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::node_id::NodeId;
   5 use crate::lint::BufferedEarlyLint;
   6
   7 use rustc_errors::{Applicability, emitter::SilentEmitter, Handler, ColorConfig, DiagnosticBuilder};
   8 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
   9 use rustc_data_structures::sync::{Lrc, Lock, Once};
  10 use rustc_feature::UnstableFeatures;
  11 use syntax_pos::{Symbol, Span, MultiSpan};
  12 use syntax_pos::edition::Edition;
  13 use syntax_pos::hygiene::ExpnId;
  14 use syntax_pos::source_map::{SourceMap, FilePathMapping};
  15
  16 use std::path::PathBuf;
  17 use std::str;
  18
  19 // Duplicated from syntax::ast for now
  20 type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
  21
  22 /// Collected spans during parsing for places where a certain feature was
  23 /// used and should be feature gated accordingly in `check_crate`.
  24 #[derive(Default)]
  25 pub struct GatedSpans {
  26     pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
  27 }
  28
  29 impl GatedSpans {
  30     /// Feature gate the given `span` under the given `feature`
  31     /// which is same `Symbol` used in `active.rs`.
  32     pub fn gate(&self, feature: Symbol, span: Span) {
  33         self.spans
  34             .borrow_mut()
  35             .entry(feature)
  36             .or_default()
  37             .push(span);
  38     }
  39
  40     /// Ungate the last span under the given `feature`.
  41     /// Panics if the given `span` wasn't the last one.
  42     ///
  43     /// Using this is discouraged unless you have a really good reason to.
  44     pub fn ungate_last(&self, feature: Symbol, span: Span) {
  45         let removed_span = self.spans
  46             .borrow_mut()
  47             .entry(feature)
  48             .or_default()
  49             .pop()
  50             .unwrap();
  51         debug_assert_eq!(span, removed_span);
  52     }
  53
  54     /// Is the provided `feature` gate ungated currently?
  55     ///
  56     /// Using this is discouraged unless you have a really good reason to.
  57     pub fn is_ungated(&self, feature: Symbol) -> bool {
  58         self.spans
  59             .borrow()
  60             .get(&feature)
  61             .map_or(true, |spans| spans.is_empty())
  62     }
  63
  64     /// Prepend the given set of `spans` onto the set in `self`.
  65     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
  66         let mut inner = self.spans.borrow_mut();
  67         for (gate, mut gate_spans) in inner.drain() {
  68             spans.entry(gate).or_default().append(&mut gate_spans);
  69         }
  70         *inner = spans;
  71     }
  72 }
  73
  74 /// Info about a parsing session.
  75 pub struct ParseSess {
  76     pub span_diagnostic: Handler,
  77     pub unstable_features: UnstableFeatures,
  78     pub config: CrateConfig,
  79     pub edition: Edition,
  80     pub missing_fragment_specifiers: Lock<FxHashSet<Span>>,
  81     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
  82     pub raw_identifier_spans: Lock<Vec<Span>>,
  83     /// Used to determine and report recursive module inclusions.
  84     pub included_mod_stack: Lock<Vec<PathBuf>>,
  85     source_map: Lrc<SourceMap>,
  86     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
  87     /// Contains the spans of block expressions that could have been incomplete based on the
  88     /// operation token that followed it, but that the parser cannot identify without further
  89     /// analysis.
  90     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
  91     pub injected_crate_name: Once<Symbol>,
  92     pub gated_spans: GatedSpans,
  93     /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
  94     pub reached_eof: Lock<bool>,
  95 }
  96
  97 impl ParseSess {
  98     pub fn new(file_path_mapping: FilePathMapping) -> Self {
  99         let cm = Lrc::new(SourceMap::new(file_path_mapping));
 100         let handler = Handler::with_tty_emitter(
 101             ColorConfig::Auto,
 102             true,
 103             None,
 104             Some(cm.clone()),
 105         );
 106         ParseSess::with_span_handler(handler, cm)
 107     }
 108
 109     pub fn with_span_handler(
 110         handler: Handler,
 111         source_map: Lrc<SourceMap>,
 112     ) -> Self {
 113         Self {
 114             span_diagnostic: handler,
 115             unstable_features: UnstableFeatures::from_environment(),
 116             config: FxHashSet::default(),
 117             edition: ExpnId::root().expn_data().edition,
 118             missing_fragment_specifiers: Lock::new(FxHashSet::default()),
 119             raw_identifier_spans: Lock::new(Vec::new()),
 120             included_mod_stack: Lock::new(vec![]),
 121             source_map,
 122             buffered_lints: Lock::new(vec![]),
 123             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
 124             injected_crate_name: Once::new(),
 125             gated_spans: GatedSpans::default(),
 126             reached_eof: Lock::new(false),
 127         }
 128     }
 129
 130     pub fn with_silent_emitter() -> Self {
 131         let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 132         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
 133         ParseSess::with_span_handler(handler, cm)
 134     }
 135
 136     #[inline]
 137     pub fn source_map(&self) -> &SourceMap {
 138         &self.source_map
 139     }
 140
 141     pub fn buffer_lint(
 142         &self,
 143         lint_id: &'static crate::lint::Lint,
 144         span: impl Into<MultiSpan>,
 145         id: NodeId,
 146         msg: &str,
 147     ) {
 148         self.buffered_lints.with_lock(|buffered_lints| {
 149             buffered_lints.push(BufferedEarlyLint{
 150                 span: span.into(),
 151                 id,
 152                 msg: msg.into(),
 153                 lint_id,
 154             });
 155         });
 156     }
 157
 158     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 159     /// parser to continue parsing the following operation as part of the same expression.
 160     pub fn expr_parentheses_needed(
 161         &self,
 162         err: &mut DiagnosticBuilder<'_>,
 163         span: Span,
 164         alt_snippet: Option<String>,
 165     ) {
 166         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
 167             err.span_suggestion(
 168                 span,
 169                 "parentheses are required to parse this as an expression",
 170                 format!("({})", snippet),
 171                 Applicability::MachineApplicable,
 172             );
 173         }
 174     }
 175 }