compiler/rustc_errors/src/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 rustc_span::source_map::{FilePathMapping, SourceMap};
  13
  14 use crate::emitter::{Emitter, HumanReadableErrorType};
  15 use crate::registry::Registry;
  16 use crate::translation::Translate;
  17 use crate::DiagnosticId;
  18 use crate::{
  19     CodeSuggestion, FluentBundle, LazyFallbackBundle, MultiSpan, SpanLabel, SubDiagnostic,
  20 };
  21 use rustc_lint_defs::Applicability;
  22
  23 use rustc_data_structures::sync::Lrc;
  24 use rustc_error_messages::FluentArgs;
  25 use rustc_span::hygiene::ExpnData;
  26 use rustc_span::Span;
  27 use std::io::{self, Write};
  28 use std::path::Path;
  29 use std::sync::{Arc, Mutex};
  30 use std::vec;
  31
  32 use serde::Serialize;
  33
  34 #[cfg(test)]
  35 mod tests;
  36
  37 pub struct JsonEmitter {
  38     dst: Box<dyn Write + Send>,
  39     registry: Option<Registry>,
  40     sm: Lrc<SourceMap>,
  41     fluent_bundle: Option<Lrc<FluentBundle>>,
  42     fallback_bundle: LazyFallbackBundle,
  43     pretty: bool,
  44     ui_testing: bool,
  45     json_rendered: HumanReadableErrorType,
  46     diagnostic_width: Option<usize>,
  47     macro_backtrace: bool,
  48 }
  49
  50 impl JsonEmitter {
  51     pub fn stderr(
  52         registry: Option<Registry>,
  53         source_map: Lrc<SourceMap>,
  54         fluent_bundle: Option<Lrc<FluentBundle>>,
  55         fallback_bundle: LazyFallbackBundle,
  56         pretty: bool,
  57         json_rendered: HumanReadableErrorType,
  58         diagnostic_width: Option<usize>,
  59         macro_backtrace: bool,
  60     ) -> JsonEmitter {
  61         JsonEmitter {
  62             dst: Box::new(io::BufWriter::new(io::stderr())),
  63             registry,
  64             sm: source_map,
  65             fluent_bundle,
  66             fallback_bundle,
  67             pretty,
  68             ui_testing: false,
  69             json_rendered,
  70             diagnostic_width,
  71             macro_backtrace,
  72         }
  73     }
  74
  75     pub fn basic(
  76         pretty: bool,
  77         json_rendered: HumanReadableErrorType,
  78         fluent_bundle: Option<Lrc<FluentBundle>>,
  79         fallback_bundle: LazyFallbackBundle,
  80         diagnostic_width: Option<usize>,
  81         macro_backtrace: bool,
  82     ) -> JsonEmitter {
  83         let file_path_mapping = FilePathMapping::empty();
  84         JsonEmitter::stderr(
  85             None,
  86             Lrc::new(SourceMap::new(file_path_mapping)),
  87             fluent_bundle,
  88             fallback_bundle,
  89             pretty,
  90             json_rendered,
  91             diagnostic_width,
  92             macro_backtrace,
  93         )
  94     }
  95
  96     pub fn new(
  97         dst: Box<dyn Write + Send>,
  98         registry: Option<Registry>,
  99         source_map: Lrc<SourceMap>,
 100         fluent_bundle: Option<Lrc<FluentBundle>>,
 101         fallback_bundle: LazyFallbackBundle,
 102         pretty: bool,
 103         json_rendered: HumanReadableErrorType,
 104         diagnostic_width: Option<usize>,
 105         macro_backtrace: bool,
 106     ) -> JsonEmitter {
 107         JsonEmitter {
 108             dst,
 109             registry,
 110             sm: source_map,
 111             fluent_bundle,
 112             fallback_bundle,
 113             pretty,
 114             ui_testing: false,
 115             json_rendered,
 116             diagnostic_width,
 117             macro_backtrace,
 118         }
 119     }
 120
 121     pub fn ui_testing(self, ui_testing: bool) -> Self {
 122         Self { ui_testing, ..self }
 123     }
 124 }
 125
 126 impl Translate for JsonEmitter {
 127     fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
 128         self.fluent_bundle.as_ref()
 129     }
 130
 131     fn fallback_fluent_bundle(&self) -> &FluentBundle {
 132         &**self.fallback_bundle
 133     }
 134 }
 135
 136 impl Emitter for JsonEmitter {
 137     fn emit_diagnostic(&mut self, diag: &crate::Diagnostic) {
 138         let data = Diagnostic::from_errors_diagnostic(diag, self);
 139         let result = if self.pretty {
 140             writeln!(&mut self.dst, "{}", serde_json::to_string_pretty(&data).unwrap())
 141         } else {
 142             writeln!(&mut self.dst, "{}", serde_json::to_string(&data).unwrap())
 143         }
 144         .and_then(|_| self.dst.flush());
 145         if let Err(e) = result {
 146             panic!("failed to print diagnostics: {:?}", e);
 147         }
 148     }
 149
 150     fn emit_artifact_notification(&mut self, path: &Path, artifact_type: &str) {
 151         let data = ArtifactNotification { artifact: path, emit: artifact_type };
 152         let result = if self.pretty {
 153             writeln!(&mut self.dst, "{}", serde_json::to_string_pretty(&data).unwrap())
 154         } else {
 155             writeln!(&mut self.dst, "{}", serde_json::to_string(&data).unwrap())
 156         }
 157         .and_then(|_| self.dst.flush());
 158         if let Err(e) = result {
 159             panic!("failed to print notification: {:?}", e);
 160         }
 161     }
 162
 163     fn emit_future_breakage_report(&mut self, diags: Vec<crate::Diagnostic>) {
 164         let data: Vec<FutureBreakageItem> = diags
 165             .into_iter()
 166             .map(|mut diag| {
 167                 if diag.level == crate::Level::Allow {
 168                     diag.level = crate::Level::Warning(None);
 169                 }
 170                 FutureBreakageItem { diagnostic: Diagnostic::from_errors_diagnostic(&diag, self) }
 171             })
 172             .collect();
 173         let report = FutureIncompatReport { future_incompat_report: data };
 174         let result = if self.pretty {
 175             writeln!(&mut self.dst, "{}", serde_json::to_string_pretty(&report).unwrap())
 176         } else {
 177             writeln!(&mut self.dst, "{}", serde_json::to_string(&report).unwrap())
 178         }
 179         .and_then(|_| self.dst.flush());
 180         if let Err(e) = result {
 181             panic!("failed to print future breakage report: {:?}", e);
 182         }
 183     }
 184
 185     fn emit_unused_externs(&mut self, lint_level: rustc_lint_defs::Level, unused_externs: &[&str]) {
 186         let lint_level = lint_level.as_str();
 187         let data = UnusedExterns { lint_level, unused_extern_names: unused_externs };
 188         let result = if self.pretty {
 189             writeln!(&mut self.dst, "{}", serde_json::to_string_pretty(&data).unwrap())
 190         } else {
 191             writeln!(&mut self.dst, "{}", serde_json::to_string(&data).unwrap())
 192         }
 193         .and_then(|_| self.dst.flush());
 194         if let Err(e) = result {
 195             panic!("failed to print unused externs: {:?}", e);
 196         }
 197     }
 198
 199     fn source_map(&self) -> Option<&Lrc<SourceMap>> {
 200         Some(&self.sm)
 201     }
 202
 203     fn should_show_explain(&self) -> bool {
 204         !matches!(self.json_rendered, HumanReadableErrorType::Short(_))
 205     }
 206 }
 207
 208 // The following data types are provided just for serialisation.
 209
 210 #[derive(Serialize)]
 211 struct Diagnostic {
 212     /// The primary error message.
 213     message: String,
 214     code: Option<DiagnosticCode>,
 215     /// "error: internal compiler error", "error", "warning", "note", "help".
 216     level: &'static str,
 217     spans: Vec<DiagnosticSpan>,
 218     /// Associated diagnostic messages.
 219     children: Vec<Diagnostic>,
 220     /// The message as rustc would render it.
 221     rendered: Option<String>,
 222 }
 223
 224 #[derive(Serialize)]
 225 struct DiagnosticSpan {
 226     file_name: String,
 227     byte_start: u32,
 228     byte_end: u32,
 229     /// 1-based.
 230     line_start: usize,
 231     line_end: usize,
 232     /// 1-based, character offset.
 233     column_start: usize,
 234     column_end: usize,
 235     /// Is this a "primary" span -- meaning the point, or one of the points,
 236     /// where the error occurred?
 237     is_primary: bool,
 238     /// Source text from the start of line_start to the end of line_end.
 239     text: Vec<DiagnosticSpanLine>,
 240     /// Label that should be placed at this location (if any)
 241     label: Option<String>,
 242     /// If we are suggesting a replacement, this will contain text
 243     /// that should be sliced in atop this span.
 244     suggested_replacement: Option<String>,
 245     /// If the suggestion is approximate
 246     suggestion_applicability: Option<Applicability>,
 247     /// Macro invocations that created the code at this span, if any.
 248     expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
 249 }
 250
 251 #[derive(Serialize)]
 252 struct DiagnosticSpanLine {
 253     text: String,
 254
 255     /// 1-based, character offset in self.text.
 256     highlight_start: usize,
 257
 258     highlight_end: usize,
 259 }
 260
 261 #[derive(Serialize)]
 262 struct DiagnosticSpanMacroExpansion {
 263     /// span where macro was applied to generate this code; note that
 264     /// this may itself derive from a macro (if
 265     /// `span.expansion.is_some()`)
 266     span: DiagnosticSpan,
 267
 268     /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
 269     macro_decl_name: String,
 270
 271     /// span where macro was defined (if known)
 272     def_site_span: DiagnosticSpan,
 273 }
 274
 275 #[derive(Serialize)]
 276 struct DiagnosticCode {
 277     /// The code itself.
 278     code: String,
 279     /// An explanation for the code.
 280     explanation: Option<&'static str>,
 281 }
 282
 283 #[derive(Serialize)]
 284 struct ArtifactNotification<'a> {
 285     /// The path of the artifact.
 286     artifact: &'a Path,
 287     /// What kind of artifact we're emitting.
 288     emit: &'a str,
 289 }
 290
 291 #[derive(Serialize)]
 292 struct FutureBreakageItem {
 293     diagnostic: Diagnostic,
 294 }
 295
 296 #[derive(Serialize)]
 297 struct FutureIncompatReport {
 298     future_incompat_report: Vec<FutureBreakageItem>,
 299 }
 300
 301 // NOTE: Keep this in sync with the equivalent structs in rustdoc's
 302 // doctest component (as well as cargo).
 303 // We could unify this struct the one in rustdoc but they have different
 304 // ownership semantics, so doing so would create wasteful allocations.
 305 #[derive(Serialize)]
 306 struct UnusedExterns<'a, 'b, 'c> {
 307     /// The severity level of the unused dependencies lint
 308     lint_level: &'a str,
 309     /// List of unused externs by their names.
 310     unused_extern_names: &'b [&'c str],
 311 }
 312
 313 impl Diagnostic {
 314     fn from_errors_diagnostic(diag: &crate::Diagnostic, je: &JsonEmitter) -> Diagnostic {
 315         let args = je.to_fluent_args(diag.args());
 316         let sugg = diag.suggestions.iter().flatten().map(|sugg| {
 317             let translated_message = je.translate_message(&sugg.msg, &args);
 318             Diagnostic {
 319                 message: translated_message.to_string(),
 320                 code: None,
 321                 level: "help",
 322                 spans: DiagnosticSpan::from_suggestion(sugg, &args, je),
 323                 children: vec![],
 324                 rendered: None,
 325             }
 326         });
 327
 328         // generate regular command line output and store it in the json
 329
 330         // A threadsafe buffer for writing.
 331         #[derive(Default, Clone)]
 332         struct BufWriter(Arc<Mutex<Vec<u8>>>);
 333
 334         impl Write for BufWriter {
 335             fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
 336                 self.0.lock().unwrap().write(buf)
 337             }
 338             fn flush(&mut self) -> io::Result<()> {
 339                 self.0.lock().unwrap().flush()
 340             }
 341         }
 342         let buf = BufWriter::default();
 343         let output = buf.clone();
 344         je.json_rendered
 345             .new_emitter(
 346                 Box::new(buf),
 347                 Some(je.sm.clone()),
 348                 je.fluent_bundle.clone(),
 349                 je.fallback_bundle.clone(),
 350                 false,
 351                 je.diagnostic_width,
 352                 je.macro_backtrace,
 353             )
 354             .ui_testing(je.ui_testing)
 355             .emit_diagnostic(diag);
 356         let output = Arc::try_unwrap(output.0).unwrap().into_inner().unwrap();
 357         let output = String::from_utf8(output).unwrap();
 358
 359         let translated_message = je.translate_messages(&diag.message, &args);
 360         Diagnostic {
 361             message: translated_message.to_string(),
 362             code: DiagnosticCode::map_opt_string(diag.code.clone(), je),
 363             level: diag.level.to_str(),
 364             spans: DiagnosticSpan::from_multispan(&diag.span, &args, je),
 365             children: diag
 366                 .children
 367                 .iter()
 368                 .map(|c| Diagnostic::from_sub_diagnostic(c, &args, je))
 369                 .chain(sugg)
 370                 .collect(),
 371             rendered: Some(output),
 372         }
 373     }
 374
 375     fn from_sub_diagnostic(
 376         diag: &SubDiagnostic,
 377         args: &FluentArgs<'_>,
 378         je: &JsonEmitter,
 379     ) -> Diagnostic {
 380         let translated_message = je.translate_messages(&diag.message, args);
 381         Diagnostic {
 382             message: translated_message.to_string(),
 383             code: None,
 384             level: diag.level.to_str(),
 385             spans: diag
 386                 .render_span
 387                 .as_ref()
 388                 .map(|sp| DiagnosticSpan::from_multispan(sp, args, je))
 389                 .unwrap_or_else(|| DiagnosticSpan::from_multispan(&diag.span, args, je)),
 390             children: vec![],
 391             rendered: None,
 392         }
 393     }
 394 }
 395
 396 impl DiagnosticSpan {
 397     fn from_span_label(
 398         span: SpanLabel,
 399         suggestion: Option<(&String, Applicability)>,
 400         args: &FluentArgs<'_>,
 401         je: &JsonEmitter,
 402     ) -> DiagnosticSpan {
 403         Self::from_span_etc(
 404             span.span,
 405             span.is_primary,
 406             span.label.as_ref().map(|m| je.translate_message(m, args)).map(|m| m.to_string()),
 407             suggestion,
 408             je,
 409         )
 410     }
 411
 412     fn from_span_etc(
 413         span: Span,
 414         is_primary: bool,
 415         label: Option<String>,
 416         suggestion: Option<(&String, Applicability)>,
 417         je: &JsonEmitter,
 418     ) -> DiagnosticSpan {
 419         // obtain the full backtrace from the `macro_backtrace`
 420         // helper; in some ways, it'd be better to expand the
 421         // backtrace ourselves, but the `macro_backtrace` helper makes
 422         // some decision, such as dropping some frames, and I don't
 423         // want to duplicate that logic here.
 424         let backtrace = span.macro_backtrace();
 425         DiagnosticSpan::from_span_full(span, is_primary, label, suggestion, backtrace, je)
 426     }
 427
 428     fn from_span_full(
 429         span: Span,
 430         is_primary: bool,
 431         label: Option<String>,
 432         suggestion: Option<(&String, Applicability)>,
 433         mut backtrace: impl Iterator<Item = ExpnData>,
 434         je: &JsonEmitter,
 435     ) -> DiagnosticSpan {
 436         let start = je.sm.lookup_char_pos(span.lo());
 437         let end = je.sm.lookup_char_pos(span.hi());
 438         let backtrace_step = backtrace.next().map(|bt| {
 439             let call_site = Self::from_span_full(bt.call_site, false, None, None, backtrace, je);
 440             let def_site_span = Self::from_span_full(
 441                 je.sm.guess_head_span(bt.def_site),
 442                 false,
 443                 None,
 444                 None,
 445                 [].into_iter(),
 446                 je,
 447             );
 448             Box::new(DiagnosticSpanMacroExpansion {
 449                 span: call_site,
 450                 macro_decl_name: bt.kind.descr(),
 451                 def_site_span,
 452             })
 453         });
 454
 455         DiagnosticSpan {
 456             file_name: je.sm.filename_for_diagnostics(&start.file.name).to_string(),
 457             byte_start: start.file.original_relative_byte_pos(span.lo()).0,
 458             byte_end: start.file.original_relative_byte_pos(span.hi()).0,
 459             line_start: start.line,
 460             line_end: end.line,
 461             column_start: start.col.0 + 1,
 462             column_end: end.col.0 + 1,
 463             is_primary,
 464             text: DiagnosticSpanLine::from_span(span, je),
 465             suggested_replacement: suggestion.map(|x| x.0.clone()),
 466             suggestion_applicability: suggestion.map(|x| x.1),
 467             expansion: backtrace_step,
 468             label,
 469         }
 470     }
 471
 472     fn from_multispan(
 473         msp: &MultiSpan,
 474         args: &FluentArgs<'_>,
 475         je: &JsonEmitter,
 476     ) -> Vec<DiagnosticSpan> {
 477         msp.span_labels()
 478             .into_iter()
 479             .map(|span_str| Self::from_span_label(span_str, None, args, je))
 480             .collect()
 481     }
 482
 483     fn from_suggestion(
 484         suggestion: &CodeSuggestion,
 485         args: &FluentArgs<'_>,
 486         je: &JsonEmitter,
 487     ) -> Vec<DiagnosticSpan> {
 488         suggestion
 489             .substitutions
 490             .iter()
 491             .flat_map(|substitution| {
 492                 substitution.parts.iter().map(move |suggestion_inner| {
 493                     let span_label =
 494                         SpanLabel { span: suggestion_inner.span, is_primary: true, label: None };
 495                     DiagnosticSpan::from_span_label(
 496                         span_label,
 497                         Some((&suggestion_inner.snippet, suggestion.applicability)),
 498                         args,
 499                         je,
 500                     )
 501                 })
 502             })
 503             .collect()
 504     }
 505 }
 506
 507 impl DiagnosticSpanLine {
 508     fn line_from_source_file(
 509         sf: &rustc_span::SourceFile,
 510         index: usize,
 511         h_start: usize,
 512         h_end: usize,
 513     ) -> DiagnosticSpanLine {
 514         DiagnosticSpanLine {
 515             text: sf.get_line(index).map_or_else(String::new, |l| l.into_owned()),
 516             highlight_start: h_start,
 517             highlight_end: h_end,
 518         }
 519     }
 520
 521     /// Creates a list of DiagnosticSpanLines from span - each line with any part
 522     /// of `span` gets a DiagnosticSpanLine, with the highlight indicating the
 523     /// `span` within the line.
 524     fn from_span(span: Span, je: &JsonEmitter) -> Vec<DiagnosticSpanLine> {
 525         je.sm
 526             .span_to_lines(span)
 527             .map(|lines| {
 528                 // We can't get any lines if the source is unavailable.
 529                 if !je.sm.ensure_source_file_source_present(lines.file.clone()) {
 530                     return vec![];
 531                 }
 532
 533                 let sf = &*lines.file;
 534                 lines
 535                     .lines
 536                     .iter()
 537                     .map(|line| {
 538                         DiagnosticSpanLine::line_from_source_file(
 539                             sf,
 540                             line.line_index,
 541                             line.start_col.0 + 1,
 542                             line.end_col.0 + 1,
 543                         )
 544                     })
 545                     .collect()
 546             })
 547             .unwrap_or_else(|_| vec![])
 548     }
 549 }
 550
 551 impl DiagnosticCode {
 552     fn map_opt_string(s: Option<DiagnosticId>, je: &JsonEmitter) -> Option<DiagnosticCode> {
 553         s.map(|s| {
 554             let s = match s {
 555                 DiagnosticId::Error(s) => s,
 556                 DiagnosticId::Lint { name, .. } => name,
 557             };
 558             let je_result =
 559                 je.registry.as_ref().map(|registry| registry.try_find_description(&s)).unwrap();
 560
 561             DiagnosticCode { code: s, explanation: je_result.unwrap_or(None) }
 562         })
 563     }
 564 }