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_error_codes::E0658;
10 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
11 use rustc_errors::{error_code, Applicability, DiagnosticBuilder};
12 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
13 use rustc_span::edition::Edition;
14 use rustc_span::hygiene::ExpnId;
15 use rustc_span::source_map::{FilePathMapping, SourceMap};
16 use rustc_span::{MultiSpan, Span, Symbol};
18 use std::path::PathBuf;
21 /// The set of keys (and, optionally, values) that define the compilation
22 /// environment of the crate, used to drive conditional compilation.
23 pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
25 /// Collected spans during parsing for places where a certain feature was
26 /// used and should be feature gated accordingly in `check_crate`.
28 pub struct GatedSpans {
29 pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
33 /// Feature gate the given `span` under the given `feature`
34 /// which is same `Symbol` used in `active.rs`.
35 pub fn gate(&self, feature: Symbol, span: Span) {
36 self.spans.borrow_mut().entry(feature).or_default().push(span);
39 /// Ungate the last span under the given `feature`.
40 /// Panics if the given `span` wasn't the last one.
42 /// Using this is discouraged unless you have a really good reason to.
43 pub fn ungate_last(&self, feature: Symbol, span: Span) {
44 let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
45 debug_assert_eq!(span, removed_span);
48 /// Is the provided `feature` gate ungated currently?
50 /// Using this is discouraged unless you have a really good reason to.
51 pub fn is_ungated(&self, feature: Symbol) -> bool {
52 self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
55 /// Prepend the given set of `spans` onto the set in `self`.
56 pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
57 let mut inner = self.spans.borrow_mut();
58 for (gate, mut gate_spans) in inner.drain() {
59 spans.entry(gate).or_default().append(&mut gate_spans);
65 /// The strenght of a feature gate.
66 /// Either it is a `Hard` error, or only a `Soft` warning.
67 #[derive(Debug, Copy, Clone, PartialEq)]
68 pub enum GateStrength {
69 /// A hard error. (Most feature gates should use this.)
71 /// Only a warning. (Use this only as backwards-compatibility demands.)
75 /// Construct a diagnostic for a language feature error due to the given `span`.
76 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
77 pub fn feature_err<'a>(
80 span: impl Into<MultiSpan>,
82 ) -> DiagnosticBuilder<'a> {
83 feature_err_issue(sess, feature, span, GateIssue::Language, explain)
86 /// Construct a diagnostic for a feature gate error.
88 /// This variant allows you to control whether it is a library or language feature.
89 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
90 pub fn feature_err_issue<'a>(
93 span: impl Into<MultiSpan>,
96 ) -> DiagnosticBuilder<'a> {
97 leveled_feature_err(sess, feature, span, issue, explain, GateStrength::Hard)
100 /// Construct a diagnostic for a feature gate error / warning.
102 /// You should typically just use `feature_err` instead.
103 pub fn leveled_feature_err<'a>(
106 span: impl Into<MultiSpan>,
110 ) -> DiagnosticBuilder<'a> {
111 let diag = &sess.span_diagnostic;
113 let mut err = match level {
114 GateStrength::Hard => diag.struct_span_err_with_code(span, explain, error_code!(E0658)),
115 GateStrength::Soft => diag.struct_span_warn(span, explain),
118 if let Some(n) = find_feature_issue(feature, issue) {
120 "for more information, see https://github.com/rust-lang/rust/issues/{}",
125 // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
126 if sess.unstable_features.is_nightly_build() {
127 err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
130 // If we're on stable and only emitting a "soft" warning, add a note to
131 // clarify that the feature isn't "on" (rather than being on but
133 if !sess.unstable_features.is_nightly_build() && level == GateStrength::Soft {
134 err.help("a nightly build of the compiler is required to enable this feature");
140 /// Info about a parsing session.
141 pub struct ParseSess {
142 pub span_diagnostic: Handler,
143 pub unstable_features: UnstableFeatures,
144 pub config: CrateConfig,
145 pub edition: Edition,
146 pub missing_fragment_specifiers: Lock<FxHashSet<Span>>,
147 /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
148 pub raw_identifier_spans: Lock<Vec<Span>>,
149 /// Used to determine and report recursive module inclusions.
150 pub included_mod_stack: Lock<Vec<PathBuf>>,
151 source_map: Lrc<SourceMap>,
152 pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
153 /// Contains the spans of block expressions that could have been incomplete based on the
154 /// operation token that followed it, but that the parser cannot identify without further
156 pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
157 pub injected_crate_name: Once<Symbol>,
158 pub gated_spans: GatedSpans,
159 /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
160 pub reached_eof: Lock<bool>,
164 pub fn new(file_path_mapping: FilePathMapping) -> Self {
165 let cm = Lrc::new(SourceMap::new(file_path_mapping));
166 let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(cm.clone()));
167 ParseSess::with_span_handler(handler, cm)
170 pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
172 span_diagnostic: handler,
173 unstable_features: UnstableFeatures::from_environment(),
174 config: FxHashSet::default(),
175 edition: ExpnId::root().expn_data().edition,
176 missing_fragment_specifiers: Lock::new(FxHashSet::default()),
177 raw_identifier_spans: Lock::new(Vec::new()),
178 included_mod_stack: Lock::new(vec![]),
180 buffered_lints: Lock::new(vec![]),
181 ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
182 injected_crate_name: Once::new(),
183 gated_spans: GatedSpans::default(),
184 reached_eof: Lock::new(false),
188 pub fn with_silent_emitter() -> Self {
189 let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
190 let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
191 ParseSess::with_span_handler(handler, cm)
195 pub fn source_map(&self) -> &SourceMap {
202 span: impl Into<MultiSpan>,
206 self.buffered_lints.with_lock(|buffered_lints| {
207 buffered_lints.push(BufferedEarlyLint {
211 lint_id: LintId::of(lint),
212 diagnostic: BuiltinLintDiagnostics::Normal,
217 /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
218 /// parser to continue parsing the following operation as part of the same expression.
219 pub fn expr_parentheses_needed(
221 err: &mut DiagnosticBuilder<'_>,
223 alt_snippet: Option<String>,
225 if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
228 "parentheses are required to parse this as an expression",
229 format!("({})", snippet),
230 Applicability::MachineApplicable,