src/libsyntax/json.rs

   1 //! A JSON emitter for errors.
   2 //!
   3 //! This works by converting errors to a simplified structural format (see the
   4 //! structs at the start of the file) and then serializing them. These should
   5 //! contain as much information about the error as possible.
   6 //!
   7 //! The format of the JSON output should be considered *unstable*. For now the
   8 //! structs at the end of this file (Diagnostic*) specify the error format.
   9
  10 // FIXME: spec the JSON output properly.
  11
  12 use crate::source_map::{SourceMap, FilePathMapping};
  13
  14 use errors::registry::Registry;
  15 use errors::{SubDiagnostic, CodeSuggestion, SourceMapper};
  16 use errors::{DiagnosticId, Applicability};
  17 use errors::emitter::{Emitter, HumanReadableErrorType};
  18
  19 use syntax_pos::{MacroBacktrace, Span, SpanLabel, MultiSpan};
  20 use rustc_data_structures::sync::{self, Lrc};
  21 use std::io::{self, Write};
  22 use std::path::Path;
  23 use std::vec;
  24 use std::sync::{Arc, Mutex};
  25
  26 use rustc_serialize::json::{as_json, as_pretty_json};
  27
  28 #[cfg(test)]
  29 mod tests;
  30
  31 pub struct JsonEmitter {
  32     dst: Box<dyn Write + Send>,
  33     registry: Option<Registry>,
  34     sm: Lrc<dyn SourceMapper + sync::Send + sync::Sync>,
  35     pretty: bool,
  36     ui_testing: bool,
  37     json_rendered: HumanReadableErrorType,
  38     external_macro_backtrace: bool,
  39 }
  40
  41 impl JsonEmitter {
  42     pub fn stderr(
  43         registry: Option<Registry>,
  44         source_map: Lrc<SourceMap>,
  45         pretty: bool,
  46         json_rendered: HumanReadableErrorType,
  47         external_macro_backtrace: bool,
  48     ) -> JsonEmitter {
  49         JsonEmitter {
  50             dst: Box::new(io::stderr()),
  51             registry,
  52             sm: source_map,
  53             pretty,
  54             ui_testing: false,
  55             json_rendered,
  56             external_macro_backtrace,
  57         }
  58     }
  59
  60     pub fn basic(
  61         pretty: bool,
  62         json_rendered: HumanReadableErrorType,
  63         external_macro_backtrace: bool,
  64     ) -> JsonEmitter {
  65         let file_path_mapping = FilePathMapping::empty();
  66         JsonEmitter::stderr(None, Lrc::new(SourceMap::new(file_path_mapping)),
  67                             pretty, json_rendered, external_macro_backtrace)
  68     }
  69
  70     pub fn new(
  71         dst: Box<dyn Write + Send>,
  72         registry: Option<Registry>,
  73         source_map: Lrc<SourceMap>,
  74         pretty: bool,
  75         json_rendered: HumanReadableErrorType,
  76         external_macro_backtrace: bool,
  77     ) -> JsonEmitter {
  78         JsonEmitter {
  79             dst,
  80             registry,
  81             sm: source_map,
  82             pretty,
  83             ui_testing: false,
  84             json_rendered,
  85             external_macro_backtrace,
  86         }
  87     }
  88
  89     pub fn ui_testing(self, ui_testing: bool) -> Self {
  90         Self { ui_testing, ..self }
  91     }
  92 }
  93
  94 impl Emitter for JsonEmitter {
  95     fn emit_diagnostic(&mut self, db: &errors::Diagnostic) {
  96         let data = Diagnostic::from_errors_diagnostic(db, self);
  97         let result = if self.pretty {
  98             writeln!(&mut self.dst, "{}", as_pretty_json(&data))
  99         } else {
 100             writeln!(&mut self.dst, "{}", as_json(&data))
 101         };
 102         if let Err(e) = result {
 103             panic!("failed to print diagnostics: {:?}", e);
 104         }
 105     }
 106
 107     fn emit_artifact_notification(&mut self, path: &Path, artifact_type: &str) {
 108         let data = ArtifactNotification { artifact: path, emit: artifact_type };
 109         let result = if self.pretty {
 110             writeln!(&mut self.dst, "{}", as_pretty_json(&data))
 111         } else {
 112             writeln!(&mut self.dst, "{}", as_json(&data))
 113         };
 114         if let Err(e) = result {
 115             panic!("failed to print notification: {:?}", e);
 116         }
 117     }
 118
 119     fn should_show_explain(&self) -> bool {
 120         match self.json_rendered {
 121             HumanReadableErrorType::Short(_) => false,
 122             _ => true,
 123         }
 124     }
 125 }
 126
 127 // The following data types are provided just for serialisation.
 128
 129 #[derive(RustcEncodable)]
 130 struct Diagnostic {
 131     /// The primary error message.
 132     message: String,
 133     code: Option<DiagnosticCode>,
 134     /// "error: internal compiler error", "error", "warning", "note", "help".
 135     level: &'static str,
 136     spans: Vec<DiagnosticSpan>,
 137     /// Associated diagnostic messages.
 138     children: Vec<Diagnostic>,
 139     /// The message as rustc would render it.
 140     rendered: Option<String>,
 141 }
 142
 143 #[derive(RustcEncodable)]
 144 struct DiagnosticSpan {
 145     file_name: String,
 146     byte_start: u32,
 147     byte_end: u32,
 148     /// 1-based.
 149     line_start: usize,
 150     line_end: usize,
 151     /// 1-based, character offset.
 152     column_start: usize,
 153     column_end: usize,
 154     /// Is this a "primary" span -- meaning the point, or one of the points,
 155     /// where the error occurred?
 156     is_primary: bool,
 157     /// Source text from the start of line_start to the end of line_end.
 158     text: Vec<DiagnosticSpanLine>,
 159     /// Label that should be placed at this location (if any)
 160     label: Option<String>,
 161     /// If we are suggesting a replacement, this will contain text
 162     /// that should be sliced in atop this span.
 163     suggested_replacement: Option<String>,
 164     /// If the suggestion is approximate
 165     suggestion_applicability: Option<Applicability>,
 166     /// Macro invocations that created the code at this span, if any.
 167     expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
 168 }
 169
 170 #[derive(RustcEncodable)]
 171 struct DiagnosticSpanLine {
 172     text: String,
 173
 174     /// 1-based, character offset in self.text.
 175     highlight_start: usize,
 176
 177     highlight_end: usize,
 178 }
 179
 180 #[derive(RustcEncodable)]
 181 struct DiagnosticSpanMacroExpansion {
 182     /// span where macro was applied to generate this code; note that
 183     /// this may itself derive from a macro (if
 184     /// `span.expansion.is_some()`)
 185     span: DiagnosticSpan,
 186
 187     /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
 188     macro_decl_name: String,
 189
 190     /// span where macro was defined (if known)
 191     def_site_span: DiagnosticSpan,
 192 }
 193
 194 #[derive(RustcEncodable)]
 195 struct DiagnosticCode {
 196     /// The code itself.
 197     code: String,
 198     /// An explanation for the code.
 199     explanation: Option<&'static str>,
 200 }
 201
 202 #[derive(RustcEncodable)]
 203 struct ArtifactNotification<'a> {
 204     /// The path of the artifact.
 205     artifact: &'a Path,
 206     /// What kind of artifact we're emitting.
 207     emit: &'a str,
 208 }
 209
 210 impl Diagnostic {
 211     fn from_errors_diagnostic(db: &errors::Diagnostic,
 212                                je: &JsonEmitter)
 213                                -> Diagnostic {
 214         let sugg = db.suggestions.iter().map(|sugg| {
 215             Diagnostic {
 216                 message: sugg.msg.clone(),
 217                 code: None,
 218                 level: "help",
 219                 spans: DiagnosticSpan::from_suggestion(sugg, je),
 220                 children: vec![],
 221                 rendered: None,
 222             }
 223         });
 224
 225         // generate regular command line output and store it in the json
 226
 227         // A threadsafe buffer for writing.
 228         #[derive(Default, Clone)]
 229         struct BufWriter(Arc<Mutex<Vec<u8>>>);
 230
 231         impl Write for BufWriter {
 232             fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
 233                 self.0.lock().unwrap().write(buf)
 234             }
 235             fn flush(&mut self) -> io::Result<()> {
 236                 self.0.lock().unwrap().flush()
 237             }
 238         }
 239         let buf = BufWriter::default();
 240         let output = buf.clone();
 241         je.json_rendered.new_emitter(
 242             Box::new(buf), Some(je.sm.clone()), false, None, je.external_macro_backtrace
 243         ).ui_testing(je.ui_testing).emit_diagnostic(db);
 244         let output = Arc::try_unwrap(output.0).unwrap().into_inner().unwrap();
 245         let output = String::from_utf8(output).unwrap();
 246
 247         Diagnostic {
 248             message: db.message(),
 249             code: DiagnosticCode::map_opt_string(db.code.clone(), je),
 250             level: db.level.to_str(),
 251             spans: DiagnosticSpan::from_multispan(&db.span, je),
 252             children: db.children.iter().map(|c| {
 253                 Diagnostic::from_sub_diagnostic(c, je)
 254             }).chain(sugg).collect(),
 255             rendered: Some(output),
 256         }
 257     }
 258
 259     fn from_sub_diagnostic(db: &SubDiagnostic, je: &JsonEmitter) -> Diagnostic {
 260         Diagnostic {
 261             message: db.message(),
 262             code: None,
 263             level: db.level.to_str(),
 264             spans: db.render_span.as_ref()
 265                      .map(|sp| DiagnosticSpan::from_multispan(sp, je))
 266                      .unwrap_or_else(|| DiagnosticSpan::from_multispan(&db.span, je)),
 267             children: vec![],
 268             rendered: None,
 269         }
 270     }
 271 }
 272
 273 impl DiagnosticSpan {
 274     fn from_span_label(span: SpanLabel,
 275                        suggestion: Option<(&String, Applicability)>,
 276                        je: &JsonEmitter)
 277                        -> DiagnosticSpan {
 278         Self::from_span_etc(span.span,
 279                             span.is_primary,
 280                             span.label,
 281                             suggestion,
 282                             je)
 283     }
 284
 285     fn from_span_etc(span: Span,
 286                      is_primary: bool,
 287                      label: Option<String>,
 288                      suggestion: Option<(&String, Applicability)>,
 289                      je: &JsonEmitter)
 290                      -> DiagnosticSpan {
 291         // obtain the full backtrace from the `macro_backtrace`
 292         // helper; in some ways, it'd be better to expand the
 293         // backtrace ourselves, but the `macro_backtrace` helper makes
 294         // some decision, such as dropping some frames, and I don't
 295         // want to duplicate that logic here.
 296         let backtrace = span.macro_backtrace().into_iter();
 297         DiagnosticSpan::from_span_full(span,
 298                                        is_primary,
 299                                        label,
 300                                        suggestion,
 301                                        backtrace,
 302                                        je)
 303     }
 304
 305     fn from_span_full(span: Span,
 306                       is_primary: bool,
 307                       label: Option<String>,
 308                       suggestion: Option<(&String, Applicability)>,
 309                       mut backtrace: vec::IntoIter<MacroBacktrace>,
 310                       je: &JsonEmitter)
 311                       -> DiagnosticSpan {
 312         let start = je.sm.lookup_char_pos(span.lo());
 313         let end = je.sm.lookup_char_pos(span.hi());
 314         let backtrace_step = backtrace.next().map(|bt| {
 315             let call_site =
 316                 Self::from_span_full(bt.call_site,
 317                                      false,
 318                                      None,
 319                                      None,
 320                                      backtrace,
 321                                      je);
 322             let def_site_span =
 323                 Self::from_span_full(bt.def_site_span,
 324                                      false,
 325                                      None,
 326                                      None,
 327                                      vec![].into_iter(),
 328                                      je);
 329             Box::new(DiagnosticSpanMacroExpansion {
 330                 span: call_site,
 331                 macro_decl_name: bt.macro_decl_name,
 332                 def_site_span,
 333             })
 334         });
 335
 336         DiagnosticSpan {
 337             file_name: start.file.name.to_string(),
 338             byte_start: start.file.original_relative_byte_pos(span.lo()).0,
 339             byte_end: start.file.original_relative_byte_pos(span.hi()).0,
 340             line_start: start.line,
 341             line_end: end.line,
 342             column_start: start.col.0 + 1,
 343             column_end: end.col.0 + 1,
 344             is_primary,
 345             text: DiagnosticSpanLine::from_span(span, je),
 346             suggested_replacement: suggestion.map(|x| x.0.clone()),
 347             suggestion_applicability: suggestion.map(|x| x.1),
 348             expansion: backtrace_step,
 349             label,
 350         }
 351     }
 352
 353     fn from_multispan(msp: &MultiSpan, je: &JsonEmitter) -> Vec<DiagnosticSpan> {
 354         msp.span_labels()
 355            .into_iter()
 356            .map(|span_str| Self::from_span_label(span_str, None, je))
 357            .collect()
 358     }
 359
 360     fn from_suggestion(suggestion: &CodeSuggestion, je: &JsonEmitter)
 361                        -> Vec<DiagnosticSpan> {
 362         suggestion.substitutions
 363                       .iter()
 364                       .flat_map(|substitution| {
 365                           substitution.parts.iter().map(move |suggestion_inner| {
 366                               let span_label = SpanLabel {
 367                                   span: suggestion_inner.span,
 368                                   is_primary: true,
 369                                   label: None,
 370                               };
 371                               DiagnosticSpan::from_span_label(span_label,
 372                                                               Some((&suggestion_inner.snippet,
 373                                                                    suggestion.applicability)),
 374                                                               je)
 375                           })
 376                       })
 377                       .collect()
 378     }
 379 }
 380
 381 impl DiagnosticSpanLine {
 382     fn line_from_source_file(fm: &syntax_pos::SourceFile,
 383                          index: usize,
 384                          h_start: usize,
 385                          h_end: usize)
 386                          -> DiagnosticSpanLine {
 387         DiagnosticSpanLine {
 388             text: fm.get_line(index).map_or(String::new(), |l| l.into_owned()),
 389             highlight_start: h_start,
 390             highlight_end: h_end,
 391         }
 392     }
 393
 394     /// Creates a list of DiagnosticSpanLines from span - each line with any part
 395     /// of `span` gets a DiagnosticSpanLine, with the highlight indicating the
 396     /// `span` within the line.
 397     fn from_span(span: Span, je: &JsonEmitter) -> Vec<DiagnosticSpanLine> {
 398         je.sm.span_to_lines(span)
 399             .map(|lines| {
 400                 let fm = &*lines.file;
 401                 lines.lines
 402                     .iter()
 403                     .map(|line| DiagnosticSpanLine::line_from_source_file(
 404                         fm,
 405                         line.line_index,
 406                         line.start_col.0 + 1,
 407                         line.end_col.0 + 1,
 408                     )).collect()
 409             }).unwrap_or_else(|_| vec![])
 410     }
 411 }
 412
 413 impl DiagnosticCode {
 414     fn map_opt_string(s: Option<DiagnosticId>, je: &JsonEmitter) -> Option<DiagnosticCode> {
 415         s.map(|s| {
 416             let s = match s {
 417                 DiagnosticId::Error(s) => s,
 418                 DiagnosticId::Lint(s) => s,
 419             };
 420             let explanation = je.registry
 421                                 .as_ref()
 422                                 .and_then(|registry| registry.find_description(&s));
 423
 424             DiagnosticCode {
 425                 code: s,
 426                 explanation,
 427             }
 428         })
 429     }
 430 }