1 //! Contains `ParseSess` which holds state living beyond what one `Parser` might.
2 //! It also serves as an input to the parser itself.
4 use crate::lint::{BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId};
5 use crate::node_id::NodeId;
7 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
8 use rustc_data_structures::sync::{Lock, Lrc, Once};
9 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
10 use rustc_errors::{error_code, Applicability, DiagnosticBuilder};
11 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
12 use rustc_span::edition::Edition;
13 use rustc_span::hygiene::ExpnId;
14 use rustc_span::source_map::{FilePathMapping, SourceMap};
15 use rustc_span::{MultiSpan, Span, Symbol};
17 use std::path::PathBuf;
20 /// The set of keys (and, optionally, values) that define the compilation
21 /// environment of the crate, used to drive conditional compilation.
22 pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
24 /// Collected spans during parsing for places where a certain feature was
25 /// used and should be feature gated accordingly in `check_crate`.
27 pub struct GatedSpans {
28 pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
32 /// Feature gate the given `span` under the given `feature`
33 /// which is same `Symbol` used in `active.rs`.
34 pub fn gate(&self, feature: Symbol, span: Span) {
35 self.spans.borrow_mut().entry(feature).or_default().push(span);
38 /// Ungate the last span under the given `feature`.
39 /// Panics if the given `span` wasn't the last one.
41 /// Using this is discouraged unless you have a really good reason to.
42 pub fn ungate_last(&self, feature: Symbol, span: Span) {
43 let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
44 debug_assert_eq!(span, removed_span);
47 /// Is the provided `feature` gate ungated currently?
49 /// Using this is discouraged unless you have a really good reason to.
50 pub fn is_ungated(&self, feature: Symbol) -> bool {
51 self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
54 /// Prepend the given set of `spans` onto the set in `self`.
55 pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
56 let mut inner = self.spans.borrow_mut();
57 for (gate, mut gate_spans) in inner.drain() {
58 spans.entry(gate).or_default().append(&mut gate_spans);
64 /// Construct a diagnostic for a language feature error due to the given `span`.
65 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
66 pub fn feature_err<'a>(
69 span: impl Into<MultiSpan>,
71 ) -> DiagnosticBuilder<'a> {
72 feature_err_issue(sess, feature, span, GateIssue::Language, explain)
75 /// Construct a diagnostic for a feature gate error.
77 /// This variant allows you to control whether it is a library or language feature.
78 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
79 pub fn feature_err_issue<'a>(
82 span: impl Into<MultiSpan>,
85 ) -> DiagnosticBuilder<'a> {
86 let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));
88 if let Some(n) = find_feature_issue(feature, issue) {
90 "for more information, see https://github.com/rust-lang/rust/issues/{}",
95 // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
96 if sess.unstable_features.is_nightly_build() {
97 err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
103 /// Info about a parsing session.
104 pub struct ParseSess {
105 pub span_diagnostic: Handler,
106 pub unstable_features: UnstableFeatures,
107 pub config: CrateConfig,
108 pub edition: Edition,
109 pub missing_fragment_specifiers: Lock<FxHashSet<Span>>,
110 /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
111 pub raw_identifier_spans: Lock<Vec<Span>>,
112 /// Used to determine and report recursive module inclusions.
113 pub included_mod_stack: Lock<Vec<PathBuf>>,
114 source_map: Lrc<SourceMap>,
115 pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
116 /// Contains the spans of block expressions that could have been incomplete based on the
117 /// operation token that followed it, but that the parser cannot identify without further
119 pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
120 pub injected_crate_name: Once<Symbol>,
121 pub gated_spans: GatedSpans,
122 /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
123 pub reached_eof: Lock<bool>,
127 pub fn new(file_path_mapping: FilePathMapping) -> Self {
128 let cm = Lrc::new(SourceMap::new(file_path_mapping));
129 let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(cm.clone()));
130 ParseSess::with_span_handler(handler, cm)
133 pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
135 span_diagnostic: handler,
136 unstable_features: UnstableFeatures::from_environment(),
137 config: FxHashSet::default(),
138 edition: ExpnId::root().expn_data().edition,
139 missing_fragment_specifiers: Lock::new(FxHashSet::default()),
140 raw_identifier_spans: Lock::new(Vec::new()),
141 included_mod_stack: Lock::new(vec![]),
143 buffered_lints: Lock::new(vec![]),
144 ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
145 injected_crate_name: Once::new(),
146 gated_spans: GatedSpans::default(),
147 reached_eof: Lock::new(false),
151 pub fn with_silent_emitter() -> Self {
152 let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
153 let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
154 ParseSess::with_span_handler(handler, cm)
158 pub fn source_map(&self) -> &SourceMap {
165 span: impl Into<MultiSpan>,
169 self.buffered_lints.with_lock(|buffered_lints| {
170 buffered_lints.push(BufferedEarlyLint {
174 lint_id: LintId::of(lint),
175 diagnostic: BuiltinLintDiagnostics::Normal,
180 /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
181 /// parser to continue parsing the following operation as part of the same expression.
182 pub fn expr_parentheses_needed(
184 err: &mut DiagnosticBuilder<'_>,
186 alt_snippet: Option<String>,
188 if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
191 "parentheses are required to parse this as an expression",
192 format!("({})", snippet),
193 Applicability::MachineApplicable,