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 /// 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
  35             .borrow_mut()
  36             .entry(feature)
  37             .or_default()
  38             .push(span);
  39     }
  40
  41     /// Ungate the last span under the given `feature`.
  42     /// Panics if the given `span` wasn't the last one.
  43     ///
  44     /// Using this is discouraged unless you have a really good reason to.
  45     pub fn ungate_last(&self, feature: Symbol, span: Span) {
  46         let removed_span = self.spans
  47             .borrow_mut()
  48             .entry(feature)
  49             .or_default()
  50             .pop()
  51             .unwrap();
  52         debug_assert_eq!(span, removed_span);
  53     }
  54
  55     /// Is the provided `feature` gate ungated currently?
  56     ///
  57     /// Using this is discouraged unless you have a really good reason to.
  58     pub fn is_ungated(&self, feature: Symbol) -> bool {
  59         self.spans
  60             .borrow()
  61             .get(&feature)
  62             .map_or(true, |spans| spans.is_empty())
  63     }
  64
  65     /// Prepend the given set of `spans` onto the set in `self`.
  66     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
  67         let mut inner = self.spans.borrow_mut();
  68         for (gate, mut gate_spans) in inner.drain() {
  69             spans.entry(gate).or_default().append(&mut gate_spans);
  70         }
  71         *inner = spans;
  72     }
  73 }
  74
  75 /// Info about a parsing session.
  76 pub struct ParseSess {
  77     pub span_diagnostic: Handler,
  78     pub unstable_features: UnstableFeatures,
  79     pub config: CrateConfig,
  80     pub edition: Edition,
  81     pub missing_fragment_specifiers: Lock<FxHashSet<Span>>,
  82     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
  83     pub raw_identifier_spans: Lock<Vec<Span>>,
  84     /// Used to determine and report recursive module inclusions.
  85     pub included_mod_stack: Lock<Vec<PathBuf>>,
  86     source_map: Lrc<SourceMap>,
  87     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
  88     /// Contains the spans of block expressions that could have been incomplete based on the
  89     /// operation token that followed it, but that the parser cannot identify without further
  90     /// analysis.
  91     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
  92     pub injected_crate_name: Once<Symbol>,
  93     pub gated_spans: GatedSpans,
  94     /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
  95     pub reached_eof: Lock<bool>,
  96 }
  97
  98 impl ParseSess {
  99     pub fn new(file_path_mapping: FilePathMapping) -> Self {
 100         let cm = Lrc::new(SourceMap::new(file_path_mapping));
 101         let handler = Handler::with_tty_emitter(
 102             ColorConfig::Auto,
 103             true,
 104             None,
 105             Some(cm.clone()),
 106         );
 107         ParseSess::with_span_handler(handler, cm)
 108     }
 109
 110     pub fn with_span_handler(
 111         handler: Handler,
 112         source_map: Lrc<SourceMap>,
 113     ) -> Self {
 114         Self {
 115             span_diagnostic: handler,
 116             unstable_features: UnstableFeatures::from_environment(),
 117             config: FxHashSet::default(),
 118             edition: ExpnId::root().expn_data().edition,
 119             missing_fragment_specifiers: Lock::new(FxHashSet::default()),
 120             raw_identifier_spans: Lock::new(Vec::new()),
 121             included_mod_stack: Lock::new(vec![]),
 122             source_map,
 123             buffered_lints: Lock::new(vec![]),
 124             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
 125             injected_crate_name: Once::new(),
 126             gated_spans: GatedSpans::default(),
 127             reached_eof: Lock::new(false),
 128         }
 129     }
 130
 131     pub fn with_silent_emitter() -> Self {
 132         let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 133         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
 134         ParseSess::with_span_handler(handler, cm)
 135     }
 136
 137     #[inline]
 138     pub fn source_map(&self) -> &SourceMap {
 139         &self.source_map
 140     }
 141
 142     pub fn buffer_lint(
 143         &self,
 144         lint_id: &'static crate::lint::Lint,
 145         span: impl Into<MultiSpan>,
 146         id: NodeId,
 147         msg: &str,
 148     ) {
 149         self.buffered_lints.with_lock(|buffered_lints| {
 150             buffered_lints.push(BufferedEarlyLint{
 151                 span: span.into(),
 152                 id,
 153                 msg: msg.into(),
 154                 lint_id,
 155             });
 156         });
 157     }
 158
 159     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 160     /// parser to continue parsing the following operation as part of the same expression.
 161     pub fn expr_parentheses_needed(
 162         &self,
 163         err: &mut DiagnosticBuilder<'_>,
 164         span: Span,
 165         alt_snippet: Option<String>,
 166     ) {
 167         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
 168             err.span_suggestion(
 169                 span,
 170                 "parentheses are required to parse this as an expression",
 171                 format!("({})", snippet),
 172                 Applicability::MachineApplicable,
 173             );
 174         }
 175     }
 176 }