compiler/rustc_parse/src/lib.rs

   1 //! The main parser interface.
   2
   3 #![feature(array_windows)]
   4 #![feature(box_patterns)]
   5 #![feature(if_let_guard)]
   6 #![feature(iter_intersperse)]
   7 #![feature(let_chains)]
   8 #![feature(never_type)]
   9 #![feature(rustc_attrs)]
  10 #![recursion_limit = "256"]
  11
  12 #[macro_use]
  13 extern crate tracing;
  14
  15 use rustc_ast as ast;
  16 use rustc_ast::token;
  17 use rustc_ast::tokenstream::TokenStream;
  18 use rustc_ast::{AttrItem, Attribute, MetaItem};
  19 use rustc_ast_pretty::pprust;
  20 use rustc_data_structures::sync::Lrc;
  21 use rustc_errors::{Applicability, Diagnostic, FatalError, Level, PResult};
  22 use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
  23 use rustc_macros::fluent_messages;
  24 use rustc_session::parse::ParseSess;
  25 use rustc_span::{FileName, SourceFile, Span};
  26
  27 use std::path::Path;
  28
  29 pub const MACRO_ARGUMENTS: Option<&str> = Some("macro arguments");
  30
  31 #[macro_use]
  32 pub mod parser;
  33 use parser::{make_unclosed_delims_error, Parser};
  34 pub mod lexer;
  35 pub mod validate_attr;
  36
  37 mod errors;
  38
  39 fluent_messages! { "../messages.ftl" }
  40
  41 // A bunch of utility functions of the form `parse_<thing>_from_<source>`
  42 // where <thing> includes crate, expr, item, stmt, tts, and one that
  43 // uses a HOF to parse anything, and <source> includes file and
  44 // `source_str`.
  45
  46 /// A variant of 'panictry!' that works on a `Vec<Diagnostic>` instead of a single
  47 /// `DiagnosticBuilder`.
  48 macro_rules! panictry_buffer {
  49     ($handler:expr, $e:expr) => {{
  50         use rustc_errors::FatalError;
  51         use std::result::Result::{Err, Ok};
  52         match $e {
  53             Ok(e) => e,
  54             Err(errs) => {
  55                 for mut e in errs {
  56                     $handler.emit_diagnostic(&mut e);
  57                 }
  58                 FatalError.raise()
  59             }
  60         }
  61     }};
  62 }
  63
  64 pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> {
  65     let mut parser = new_parser_from_file(sess, input, None);
  66     parser.parse_crate_mod()
  67 }
  68
  69 pub fn parse_crate_attrs_from_file<'a>(
  70     input: &Path,
  71     sess: &'a ParseSess,
  72 ) -> PResult<'a, ast::AttrVec> {
  73     let mut parser = new_parser_from_file(sess, input, None);
  74     parser.parse_inner_attributes()
  75 }
  76
  77 pub fn parse_crate_from_source_str(
  78     name: FileName,
  79     source: String,
  80     sess: &ParseSess,
  81 ) -> PResult<'_, ast::Crate> {
  82     new_parser_from_source_str(sess, name, source).parse_crate_mod()
  83 }
  84
  85 pub fn parse_crate_attrs_from_source_str(
  86     name: FileName,
  87     source: String,
  88     sess: &ParseSess,
  89 ) -> PResult<'_, ast::AttrVec> {
  90     new_parser_from_source_str(sess, name, source).parse_inner_attributes()
  91 }
  92
  93 pub fn parse_stream_from_source_str(
  94     name: FileName,
  95     source: String,
  96     sess: &ParseSess,
  97     override_span: Option<Span>,
  98 ) -> TokenStream {
  99     source_file_to_stream(sess, sess.source_map().new_source_file(name, source), override_span)
 100 }
 101
 102 /// Creates a new parser from a source string.
 103 pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> {
 104     panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source))
 105 }
 106
 107 /// Creates a new parser from a source string. Returns any buffered errors from lexing the initial
 108 /// token stream.
 109 pub fn maybe_new_parser_from_source_str(
 110     sess: &ParseSess,
 111     name: FileName,
 112     source: String,
 113 ) -> Result<Parser<'_>, Vec<Diagnostic>> {
 114     maybe_source_file_to_parser(sess, sess.source_map().new_source_file(name, source))
 115 }
 116
 117 /// Creates a new parser, handling errors as appropriate if the file doesn't exist.
 118 /// If a span is given, that is used on an error as the source of the problem.
 119 pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path, sp: Option<Span>) -> Parser<'a> {
 120     source_file_to_parser(sess, file_to_source_file(sess, path, sp))
 121 }
 122
 123 /// Given a session and a `source_file`, returns a parser.
 124 fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> {
 125     panictry_buffer!(&sess.span_diagnostic, maybe_source_file_to_parser(sess, source_file))
 126 }
 127
 128 /// Given a session and a `source_file`, return a parser. Returns any buffered errors from lexing the
 129 /// initial token stream.
 130 fn maybe_source_file_to_parser(
 131     sess: &ParseSess,
 132     source_file: Lrc<SourceFile>,
 133 ) -> Result<Parser<'_>, Vec<Diagnostic>> {
 134     let end_pos = source_file.end_pos;
 135     let stream = maybe_file_to_stream(sess, source_file, None)?;
 136     let mut parser = stream_to_parser(sess, stream, None);
 137     if parser.token == token::Eof {
 138         parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt(), None);
 139     }
 140
 141     Ok(parser)
 142 }
 143
 144 // Base abstractions
 145
 146 /// Given a session and a path and an optional span (for error reporting),
 147 /// add the path to the session's source_map and return the new source_file or
 148 /// error when a file can't be read.
 149 fn try_file_to_source_file(
 150     sess: &ParseSess,
 151     path: &Path,
 152     spanopt: Option<Span>,
 153 ) -> Result<Lrc<SourceFile>, Diagnostic> {
 154     sess.source_map().load_file(path).map_err(|e| {
 155         let msg = format!("couldn't read {}: {}", path.display(), e);
 156         let mut diag = Diagnostic::new(Level::Fatal, &msg);
 157         if let Some(sp) = spanopt {
 158             diag.set_span(sp);
 159         }
 160         diag
 161     })
 162 }
 163
 164 /// Given a session and a path and an optional span (for error reporting),
 165 /// adds the path to the session's `source_map` and returns the new `source_file`.
 166 fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>) -> Lrc<SourceFile> {
 167     match try_file_to_source_file(sess, path, spanopt) {
 168         Ok(source_file) => source_file,
 169         Err(mut d) => {
 170             sess.span_diagnostic.emit_diagnostic(&mut d);
 171             FatalError.raise();
 172         }
 173     }
 174 }
 175
 176 /// Given a `source_file`, produces a sequence of token trees.
 177 pub fn source_file_to_stream(
 178     sess: &ParseSess,
 179     source_file: Lrc<SourceFile>,
 180     override_span: Option<Span>,
 181 ) -> TokenStream {
 182     panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span))
 183 }
 184
 185 /// Given a source file, produces a sequence of token trees. Returns any buffered errors from
 186 /// parsing the token stream.
 187 pub fn maybe_file_to_stream(
 188     sess: &ParseSess,
 189     source_file: Lrc<SourceFile>,
 190     override_span: Option<Span>,
 191 ) -> Result<TokenStream, Vec<Diagnostic>> {
 192     let src = source_file.src.as_ref().unwrap_or_else(|| {
 193         sess.span_diagnostic.bug(&format!(
 194             "cannot lex `source_file` without source: {}",
 195             sess.source_map().filename_for_diagnostics(&source_file.name)
 196         ));
 197     });
 198
 199     lexer::parse_token_trees(sess, src.as_str(), source_file.start_pos, override_span)
 200 }
 201
 202 /// Given a stream and the `ParseSess`, produces a parser.
 203 pub fn stream_to_parser<'a>(
 204     sess: &'a ParseSess,
 205     stream: TokenStream,
 206     subparser_name: Option<&'static str>,
 207 ) -> Parser<'a> {
 208     Parser::new(sess, stream, false, subparser_name)
 209 }
 210
 211 /// Runs the given subparser `f` on the tokens of the given `attr`'s item.
 212 pub fn parse_in<'a, T>(
 213     sess: &'a ParseSess,
 214     tts: TokenStream,
 215     name: &'static str,
 216     mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 217 ) -> PResult<'a, T> {
 218     let mut parser = Parser::new(sess, tts, false, Some(name));
 219     let result = f(&mut parser)?;
 220     if parser.token != token::Eof {
 221         parser.unexpected()?;
 222     }
 223     Ok(result)
 224 }
 225
 226 pub fn fake_token_stream_for_item(sess: &ParseSess, item: &ast::Item) -> TokenStream {
 227     let source = pprust::item_to_string(item);
 228     let filename = FileName::macro_expansion_source_code(&source);
 229     parse_stream_from_source_str(filename, source, sess, Some(item.span))
 230 }
 231
 232 pub fn fake_token_stream_for_crate(sess: &ParseSess, krate: &ast::Crate) -> TokenStream {
 233     let source = pprust::crate_to_string_for_macros(krate);
 234     let filename = FileName::macro_expansion_source_code(&source);
 235     parse_stream_from_source_str(filename, source, sess, Some(krate.spans.inner_span))
 236 }
 237
 238 pub fn parse_cfg_attr(
 239     attr: &Attribute,
 240     parse_sess: &ParseSess,
 241 ) -> Option<(MetaItem, Vec<(AttrItem, Span)>)> {
 242     match attr.get_normal_item().args {
 243         ast::AttrArgs::Delimited(ast::DelimArgs { dspan, delim, ref tokens })
 244             if !tokens.is_empty() =>
 245         {
 246             let msg = "wrong `cfg_attr` delimiters";
 247             crate::validate_attr::check_meta_bad_delim(parse_sess, dspan, delim, msg);
 248             match parse_in(parse_sess, tokens.clone(), "`cfg_attr` input", |p| p.parse_cfg_attr()) {
 249                 Ok(r) => return Some(r),
 250                 Err(mut e) => {
 251                     e.help(&format!("the valid syntax is `{}`", CFG_ATTR_GRAMMAR_HELP))
 252                         .note(CFG_ATTR_NOTE_REF)
 253                         .emit();
 254                 }
 255             }
 256         }
 257         _ => error_malformed_cfg_attr_missing(attr.span, parse_sess),
 258     }
 259     None
 260 }
 261
 262 const CFG_ATTR_GRAMMAR_HELP: &str = "#[cfg_attr(condition, attribute, other_attribute, ...)]";
 263 const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
 264     <https://doc.rust-lang.org/reference/conditional-compilation.html\
 265     #the-cfg_attr-attribute>";
 266
 267 fn error_malformed_cfg_attr_missing(span: Span, parse_sess: &ParseSess) {
 268     parse_sess
 269         .span_diagnostic
 270         .struct_span_err(span, "malformed `cfg_attr` attribute input")
 271         .span_suggestion(
 272             span,
 273             "missing condition and attribute",
 274             CFG_ATTR_GRAMMAR_HELP,
 275             Applicability::HasPlaceholders,
 276         )
 277         .note(CFG_ATTR_NOTE_REF)
 278         .emit();
 279 }