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