| //! The main parser interface. |
| |
| use crate::ast::{self, CrateConfig, NodeId}; |
| use crate::early_buffered_lints::{BufferedEarlyLint, BufferedEarlyLintId}; |
| use crate::source_map::{SourceMap, FilePathMapping}; |
| use crate::feature_gate::UnstableFeatures; |
| use crate::parse::parser::{Parser, emit_unclosed_delims}; |
| use crate::parse::token::{Nonterminal, TokenKind}; |
| use crate::tokenstream::{self, TokenStream, TokenTree}; |
| use crate::print::pprust; |
| use crate::symbol::Symbol; |
| |
| use errors::{Applicability, FatalError, Level, Handler, ColorConfig, Diagnostic, DiagnosticBuilder}; |
| use rustc_data_structures::fx::{FxHashSet, FxHashMap}; |
| #[cfg(target_arch = "x86_64")] |
| use rustc_data_structures::static_assert_size; |
| use rustc_data_structures::sync::{Lrc, Lock, Once}; |
| use syntax_pos::{Span, SourceFile, FileName, MultiSpan}; |
| use syntax_pos::edition::Edition; |
| use syntax_pos::hygiene::ExpnId; |
| |
| use std::borrow::Cow; |
| use std::path::{Path, PathBuf}; |
| use std::str; |
| |
| use log::info; |
| |
| #[cfg(test)] |
| mod tests; |
| |
| #[macro_use] |
| pub mod parser; |
| pub mod attr; |
| pub mod lexer; |
| pub mod token; |
| |
| crate mod classify; |
| crate mod diagnostics; |
| crate mod literal; |
| crate mod unescape_error_reporting; |
| |
| pub type PResult<'a, T> = Result<T, DiagnosticBuilder<'a>>; |
| |
| // `PResult` is used a lot. Make sure it doesn't unintentionally get bigger. |
| // (See also the comment on `DiagnosticBuilderInner`.) |
| #[cfg(target_arch = "x86_64")] |
| static_assert_size!(PResult<'_, bool>, 16); |
| |
| /// 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 { |
| /// Spans collected for gating `let_chains`, e.g. `if a && let b = c {}`. |
| pub let_chains: Lock<Vec<Span>>, |
| /// Spans collected for gating `async_closure`, e.g. `async || ..`. |
| pub async_closure: Lock<Vec<Span>>, |
| /// Spans collected for gating `yield e?` expressions (`generators` gate). |
| pub yields: Lock<Vec<Span>>, |
| /// Spans collected for gating `or_patterns`, e.g. `Some(Foo | Bar)`. |
| pub or_patterns: Lock<Vec<Span>>, |
| /// Spans collected for gating `const_extern_fn`, e.g. `const extern fn foo`. |
| pub const_extern_fn: Lock<Vec<Span>>, |
| } |
| |
| /// 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<FxHashSet<Span>>, |
| /// 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. |
| 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: Once<Symbol>, |
| pub gated_spans: GatedSpans, |
| } |
| |
| impl ParseSess { |
| pub fn new(file_path_mapping: FilePathMapping) -> Self { |
| let cm = Lrc::new(SourceMap::new(file_path_mapping)); |
| let handler = Handler::with_tty_emitter( |
| ColorConfig::Auto, |
| true, |
| None, |
| Some(cm.clone()), |
| ); |
| ParseSess::with_span_handler(handler, cm) |
| } |
| |
| 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: Lock::new(FxHashSet::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: Once::new(), |
| gated_spans: GatedSpans::default(), |
| } |
| } |
| |
| #[inline] |
| pub fn source_map(&self) -> &SourceMap { |
| &self.source_map |
| } |
| |
| pub fn buffer_lint<S: Into<MultiSpan>>(&self, |
| lint_id: BufferedEarlyLintId, |
| span: S, |
| id: NodeId, |
| msg: &str, |
| ) { |
| self.buffered_lints.with_lock(|buffered_lints| { |
| buffered_lints.push(BufferedEarlyLint{ |
| span: span.into(), |
| id, |
| msg: msg.into(), |
| lint_id, |
| }); |
| }); |
| } |
| |
| /// 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, |
| ); |
| } |
| } |
| } |
| |
| #[derive(Clone)] |
| pub struct Directory<'a> { |
| pub path: Cow<'a, Path>, |
| pub ownership: DirectoryOwnership, |
| } |
| |
| #[derive(Copy, Clone)] |
| pub enum DirectoryOwnership { |
| Owned { |
| // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`. |
| relative: Option<ast::Ident>, |
| }, |
| UnownedViaBlock, |
| UnownedViaMod(bool /* legacy warnings? */), |
| } |
| |
| // A bunch of utility functions of the form `parse_<thing>_from_<source>` |
| // where <thing> includes crate, expr, item, stmt, tts, and one that |
| // uses a HOF to parse anything, and <source> includes file and |
| // `source_str`. |
| |
| pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> { |
| let mut parser = new_parser_from_file(sess, input); |
| parser.parse_crate_mod() |
| } |
| |
| pub fn parse_crate_attrs_from_file<'a>(input: &Path, sess: &'a ParseSess) |
| -> PResult<'a, Vec<ast::Attribute>> { |
| let mut parser = new_parser_from_file(sess, input); |
| parser.parse_inner_attributes() |
| } |
| |
| pub fn parse_crate_from_source_str(name: FileName, source: String, sess: &ParseSess) |
| -> PResult<'_, ast::Crate> { |
| new_parser_from_source_str(sess, name, source).parse_crate_mod() |
| } |
| |
| pub fn parse_crate_attrs_from_source_str(name: FileName, source: String, sess: &ParseSess) |
| -> PResult<'_, Vec<ast::Attribute>> { |
| new_parser_from_source_str(sess, name, source).parse_inner_attributes() |
| } |
| |
| pub fn parse_stream_from_source_str( |
| name: FileName, |
| source: String, |
| sess: &ParseSess, |
| override_span: Option<Span>, |
| ) -> TokenStream { |
| let (stream, mut errors) = source_file_to_stream( |
| sess, |
| sess.source_map().new_source_file(name, source), |
| override_span, |
| ); |
| emit_unclosed_delims(&mut errors, &sess.span_diagnostic); |
| stream |
| } |
| |
| /// Creates a new parser from a source string. |
| pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> { |
| panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source)) |
| } |
| |
| /// Creates a new parser from a source string. Returns any buffered errors from lexing the initial |
| /// token stream. |
| pub fn maybe_new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) |
| -> Result<Parser<'_>, Vec<Diagnostic>> |
| { |
| let mut parser = maybe_source_file_to_parser(sess, |
| sess.source_map().new_source_file(name, source))?; |
| parser.recurse_into_file_modules = false; |
| Ok(parser) |
| } |
| |
| /// Creates a new parser, handling errors as appropriate if the file doesn't exist. |
| pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path) -> Parser<'a> { |
| source_file_to_parser(sess, file_to_source_file(sess, path, None)) |
| } |
| |
| /// Creates a new parser, returning buffered diagnostics if the file doesn't exist, |
| /// or from lexing the initial token stream. |
| pub fn maybe_new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path) |
| -> Result<Parser<'a>, Vec<Diagnostic>> { |
| let file = try_file_to_source_file(sess, path, None).map_err(|db| vec![db])?; |
| maybe_source_file_to_parser(sess, file) |
| } |
| |
| /// Given a session, a crate config, a path, and a span, add |
| /// the file at the given path to the `source_map`, and returns a parser. |
| /// On an error, uses the given span as the source of the problem. |
| pub fn new_sub_parser_from_file<'a>(sess: &'a ParseSess, |
| path: &Path, |
| directory_ownership: DirectoryOwnership, |
| module_name: Option<String>, |
| sp: Span) -> Parser<'a> { |
| let mut p = source_file_to_parser(sess, file_to_source_file(sess, path, Some(sp))); |
| p.directory.ownership = directory_ownership; |
| p.root_module_name = module_name; |
| p |
| } |
| |
| /// Given a `source_file` and config, returns a parser. |
| fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> { |
| panictry_buffer!(&sess.span_diagnostic, |
| maybe_source_file_to_parser(sess, source_file)) |
| } |
| |
| /// Given a `source_file` and config, return a parser. Returns any buffered errors from lexing the |
| /// initial token stream. |
| fn maybe_source_file_to_parser( |
| sess: &ParseSess, |
| source_file: Lrc<SourceFile>, |
| ) -> Result<Parser<'_>, Vec<Diagnostic>> { |
| let end_pos = source_file.end_pos; |
| let (stream, unclosed_delims) = maybe_file_to_stream(sess, source_file, None)?; |
| let mut parser = stream_to_parser(sess, stream, None); |
| parser.unclosed_delims = unclosed_delims; |
| if parser.token == token::Eof && parser.token.span.is_dummy() { |
| parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt()); |
| } |
| |
| Ok(parser) |
| } |
| |
| // Must preserve old name for now, because `quote!` from the *existing* |
| // compiler expands into it. |
| pub fn new_parser_from_tts(sess: &ParseSess, tts: Vec<TokenTree>) -> Parser<'_> { |
| stream_to_parser(sess, tts.into_iter().collect(), crate::MACRO_ARGUMENTS) |
| } |
| |
| |
| // Base abstractions |
| |
| /// Given a session and a path and an optional span (for error reporting), |
| /// add the path to the session's source_map and return the new source_file or |
| /// error when a file can't be read. |
| fn try_file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>) |
| -> Result<Lrc<SourceFile>, Diagnostic> { |
| sess.source_map().load_file(path) |
| .map_err(|e| { |
| let msg = format!("couldn't read {}: {}", path.display(), e); |
| let mut diag = Diagnostic::new(Level::Fatal, &msg); |
| if let Some(sp) = spanopt { |
| diag.set_span(sp); |
| } |
| diag |
| }) |
| } |
| |
| /// Given a session and a path and an optional span (for error reporting), |
| /// adds the path to the session's `source_map` and returns the new `source_file`. |
| fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>) |
| -> Lrc<SourceFile> { |
| match try_file_to_source_file(sess, path, spanopt) { |
| Ok(source_file) => source_file, |
| Err(d) => { |
| sess.span_diagnostic.emit_diagnostic(&d); |
| FatalError.raise(); |
| } |
| } |
| } |
| |
| /// Given a `source_file`, produces a sequence of token trees. |
| pub fn source_file_to_stream( |
| sess: &ParseSess, |
| source_file: Lrc<SourceFile>, |
| override_span: Option<Span>, |
| ) -> (TokenStream, Vec<lexer::UnmatchedBrace>) { |
| panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span)) |
| } |
| |
| /// Given a source file, produces a sequence of token trees. Returns any buffered errors from |
| /// parsing the token stream. |
| pub fn maybe_file_to_stream( |
| sess: &ParseSess, |
| source_file: Lrc<SourceFile>, |
| override_span: Option<Span>, |
| ) -> Result<(TokenStream, Vec<lexer::UnmatchedBrace>), Vec<Diagnostic>> { |
| let srdr = lexer::StringReader::new(sess, source_file, override_span); |
| let (token_trees, unmatched_braces) = srdr.into_token_trees(); |
| |
| match token_trees { |
| Ok(stream) => Ok((stream, unmatched_braces)), |
| Err(err) => { |
| let mut buffer = Vec::with_capacity(1); |
| err.buffer(&mut buffer); |
| // Not using `emit_unclosed_delims` to use `db.buffer` |
| for unmatched in unmatched_braces { |
| let mut db = sess.span_diagnostic.struct_span_err(unmatched.found_span, &format!( |
| "incorrect close delimiter: `{}`", |
| pprust::token_kind_to_string(&token::CloseDelim(unmatched.found_delim)), |
| )); |
| db.span_label(unmatched.found_span, "incorrect close delimiter"); |
| if let Some(sp) = unmatched.candidate_span { |
| db.span_label(sp, "close delimiter possibly meant for this"); |
| } |
| if let Some(sp) = unmatched.unclosed_span { |
| db.span_label(sp, "un-closed delimiter"); |
| } |
| db.buffer(&mut buffer); |
| } |
| Err(buffer) |
| } |
| } |
| } |
| |
| /// Given a stream and the `ParseSess`, produces a parser. |
| pub fn stream_to_parser<'a>( |
| sess: &'a ParseSess, |
| stream: TokenStream, |
| subparser_name: Option<&'static str>, |
| ) -> Parser<'a> { |
| Parser::new(sess, stream, None, true, false, subparser_name) |
| } |
| |
| /// Given a stream, the `ParseSess` and the base directory, produces a parser. |
| /// |
| /// Use this function when you are creating a parser from the token stream |
| /// and also care about the current working directory of the parser (e.g., |
| /// you are trying to resolve modules defined inside a macro invocation). |
| /// |
| /// # Note |
| /// |
| /// The main usage of this function is outside of rustc, for those who uses |
| /// libsyntax as a library. Please do not remove this function while refactoring |
| /// just because it is not used in rustc codebase! |
| pub fn stream_to_parser_with_base_dir<'a>( |
| sess: &'a ParseSess, |
| stream: TokenStream, |
| base_dir: Directory<'a>, |
| ) -> Parser<'a> { |
| Parser::new(sess, stream, Some(base_dir), true, false, None) |
| } |
| |
| /// A sequence separator. |
| pub struct SeqSep { |
| /// The separator token. |
| pub sep: Option<TokenKind>, |
| /// `true` if a trailing separator is allowed. |
| pub trailing_sep_allowed: bool, |
| } |
| |
| impl SeqSep { |
| pub fn trailing_allowed(t: TokenKind) -> SeqSep { |
| SeqSep { |
| sep: Some(t), |
| trailing_sep_allowed: true, |
| } |
| } |
| |
| pub fn none() -> SeqSep { |
| SeqSep { |
| sep: None, |
| trailing_sep_allowed: false, |
| } |
| } |
| } |
| |
| // NOTE(Centril): The following probably shouldn't be here but it acknowledges the |
| // fact that architecturally, we are using parsing (read on below to understand why). |
| |
| pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> TokenStream { |
| // A `Nonterminal` is often a parsed AST item. At this point we now |
| // need to convert the parsed AST to an actual token stream, e.g. |
| // un-parse it basically. |
| // |
| // Unfortunately there's not really a great way to do that in a |
| // guaranteed lossless fashion right now. The fallback here is to just |
| // stringify the AST node and reparse it, but this loses all span |
| // information. |
| // |
| // As a result, some AST nodes are annotated with the token stream they |
| // came from. Here we attempt to extract these lossless token streams |
| // before we fall back to the stringification. |
| let tokens = match *nt { |
| Nonterminal::NtItem(ref item) => { |
| prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span) |
| } |
| Nonterminal::NtTraitItem(ref item) => { |
| prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span) |
| } |
| Nonterminal::NtImplItem(ref item) => { |
| prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span) |
| } |
| Nonterminal::NtIdent(ident, is_raw) => { |
| Some(tokenstream::TokenTree::token(token::Ident(ident.name, is_raw), ident.span).into()) |
| } |
| Nonterminal::NtLifetime(ident) => { |
| Some(tokenstream::TokenTree::token(token::Lifetime(ident.name), ident.span).into()) |
| } |
| Nonterminal::NtTT(ref tt) => { |
| Some(tt.clone().into()) |
| } |
| _ => None, |
| }; |
| |
| // FIXME(#43081): Avoid this pretty-print + reparse hack |
| let source = pprust::nonterminal_to_string(nt); |
| let filename = FileName::macro_expansion_source_code(&source); |
| let tokens_for_real = parse_stream_from_source_str(filename, source, sess, Some(span)); |
| |
| // During early phases of the compiler the AST could get modified |
| // directly (e.g., attributes added or removed) and the internal cache |
| // of tokens my not be invalidated or updated. Consequently if the |
| // "lossless" token stream disagrees with our actual stringification |
| // (which has historically been much more battle-tested) then we go |
| // with the lossy stream anyway (losing span information). |
| // |
| // Note that the comparison isn't `==` here to avoid comparing spans, |
| // but it *also* is a "probable" equality which is a pretty weird |
| // definition. We mostly want to catch actual changes to the AST |
| // like a `#[cfg]` being processed or some weird `macro_rules!` |
| // expansion. |
| // |
| // What we *don't* want to catch is the fact that a user-defined |
| // literal like `0xf` is stringified as `15`, causing the cached token |
| // stream to not be literal `==` token-wise (ignoring spans) to the |
| // token stream we got from stringification. |
| // |
| // Instead the "probably equal" check here is "does each token |
| // recursively have the same discriminant?" We basically don't look at |
| // the token values here and assume that such fine grained token stream |
| // modifications, including adding/removing typically non-semantic |
| // tokens such as extra braces and commas, don't happen. |
| if let Some(tokens) = tokens { |
| if tokens.probably_equal_for_proc_macro(&tokens_for_real) { |
| return tokens |
| } |
| info!("cached tokens found, but they're not \"probably equal\", \ |
| going with stringified version"); |
| } |
| return tokens_for_real |
| } |
| |
| fn prepend_attrs( |
| sess: &ParseSess, |
| attrs: &[ast::Attribute], |
| tokens: Option<&tokenstream::TokenStream>, |
| span: syntax_pos::Span |
| ) -> Option<tokenstream::TokenStream> { |
| let tokens = tokens?; |
| if attrs.len() == 0 { |
| return Some(tokens.clone()) |
| } |
| let mut builder = tokenstream::TokenStreamBuilder::new(); |
| for attr in attrs { |
| assert_eq!(attr.style, ast::AttrStyle::Outer, |
| "inner attributes should prevent cached tokens from existing"); |
| |
| let source = pprust::attribute_to_string(attr); |
| let macro_filename = FileName::macro_expansion_source_code(&source); |
| if attr.is_sugared_doc { |
| let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span)); |
| builder.push(stream); |
| continue |
| } |
| |
| // synthesize # [ $path $tokens ] manually here |
| let mut brackets = tokenstream::TokenStreamBuilder::new(); |
| |
| // For simple paths, push the identifier directly |
| if attr.path.segments.len() == 1 && attr.path.segments[0].args.is_none() { |
| let ident = attr.path.segments[0].ident; |
| let token = token::Ident(ident.name, ident.as_str().starts_with("r#")); |
| brackets.push(tokenstream::TokenTree::token(token, ident.span)); |
| |
| // ... and for more complicated paths, fall back to a reparse hack that |
| // should eventually be removed. |
| } else { |
| let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span)); |
| brackets.push(stream); |
| } |
| |
| brackets.push(attr.tokens.clone()); |
| |
| // The span we list here for `#` and for `[ ... ]` are both wrong in |
| // that it encompasses more than each token, but it hopefully is "good |
| // enough" for now at least. |
| builder.push(tokenstream::TokenTree::token(token::Pound, attr.span)); |
| let delim_span = tokenstream::DelimSpan::from_single(attr.span); |
| builder.push(tokenstream::TokenTree::Delimited( |
| delim_span, token::DelimToken::Bracket, brackets.build().into())); |
| } |
| builder.push(tokens.clone()); |
| Some(builder.build()) |
| } |