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, Attribute};
   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     /// Process the potential `cfg` attributes on a module.
  93     /// Also determine if the module should be included in this configuration.
  94     ///
  95     /// HACK(Centril): This is used to break a cyclic dependency between
  96     /// the parser and cfg-stripping as defined in `syntax_expand::config`.
  97     /// The dependency edge from the parser comes from `parse_item_mod`.
  98     /// A principled solution to this hack would be to implement [#64197].
  99     ///
 100     /// [#64197]: https://github.com/rust-lang/rust/issues/64197
 101     pub process_cfg_mod: ProcessCfgMod,
 102 }
 103
 104 pub type ProcessCfgMod = fn(&ParseSess, bool, &[Attribute]) -> (bool, Vec<Attribute>);
 105
 106 impl ParseSess {
 107     pub fn new(file_path_mapping: FilePathMapping, process_cfg_mod: ProcessCfgMod) -> Self {
 108         let cm = Lrc::new(SourceMap::new(file_path_mapping));
 109         let handler = Handler::with_tty_emitter(
 110             ColorConfig::Auto,
 111             true,
 112             None,
 113             Some(cm.clone()),
 114         );
 115         ParseSess::with_span_handler(handler, cm, process_cfg_mod)
 116     }
 117
 118     pub fn with_span_handler(
 119         handler: Handler,
 120         source_map: Lrc<SourceMap>,
 121         process_cfg_mod: ProcessCfgMod,
 122     ) -> Self {
 123         Self {
 124             span_diagnostic: handler,
 125             process_cfg_mod,
 126             unstable_features: UnstableFeatures::from_environment(),
 127             config: FxHashSet::default(),
 128             edition: ExpnId::root().expn_data().edition,
 129             missing_fragment_specifiers: Lock::new(FxHashSet::default()),
 130             raw_identifier_spans: Lock::new(Vec::new()),
 131             included_mod_stack: Lock::new(vec![]),
 132             source_map,
 133             buffered_lints: Lock::new(vec![]),
 134             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
 135             injected_crate_name: Once::new(),
 136             gated_spans: GatedSpans::default(),
 137             reached_eof: Lock::new(false),
 138         }
 139     }
 140
 141     pub fn with_silent_emitter(process_cfg_mod: ProcessCfgMod) -> Self {
 142         let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 143         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
 144         ParseSess::with_span_handler(handler, cm, process_cfg_mod)
 145     }
 146
 147     #[inline]
 148     pub fn source_map(&self) -> &SourceMap {
 149         &self.source_map
 150     }
 151
 152     pub fn buffer_lint(
 153         &self,
 154         lint_id: BufferedEarlyLintId,
 155         span: impl Into<MultiSpan>,
 156         id: NodeId,
 157         msg: &str,
 158     ) {
 159         self.buffered_lints.with_lock(|buffered_lints| {
 160             buffered_lints.push(BufferedEarlyLint{
 161                 span: span.into(),
 162                 id,
 163                 msg: msg.into(),
 164                 lint_id,
 165             });
 166         });
 167     }
 168
 169     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 170     /// parser to continue parsing the following operation as part of the same expression.
 171     pub fn expr_parentheses_needed(
 172         &self,
 173         err: &mut DiagnosticBuilder<'_>,
 174         span: Span,
 175         alt_snippet: Option<String>,
 176     ) {
 177         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
 178             err.span_suggestion(
 179                 span,
 180                 "parentheses are required to parse this as an expression",
 181                 format!("({})", snippet),
 182                 Applicability::MachineApplicable,
 183             );
 184         }
 185     }
 186 }