compiler/rustc_session/src/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};
   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::str;
  17
  18 /// The set of keys (and, optionally, values) that define the compilation
  19 /// environment of the crate, used to drive conditional compilation.
  20 pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
  21
  22 /// Collected spans during parsing for places where a certain feature was
  23 /// used and should be feature gated accordingly in `check_crate`.
  24 #[derive(Default)]
  25 pub struct GatedSpans {
  26     pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
  27 }
  28
  29 impl GatedSpans {
  30     /// Feature gate the given `span` under the given `feature`
  31     /// which is same `Symbol` used in `active.rs`.
  32     pub fn gate(&self, feature: Symbol, span: Span) {
  33         self.spans.borrow_mut().entry(feature).or_default().push(span);
  34     }
  35
  36     /// Ungate the last span under the given `feature`.
  37     /// Panics if the given `span` wasn't the last one.
  38     ///
  39     /// Using this is discouraged unless you have a really good reason to.
  40     pub fn ungate_last(&self, feature: Symbol, span: Span) {
  41         let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
  42         debug_assert_eq!(span, removed_span);
  43     }
  44
  45     /// Is the provided `feature` gate ungated currently?
  46     ///
  47     /// Using this is discouraged unless you have a really good reason to.
  48     pub fn is_ungated(&self, feature: Symbol) -> bool {
  49         self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
  50     }
  51
  52     /// Prepend the given set of `spans` onto the set in `self`.
  53     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
  54         let mut inner = self.spans.borrow_mut();
  55         for (gate, mut gate_spans) in inner.drain() {
  56             spans.entry(gate).or_default().append(&mut gate_spans);
  57         }
  58         *inner = spans;
  59     }
  60 }
  61
  62 #[derive(Default)]
  63 pub struct SymbolGallery {
  64     /// All symbols occurred and their first occurrence span.
  65     pub symbols: Lock<FxHashMap<Symbol, Span>>,
  66 }
  67
  68 impl SymbolGallery {
  69     /// Insert a symbol and its span into symbol gallery.
  70     /// If the symbol has occurred before, ignore the new occurance.
  71     pub fn insert(&self, symbol: Symbol, span: Span) {
  72         self.symbols.lock().entry(symbol).or_insert(span);
  73     }
  74 }
  75
  76 /// Construct a diagnostic for a language feature error due to the given `span`.
  77 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
  78 pub fn feature_err<'a>(
  79     sess: &'a ParseSess,
  80     feature: Symbol,
  81     span: impl Into<MultiSpan>,
  82     explain: &str,
  83 ) -> DiagnosticBuilder<'a> {
  84     feature_err_issue(sess, feature, span, GateIssue::Language, explain)
  85 }
  86
  87 /// Construct a diagnostic for a feature gate error.
  88 ///
  89 /// This variant allows you to control whether it is a library or language feature.
  90 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
  91 pub fn feature_err_issue<'a>(
  92     sess: &'a ParseSess,
  93     feature: Symbol,
  94     span: impl Into<MultiSpan>,
  95     issue: GateIssue,
  96     explain: &str,
  97 ) -> DiagnosticBuilder<'a> {
  98     let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));
  99
 100     if let Some(n) = find_feature_issue(feature, issue) {
 101         err.note(&format!(
 102             "see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information",
 103             n, n,
 104         ));
 105     }
 106
 107     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
 108     if sess.unstable_features.is_nightly_build() {
 109         err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
 110     }
 111
 112     err
 113 }
 114
 115 /// Info about a parsing session.
 116 pub struct ParseSess {
 117     pub span_diagnostic: Handler,
 118     pub unstable_features: UnstableFeatures,
 119     pub config: CrateConfig,
 120     pub edition: Edition,
 121     pub missing_fragment_specifiers: Lock<FxHashMap<Span, NodeId>>,
 122     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
 123     pub raw_identifier_spans: Lock<Vec<Span>>,
 124     source_map: Lrc<SourceMap>,
 125     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
 126     /// Contains the spans of block expressions that could have been incomplete based on the
 127     /// operation token that followed it, but that the parser cannot identify without further
 128     /// analysis.
 129     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
 130     pub gated_spans: GatedSpans,
 131     pub symbol_gallery: SymbolGallery,
 132     /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
 133     pub reached_eof: Lock<bool>,
 134     /// Environment variables accessed during the build and their values when they exist.
 135     pub env_depinfo: Lock<FxHashSet<(Symbol, Option<Symbol>)>>,
 136     /// File paths accessed during the build.
 137     pub file_depinfo: Lock<FxHashSet<Symbol>>,
 138     /// All the type ascriptions expressions that have had a suggestion for likely path typo.
 139     pub type_ascription_path_suggestions: Lock<FxHashSet<Span>>,
 140     /// Whether cfg(version) should treat the current release as incomplete
 141     pub assume_incomplete_release: bool,
 142     /// Spans passed to `proc_macro::quote_span`. Each span has a numerical
 143     /// identifier represented by its position in the vector.
 144     pub proc_macro_quoted_spans: Lock<Vec<Span>>,
 145 }
 146
 147 impl ParseSess {
 148     /// Used for testing.
 149     pub fn new(file_path_mapping: FilePathMapping) -> Self {
 150         let sm = Lrc::new(SourceMap::new(file_path_mapping));
 151         let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(sm.clone()));
 152         ParseSess::with_span_handler(handler, sm)
 153     }
 154
 155     pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
 156         Self {
 157             span_diagnostic: handler,
 158             unstable_features: UnstableFeatures::from_environment(None),
 159             config: FxHashSet::default(),
 160             edition: ExpnId::root().expn_data().edition,
 161             missing_fragment_specifiers: Default::default(),
 162             raw_identifier_spans: Lock::new(Vec::new()),
 163             source_map,
 164             buffered_lints: Lock::new(vec![]),
 165             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
 166             gated_spans: GatedSpans::default(),
 167             symbol_gallery: SymbolGallery::default(),
 168             reached_eof: Lock::new(false),
 169             env_depinfo: Default::default(),
 170             file_depinfo: Default::default(),
 171             type_ascription_path_suggestions: Default::default(),
 172             assume_incomplete_release: false,
 173             proc_macro_quoted_spans: Default::default(),
 174         }
 175     }
 176
 177     pub fn with_silent_emitter() -> Self {
 178         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 179         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
 180         ParseSess::with_span_handler(handler, sm)
 181     }
 182
 183     #[inline]
 184     pub fn source_map(&self) -> &SourceMap {
 185         &self.source_map
 186     }
 187
 188     pub fn clone_source_map(&self) -> Lrc<SourceMap> {
 189         self.source_map.clone()
 190     }
 191
 192     pub fn buffer_lint(
 193         &self,
 194         lint: &'static Lint,
 195         span: impl Into<MultiSpan>,
 196         node_id: NodeId,
 197         msg: &str,
 198     ) {
 199         self.buffered_lints.with_lock(|buffered_lints| {
 200             buffered_lints.push(BufferedEarlyLint {
 201                 span: span.into(),
 202                 node_id,
 203                 msg: msg.into(),
 204                 lint_id: LintId::of(lint),
 205                 diagnostic: BuiltinLintDiagnostics::Normal,
 206             });
 207         });
 208     }
 209
 210     pub fn buffer_lint_with_diagnostic(
 211         &self,
 212         lint: &'static Lint,
 213         span: impl Into<MultiSpan>,
 214         node_id: NodeId,
 215         msg: &str,
 216         diagnostic: BuiltinLintDiagnostics,
 217     ) {
 218         self.buffered_lints.with_lock(|buffered_lints| {
 219             buffered_lints.push(BufferedEarlyLint {
 220                 span: span.into(),
 221                 node_id,
 222                 msg: msg.into(),
 223                 lint_id: LintId::of(lint),
 224                 diagnostic,
 225             });
 226         });
 227     }
 228
 229     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
 230     /// parser to continue parsing the following operation as part of the same expression.
 231     pub fn expr_parentheses_needed(&self, err: &mut DiagnosticBuilder<'_>, span: Span) {
 232         err.multipart_suggestion(
 233             "parentheses are required to parse this as an expression",
 234             vec![(span.shrink_to_lo(), "(".to_string()), (span.shrink_to_hi(), ")".to_string())],
 235             Applicability::MachineApplicable,
 236         );
 237     }
 238
 239     pub fn save_proc_macro_span(&self, span: Span) -> usize {
 240         let mut spans = self.proc_macro_quoted_spans.lock();
 241         spans.push(span);
 242         return spans.len() - 1;
 243     }
 244
 245     pub fn proc_macro_quoted_spans(&self) -> Vec<Span> {
 246         self.proc_macro_quoted_spans.lock().clone()
 247     }
 248 }