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