src/librustc_session/parse.rs - third_party/rust - Git at Google

 //! Contains `ParseSess` which holds state living beyond what one `Parser` might.
 //! It also serves as an input to the parser itself.

 use crate::lint::{BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId};
 use rustc_ast::node_id::NodeId;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::{Lock, Lrc, OnceCell};
 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
 use rustc_errors::{error_code, Applicability, DiagnosticBuilder};
 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::ExpnId;
 use rustc_span::source_map::{FilePathMapping, SourceMap};
 use rustc_span::{MultiSpan, Span, Symbol};

 use std::collections::BTreeMap;
 use std::path::PathBuf;
 use std::str;

 /// The set of keys (and, optionally, values) that define the compilation
 /// environment of the crate, used to drive conditional compilation.
 pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;

 /// Collected spans during parsing for places where a certain feature was
 /// used and should be feature gated accordingly in `check_crate`.
 #[derive(Default)]
 pub struct GatedSpans {
     pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
 }

 impl GatedSpans {
     /// Feature gate the given `span` under the given `feature`
     /// which is same `Symbol` used in `active.rs`.
     pub fn gate(&self, feature: Symbol, span: Span) {
         self.spans.borrow_mut().entry(feature).or_default().push(span);
     }

     /// Ungate the last span under the given `feature`.
     /// Panics if the given `span` wasn't the last one.
     ///
     /// Using this is discouraged unless you have a really good reason to.
     pub fn ungate_last(&self, feature: Symbol, span: Span) {
         let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
         debug_assert_eq!(span, removed_span);
     }

     /// Is the provided `feature` gate ungated currently?
     ///
     /// Using this is discouraged unless you have a really good reason to.
     pub fn is_ungated(&self, feature: Symbol) -> bool {
         self.spans.borrow().get(&feature).map_or(true, |spans| spans.is_empty())
     }

     /// Prepend the given set of `spans` onto the set in `self`.
     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
         let mut inner = self.spans.borrow_mut();
         for (gate, mut gate_spans) in inner.drain() {
             spans.entry(gate).or_default().append(&mut gate_spans);
         }
         *inner = spans;
     }
 }

 #[derive(Default)]
 pub struct SymbolGallery {
     /// All symbols occurred and their first occurrance span.
     pub symbols: Lock<BTreeMap<Symbol, Span>>,
 }

 impl SymbolGallery {
     /// Insert a symbol and its span into symbol gallery.
     /// If the symbol has occurred before, ignore the new occurance.
     pub fn insert(&self, symbol: Symbol, span: Span) {
         self.symbols.lock().entry(symbol).or_insert(span);
     }
 }

 /// Construct a diagnostic for a language feature error due to the given `span`.
 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
 pub fn feature_err<'a>(
     sess: &'a ParseSess,
     feature: Symbol,
     span: impl Into<MultiSpan>,
     explain: &str,
 ) -> DiagnosticBuilder<'a> {
     feature_err_issue(sess, feature, span, GateIssue::Language, explain)
 }

 /// Construct a diagnostic for a feature gate error.
 ///
 /// This variant allows you to control whether it is a library or language feature.
 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
 pub fn feature_err_issue<'a>(
     sess: &'a ParseSess,
     feature: Symbol,
     span: impl Into<MultiSpan>,
     issue: GateIssue,
     explain: &str,
 ) -> DiagnosticBuilder<'a> {
     let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));

     if let Some(n) = find_feature_issue(feature, issue) {
         err.note(&format!(
             "see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information",
             n, n,
         ));
     }

     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
     if sess.unstable_features.is_nightly_build() {
         err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
     }

     err
 }

 /// Info about a parsing session.
 pub struct ParseSess {
     pub span_diagnostic: Handler,
     pub unstable_features: UnstableFeatures,
     pub config: CrateConfig,
     pub edition: Edition,
     pub missing_fragment_specifiers: Lock<FxHashMap<Span, NodeId>>,
     /// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
     pub raw_identifier_spans: Lock<Vec<Span>>,
     /// Used to determine and report recursive module inclusions.
     pub included_mod_stack: Lock<Vec<PathBuf>>,
     source_map: Lrc<SourceMap>,
     pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
     /// Contains the spans of block expressions that could have been incomplete based on the
     /// operation token that followed it, but that the parser cannot identify without further
     /// analysis.
     pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
     pub injected_crate_name: OnceCell<Symbol>,
     pub gated_spans: GatedSpans,
     pub symbol_gallery: SymbolGallery,
     /// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
     pub reached_eof: Lock<bool>,
     /// Environment variables accessed during the build and their values when they exist.
     pub env_depinfo: Lock<FxHashSet<(Symbol, Option<Symbol>)>>,
 }

 impl ParseSess {
     pub fn new(file_path_mapping: FilePathMapping) -> Self {
         let sm = Lrc::new(SourceMap::new(file_path_mapping));
         let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(sm.clone()));
         ParseSess::with_span_handler(handler, sm)
     }

     pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
         Self {
             span_diagnostic: handler,
             unstable_features: UnstableFeatures::from_environment(),
             config: FxHashSet::default(),
             edition: ExpnId::root().expn_data().edition,
             missing_fragment_specifiers: Default::default(),
             raw_identifier_spans: Lock::new(Vec::new()),
             included_mod_stack: Lock::new(vec![]),
             source_map,
             buffered_lints: Lock::new(vec![]),
             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
             injected_crate_name: OnceCell::new(),
             gated_spans: GatedSpans::default(),
             symbol_gallery: SymbolGallery::default(),
             reached_eof: Lock::new(false),
             env_depinfo: Default::default(),
         }
     }

     pub fn with_silent_emitter() -> Self {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
         ParseSess::with_span_handler(handler, sm)
     }

     #[inline]
     pub fn source_map(&self) -> &SourceMap {
         &self.source_map
     }

     pub fn clone_source_map(&self) -> Lrc<SourceMap> {
         self.source_map.clone()
     }

     pub fn buffer_lint(
         &self,
         lint: &'static Lint,
         span: impl Into<MultiSpan>,
         node_id: NodeId,
         msg: &str,
     ) {
         self.buffered_lints.with_lock(|buffered_lints| {
             buffered_lints.push(BufferedEarlyLint {
                 span: span.into(),
                 node_id,
                 msg: msg.into(),
                 lint_id: LintId::of(lint),
                 diagnostic: BuiltinLintDiagnostics::Normal,
             });
         });
     }

     pub fn buffer_lint_with_diagnostic(
         &self,
         lint: &'static Lint,
         span: impl Into<MultiSpan>,
         node_id: NodeId,
         msg: &str,
         diagnostic: BuiltinLintDiagnostics,
     ) {
         self.buffered_lints.with_lock(|buffered_lints| {
             buffered_lints.push(BufferedEarlyLint {
                 span: span.into(),
                 node_id,
                 msg: msg.into(),
                 lint_id: LintId::of(lint),
                 diagnostic,
             });
         });
     }

     /// Extend an error with a suggestion to wrap an expression with parentheses to allow the
     /// parser to continue parsing the following operation as part of the same expression.
     pub fn expr_parentheses_needed(
         &self,
         err: &mut DiagnosticBuilder<'_>,
         span: Span,
         alt_snippet: Option<String>,
     ) {
         if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
             err.span_suggestion(
                 span,
                 "parentheses are required to parse this as an expression",
                 format!("({})", snippet),
                 Applicability::MachineApplicable,
             );
         }
     }
 }
	//! Contains `ParseSess` which holds state living beyond what one `Parser` might.
	//! It also serves as an input to the parser itself.

	use crate::lint::{BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId};
	use rustc_ast::node_id::NodeId;
	use rustc_data_structures::fx::{FxHashMap, FxHashSet};
	use rustc_data_structures::sync::{Lock, Lrc, OnceCell};
	use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
	use rustc_errors::{error_code, Applicability, DiagnosticBuilder};
	use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
	use rustc_span::edition::Edition;
	use rustc_span::hygiene::ExpnId;
	use rustc_span::source_map::{FilePathMapping, SourceMap};
	use rustc_span::{MultiSpan, Span, Symbol};

	use std::collections::BTreeMap;
	use std::path::PathBuf;
	use std::str;

	/// The set of keys (and, optionally, values) that define the compilation
	/// environment of the crate, used to drive conditional compilation.
	pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;

	/// Collected spans during parsing for places where a certain feature was
	/// used and should be feature gated accordingly in `check_crate`.
	#[derive(Default)]
	pub struct GatedSpans {
	pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
	}

	impl GatedSpans {
	/// Feature gate the given `span` under the given `feature`
	/// which is same `Symbol` used in `active.rs`.
	pub fn gate(&self, feature: Symbol, span: Span) {
	self.spans.borrow_mut().entry(feature).or_default().push(span);
	}

	/// Ungate the last span under the given `feature`.
	/// Panics if the given `span` wasn't the last one.
	///
	/// Using this is discouraged unless you have a really good reason to.
	pub fn ungate_last(&self, feature: Symbol, span: Span) {
	let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
	debug_assert_eq!(span, removed_span);
	}

	/// Is the provided `feature` gate ungated currently?
	///
	/// Using this is discouraged unless you have a really good reason to.
	pub fn is_ungated(&self, feature: Symbol) -> bool {
	self.spans.borrow().get(&feature).map_or(true, \|spans\| spans.is_empty())
	}

	/// Prepend the given set of `spans` onto the set in `self`.
	pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
	let mut inner = self.spans.borrow_mut();
	for (gate, mut gate_spans) in inner.drain() {
	spans.entry(gate).or_default().append(&mut gate_spans);
	}
	*inner = spans;
	}
	}

	#[derive(Default)]
	pub struct SymbolGallery {
	/// All symbols occurred and their first occurrance span.
	pub symbols: Lock<BTreeMap<Symbol, Span>>,
	}

	impl SymbolGallery {
	/// Insert a symbol and its span into symbol gallery.
	/// If the symbol has occurred before, ignore the new occurance.
	pub fn insert(&self, symbol: Symbol, span: Span) {
	self.symbols.lock().entry(symbol).or_insert(span);
	}
	}

	/// Construct a diagnostic for a language feature error due to the given `span`.
	/// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
	pub fn feature_err<'a>(
	sess: &'a ParseSess,
	feature: Symbol,
	span: impl Into<MultiSpan>,
	explain: &str,
	) -> DiagnosticBuilder<'a> {
	feature_err_issue(sess, feature, span, GateIssue::Language, explain)
	}

	/// Construct a diagnostic for a feature gate error.
	///
	/// This variant allows you to control whether it is a library or language feature.
	/// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
	pub fn feature_err_issue<'a>(
	sess: &'a ParseSess,
	feature: Symbol,
	span: impl Into<MultiSpan>,
	issue: GateIssue,
	explain: &str,
	) -> DiagnosticBuilder<'a> {
	let mut err = sess.span_diagnostic.struct_span_err_with_code(span, explain, error_code!(E0658));

	if let Some(n) = find_feature_issue(feature, issue) {
	err.note(&format!(
	"see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information",
	n, n,
	));
	}

	// #23973: do not suggest `#![feature(...)]` if we are in beta/stable
	if sess.unstable_features.is_nightly_build() {
	err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
	}

	err
	}

	/// Info about a parsing session.
	pub struct ParseSess {
	pub span_diagnostic: Handler,
	pub unstable_features: UnstableFeatures,
	pub config: CrateConfig,
	pub edition: Edition,
	pub missing_fragment_specifiers: Lock<FxHashMap<Span, NodeId>>,
	/// Places where raw identifiers were used. This is used for feature-gating raw identifiers.
	pub raw_identifier_spans: Lock<Vec<Span>>,
	/// Used to determine and report recursive module inclusions.
	pub included_mod_stack: Lock<Vec<PathBuf>>,
	source_map: Lrc<SourceMap>,
	pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
	/// Contains the spans of block expressions that could have been incomplete based on the
	/// operation token that followed it, but that the parser cannot identify without further
	/// analysis.
	pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
	pub injected_crate_name: OnceCell<Symbol>,
	pub gated_spans: GatedSpans,
	pub symbol_gallery: SymbolGallery,
	/// The parser has reached `Eof` due to an unclosed brace. Used to silence unnecessary errors.
	pub reached_eof: Lock<bool>,
	/// Environment variables accessed during the build and their values when they exist.
	pub env_depinfo: Lock<FxHashSet<(Symbol, Option<Symbol>)>>,
	}

	impl ParseSess {
	pub fn new(file_path_mapping: FilePathMapping) -> Self {
	let sm = Lrc::new(SourceMap::new(file_path_mapping));
	let handler = Handler::with_tty_emitter(ColorConfig::Auto, true, None, Some(sm.clone()));
	ParseSess::with_span_handler(handler, sm)
	}

	pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
	Self {
	span_diagnostic: handler,
	unstable_features: UnstableFeatures::from_environment(),
	config: FxHashSet::default(),
	edition: ExpnId::root().expn_data().edition,
	missing_fragment_specifiers: Default::default(),
	raw_identifier_spans: Lock::new(Vec::new()),
	included_mod_stack: Lock::new(vec![]),
	source_map,
	buffered_lints: Lock::new(vec![]),
	ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
	injected_crate_name: OnceCell::new(),
	gated_spans: GatedSpans::default(),
	symbol_gallery: SymbolGallery::default(),
	reached_eof: Lock::new(false),
	env_depinfo: Default::default(),
	}
	}

	pub fn with_silent_emitter() -> Self {
	let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
	let handler = Handler::with_emitter(false, None, Box::new(SilentEmitter));
	ParseSess::with_span_handler(handler, sm)
	}

	#[inline]
	pub fn source_map(&self) -> &SourceMap {
	&self.source_map
	}

	pub fn clone_source_map(&self) -> Lrc<SourceMap> {
	self.source_map.clone()
	}

	pub fn buffer_lint(
	&self,
	lint: &'static Lint,
	span: impl Into<MultiSpan>,
	node_id: NodeId,
	msg: &str,
	) {
	self.buffered_lints.with_lock(\|buffered_lints\| {
	buffered_lints.push(BufferedEarlyLint {
	span: span.into(),
	node_id,
	msg: msg.into(),
	lint_id: LintId::of(lint),
	diagnostic: BuiltinLintDiagnostics::Normal,
	});
	});
	}

	pub fn buffer_lint_with_diagnostic(
	&self,
	lint: &'static Lint,
	span: impl Into<MultiSpan>,
	node_id: NodeId,
	msg: &str,
	diagnostic: BuiltinLintDiagnostics,
	) {
	self.buffered_lints.with_lock(\|buffered_lints\| {
	buffered_lints.push(BufferedEarlyLint {
	span: span.into(),
	node_id,
	msg: msg.into(),
	lint_id: LintId::of(lint),
	diagnostic,
	});
	});
	}

	/// Extend an error with a suggestion to wrap an expression with parentheses to allow the
	/// parser to continue parsing the following operation as part of the same expression.
	pub fn expr_parentheses_needed(
	&self,
	err: &mut DiagnosticBuilder<'_>,
	span: Span,
	alt_snippet: Option<String>,
	) {
	if let Some(snippet) = self.source_map().span_to_snippet(span).ok().or(alt_snippet) {
	err.span_suggestion(
	span,
	"parentheses are required to parse this as an expression",
	format!("({})", snippet),
	Applicability::MachineApplicable,
	);
	}
	}
	}