec247 | 9 | use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor}; |
ba9703b0 XL |
10 | use rustc_middle::hir::map::Map; |
11 | use rustc_middle::middle::lib_features::LibFeatures; | |
12 | use rustc_middle::ty::query::Providers; | |
13 | use rustc_middle::ty::TyCtxt; | |
dfeec247 XL |
14 | use rustc_span::symbol::Symbol; |
15 | use rustc_span::{sym, Span}; | |
60c5eb7d | 16 | |
dfeec247 XL |
17 | fn new_lib_features() -> LibFeatures { |
18 | LibFeatures { stable: Default::default(), unstable: Default::default() } | |
b7449926 XL |
19 | } |
20 | ||
dc9dc135 XL |
21 | pub struct LibFeatureCollector<'tcx> { |
22 | tcx: TyCtxt<'tcx>, | |
b7449926 XL |
23 | lib_features: LibFeatures, |
24 | } | |
25 | ||
dc9dc135 XL |
26 | impl LibFeatureCollector<'tcx> { |
27 | fn new(tcx: TyCtxt<'tcx>) -> LibFeatureCollector<'tcx> { | |
dfeec247 | 28 | LibFeatureCollector { tcx, lib_features: new_lib_features() } |
b7449926 XL |
29 | } |
30 | ||
31 | fn extract(&self, attr: &Attribute) -> Option<(Symbol, Option<Symbol>, Span)> { | |
48663c56 | 32 | let stab_attrs = [sym::stable, sym::unstable, sym::rustc_const_unstable]; |
b7449926 | 33 | |
0731742a | 34 | // Find a stability attribute (i.e., `#[stable (..)]`, `#[unstable (..)]`, |
b7449926 | 35 | // `#[rustc_const_unstable (..)]`). |
94222f64 | 36 | if let Some(stab_attr) = stab_attrs.iter().find(|stab_attr| attr.has_name(**stab_attr)) { |
b7449926 | 37 | let meta_item = attr.meta(); |
e74abb32 | 38 | if let Some(MetaItem { kind: MetaItemKind::List(ref metas), .. }) = meta_item { |
b7449926 XL |
39 | let mut feature = None; |
40 | let mut since = None; | |
41 | for meta in metas { | |
42 | if let Some(mi) = meta.meta_item() { | |
43 | // Find the `feature = ".."` meta-item. | |
48663c56 XL |
44 | match (mi.name_or_empty(), mi.value_str()) { |
45 | (sym::feature, val) => feature = val, | |
46 | (sym::since, val) => since = val, | |
b7449926 XL |
47 | _ => {} |
48 | } | |
49 | } | |
50 | } | |
51 | if let Some(feature) = feature { | |
52 | // This additional check for stability is to make sure we | |
53 | // don't emit additional, irrelevant errors for malformed | |
54 | // attributes. | |
48663c56 | 55 | if *stab_attr != sym::stable || since.is_some() { |
b7449926 XL |
56 | return Some((feature, since, attr.span)); |
57 | } | |
58 | } | |
59 | // We need to iterate over the other attributes, because | |
60 | // `rustc_const_unstable` is not mutually exclusive with | |
61 | // the other stability attributes, so we can't just `break` | |
62 | // here. | |
63 | } | |
64 | } | |
65 | ||
66 | None | |
67 | } | |
68 | ||
69 | fn collect_feature(&mut self, feature: Symbol, since: Option<Symbol>, span: Span) { | |
70 | let already_in_stable = self.lib_features.stable.contains_key(&feature); | |
71 | let already_in_unstable = self.lib_features.unstable.contains(&feature); | |
72 | ||
73 | match (since, already_in_stable, already_in_unstable) { | |
74 | (Some(since), _, false) => { | |
75 | if let Some(prev_since) = self.lib_features.stable.get(&feature) { | |
76 | if *prev_since != since { | |
60c5eb7d XL |
77 | self.span_feature_error( |
78 | span, | |
79 | &format!( | |
80 | "feature `{}` is declared stable since {}, \ | |
81 | but was previously declared stable since {}", | |
dfeec247 | 82 | feature, since, prev_since, |
60c5eb7d | 83 | ), |
b7449926 | 84 | ); |
b7449926 XL |
85 | return; |
86 | } | |
87 | } | |
88 | ||
89 | self.lib_features.stable.insert(feature, since); | |
90 | } | |
91 | (None, false, _) => { | |
92 | self.lib_features.unstable.insert(feature); | |
93 | } | |
94 | (Some(_), _, true) | (None, true, _) => { | |
60c5eb7d XL |
95 | self.span_feature_error( |
96 | span, | |
97 | &format!( | |
98 | "feature `{}` is declared {}, but was previously declared {}", | |
99 | feature, | |
100 | if since.is_some() { "stable" } else { "unstable" }, | |
101 | if since.is_none() { "stable" } else { "unstable" }, | |
102 | ), | |
b7449926 | 103 | ); |
b7449926 XL |
104 | } |
105 | } | |
106 | } | |
60c5eb7d XL |
107 | |
108 | fn span_feature_error(&self, span: Span, msg: &str) { | |
6a06907d | 109 | struct_span_err!(self.tcx.sess, span, E0711, "{}", &msg).emit(); |
60c5eb7d | 110 | } |
b7449926 XL |
111 | } |
112 | ||
dc9dc135 | 113 | impl Visitor<'tcx> for LibFeatureCollector<'tcx> { |
dfeec247 XL |
114 | type Map = Map<'tcx>; |
115 | ||
ba9703b0 XL |
116 | fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { |
117 | NestedVisitorMap::All(self.tcx.hir()) | |
b7449926 XL |
118 | } |
119 | ||
6a06907d | 120 | fn visit_attribute(&mut self, _: rustc_hir::HirId, attr: &'tcx Attribute) { |
b7449926 XL |
121 | if let Some((feature, stable, span)) = self.extract(attr) { |
122 | self.collect_feature(feature, stable, span); | |
123 | } | |
124 | } | |
125 | } | |
126 | ||
17df50a5 | 127 | fn get_lib_features(tcx: TyCtxt<'_>, (): ()) -> LibFeatures { |
b7449926 | 128 | let mut collector = LibFeatureCollector::new(tcx); |
416331ca | 129 | let krate = tcx.hir().krate(); |
94222f64 | 130 | |
416331ca | 131 | intravisit::walk_crate(&mut collector, krate); |
b7449926 XL |
132 | collector.lib_features |
133 | } | |
dfeec247 | 134 | |
f035d41b | 135 | pub fn provide(providers: &mut Providers) { |
17df50a5 | 136 | providers.get_lib_features = get_lib_features; |
dfeec247 | 137 | } |