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::collections::BTreeMap;
  17 use std::path::PathBuf;
  18 use std::str;
  19
  20 /// The set of keys (and, optionally, values) that define the compilation
  21 /// environment of the crate, used to drive conditional compilation.
  22 pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
  23
  24 /// Collected spans during parsing for places where a certain feature was
  25 /// used and should be feature gated accordingly in `check_crate`.
  26 #[derive(Default)]
  27 pub struct GatedSpans {
  28     pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
  29 }
  30
  31 impl GatedSpans {
  32     /// Feature gate the given `span` under the given `feature`
  33     /// which is same `Symbol` used in `active.rs`.
  34     pub fn gate(&self, feature: Symbol, span: Span) {
  35         self.spans.borrow_mut().entry(feature).or_default().push(span);
  36     }
  37
  38     /// Ungate the last span under the given `feature`.
  39     /// Panics if the given `span` wasn't the last one.
  40     ///
  41     /// Using this is discouraged unless you have a really good reason to.
  42     pub fn ungate_last(&self, feature: Symbol, span: Span) {
  43         let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
  44         debug_assert_eq!(span, removed_span);
  45     }
  46
  47     /// Is the provided `feature` gate ungated currently?
  48     ///
  49     /// Using this is discouraged unless you have a really good reason to.
  50     pub fn is_ungated(&self, feature: Symbol) -> bool {
  51         self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
  52     }
  53
  54     /// Prepend the given set of `spans` onto the set in `self`.
  55     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
  56         let mut inner = self.spans.borrow_mut();
  57         for (gate, mut gate_spans) in inner.drain() {
  58             spans.entry(gate).or_default().append(&mut gate_spans);
  59         }
  60         *inner = spans;
  61     }
  62 }
  63
  64 #[derive(Default)]
  65 pub struct SymbolGallery {
  66     /// All symbols occurred and their first occurrance span.
  67     pub symbols: Lock<BTreeMap<Symbol, Span>>,
  68 }
  69
  70 impl SymbolGallery {
  71     /// Insert a symbol and its span into symbol gallery.
  72     /// If the symbol has occurred before, ignore the new occurance.
  73     pub fn insert(&self, symbol: Symbol, span: Span) {
  74         self.symbols.lock().entry(symbol).or_insert(span);
  75     }
  76 }
  77
  78 /// Construct a diagnostic for a language feature error due to the given `span`.
  79 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
  80 pub fn feature_err<'a>(
  81     sess: &'a ParseSess,
  82     feature: Symbol,
  83     span: impl Into<MultiSpan>,
  84     explain: &str,
  85 ) -> DiagnosticBuilder<'a> {
  86     feature_err_issue(sess, feature, span, GateIssue::Language, explain)
  87 }
  88
  89 /// Construct a diagnostic for a feature gate error.
  90 ///
  91 /// This variant allows you to control whether it is a library or language feature.
  92 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
  93 pub fn feature_err_issue<'a>(
  94     sess: &'a ParseSess,
  95     feature: Symbol,
  96     span: impl Into<MultiSpan>,
  97     issue: GateIssue,
  98     explain: &str,
  99 ) -> DiagnosticBuilder<'a> {
 100     let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));
 101
 102     if let Some(n) = find_feature_issue(feature, issue) {
 103         err.note(&format!(
 104             "see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information",
 105             n, n,
 106         ));
 107     }
 108
 109     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
 110     if sess.unstable_features.is_nightly_build() {
 111         err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
 112     }
 113
 114     err
 115 }
 116
 117 /// Info about a parsing session.
 118 pub struct ParseSess {
 119     pub span_diagnostic: Handler,
 120     pub unstable_features: UnstableFeatures,
 121     pub config: CrateConfig,
 122     pub edition: Edition,
 123     pub missing_fragment_specifiers: Lock<FxHashMap<Span, NodeId>>,
 124     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
 125     pub raw_identifier_spans: Lock<Vec<Span>>,
 126     /// Used to determine and report recursive module inclusions.
 127     pub included_mod_stack: Lock<Vec<PathBuf>>,
 128     source_map: Lrc<SourceMap>,
 129     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
 130     /// Contains the spans of block expressions that could have been incomplete based on the
 131     /// operation token that followed it, but that the parser cannot identify without further
 132     /// analysis.
 133     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
 134     pub injected_crate_name: OnceCell<Symbol>,
 135     pub gated_spans: GatedSpans,
 136     pub symbol_gallery: SymbolGallery,
 137     /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
 138     pub reached_eof: Lock<bool>,
 139     /// Environment variables accessed during the build and their values when they exist.
 140     pub env_depinfo: Lock<FxHashSet<(Symbol, Option<Symbol>)>>,
 141 }
 142
 143 impl ParseSess {
 144     pub fn new(file_path_mapping: FilePathMapping) -> Self {
 145         let sm = Lrc::new(SourceMap::new(file_path_mapping));
 146         let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(sm.clone()));
 147         ParseSess::with_span_handler(handler, sm)
 148     }
 149
 150     pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
 151         Self {
 152             span_diagnostic: handler,
 153             unstable_features: UnstableFeatures::from_environment(),
 154             config: FxHashSet::default(),
 155             edition: ExpnId::root().expn_data().edition,
 156             missing_fragment_specifiers: Default::default(),
 157             raw_identifier_spans: Lock::new(Vec::new()),
 158             included_mod_stack: Lock::new(vec![]),
 159             source_map,
 160             buffered_lints: Lock::new(vec![]),
 161             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
 162             injected_crate_name: OnceCell::new(),
 163             gated_spans: GatedSpans::default(),
 164             symbol_gallery: SymbolGallery::default(),
 165             reached_eof: Lock::new(false),
 166             env_depinfo: Default::default(),
 167         }
 168     }
 169
 170     pub fn with_silent_emitter() -> Self {
 171         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 172         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
 173         ParseSess::with_span_handler(handler, sm)
 174     }
 175
 176     #[inline]
 177     pub fn source_map(&self) -> &SourceMap {
 178         &self.source_map
 179     }
 180
 181     pub fn clone_source_map(&self) -> Lrc<SourceMap> {
 182         self.source_map.clone()
 183     }
 184
 185     pub fn buffer_lint(
 186         &self,
 187         lint: &'static Lint,
 188         span: impl Into<MultiSpan>,
 189         node_id: NodeId,
 190         msg: &str,
 191     ) {
 192         self.buffered_lints.with_lock(|buffered_lints| {
 193             buffered_lints.push(BufferedEarlyLint {
 194                 span: span.into(),
 195                 node_id,
 196                 msg: msg.into(),
 197                 lint_id: LintId::of(lint),
 198                 diagnostic: BuiltinLintDiagnostics::Normal,
 199             });
 200         });
 201     }
 202
 203     pub fn buffer_lint_with_diagnostic(
 204         &self,
 205         lint: &'static Lint,
 206         span: impl Into<MultiSpan>,
 207         node_id: NodeId,
 208         msg: &str,
 209         diagnostic: BuiltinLintDiagnostics,
 210     ) {
 211         self.buffered_lints.with_lock(|buffered_lints| {
 212             buffered_lints.push(BufferedEarlyLint {
 213                 span: span.into(),
 214                 node_id,
 215                 msg: msg.into(),
 216                 lint_id: LintId::of(lint),
 217                 diagnostic,
 218             });
 219         });
 220     }
 221
 222     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 223     /// parser to continue parsing the following operation as part of the same expression.
 224     pub fn expr_parentheses_needed(
 225         &self,
 226         err: &mut DiagnosticBuilder<'_>,
 227         span: Span,
 228         alt_snippet: Option<String>,
 229     ) {
 230         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
 231             err.span_suggestion(
 232                 span,
 233                 "parentheses are required to parse this as an expression",
 234                 format!("({})", snippet),
 235                 Applicability::MachineApplicable,
 236             );
 237         }
 238     }
 239 }