src/librustc_session/parse.rs

   1 //! Contains `ParseSess` which holds state living beyond what one `Parser` might.
   2 //! It also serves as an input to the parser itself.
   3
   4 use crate::lint::{BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId};
   5 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
   6 use rustc_data_structures::sync::{Lock, Lrc, Once};
   7 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
   8 use rustc_errors::{error_code, Applicability, DiagnosticBuilder};
   9 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
  10 use rustc_span::edition::Edition;
  11 use rustc_span::hygiene::ExpnId;
  12 use rustc_span::source_map::{FilePathMapping, SourceMap};
  13 use rustc_span::{MultiSpan, Span, Symbol};
  14 use syntax::node_id::NodeId;
  15
  16 use std::path::PathBuf;
  17 use std::str;
  18
  19 /// The set of keys (and, optionally, values) that define the compilation
  20 /// environment of the crate, used to drive conditional compilation.
  21 pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
  22
  23 /// Collected spans during parsing for places where a certain feature was
  24 /// used and should be feature gated accordingly in `check_crate`.
  25 #[derive(Default)]
  26 pub struct GatedSpans {
  27     pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
  28 }
  29
  30 impl GatedSpans {
  31     /// Feature gate the given `span` under the given `feature`
  32     /// which is same `Symbol` used in `active.rs`.
  33     pub fn gate(&self, feature: Symbol, span: Span) {
  34         self.spans.borrow_mut().entry(feature).or_default().push(span);
  35     }
  36
  37     /// Ungate the last span under the given `feature`.
  38     /// Panics if the given `span` wasn't the last one.
  39     ///
  40     /// Using this is discouraged unless you have a really good reason to.
  41     pub fn ungate_last(&self, feature: Symbol, span: Span) {
  42         let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
  43         debug_assert_eq!(span, removed_span);
  44     }
  45
  46     /// Is the provided `feature` gate ungated currently?
  47     ///
  48     /// Using this is discouraged unless you have a really good reason to.
  49     pub fn is_ungated(&self, feature: Symbol) -> bool {
  50         self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
  51     }
  52
  53     /// Prepend the given set of `spans` onto the set in `self`.
  54     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
  55         let mut inner = self.spans.borrow_mut();
  56         for (gate, mut gate_spans) in inner.drain() {
  57             spans.entry(gate).or_default().append(&mut gate_spans);
  58         }
  59         *inner = spans;
  60     }
  61 }
  62
  63 /// Construct a diagnostic for a language feature error due to the given `span`.
  64 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
  65 pub fn feature_err<'a>(
  66     sess: &'a ParseSess,
  67     feature: Symbol,
  68     span: impl Into<MultiSpan>,
  69     explain: &str,
  70 ) -> DiagnosticBuilder<'a> {
  71     feature_err_issue(sess, feature, span, GateIssue::Language, explain)
  72 }
  73
  74 /// Construct a diagnostic for a feature gate error.
  75 ///
  76 /// This variant allows you to control whether it is a library or language feature.
  77 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
  78 pub fn feature_err_issue<'a>(
  79     sess: &'a ParseSess,
  80     feature: Symbol,
  81     span: impl Into<MultiSpan>,
  82     issue: GateIssue,
  83     explain: &str,
  84 ) -> DiagnosticBuilder<'a> {
  85     let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));
  86
  87     if let Some(n) = find_feature_issue(feature, issue) {
  88         err.note(&format!(
  89             "see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information",
  90             n, n,
  91         ));
  92     }
  93
  94     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
  95     if sess.unstable_features.is_nightly_build() {
  96         err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
  97     }
  98
  99     err
 100 }
 101
 102 /// Info about a parsing session.
 103 pub struct ParseSess {
 104     pub span_diagnostic: Handler,
 105     pub unstable_features: UnstableFeatures,
 106     pub config: CrateConfig,
 107     pub edition: Edition,
 108     pub missing_fragment_specifiers: Lock<FxHashSet<Span>>,
 109     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
 110     pub raw_identifier_spans: Lock<Vec<Span>>,
 111     /// Used to determine and report recursive module inclusions.
 112     pub included_mod_stack: Lock<Vec<PathBuf>>,
 113     source_map: Lrc<SourceMap>,
 114     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
 115     /// Contains the spans of block expressions that could have been incomplete based on the
 116     /// operation token that followed it, but that the parser cannot identify without further
 117     /// analysis.
 118     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
 119     pub injected_crate_name: Once<Symbol>,
 120     pub gated_spans: GatedSpans,
 121     /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
 122     pub reached_eof: Lock<bool>,
 123 }
 124
 125 impl ParseSess {
 126     pub fn new(file_path_mapping: FilePathMapping) -> Self {
 127         let sm = Lrc::new(SourceMap::new(file_path_mapping));
 128         let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(sm.clone()));
 129         ParseSess::with_span_handler(handler, sm)
 130     }
 131
 132     pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
 133         Self {
 134             span_diagnostic: handler,
 135             unstable_features: UnstableFeatures::from_environment(),
 136             config: FxHashSet::default(),
 137             edition: ExpnId::root().expn_data().edition,
 138             missing_fragment_specifiers: Lock::new(FxHashSet::default()),
 139             raw_identifier_spans: Lock::new(Vec::new()),
 140             included_mod_stack: Lock::new(vec![]),
 141             source_map,
 142             buffered_lints: Lock::new(vec![]),
 143             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
 144             injected_crate_name: Once::new(),
 145             gated_spans: GatedSpans::default(),
 146             reached_eof: Lock::new(false),
 147         }
 148     }
 149
 150     pub fn with_silent_emitter() -> Self {
 151         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 152         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
 153         ParseSess::with_span_handler(handler, sm)
 154     }
 155
 156     #[inline]
 157     pub fn source_map(&self) -> &SourceMap {
 158         &self.source_map
 159     }
 160
 161     pub fn buffer_lint(
 162         &self,
 163         lint: &'static Lint,
 164         span: impl Into<MultiSpan>,
 165         node_id: NodeId,
 166         msg: &str,
 167     ) {
 168         self.buffered_lints.with_lock(|buffered_lints| {
 169             buffered_lints.push(BufferedEarlyLint {
 170                 span: span.into(),
 171                 node_id,
 172                 msg: msg.into(),
 173                 lint_id: LintId::of(lint),
 174                 diagnostic: BuiltinLintDiagnostics::Normal,
 175             });
 176         });
 177     }
 178
 179     pub fn buffer_lint_with_diagnostic(
 180         &self,
 181         lint: &'static Lint,
 182         span: impl Into<MultiSpan>,
 183         node_id: NodeId,
 184         msg: &str,
 185         diagnostic: BuiltinLintDiagnostics,
 186     ) {
 187         self.buffered_lints.with_lock(|buffered_lints| {
 188             buffered_lints.push(BufferedEarlyLint {
 189                 span: span.into(),
 190                 node_id,
 191                 msg: msg.into(),
 192                 lint_id: LintId::of(lint),
 193                 diagnostic,
 194             });
 195         });
 196     }
 197
 198     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 199     /// parser to continue parsing the following operation as part of the same expression.
 200     pub fn expr_parentheses_needed(
 201         &self,
 202         err: &mut DiagnosticBuilder<'_>,
 203         span: Span,
 204         alt_snippet: Option<String>,
 205     ) {
 206         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
 207             err.span_suggestion(
 208                 span,
 209                 "parentheses are required to parse this as an expression",
 210                 format!("({})", snippet),
 211                 Applicability::MachineApplicable,
 212             );
 213         }
 214     }
 215 }