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, BuiltinLintDiagnostics, Lint, LintId};
   5 use rustc_ast::node_id::NodeId;
   6 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
   7 use rustc_data_structures::sync::{Lock, Lrc, OnceCell};
   8 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
   9 use rustc_errors::{error_code, Applicability, DiagnosticBuilder};
  10 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
  11 use rustc_span::edition::Edition;
  12 use rustc_span::hygiene::ExpnId;
  13 use rustc_span::source_map::{FilePathMapping, SourceMap};
  14 use rustc_span::{MultiSpan, Span, Symbol};
  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.borrow_mut().entry(feature).or_default().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.borrow_mut().entry(feature).or_default().pop().unwrap();
  43         debug_assert_eq!(span, removed_span);
  44     }
  45
  46     /// Is the provided `feature` gate ungated currently?
  47     ///
  48     /// Using this is discouraged unless you have a really good reason to.
  49     pub fn is_ungated(&self, feature: Symbol) -> bool {
  50         self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
  51     }
  52
  53     /// Prepend the given set of `spans` onto the set in `self`.
  54     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
  55         let mut inner = self.spans.borrow_mut();
  56         for (gate, mut gate_spans) in inner.drain() {
  57             spans.entry(gate).or_default().append(&mut gate_spans);
  58         }
  59         *inner = spans;
  60     }
  61 }
  62
  63 #[derive(Default)]
  64 pub struct SymbolGallery {
  65     /// All symbols occurred and their first occurrance span.
  66     pub symbols: Lock<FxHashMap<Symbol, Span>>,
  67 }
  68
  69 impl SymbolGallery {
  70     /// Insert a symbol and its span into symbol gallery.
  71     /// If the symbol has occurred before, ignore the new occurance.
  72     pub fn insert(&self, symbol: Symbol, span: Span) {
  73         self.symbols.lock().entry(symbol).or_insert(span);
  74     }
  75 }
  76
  77 /// Construct a diagnostic for a language feature error due to the given `span`.
  78 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
  79 pub fn feature_err<'a>(
  80     sess: &'a ParseSess,
  81     feature: Symbol,
  82     span: impl Into<MultiSpan>,
  83     explain: &str,
  84 ) -> DiagnosticBuilder<'a> {
  85     feature_err_issue(sess, feature, span, GateIssue::Language, explain)
  86 }
  87
  88 /// Construct a diagnostic for a feature gate error.
  89 ///
  90 /// This variant allows you to control whether it is a library or language feature.
  91 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
  92 pub fn feature_err_issue<'a>(
  93     sess: &'a ParseSess,
  94     feature: Symbol,
  95     span: impl Into<MultiSpan>,
  96     issue: GateIssue,
  97     explain: &str,
  98 ) -> DiagnosticBuilder<'a> {
  99     let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));
 100
 101     if let Some(n) = find_feature_issue(feature, issue) {
 102         err.note(&format!(
 103             "see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information",
 104             n, n,
 105         ));
 106     }
 107
 108     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
 109     if sess.unstable_features.is_nightly_build() {
 110         err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
 111     }
 112
 113     err
 114 }
 115
 116 /// Info about a parsing session.
 117 pub struct ParseSess {
 118     pub span_diagnostic: Handler,
 119     pub unstable_features: UnstableFeatures,
 120     pub config: CrateConfig,
 121     pub edition: Edition,
 122     pub missing_fragment_specifiers: Lock<FxHashMap<Span, NodeId>>,
 123     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
 124     pub raw_identifier_spans: Lock<Vec<Span>>,
 125     /// Used to determine and report recursive module inclusions.
 126     pub included_mod_stack: Lock<Vec<PathBuf>>,
 127     source_map: Lrc<SourceMap>,
 128     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
 129     /// Contains the spans of block expressions that could have been incomplete based on the
 130     /// operation token that followed it, but that the parser cannot identify without further
 131     /// analysis.
 132     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
 133     pub injected_crate_name: OnceCell<Symbol>,
 134     pub gated_spans: GatedSpans,
 135     pub symbol_gallery: SymbolGallery,
 136     /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
 137     pub reached_eof: Lock<bool>,
 138 }
 139
 140 impl ParseSess {
 141     pub fn new(file_path_mapping: FilePathMapping) -> Self {
 142         let sm = Lrc::new(SourceMap::new(file_path_mapping));
 143         let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(sm.clone()));
 144         ParseSess::with_span_handler(handler, sm)
 145     }
 146
 147     pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
 148         Self {
 149             span_diagnostic: handler,
 150             unstable_features: UnstableFeatures::from_environment(),
 151             config: FxHashSet::default(),
 152             edition: ExpnId::root().expn_data().edition,
 153             missing_fragment_specifiers: Default::default(),
 154             raw_identifier_spans: Lock::new(Vec::new()),
 155             included_mod_stack: Lock::new(vec![]),
 156             source_map,
 157             buffered_lints: Lock::new(vec![]),
 158             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
 159             injected_crate_name: OnceCell::new(),
 160             gated_spans: GatedSpans::default(),
 161             symbol_gallery: SymbolGallery::default(),
 162             reached_eof: Lock::new(false),
 163         }
 164     }
 165
 166     pub fn with_silent_emitter() -> Self {
 167         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 168         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
 169         ParseSess::with_span_handler(handler, sm)
 170     }
 171
 172     #[inline]
 173     pub fn source_map(&self) -> &SourceMap {
 174         &self.source_map
 175     }
 176
 177     pub fn clone_source_map(&self) -> Lrc<SourceMap> {
 178         self.source_map.clone()
 179     }
 180
 181     pub fn buffer_lint(
 182         &self,
 183         lint: &'static Lint,
 184         span: impl Into<MultiSpan>,
 185         node_id: NodeId,
 186         msg: &str,
 187     ) {
 188         self.buffered_lints.with_lock(|buffered_lints| {
 189             buffered_lints.push(BufferedEarlyLint {
 190                 span: span.into(),
 191                 node_id,
 192                 msg: msg.into(),
 193                 lint_id: LintId::of(lint),
 194                 diagnostic: BuiltinLintDiagnostics::Normal,
 195             });
 196         });
 197     }
 198
 199     pub fn buffer_lint_with_diagnostic(
 200         &self,
 201         lint: &'static Lint,
 202         span: impl Into<MultiSpan>,
 203         node_id: NodeId,
 204         msg: &str,
 205         diagnostic: BuiltinLintDiagnostics,
 206     ) {
 207         self.buffered_lints.with_lock(|buffered_lints| {
 208             buffered_lints.push(BufferedEarlyLint {
 209                 span: span.into(),
 210                 node_id,
 211                 msg: msg.into(),
 212                 lint_id: LintId::of(lint),
 213                 diagnostic,
 214             });
 215         });
 216     }
 217
 218     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 219     /// parser to continue parsing the following operation as part of the same expression.
 220     pub fn expr_parentheses_needed(
 221         &self,
 222         err: &mut DiagnosticBuilder<'_>,
 223         span: Span,
 224         alt_snippet: Option<String>,
 225     ) {
 226         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
 227             err.span_suggestion(
 228                 span,
 229                 "parentheses are required to parse this as an expression",
 230                 format!("({})", snippet),
 231                 Applicability::MachineApplicable,
 232             );
 233         }
 234     }
 235 }