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