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, 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 crate struct GatedSpans {
  23     /// Spans collected for gating `let_chains`, e.g. `if a && let b = c {}`.
  24     crate let_chains: Lock<Vec<Span>>,
  25     /// Spans collected for gating `async_closure`, e.g. `async || ..`.
  26     crate async_closure: Lock<Vec<Span>>,
  27     /// Spans collected for gating `yield e?` expressions (`generators` gate).
  28     crate yields: Lock<Vec<Span>>,
  29     /// Spans collected for gating `or_patterns`, e.g. `Some(Foo | Bar)`.
  30     crate or_patterns: Lock<Vec<Span>>,
  31     /// Spans collected for gating `const_extern_fn`, e.g. `const extern fn foo`.
  32     crate const_extern_fn: Lock<Vec<Span>>,
  33 }
  34
  35 /// Info about a parsing session.
  36 pub struct ParseSess {
  37     pub span_diagnostic: Handler,
  38     crate unstable_features: UnstableFeatures,
  39     pub config: CrateConfig,
  40     pub edition: Edition,
  41     pub missing_fragment_specifiers: Lock<FxHashSet<Span>>,
  42     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
  43     pub raw_identifier_spans: Lock<Vec<Span>>,
  44     /// Used to determine and report recursive module inclusions.
  45     pub(super) included_mod_stack: Lock<Vec<PathBuf>>,
  46     source_map: Lrc<SourceMap>,
  47     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
  48     /// Contains the spans of block expressions that could have been incomplete based on the
  49     /// operation token that followed it, but that the parser cannot identify without further
  50     /// analysis.
  51     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
  52     pub injected_crate_name: Once<Symbol>,
  53     crate gated_spans: GatedSpans,
  54 }
  55
  56 impl ParseSess {
  57     pub fn new(file_path_mapping: FilePathMapping) -> Self {
  58         let cm = Lrc::new(SourceMap::new(file_path_mapping));
  59         let handler = Handler::with_tty_emitter(
  60             ColorConfig::Auto,
  61             true,
  62             None,
  63             Some(cm.clone()),
  64         );
  65         ParseSess::with_span_handler(handler, cm)
  66     }
  67
  68     pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
  69         Self {
  70             span_diagnostic: handler,
  71             unstable_features: UnstableFeatures::from_environment(),
  72             config: FxHashSet::default(),
  73             edition: ExpnId::root().expn_data().edition,
  74             missing_fragment_specifiers: Lock::new(FxHashSet::default()),
  75             raw_identifier_spans: Lock::new(Vec::new()),
  76             included_mod_stack: Lock::new(vec![]),
  77             source_map,
  78             buffered_lints: Lock::new(vec![]),
  79             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
  80             injected_crate_name: Once::new(),
  81             gated_spans: GatedSpans::default(),
  82         }
  83     }
  84
  85     #[inline]
  86     pub fn source_map(&self) -> &SourceMap {
  87         &self.source_map
  88     }
  89
  90     pub fn buffer_lint(
  91         &self,
  92         lint_id: BufferedEarlyLintId,
  93         span: impl Into<MultiSpan>,
  94         id: NodeId,
  95         msg: &str,
  96     ) {
  97         self.buffered_lints.with_lock(|buffered_lints| {
  98             buffered_lints.push(BufferedEarlyLint{
  99                 span: span.into(),
 100                 id,
 101                 msg: msg.into(),
 102                 lint_id,
 103             });
 104         });
 105     }
 106
 107     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 108     /// parser to continue parsing the following operation as part of the same expression.
 109     pub fn expr_parentheses_needed(
 110         &self,
 111         err: &mut DiagnosticBuilder<'_>,
 112         span: Span,
 113         alt_snippet: Option<String>,
 114     ) {
 115         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
 116             err.span_suggestion(
 117                 span,
 118                 "parentheses are required to parse this as an expression",
 119                 format!("({})", snippet),
 120                 Applicability::MachineApplicable,
 121             );
 122         }
 123     }
 124 }