compiler/rustc_errors/src/emitter.rs

   1 //! The current rustc diagnostics emitter.
   2 //!
   3 //! An `Emitter` takes care of generating the output from a `DiagnosticBuilder` struct.
   4 //!
   5 //! There are various `Emitter` implementations that generate different output formats such as
   6 //! JSON and human readable output.
   7 //!
   8 //! The output types are defined in `rustc_session::config::ErrorOutputType`.
   9
  10 use Destination::*;
  11
  12 use rustc_span::source_map::SourceMap;
  13 use rustc_span::{FileLines, SourceFile, Span};
  14
  15 use crate::snippet::{Annotation, AnnotationType, Line, MultilineAnnotation, Style, StyledString};
  16 use crate::styled_buffer::StyledBuffer;
  17 use crate::translation::{to_fluent_args, Translate};
  18 use crate::{
  19     diagnostic::DiagnosticLocation, CodeSuggestion, Diagnostic, DiagnosticId, DiagnosticMessage,
  20     FluentBundle, Handler, LazyFallbackBundle, Level, MultiSpan, SubDiagnostic,
  21     SubstitutionHighlight, SuggestionStyle,
  22 };
  23 use rustc_lint_defs::pluralize;
  24
  25 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
  26 use rustc_data_structures::sync::Lrc;
  27 use rustc_error_messages::FluentArgs;
  28 use rustc_span::hygiene::{ExpnKind, MacroKind};
  29 use std::borrow::Cow;
  30 use std::cmp::{max, min, Reverse};
  31 use std::io;
  32 use std::io::prelude::*;
  33 use std::iter;
  34 use std::path::Path;
  35 use termcolor::{Ansi, BufferWriter, ColorChoice, ColorSpec, StandardStream};
  36 use termcolor::{Buffer, Color, WriteColor};
  37
  38 /// Default column width, used in tests and when terminal dimensions cannot be determined.
  39 const DEFAULT_COLUMN_WIDTH: usize = 140;
  40
  41 /// Describes the way the content of the `rendered` field of the json output is generated
  42 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
  43 pub enum HumanReadableErrorType {
  44     Default(ColorConfig),
  45     AnnotateSnippet(ColorConfig),
  46     Short(ColorConfig),
  47 }
  48
  49 impl HumanReadableErrorType {
  50     /// Returns a (`short`, `color`) tuple
  51     pub fn unzip(self) -> (bool, ColorConfig) {
  52         match self {
  53             HumanReadableErrorType::Default(cc) => (false, cc),
  54             HumanReadableErrorType::Short(cc) => (true, cc),
  55             HumanReadableErrorType::AnnotateSnippet(cc) => (false, cc),
  56         }
  57     }
  58     pub fn new_emitter(
  59         self,
  60         dst: Box<dyn Write + Send>,
  61         source_map: Option<Lrc<SourceMap>>,
  62         bundle: Option<Lrc<FluentBundle>>,
  63         fallback_bundle: LazyFallbackBundle,
  64         teach: bool,
  65         diagnostic_width: Option<usize>,
  66         macro_backtrace: bool,
  67         track_diagnostics: bool,
  68     ) -> EmitterWriter {
  69         let (short, color_config) = self.unzip();
  70         let color = color_config.suggests_using_colors();
  71         EmitterWriter::new(
  72             dst,
  73             source_map,
  74             bundle,
  75             fallback_bundle,
  76             short,
  77             teach,
  78             color,
  79             diagnostic_width,
  80             macro_backtrace,
  81             track_diagnostics,
  82         )
  83     }
  84 }
  85
  86 #[derive(Clone, Copy, Debug)]
  87 struct Margin {
  88     /// The available whitespace in the left that can be consumed when centering.
  89     pub whitespace_left: usize,
  90     /// The column of the beginning of left-most span.
  91     pub span_left: usize,
  92     /// The column of the end of right-most span.
  93     pub span_right: usize,
  94     /// The beginning of the line to be displayed.
  95     pub computed_left: usize,
  96     /// The end of the line to be displayed.
  97     pub computed_right: usize,
  98     /// The current width of the terminal. Uses value of `DEFAULT_COLUMN_WIDTH` constant by default
  99     /// and in tests.
 100     pub column_width: usize,
 101     /// The end column of a span label, including the span. Doesn't account for labels not in the
 102     /// same line as the span.
 103     pub label_right: usize,
 104 }
 105
 106 impl Margin {
 107     fn new(
 108         whitespace_left: usize,
 109         span_left: usize,
 110         span_right: usize,
 111         label_right: usize,
 112         column_width: usize,
 113         max_line_len: usize,
 114     ) -> Self {
 115         // The 6 is padding to give a bit of room for `...` when displaying:
 116         // ```
 117         // error: message
 118         //   --> file.rs:16:58
 119         //    |
 120         // 16 | ... fn foo(self) -> Self::Bar {
 121         //    |                     ^^^^^^^^^
 122         // ```
 123
 124         let mut m = Margin {
 125             whitespace_left: whitespace_left.saturating_sub(6),
 126             span_left: span_left.saturating_sub(6),
 127             span_right: span_right + 6,
 128             computed_left: 0,
 129             computed_right: 0,
 130             column_width,
 131             label_right: label_right + 6,
 132         };
 133         m.compute(max_line_len);
 134         m
 135     }
 136
 137     fn was_cut_left(&self) -> bool {
 138         self.computed_left > 0
 139     }
 140
 141     fn was_cut_right(&self, line_len: usize) -> bool {
 142         let right =
 143             if self.computed_right == self.span_right || self.computed_right == self.label_right {
 144                 // Account for the "..." padding given above. Otherwise we end up with code lines that
 145                 // do fit but end in "..." as if they were trimmed.
 146                 self.computed_right - 6
 147             } else {
 148                 self.computed_right
 149             };
 150         right < line_len && self.computed_left + self.column_width < line_len
 151     }
 152
 153     fn compute(&mut self, max_line_len: usize) {
 154         // When there's a lot of whitespace (>20), we want to trim it as it is useless.
 155         self.computed_left = if self.whitespace_left > 20 {
 156             self.whitespace_left - 16 // We want some padding.
 157         } else {
 158             0
 159         };
 160         // We want to show as much as possible, max_line_len is the right-most boundary for the
 161         // relevant code.
 162         self.computed_right = max(max_line_len, self.computed_left);
 163
 164         if self.computed_right - self.computed_left > self.column_width {
 165             // Trimming only whitespace isn't enough, let's get craftier.
 166             if self.label_right - self.whitespace_left <= self.column_width {
 167                 // Attempt to fit the code window only trimming whitespace.
 168                 self.computed_left = self.whitespace_left;
 169                 self.computed_right = self.computed_left + self.column_width;
 170             } else if self.label_right - self.span_left <= self.column_width {
 171                 // Attempt to fit the code window considering only the spans and labels.
 172                 let padding_left = (self.column_width - (self.label_right - self.span_left)) / 2;
 173                 self.computed_left = self.span_left.saturating_sub(padding_left);
 174                 self.computed_right = self.computed_left + self.column_width;
 175             } else if self.span_right - self.span_left <= self.column_width {
 176                 // Attempt to fit the code window considering the spans and labels plus padding.
 177                 let padding_left = (self.column_width - (self.span_right - self.span_left)) / 5 * 2;
 178                 self.computed_left = self.span_left.saturating_sub(padding_left);
 179                 self.computed_right = self.computed_left + self.column_width;
 180             } else {
 181                 // Mostly give up but still don't show the full line.
 182                 self.computed_left = self.span_left;
 183                 self.computed_right = self.span_right;
 184             }
 185         }
 186     }
 187
 188     fn left(&self, line_len: usize) -> usize {
 189         min(self.computed_left, line_len)
 190     }
 191
 192     fn right(&self, line_len: usize) -> usize {
 193         if line_len.saturating_sub(self.computed_left) <= self.column_width {
 194             line_len
 195         } else {
 196             min(line_len, self.computed_right)
 197         }
 198     }
 199 }
 200
 201 const ANONYMIZED_LINE_NUM: &str = "LL";
 202
 203 /// Emitter trait for emitting errors.
 204 pub trait Emitter: Translate {
 205     /// Emit a structured diagnostic.
 206     fn emit_diagnostic(&mut self, diag: &Diagnostic);
 207
 208     /// Emit a notification that an artifact has been output.
 209     /// This is currently only supported for the JSON format,
 210     /// other formats can, and will, simply ignore it.
 211     fn emit_artifact_notification(&mut self, _path: &Path, _artifact_type: &str) {}
 212
 213     fn emit_future_breakage_report(&mut self, _diags: Vec<Diagnostic>) {}
 214
 215     /// Emit list of unused externs
 216     fn emit_unused_externs(
 217         &mut self,
 218         _lint_level: rustc_lint_defs::Level,
 219         _unused_externs: &[&str],
 220     ) {
 221     }
 222
 223     /// Checks if should show explanations about "rustc --explain"
 224     fn should_show_explain(&self) -> bool {
 225         true
 226     }
 227
 228     /// Checks if we can use colors in the current output stream.
 229     fn supports_color(&self) -> bool {
 230         false
 231     }
 232
 233     fn source_map(&self) -> Option<&Lrc<SourceMap>>;
 234
 235     /// Formats the substitutions of the primary_span
 236     ///
 237     /// There are a lot of conditions to this method, but in short:
 238     ///
 239     /// * If the current `Diagnostic` has only one visible `CodeSuggestion`,
 240     ///   we format the `help` suggestion depending on the content of the
 241     ///   substitutions. In that case, we return the modified span only.
 242     ///
 243     /// * If the current `Diagnostic` has multiple suggestions,
 244     ///   we return the original `primary_span` and the original suggestions.
 245     fn primary_span_formatted<'a>(
 246         &mut self,
 247         diag: &'a Diagnostic,
 248         fluent_args: &FluentArgs<'_>,
 249     ) -> (MultiSpan, &'a [CodeSuggestion]) {
 250         let mut primary_span = diag.span.clone();
 251         let suggestions = diag.suggestions.as_ref().map_or(&[][..], |suggestions| &suggestions[..]);
 252         if let Some((sugg, rest)) = suggestions.split_first() {
 253             let msg = self.translate_message(&sugg.msg, fluent_args);
 254             if rest.is_empty() &&
 255                // ^ if there is only one suggestion
 256                // don't display multi-suggestions as labels
 257                sugg.substitutions.len() == 1 &&
 258                // don't display multipart suggestions as labels
 259                sugg.substitutions[0].parts.len() == 1 &&
 260                // don't display long messages as labels
 261                msg.split_whitespace().count() < 10 &&
 262                // don't display multiline suggestions as labels
 263                !sugg.substitutions[0].parts[0].snippet.contains('\n') &&
 264                ![
 265                     // when this style is set we want the suggestion to be a message, not inline
 266                     SuggestionStyle::HideCodeAlways,
 267                     // trivial suggestion for tooling's sake, never shown
 268                     SuggestionStyle::CompletelyHidden,
 269                     // subtle suggestion, never shown inline
 270                     SuggestionStyle::ShowAlways,
 271                ].contains(&sugg.style)
 272             {
 273                 let substitution = &sugg.substitutions[0].parts[0].snippet.trim();
 274                 let msg = if substitution.is_empty() || sugg.style.hide_inline() {
 275                     // This substitution is only removal OR we explicitly don't want to show the
 276                     // code inline (`hide_inline`). Therefore, we don't show the substitution.
 277                     format!("help: {}", &msg)
 278                 } else {
 279                     // Show the default suggestion text with the substitution
 280                     format!(
 281                         "help: {}{}: `{}`",
 282                         &msg,
 283                         if self
 284                             .source_map()
 285                             .map(|sm| is_case_difference(
 286                                 &**sm,
 287                                 substitution,
 288                                 sugg.substitutions[0].parts[0].span,
 289                             ))
 290                             .unwrap_or(false)
 291                         {
 292                             " (notice the capitalization)"
 293                         } else {
 294                             ""
 295                         },
 296                         substitution,
 297                     )
 298                 };
 299                 primary_span.push_span_label(sugg.substitutions[0].parts[0].span, msg);
 300
 301                 // We return only the modified primary_span
 302                 (primary_span, &[])
 303             } else {
 304                 // if there are multiple suggestions, print them all in full
 305                 // to be consistent. We could try to figure out if we can
 306                 // make one (or the first one) inline, but that would give
 307                 // undue importance to a semi-random suggestion
 308                 (primary_span, suggestions)
 309             }
 310         } else {
 311             (primary_span, suggestions)
 312         }
 313     }
 314
 315     fn fix_multispans_in_extern_macros_and_render_macro_backtrace(
 316         &self,
 317         source_map: &Option<Lrc<SourceMap>>,
 318         span: &mut MultiSpan,
 319         children: &mut Vec<SubDiagnostic>,
 320         level: &Level,
 321         backtrace: bool,
 322     ) {
 323         // Check for spans in macros, before `fix_multispans_in_extern_macros`
 324         // has a chance to replace them.
 325         let has_macro_spans: Vec<_> = iter::once(&*span)
 326             .chain(children.iter().map(|child| &child.span))
 327             .flat_map(|span| span.primary_spans())
 328             .flat_map(|sp| sp.macro_backtrace())
 329             .filter_map(|expn_data| {
 330                 match expn_data.kind {
 331                     ExpnKind::Root => None,
 332
 333                     // Skip past non-macro entries, just in case there
 334                     // are some which do actually involve macros.
 335                     ExpnKind::Inlined | ExpnKind::Desugaring(..) | ExpnKind::AstPass(..) => None,
 336
 337                     ExpnKind::Macro(macro_kind, name) => Some((macro_kind, name)),
 338                 }
 339             })
 340             .collect();
 341
 342         if !backtrace {
 343             self.fix_multispans_in_extern_macros(source_map, span, children);
 344         }
 345
 346         self.render_multispans_macro_backtrace(span, children, backtrace);
 347
 348         if !backtrace {
 349             if let Some((macro_kind, name)) = has_macro_spans.first() {
 350                 // Mark the actual macro this originates from
 351                 let and_then = if let Some((macro_kind, last_name)) = has_macro_spans.last()
 352                     && last_name != name
 353                 {
 354                     let descr = macro_kind.descr();
 355                     format!(
 356                         " which comes from the expansion of the {descr} `{last_name}`",
 357                     )
 358                 } else {
 359                     "".to_string()
 360                 };
 361
 362                 let descr = macro_kind.descr();
 363                 let msg = format!(
 364                     "this {level} originates in the {descr} `{name}`{and_then} \
 365                     (in Nightly builds, run with -Z macro-backtrace for more info)",
 366                 );
 367
 368                 children.push(SubDiagnostic {
 369                     level: Level::Note,
 370                     message: vec![(DiagnosticMessage::Str(msg), Style::NoStyle)],
 371                     span: MultiSpan::new(),
 372                     render_span: None,
 373                 });
 374             }
 375         }
 376     }
 377
 378     fn render_multispans_macro_backtrace(
 379         &self,
 380         span: &mut MultiSpan,
 381         children: &mut Vec<SubDiagnostic>,
 382         backtrace: bool,
 383     ) {
 384         for span in iter::once(span).chain(children.iter_mut().map(|child| &mut child.span)) {
 385             self.render_multispan_macro_backtrace(span, backtrace);
 386         }
 387     }
 388
 389     fn render_multispan_macro_backtrace(&self, span: &mut MultiSpan, always_backtrace: bool) {
 390         let mut new_labels: Vec<(Span, String)> = vec![];
 391
 392         for &sp in span.primary_spans() {
 393             if sp.is_dummy() {
 394                 continue;
 395             }
 396
 397             // FIXME(eddyb) use `retain` on `macro_backtrace` to remove all the
 398             // entries we don't want to print, to make sure the indices being
 399             // printed are contiguous (or omitted if there's only one entry).
 400             let macro_backtrace: Vec<_> = sp.macro_backtrace().collect();
 401             for (i, trace) in macro_backtrace.iter().rev().enumerate() {
 402                 if trace.def_site.is_dummy() {
 403                     continue;
 404                 }
 405
 406                 if always_backtrace && !matches!(trace.kind, ExpnKind::Inlined) {
 407                     new_labels.push((
 408                         trace.def_site,
 409                         format!(
 410                             "in this expansion of `{}`{}",
 411                             trace.kind.descr(),
 412                             if macro_backtrace.len() > 1 {
 413                                 // if macro_backtrace.len() == 1 it'll be
 414                                 // pointed at by "in this macro invocation"
 415                                 format!(" (#{})", i + 1)
 416                             } else {
 417                                 String::new()
 418                             },
 419                         ),
 420                     ));
 421                 }
 422
 423                 // Don't add a label on the call site if the diagnostic itself
 424                 // already points to (a part of) that call site, as the label
 425                 // is meant for showing the relevant invocation when the actual
 426                 // diagnostic is pointing to some part of macro definition.
 427                 //
 428                 // This also handles the case where an external span got replaced
 429                 // with the call site span by `fix_multispans_in_extern_macros`.
 430                 //
 431                 // NB: `-Zmacro-backtrace` overrides this, for uniformity, as the
 432                 // "in this expansion of" label above is always added in that mode,
 433                 // and it needs an "in this macro invocation" label to match that.
 434                 let redundant_span = trace.call_site.contains(sp);
 435
 436                 if !redundant_span || always_backtrace {
 437                     let msg: Cow<'static, _> = match trace.kind {
 438                         ExpnKind::Macro(MacroKind::Attr, _) => {
 439                             "this procedural macro expansion".into()
 440                         }
 441                         ExpnKind::Macro(MacroKind::Derive, _) => {
 442                             "this derive macro expansion".into()
 443                         }
 444                         ExpnKind::Macro(MacroKind::Bang, _) => "this macro invocation".into(),
 445                         ExpnKind::Inlined => "this inlined function call".into(),
 446                         ExpnKind::Root => "the crate root".into(),
 447                         ExpnKind::AstPass(kind) => kind.descr().into(),
 448                         ExpnKind::Desugaring(kind) => {
 449                             format!("this {} desugaring", kind.descr()).into()
 450                         }
 451                     };
 452                     new_labels.push((
 453                         trace.call_site,
 454                         format!(
 455                             "in {}{}",
 456                             msg,
 457                             if macro_backtrace.len() > 1 && always_backtrace {
 458                                 // only specify order when the macro
 459                                 // backtrace is multiple levels deep
 460                                 format!(" (#{})", i + 1)
 461                             } else {
 462                                 String::new()
 463                             },
 464                         ),
 465                     ));
 466                 }
 467                 if !always_backtrace {
 468                     break;
 469                 }
 470             }
 471         }
 472
 473         for (label_span, label_text) in new_labels {
 474             span.push_span_label(label_span, label_text);
 475         }
 476     }
 477
 478     // This does a small "fix" for multispans by looking to see if it can find any that
 479     // point directly at external macros. Since these are often difficult to read,
 480     // this will change the span to point at the use site.
 481     fn fix_multispans_in_extern_macros(
 482         &self,
 483         source_map: &Option<Lrc<SourceMap>>,
 484         span: &mut MultiSpan,
 485         children: &mut Vec<SubDiagnostic>,
 486     ) {
 487         let Some(source_map) = source_map else { return };
 488         debug!("fix_multispans_in_extern_macros: before: span={:?} children={:?}", span, children);
 489         self.fix_multispan_in_extern_macros(source_map, span);
 490         for child in children.iter_mut() {
 491             self.fix_multispan_in_extern_macros(source_map, &mut child.span);
 492         }
 493         debug!("fix_multispans_in_extern_macros: after: span={:?} children={:?}", span, children);
 494     }
 495
 496     // This "fixes" MultiSpans that contain `Span`s pointing to locations inside of external macros.
 497     // Since these locations are often difficult to read,
 498     // we move these spans from the external macros to their corresponding use site.
 499     fn fix_multispan_in_extern_macros(&self, source_map: &Lrc<SourceMap>, span: &mut MultiSpan) {
 500         // First, find all the spans in external macros and point instead at their use site.
 501         let replacements: Vec<(Span, Span)> = span
 502             .primary_spans()
 503             .iter()
 504             .copied()
 505             .chain(span.span_labels().iter().map(|sp_label| sp_label.span))
 506             .filter_map(|sp| {
 507                 if !sp.is_dummy() && source_map.is_imported(sp) {
 508                     let maybe_callsite = sp.source_callsite();
 509                     if sp != maybe_callsite {
 510                         return Some((sp, maybe_callsite));
 511                     }
 512                 }
 513                 None
 514             })
 515             .collect();
 516
 517         // After we have them, make sure we replace these 'bad' def sites with their use sites.
 518         for (from, to) in replacements {
 519             span.replace(from, to);
 520         }
 521     }
 522 }
 523
 524 impl Translate for EmitterWriter {
 525     fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
 526         self.fluent_bundle.as_ref()
 527     }
 528
 529     fn fallback_fluent_bundle(&self) -> &FluentBundle {
 530         &**self.fallback_bundle
 531     }
 532 }
 533
 534 impl Emitter for EmitterWriter {
 535     fn source_map(&self) -> Option<&Lrc<SourceMap>> {
 536         self.sm.as_ref()
 537     }
 538
 539     fn emit_diagnostic(&mut self, diag: &Diagnostic) {
 540         let fluent_args = to_fluent_args(diag.args());
 541
 542         let mut children = diag.children.clone();
 543         let (mut primary_span, suggestions) = self.primary_span_formatted(&diag, &fluent_args);
 544         debug!("emit_diagnostic: suggestions={:?}", suggestions);
 545
 546         self.fix_multispans_in_extern_macros_and_render_macro_backtrace(
 547             &self.sm,
 548             &mut primary_span,
 549             &mut children,
 550             &diag.level,
 551             self.macro_backtrace,
 552         );
 553
 554         self.emit_messages_default(
 555             &diag.level,
 556             &diag.message,
 557             &fluent_args,
 558             &diag.code,
 559             &primary_span,
 560             &children,
 561             &suggestions,
 562             self.track_diagnostics.then_some(&diag.emitted_at),
 563         );
 564     }
 565
 566     fn should_show_explain(&self) -> bool {
 567         !self.short_message
 568     }
 569
 570     fn supports_color(&self) -> bool {
 571         self.dst.supports_color()
 572     }
 573 }
 574
 575 /// An emitter that does nothing when emitting a non-fatal diagnostic.
 576 /// Fatal diagnostics are forwarded to `fatal_handler` to avoid silent
 577 /// failures of rustc, as witnessed e.g. in issue #89358.
 578 pub struct SilentEmitter {
 579     pub fatal_handler: Handler,
 580     pub fatal_note: Option<String>,
 581 }
 582
 583 impl Translate for SilentEmitter {
 584     fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
 585         None
 586     }
 587
 588     fn fallback_fluent_bundle(&self) -> &FluentBundle {
 589         panic!("silent emitter attempted to translate message")
 590     }
 591 }
 592
 593 impl Emitter for SilentEmitter {
 594     fn source_map(&self) -> Option<&Lrc<SourceMap>> {
 595         None
 596     }
 597
 598     fn emit_diagnostic(&mut self, d: &Diagnostic) {
 599         if d.level == Level::Fatal {
 600             let mut d = d.clone();
 601             if let Some(ref note) = self.fatal_note {
 602                 d.note(note);
 603             }
 604             self.fatal_handler.emit_diagnostic(&mut d);
 605         }
 606     }
 607 }
 608
 609 /// Maximum number of suggestions to be shown
 610 ///
 611 /// Arbitrary, but taken from trait import suggestion limit
 612 pub const MAX_SUGGESTIONS: usize = 4;
 613
 614 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 615 pub enum ColorConfig {
 616     Auto,
 617     Always,
 618     Never,
 619 }
 620
 621 impl ColorConfig {
 622     fn to_color_choice(self) -> ColorChoice {
 623         match self {
 624             ColorConfig::Always => {
 625                 if atty::is(atty::Stream::Stderr) {
 626                     ColorChoice::Always
 627                 } else {
 628                     ColorChoice::AlwaysAnsi
 629                 }
 630             }
 631             ColorConfig::Never => ColorChoice::Never,
 632             ColorConfig::Auto if atty::is(atty::Stream::Stderr) => ColorChoice::Auto,
 633             ColorConfig::Auto => ColorChoice::Never,
 634         }
 635     }
 636     fn suggests_using_colors(self) -> bool {
 637         match self {
 638             ColorConfig::Always | ColorConfig::Auto => true,
 639             ColorConfig::Never => false,
 640         }
 641     }
 642 }
 643
 644 /// Handles the writing of `HumanReadableErrorType::Default` and `HumanReadableErrorType::Short`
 645 pub struct EmitterWriter {
 646     dst: Destination,
 647     sm: Option<Lrc<SourceMap>>,
 648     fluent_bundle: Option<Lrc<FluentBundle>>,
 649     fallback_bundle: LazyFallbackBundle,
 650     short_message: bool,
 651     teach: bool,
 652     ui_testing: bool,
 653     diagnostic_width: Option<usize>,
 654
 655     macro_backtrace: bool,
 656     track_diagnostics: bool,
 657 }
 658
 659 #[derive(Debug)]
 660 pub struct FileWithAnnotatedLines {
 661     pub file: Lrc<SourceFile>,
 662     pub lines: Vec<Line>,
 663     multiline_depth: usize,
 664 }
 665
 666 impl EmitterWriter {
 667     pub fn stderr(
 668         color_config: ColorConfig,
 669         source_map: Option<Lrc<SourceMap>>,
 670         fluent_bundle: Option<Lrc<FluentBundle>>,
 671         fallback_bundle: LazyFallbackBundle,
 672         short_message: bool,
 673         teach: bool,
 674         diagnostic_width: Option<usize>,
 675         macro_backtrace: bool,
 676         track_diagnostics: bool,
 677     ) -> EmitterWriter {
 678         let dst = Destination::from_stderr(color_config);
 679         EmitterWriter {
 680             dst,
 681             sm: source_map,
 682             fluent_bundle,
 683             fallback_bundle,
 684             short_message,
 685             teach,
 686             ui_testing: false,
 687             diagnostic_width,
 688             macro_backtrace,
 689             track_diagnostics,
 690         }
 691     }
 692
 693     pub fn new(
 694         dst: Box<dyn Write + Send>,
 695         source_map: Option<Lrc<SourceMap>>,
 696         fluent_bundle: Option<Lrc<FluentBundle>>,
 697         fallback_bundle: LazyFallbackBundle,
 698         short_message: bool,
 699         teach: bool,
 700         colored: bool,
 701         diagnostic_width: Option<usize>,
 702         macro_backtrace: bool,
 703         track_diagnostics: bool,
 704     ) -> EmitterWriter {
 705         EmitterWriter {
 706             dst: Raw(dst, colored),
 707             sm: source_map,
 708             fluent_bundle,
 709             fallback_bundle,
 710             short_message,
 711             teach,
 712             ui_testing: false,
 713             diagnostic_width,
 714             macro_backtrace,
 715             track_diagnostics,
 716         }
 717     }
 718
 719     pub fn ui_testing(mut self, ui_testing: bool) -> Self {
 720         self.ui_testing = ui_testing;
 721         self
 722     }
 723
 724     fn maybe_anonymized(&self, line_num: usize) -> Cow<'static, str> {
 725         if self.ui_testing {
 726             Cow::Borrowed(ANONYMIZED_LINE_NUM)
 727         } else {
 728             Cow::Owned(line_num.to_string())
 729         }
 730     }
 731
 732     fn draw_line(
 733         &self,
 734         buffer: &mut StyledBuffer,
 735         source_string: &str,
 736         line_index: usize,
 737         line_offset: usize,
 738         width_offset: usize,
 739         code_offset: usize,
 740         margin: Margin,
 741     ) {
 742         // Tabs are assumed to have been replaced by spaces in calling code.
 743         debug_assert!(!source_string.contains('\t'));
 744         let line_len = source_string.len();
 745         // Create the source line we will highlight.
 746         let left = margin.left(line_len);
 747         let right = margin.right(line_len);
 748         // On long lines, we strip the source line, accounting for unicode.
 749         let mut taken = 0;
 750         let code: String = source_string
 751             .chars()
 752             .skip(left)
 753             .take_while(|ch| {
 754                 // Make sure that the trimming on the right will fall within the terminal width.
 755                 // FIXME: `unicode_width` sometimes disagrees with terminals on how wide a `char` is.
 756                 // For now, just accept that sometimes the code line will be longer than desired.
 757                 let next = unicode_width::UnicodeWidthChar::width(*ch).unwrap_or(1);
 758                 if taken + next > right - left {
 759                     return false;
 760                 }
 761                 taken += next;
 762                 true
 763             })
 764             .collect();
 765         buffer.puts(line_offset, code_offset, &code, Style::Quotation);
 766         if margin.was_cut_left() {
 767             // We have stripped some code/whitespace from the beginning, make it clear.
 768             buffer.puts(line_offset, code_offset, "...", Style::LineNumber);
 769         }
 770         if margin.was_cut_right(line_len) {
 771             // We have stripped some code after the right-most span end, make it clear we did so.
 772             buffer.puts(line_offset, code_offset + taken - 3, "...", Style::LineNumber);
 773         }
 774         buffer.puts(line_offset, 0, &self.maybe_anonymized(line_index), Style::LineNumber);
 775
 776         draw_col_separator_no_space(buffer, line_offset, width_offset - 2);
 777     }
 778
 779     fn render_source_line(
 780         &self,
 781         buffer: &mut StyledBuffer,
 782         file: Lrc<SourceFile>,
 783         line: &Line,
 784         width_offset: usize,
 785         code_offset: usize,
 786         margin: Margin,
 787     ) -> Vec<(usize, Style)> {
 788         // Draw:
 789         //
 790         //   LL | ... code ...
 791         //      |     ^^-^ span label
 792         //      |       |
 793         //      |       secondary span label
 794         //
 795         //   ^^ ^ ^^^ ^^^^ ^^^ we don't care about code too far to the right of a span, we trim it
 796         //   |  | |   |
 797         //   |  | |   actual code found in your source code and the spans we use to mark it
 798         //   |  | when there's too much wasted space to the left, trim it
 799         //   |  vertical divider between the column number and the code
 800         //   column number
 801
 802         if line.line_index == 0 {
 803             return Vec::new();
 804         }
 805
 806         let source_string = match file.get_line(line.line_index - 1) {
 807             Some(s) => normalize_whitespace(&*s),
 808             None => return Vec::new(),
 809         };
 810
 811         let line_offset = buffer.num_lines();
 812
 813         // Left trim
 814         let left = margin.left(source_string.len());
 815
 816         // Account for unicode characters of width !=0 that were removed.
 817         let left = source_string
 818             .chars()
 819             .take(left)
 820             .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
 821             .sum();
 822
 823         self.draw_line(
 824             buffer,
 825             &source_string,
 826             line.line_index,
 827             line_offset,
 828             width_offset,
 829             code_offset,
 830             margin,
 831         );
 832
 833         // Special case when there's only one annotation involved, it is the start of a multiline
 834         // span and there's no text at the beginning of the code line. Instead of doing the whole
 835         // graph:
 836         //
 837         // 2 |   fn foo() {
 838         //   |  _^
 839         // 3 | |
 840         // 4 | | }
 841         //   | |_^ test
 842         //
 843         // we simplify the output to:
 844         //
 845         // 2 | / fn foo() {
 846         // 3 | |
 847         // 4 | | }
 848         //   | |_^ test
 849         if let [ann] = &line.annotations[..] {
 850             if let AnnotationType::MultilineStart(depth) = ann.annotation_type {
 851                 if source_string.chars().take(ann.start_col).all(|c| c.is_whitespace()) {
 852                     let style = if ann.is_primary {
 853                         Style::UnderlinePrimary
 854                     } else {
 855                         Style::UnderlineSecondary
 856                     };
 857                     buffer.putc(line_offset, width_offset + depth - 1, '/', style);
 858                     return vec![(depth, style)];
 859                 }
 860             }
 861         }
 862
 863         // We want to display like this:
 864         //
 865         //      vec.push(vec.pop().unwrap());
 866         //      ---      ^^^               - previous borrow ends here
 867         //      |        |
 868         //      |        error occurs here
 869         //      previous borrow of `vec` occurs here
 870         //
 871         // But there are some weird edge cases to be aware of:
 872         //
 873         //      vec.push(vec.pop().unwrap());
 874         //      --------                    - previous borrow ends here
 875         //      ||
 876         //      |this makes no sense
 877         //      previous borrow of `vec` occurs here
 878         //
 879         // For this reason, we group the lines into "highlight lines"
 880         // and "annotations lines", where the highlight lines have the `^`.
 881
 882         // Sort the annotations by (start, end col)
 883         // The labels are reversed, sort and then reversed again.
 884         // Consider a list of annotations (A1, A2, C1, C2, B1, B2) where
 885         // the letter signifies the span. Here we are only sorting by the
 886         // span and hence, the order of the elements with the same span will
 887         // not change. On reversing the ordering (|a, b| but b.cmp(a)), you get
 888         // (C1, C2, B1, B2, A1, A2). All the elements with the same span are
 889         // still ordered first to last, but all the elements with different
 890         // spans are ordered by their spans in last to first order. Last to
 891         // first order is important, because the jiggly lines and | are on
 892         // the left, so the rightmost span needs to be rendered first,
 893         // otherwise the lines would end up needing to go over a message.
 894
 895         let mut annotations = line.annotations.clone();
 896         annotations.sort_by_key(|a| Reverse(a.start_col));
 897
 898         // First, figure out where each label will be positioned.
 899         //
 900         // In the case where you have the following annotations:
 901         //
 902         //      vec.push(vec.pop().unwrap());
 903         //      --------                    - previous borrow ends here [C]
 904         //      ||
 905         //      |this makes no sense [B]
 906         //      previous borrow of `vec` occurs here [A]
 907         //
 908         // `annotations_position` will hold [(2, A), (1, B), (0, C)].
 909         //
 910         // We try, when possible, to stick the rightmost annotation at the end
 911         // of the highlight line:
 912         //
 913         //      vec.push(vec.pop().unwrap());
 914         //      ---      ---               - previous borrow ends here
 915         //
 916         // But sometimes that's not possible because one of the other
 917         // annotations overlaps it. For example, from the test
 918         // `span_overlap_label`, we have the following annotations
 919         // (written on distinct lines for clarity):
 920         //
 921         //      fn foo(x: u32) {
 922         //      --------------
 923         //             -
 924         //
 925         // In this case, we can't stick the rightmost-most label on
 926         // the highlight line, or we would get:
 927         //
 928         //      fn foo(x: u32) {
 929         //      -------- x_span
 930         //      |
 931         //      fn_span
 932         //
 933         // which is totally weird. Instead we want:
 934         //
 935         //      fn foo(x: u32) {
 936         //      --------------
 937         //      |      |
 938         //      |      x_span
 939         //      fn_span
 940         //
 941         // which is...less weird, at least. In fact, in general, if
 942         // the rightmost span overlaps with any other span, we should
 943         // use the "hang below" version, so we can at least make it
 944         // clear where the span *starts*. There's an exception for this
 945         // logic, when the labels do not have a message:
 946         //
 947         //      fn foo(x: u32) {
 948         //      --------------
 949         //             |
 950         //             x_span
 951         //
 952         // instead of:
 953         //
 954         //      fn foo(x: u32) {
 955         //      --------------
 956         //      |      |
 957         //      |      x_span
 958         //      <EMPTY LINE>
 959         //
 960         let mut annotations_position = vec![];
 961         let mut line_len = 0;
 962         let mut p = 0;
 963         for (i, annotation) in annotations.iter().enumerate() {
 964             for (j, next) in annotations.iter().enumerate() {
 965                 if overlaps(next, annotation, 0)  // This label overlaps with another one and both
 966                     && annotation.has_label()     // take space (they have text and are not
 967                     && j > i                      // multiline lines).
 968                     && p == 0
 969                 // We're currently on the first line, move the label one line down
 970                 {
 971                     // If we're overlapping with an un-labelled annotation with the same span
 972                     // we can just merge them in the output
 973                     if next.start_col == annotation.start_col
 974                         && next.end_col == annotation.end_col
 975                         && !next.has_label()
 976                     {
 977                         continue;
 978                     }
 979
 980                     // This annotation needs a new line in the output.
 981                     p += 1;
 982                     break;
 983                 }
 984             }
 985             annotations_position.push((p, annotation));
 986             for (j, next) in annotations.iter().enumerate() {
 987                 if j > i {
 988                     let l = next.label.as_ref().map_or(0, |label| label.len() + 2);
 989                     if (overlaps(next, annotation, l) // Do not allow two labels to be in the same
 990                                                      // line if they overlap including padding, to
 991                                                      // avoid situations like:
 992                                                      //
 993                                                      //      fn foo(x: u32) {
 994                                                      //      -------^------
 995                                                      //      |      |
 996                                                      //      fn_spanx_span
 997                                                      //
 998                         && annotation.has_label()    // Both labels must have some text, otherwise
 999                         && next.has_label())         // they are not overlapping.
1000                                                      // Do not add a new line if this annotation
1001                                                      // or the next are vertical line placeholders.
1002                         || (annotation.takes_space() // If either this or the next annotation is
1003                             && next.has_label())     // multiline start/end, move it to a new line
1004                         || (annotation.has_label()   // so as not to overlap the horizontal lines.
1005                             && next.takes_space())
1006                         || (annotation.takes_space() && next.takes_space())
1007                         || (overlaps(next, annotation, l)
1008                             && next.end_col <= annotation.end_col
1009                             && next.has_label()
1010                             && p == 0)
1011                     // Avoid #42595.
1012                     {
1013                         // This annotation needs a new line in the output.
1014                         p += 1;
1015                         break;
1016                     }
1017                 }
1018             }
1019             line_len = max(line_len, p);
1020         }
1021
1022         if line_len != 0 {
1023             line_len += 1;
1024         }
1025
1026         // If there are no annotations or the only annotations on this line are
1027         // MultilineLine, then there's only code being shown, stop processing.
1028         if line.annotations.iter().all(|a| a.is_line()) {
1029             return vec![];
1030         }
1031
1032         // Write the column separator.
1033         //
1034         // After this we will have:
1035         //
1036         // 2 |   fn foo() {
1037         //   |
1038         //   |
1039         //   |
1040         // 3 |
1041         // 4 |   }
1042         //   |
1043         for pos in 0..=line_len {
1044             draw_col_separator(buffer, line_offset + pos + 1, width_offset - 2);
1045         }
1046
1047         // Write the horizontal lines for multiline annotations
1048         // (only the first and last lines need this).
1049         //
1050         // After this we will have:
1051         //
1052         // 2 |   fn foo() {
1053         //   |  __________
1054         //   |
1055         //   |
1056         // 3 |
1057         // 4 |   }
1058         //   |  _
1059         for &(pos, annotation) in &annotations_position {
1060             let style = if annotation.is_primary {
1061                 Style::UnderlinePrimary
1062             } else {
1063                 Style::UnderlineSecondary
1064             };
1065             let pos = pos + 1;
1066             match annotation.annotation_type {
1067                 AnnotationType::MultilineStart(depth) | AnnotationType::MultilineEnd(depth) => {
1068                     draw_range(
1069                         buffer,
1070                         '_',
1071                         line_offset + pos,
1072                         width_offset + depth,
1073                         (code_offset + annotation.start_col).saturating_sub(left),
1074                         style,
1075                     );
1076                 }
1077                 _ if self.teach => {
1078                     buffer.set_style_range(
1079                         line_offset,
1080                         (code_offset + annotation.start_col).saturating_sub(left),
1081                         (code_offset + annotation.end_col).saturating_sub(left),
1082                         style,
1083                         annotation.is_primary,
1084                     );
1085                 }
1086                 _ => {}
1087             }
1088         }
1089
1090         // Write the vertical lines for labels that are on a different line as the underline.
1091         //
1092         // After this we will have:
1093         //
1094         // 2 |   fn foo() {
1095         //   |  __________
1096         //   | |    |
1097         //   | |
1098         // 3 | |
1099         // 4 | | }
1100         //   | |_
1101         for &(pos, annotation) in &annotations_position {
1102             let style = if annotation.is_primary {
1103                 Style::UnderlinePrimary
1104             } else {
1105                 Style::UnderlineSecondary
1106             };
1107             let pos = pos + 1;
1108
1109             if pos > 1 && (annotation.has_label() || annotation.takes_space()) {
1110                 for p in line_offset + 1..=line_offset + pos {
1111                     buffer.putc(
1112                         p,
1113                         (code_offset + annotation.start_col).saturating_sub(left),
1114                         '|',
1115                         style,
1116                     );
1117                 }
1118             }
1119             match annotation.annotation_type {
1120                 AnnotationType::MultilineStart(depth) => {
1121                     for p in line_offset + pos + 1..line_offset + line_len + 2 {
1122                         buffer.putc(p, width_offset + depth - 1, '|', style);
1123                     }
1124                 }
1125                 AnnotationType::MultilineEnd(depth) => {
1126                     for p in line_offset..=line_offset + pos {
1127                         buffer.putc(p, width_offset + depth - 1, '|', style);
1128                     }
1129                 }
1130                 _ => (),
1131             }
1132         }
1133
1134         // Write the labels on the annotations that actually have a label.
1135         //
1136         // After this we will have:
1137         //
1138         // 2 |   fn foo() {
1139         //   |  __________
1140         //   |      |
1141         //   |      something about `foo`
1142         // 3 |
1143         // 4 |   }
1144         //   |  _  test
1145         for &(pos, annotation) in &annotations_position {
1146             let style =
1147                 if annotation.is_primary { Style::LabelPrimary } else { Style::LabelSecondary };
1148             let (pos, col) = if pos == 0 {
1149                 (pos + 1, (annotation.end_col + 1).saturating_sub(left))
1150             } else {
1151                 (pos + 2, annotation.start_col.saturating_sub(left))
1152             };
1153             if let Some(ref label) = annotation.label {
1154                 buffer.puts(line_offset + pos, code_offset + col, &label, style);
1155             }
1156         }
1157
1158         // Sort from biggest span to smallest span so that smaller spans are
1159         // represented in the output:
1160         //
1161         // x | fn foo()
1162         //   | ^^^---^^
1163         //   | |  |
1164         //   | |  something about `foo`
1165         //   | something about `fn foo()`
1166         annotations_position.sort_by_key(|(_, ann)| {
1167             // Decreasing order. When annotations share the same length, prefer `Primary`.
1168             (Reverse(ann.len()), ann.is_primary)
1169         });
1170
1171         // Write the underlines.
1172         //
1173         // After this we will have:
1174         //
1175         // 2 |   fn foo() {
1176         //   |  ____-_____^
1177         //   |      |
1178         //   |      something about `foo`
1179         // 3 |
1180         // 4 |   }
1181         //   |  _^  test
1182         for &(_, annotation) in &annotations_position {
1183             let (underline, style) = if annotation.is_primary {
1184                 ('^', Style::UnderlinePrimary)
1185             } else {
1186                 ('-', Style::UnderlineSecondary)
1187             };
1188             for p in annotation.start_col..annotation.end_col {
1189                 buffer.putc(
1190                     line_offset + 1,
1191                     (code_offset + p).saturating_sub(left),
1192                     underline,
1193                     style,
1194                 );
1195             }
1196         }
1197         annotations_position
1198             .iter()
1199             .filter_map(|&(_, annotation)| match annotation.annotation_type {
1200                 AnnotationType::MultilineStart(p) | AnnotationType::MultilineEnd(p) => {
1201                     let style = if annotation.is_primary {
1202                         Style::LabelPrimary
1203                     } else {
1204                         Style::LabelSecondary
1205                     };
1206                     Some((p, style))
1207                 }
1208                 _ => None,
1209             })
1210             .collect::<Vec<_>>()
1211     }
1212
1213     fn get_multispan_max_line_num(&mut self, msp: &MultiSpan) -> usize {
1214         let Some(ref sm) = self.sm else {
1215             return 0;
1216         };
1217
1218         let will_be_emitted = |span: Span| {
1219             !span.is_dummy() && {
1220                 let file = sm.lookup_source_file(span.hi());
1221                 sm.ensure_source_file_source_present(file)
1222             }
1223         };
1224
1225         let mut max = 0;
1226         for primary_span in msp.primary_spans() {
1227             if will_be_emitted(*primary_span) {
1228                 let hi = sm.lookup_char_pos(primary_span.hi());
1229                 max = (hi.line).max(max);
1230             }
1231         }
1232         if !self.short_message {
1233             for span_label in msp.span_labels() {
1234                 if will_be_emitted(span_label.span) {
1235                     let hi = sm.lookup_char_pos(span_label.span.hi());
1236                     max = (hi.line).max(max);
1237                 }
1238             }
1239         }
1240
1241         max
1242     }
1243
1244     fn get_max_line_num(&mut self, span: &MultiSpan, children: &[SubDiagnostic]) -> usize {
1245         let primary = self.get_multispan_max_line_num(span);
1246         children
1247             .iter()
1248             .map(|sub| self.get_multispan_max_line_num(&sub.span))
1249             .max()
1250             .unwrap_or(0)
1251             .max(primary)
1252     }
1253
1254     /// Adds a left margin to every line but the first, given a padding length and the label being
1255     /// displayed, keeping the provided highlighting.
1256     fn msg_to_buffer(
1257         &self,
1258         buffer: &mut StyledBuffer,
1259         msg: &[(DiagnosticMessage, Style)],
1260         args: &FluentArgs<'_>,
1261         padding: usize,
1262         label: &str,
1263         override_style: Option<Style>,
1264     ) {
1265         // The extra 5 ` ` is padding that's always needed to align to the `note: `:
1266         //
1267         //   error: message
1268         //     --> file.rs:13:20
1269         //      |
1270         //   13 |     <CODE>
1271         //      |      ^^^^
1272         //      |
1273         //      = note: multiline
1274         //              message
1275         //   ++^^^----xx
1276         //    |  |   | |
1277         //    |  |   | magic `2`
1278         //    |  |   length of label
1279         //    |  magic `3`
1280         //    `max_line_num_len`
1281         let padding = " ".repeat(padding + label.len() + 5);
1282
1283         /// Returns `override` if it is present and `style` is `NoStyle` or `style` otherwise
1284         fn style_or_override(style: Style, override_: Option<Style>) -> Style {
1285             match (style, override_) {
1286                 (Style::NoStyle, Some(override_)) => override_,
1287                 _ => style,
1288             }
1289         }
1290
1291         let mut line_number = 0;
1292
1293         // Provided the following diagnostic message:
1294         //
1295         //     let msg = vec![
1296         //       ("
1297         //       ("highlighted multiline\nstring to\nsee how it ", Style::NoStyle),
1298         //       ("looks", Style::Highlight),
1299         //       ("with\nvery ", Style::NoStyle),
1300         //       ("weird", Style::Highlight),
1301         //       (" formats\n", Style::NoStyle),
1302         //       ("see?", Style::Highlight),
1303         //     ];
1304         //
1305         // the expected output on a note is (* surround the highlighted text)
1306         //
1307         //        = note: highlighted multiline
1308         //                string to
1309         //                see how it *looks* with
1310         //                very *weird* formats
1311         //                see?
1312         for &(ref text, ref style) in msg.iter() {
1313             let text = self.translate_message(text, args);
1314             let lines = text.split('\n').collect::<Vec<_>>();
1315             if lines.len() > 1 {
1316                 for (i, line) in lines.iter().enumerate() {
1317                     if i != 0 {
1318                         line_number += 1;
1319                         buffer.append(line_number, &padding, Style::NoStyle);
1320                     }
1321                     buffer.append(line_number, line, style_or_override(*style, override_style));
1322                 }
1323             } else {
1324                 buffer.append(line_number, &text, style_or_override(*style, override_style));
1325             }
1326         }
1327     }
1328
1329     fn emit_message_default(
1330         &mut self,
1331         msp: &MultiSpan,
1332         msg: &[(DiagnosticMessage, Style)],
1333         args: &FluentArgs<'_>,
1334         code: &Option<DiagnosticId>,
1335         level: &Level,
1336         max_line_num_len: usize,
1337         is_secondary: bool,
1338         emitted_at: Option<&DiagnosticLocation>,
1339     ) -> io::Result<()> {
1340         let mut buffer = StyledBuffer::new();
1341
1342         if !msp.has_primary_spans() && !msp.has_span_labels() && is_secondary && !self.short_message
1343         {
1344             // This is a secondary message with no span info
1345             for _ in 0..max_line_num_len {
1346                 buffer.prepend(0, " ", Style::NoStyle);
1347             }
1348             draw_note_separator(&mut buffer, 0, max_line_num_len + 1);
1349             if *level != Level::FailureNote {
1350                 buffer.append(0, level.to_str(), Style::MainHeaderMsg);
1351                 buffer.append(0, ": ", Style::NoStyle);
1352             }
1353             self.msg_to_buffer(&mut buffer, msg, args, max_line_num_len, "note", None);
1354         } else {
1355             let mut label_width = 0;
1356             // The failure note level itself does not provide any useful diagnostic information
1357             if *level != Level::FailureNote {
1358                 buffer.append(0, level.to_str(), Style::Level(*level));
1359                 label_width += level.to_str().len();
1360             }
1361             // only render error codes, not lint codes
1362             if let Some(DiagnosticId::Error(ref code)) = *code {
1363                 buffer.append(0, "[", Style::Level(*level));
1364                 buffer.append(0, &code, Style::Level(*level));
1365                 buffer.append(0, "]", Style::Level(*level));
1366                 label_width += 2 + code.len();
1367             }
1368             let header_style = if is_secondary { Style::HeaderMsg } else { Style::MainHeaderMsg };
1369             if *level != Level::FailureNote {
1370                 buffer.append(0, ": ", header_style);
1371                 label_width += 2;
1372             }
1373             for &(ref text, _) in msg.iter() {
1374                 let text = self.translate_message(text, args);
1375                 // Account for newlines to align output to its label.
1376                 for (line, text) in normalize_whitespace(&text).lines().enumerate() {
1377                     buffer.append(
1378                         0 + line,
1379                         &format!(
1380                             "{}{}",
1381                             if line == 0 { String::new() } else { " ".repeat(label_width) },
1382                             text
1383                         ),
1384                         header_style,
1385                     );
1386                 }
1387             }
1388         }
1389         let mut annotated_files = FileWithAnnotatedLines::collect_annotations(self, args, msp);
1390
1391         // Make sure our primary file comes first
1392         let (primary_lo, sm) = if let (Some(sm), Some(ref primary_span)) =
1393             (self.sm.as_ref(), msp.primary_span().as_ref())
1394         {
1395             if !primary_span.is_dummy() {
1396                 (sm.lookup_char_pos(primary_span.lo()), sm)
1397             } else {
1398                 emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1399                 return Ok(());
1400             }
1401         } else {
1402             // If we don't have span information, emit and exit
1403             emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1404             return Ok(());
1405         };
1406         if let Ok(pos) =
1407             annotated_files.binary_search_by(|x| x.file.name.cmp(&primary_lo.file.name))
1408         {
1409             annotated_files.swap(0, pos);
1410         }
1411
1412         // Print out the annotate source lines that correspond with the error
1413         for annotated_file in annotated_files {
1414             // we can't annotate anything if the source is unavailable.
1415             if !sm.ensure_source_file_source_present(annotated_file.file.clone()) {
1416                 continue;
1417             }
1418
1419             // print out the span location and spacer before we print the annotated source
1420             // to do this, we need to know if this span will be primary
1421             let is_primary = primary_lo.file.name == annotated_file.file.name;
1422             if is_primary {
1423                 let loc = primary_lo.clone();
1424                 if !self.short_message {
1425                     // remember where we are in the output buffer for easy reference
1426                     let buffer_msg_line_offset = buffer.num_lines();
1427
1428                     buffer.prepend(buffer_msg_line_offset, "--> ", Style::LineNumber);
1429                     buffer.append(
1430                         buffer_msg_line_offset,
1431                         &format!(
1432                             "{}:{}:{}",
1433                             sm.filename_for_diagnostics(&loc.file.name),
1434                             sm.doctest_offset_line(&loc.file.name, loc.line),
1435                             loc.col.0 + 1,
1436                         ),
1437                         Style::LineAndColumn,
1438                     );
1439                     for _ in 0..max_line_num_len {
1440                         buffer.prepend(buffer_msg_line_offset, " ", Style::NoStyle);
1441                     }
1442                 } else {
1443                     buffer.prepend(
1444                         0,
1445                         &format!(
1446                             "{}:{}:{}: ",
1447                             sm.filename_for_diagnostics(&loc.file.name),
1448                             sm.doctest_offset_line(&loc.file.name, loc.line),
1449                             loc.col.0 + 1,
1450                         ),
1451                         Style::LineAndColumn,
1452                     );
1453                 }
1454             } else if !self.short_message {
1455                 // remember where we are in the output buffer for easy reference
1456                 let buffer_msg_line_offset = buffer.num_lines();
1457
1458                 // Add spacing line
1459                 draw_col_separator_no_space(
1460                     &mut buffer,
1461                     buffer_msg_line_offset,
1462                     max_line_num_len + 1,
1463                 );
1464
1465                 // Then, the secondary file indicator
1466                 buffer.prepend(buffer_msg_line_offset + 1, "::: ", Style::LineNumber);
1467                 let loc = if let Some(first_line) = annotated_file.lines.first() {
1468                     let col = if let Some(first_annotation) = first_line.annotations.first() {
1469                         format!(":{}", first_annotation.start_col + 1)
1470                     } else {
1471                         String::new()
1472                     };
1473                     format!(
1474                         "{}:{}{}",
1475                         sm.filename_for_diagnostics(&annotated_file.file.name),
1476                         sm.doctest_offset_line(&annotated_file.file.name, first_line.line_index),
1477                         col
1478                     )
1479                 } else {
1480                     format!("{}", sm.filename_for_diagnostics(&annotated_file.file.name))
1481                 };
1482                 buffer.append(buffer_msg_line_offset + 1, &loc, Style::LineAndColumn);
1483                 for _ in 0..max_line_num_len {
1484                     buffer.prepend(buffer_msg_line_offset + 1, " ", Style::NoStyle);
1485                 }
1486             }
1487
1488             if !self.short_message {
1489                 // Put in the spacer between the location and annotated source
1490                 let buffer_msg_line_offset = buffer.num_lines();
1491                 draw_col_separator_no_space(
1492                     &mut buffer,
1493                     buffer_msg_line_offset,
1494                     max_line_num_len + 1,
1495                 );
1496
1497                 // Contains the vertical lines' positions for active multiline annotations
1498                 let mut multilines = FxIndexMap::default();
1499
1500                 // Get the left-side margin to remove it
1501                 let mut whitespace_margin = usize::MAX;
1502                 for line_idx in 0..annotated_file.lines.len() {
1503                     let file = annotated_file.file.clone();
1504                     let line = &annotated_file.lines[line_idx];
1505                     if let Some(source_string) = file.get_line(line.line_index - 1) {
1506                         let leading_whitespace = source_string
1507                             .chars()
1508                             .take_while(|c| c.is_whitespace())
1509                             .map(|c| {
1510                                 match c {
1511                                     // Tabs are displayed as 4 spaces
1512                                     '\t' => 4,
1513                                     _ => 1,
1514                                 }
1515                             })
1516                             .sum();
1517                         if source_string.chars().any(|c| !c.is_whitespace()) {
1518                             whitespace_margin = min(whitespace_margin, leading_whitespace);
1519                         }
1520                     }
1521                 }
1522                 if whitespace_margin == usize::MAX {
1523                     whitespace_margin = 0;
1524                 }
1525
1526                 // Left-most column any visible span points at.
1527                 let mut span_left_margin = usize::MAX;
1528                 for line in &annotated_file.lines {
1529                     for ann in &line.annotations {
1530                         span_left_margin = min(span_left_margin, ann.start_col);
1531                         span_left_margin = min(span_left_margin, ann.end_col);
1532                     }
1533                 }
1534                 if span_left_margin == usize::MAX {
1535                     span_left_margin = 0;
1536                 }
1537
1538                 // Right-most column any visible span points at.
1539                 let mut span_right_margin = 0;
1540                 let mut label_right_margin = 0;
1541                 let mut max_line_len = 0;
1542                 for line in &annotated_file.lines {
1543                     max_line_len = max(
1544                         max_line_len,
1545                         annotated_file.file.get_line(line.line_index - 1).map_or(0, |s| s.len()),
1546                     );
1547                     for ann in &line.annotations {
1548                         span_right_margin = max(span_right_margin, ann.start_col);
1549                         span_right_margin = max(span_right_margin, ann.end_col);
1550                         // FIXME: account for labels not in the same line
1551                         let label_right = ann.label.as_ref().map_or(0, |l| l.len() + 1);
1552                         label_right_margin = max(label_right_margin, ann.end_col + label_right);
1553                     }
1554                 }
1555
1556                 let width_offset = 3 + max_line_num_len;
1557                 let code_offset = if annotated_file.multiline_depth == 0 {
1558                     width_offset
1559                 } else {
1560                     width_offset + annotated_file.multiline_depth + 1
1561                 };
1562
1563                 let column_width = if let Some(width) = self.diagnostic_width {
1564                     width.saturating_sub(code_offset)
1565                 } else if self.ui_testing {
1566                     DEFAULT_COLUMN_WIDTH
1567                 } else {
1568                     termize::dimensions()
1569                         .map(|(w, _)| w.saturating_sub(code_offset))
1570                         .unwrap_or(DEFAULT_COLUMN_WIDTH)
1571                 };
1572
1573                 let margin = Margin::new(
1574                     whitespace_margin,
1575                     span_left_margin,
1576                     span_right_margin,
1577                     label_right_margin,
1578                     column_width,
1579                     max_line_len,
1580                 );
1581
1582                 // Next, output the annotate source for this file
1583                 for line_idx in 0..annotated_file.lines.len() {
1584                     let previous_buffer_line = buffer.num_lines();
1585
1586                     let depths = self.render_source_line(
1587                         &mut buffer,
1588                         annotated_file.file.clone(),
1589                         &annotated_file.lines[line_idx],
1590                         width_offset,
1591                         code_offset,
1592                         margin,
1593                     );
1594
1595                     let mut to_add = FxHashMap::default();
1596
1597                     for (depth, style) in depths {
1598                         if multilines.remove(&depth).is_none() {
1599                             to_add.insert(depth, style);
1600                         }
1601                     }
1602
1603                     // Set the multiline annotation vertical lines to the left of
1604                     // the code in this line.
1605                     for (depth, style) in &multilines {
1606                         for line in previous_buffer_line..buffer.num_lines() {
1607                             draw_multiline_line(&mut buffer, line, width_offset, *depth, *style);
1608                         }
1609                     }
1610                     // check to see if we need to print out or elide lines that come between
1611                     // this annotated line and the next one.
1612                     if line_idx < (annotated_file.lines.len() - 1) {
1613                         let line_idx_delta = annotated_file.lines[line_idx + 1].line_index
1614                             - annotated_file.lines[line_idx].line_index;
1615                         if line_idx_delta > 2 {
1616                             let last_buffer_line_num = buffer.num_lines();
1617                             buffer.puts(last_buffer_line_num, 0, "...", Style::LineNumber);
1618
1619                             // Set the multiline annotation vertical lines on `...` bridging line.
1620                             for (depth, style) in &multilines {
1621                                 draw_multiline_line(
1622                                     &mut buffer,
1623                                     last_buffer_line_num,
1624                                     width_offset,
1625                                     *depth,
1626                                     *style,
1627                                 );
1628                             }
1629                         } else if line_idx_delta == 2 {
1630                             let unannotated_line = annotated_file
1631                                 .file
1632                                 .get_line(annotated_file.lines[line_idx].line_index)
1633                                 .unwrap_or_else(|| Cow::from(""));
1634
1635                             let last_buffer_line_num = buffer.num_lines();
1636
1637                             self.draw_line(
1638                                 &mut buffer,
1639                                 &normalize_whitespace(&unannotated_line),
1640                                 annotated_file.lines[line_idx + 1].line_index - 1,
1641                                 last_buffer_line_num,
1642                                 width_offset,
1643                                 code_offset,
1644                                 margin,
1645                             );
1646
1647                             for (depth, style) in &multilines {
1648                                 draw_multiline_line(
1649                                     &mut buffer,
1650                                     last_buffer_line_num,
1651                                     width_offset,
1652                                     *depth,
1653                                     *style,
1654                                 );
1655                             }
1656                         }
1657                     }
1658
1659                     multilines.extend(&to_add);
1660                 }
1661             }
1662         }
1663
1664         if let Some(tracked) = emitted_at {
1665             let track = format!("-Ztrack-diagnostics: created at {tracked}");
1666             let len = buffer.num_lines();
1667             buffer.append(len, &track, Style::NoStyle);
1668         }
1669
1670         // final step: take our styled buffer, render it, then output it
1671         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1672
1673         Ok(())
1674     }
1675
1676     fn emit_suggestion_default(
1677         &mut self,
1678         span: &MultiSpan,
1679         suggestion: &CodeSuggestion,
1680         args: &FluentArgs<'_>,
1681         level: &Level,
1682         max_line_num_len: usize,
1683     ) -> io::Result<()> {
1684         let Some(ref sm) = self.sm else {
1685             return Ok(());
1686         };
1687
1688         // Render the replacements for each suggestion
1689         let suggestions = suggestion.splice_lines(&**sm);
1690         debug!("emit_suggestion_default: suggestions={:?}", suggestions);
1691
1692         if suggestions.is_empty() {
1693             // Suggestions coming from macros can have malformed spans. This is a heavy handed
1694             // approach to avoid ICEs by ignoring the suggestion outright.
1695             return Ok(());
1696         }
1697
1698         let mut buffer = StyledBuffer::new();
1699
1700         // Render the suggestion message
1701         buffer.append(0, level.to_str(), Style::Level(*level));
1702         buffer.append(0, ": ", Style::HeaderMsg);
1703
1704         self.msg_to_buffer(
1705             &mut buffer,
1706             &[(suggestion.msg.to_owned(), Style::NoStyle)],
1707             args,
1708             max_line_num_len,
1709             "suggestion",
1710             Some(Style::HeaderMsg),
1711         );
1712
1713         let mut row_num = 2;
1714         draw_col_separator_no_space(&mut buffer, 1, max_line_num_len + 1);
1715         let mut notice_capitalization = false;
1716         for (complete, parts, highlights, only_capitalization) in
1717             suggestions.iter().take(MAX_SUGGESTIONS)
1718         {
1719             notice_capitalization |= only_capitalization;
1720
1721             let has_deletion = parts.iter().any(|p| p.is_deletion(sm));
1722             let is_multiline = complete.lines().count() > 1;
1723
1724             if let Some(span) = span.primary_span() {
1725                 // Compare the primary span of the diagnostic with the span of the suggestion
1726                 // being emitted.  If they belong to the same file, we don't *need* to show the
1727                 // file name, saving in verbosity, but if it *isn't* we do need it, otherwise we're
1728                 // telling users to make a change but not clarifying *where*.
1729                 let loc = sm.lookup_char_pos(parts[0].span.lo());
1730                 if loc.file.name != sm.span_to_filename(span) && loc.file.name.is_real() {
1731                     buffer.puts(row_num - 1, 0, "--> ", Style::LineNumber);
1732                     buffer.append(
1733                         row_num - 1,
1734                         &format!(
1735                             "{}:{}:{}",
1736                             sm.filename_for_diagnostics(&loc.file.name),
1737                             sm.doctest_offset_line(&loc.file.name, loc.line),
1738                             loc.col.0 + 1,
1739                         ),
1740                         Style::LineAndColumn,
1741                     );
1742                     for _ in 0..max_line_num_len {
1743                         buffer.prepend(row_num - 1, " ", Style::NoStyle);
1744                     }
1745                     row_num += 1;
1746                 }
1747             }
1748             let show_code_change = if has_deletion && !is_multiline {
1749                 DisplaySuggestion::Diff
1750             } else if (parts.len() != 1 || parts[0].snippet.trim() != complete.trim())
1751                 && !is_multiline
1752             {
1753                 DisplaySuggestion::Underline
1754             } else {
1755                 DisplaySuggestion::None
1756             };
1757
1758             if let DisplaySuggestion::Diff = show_code_change {
1759                 row_num += 1;
1760             }
1761
1762             let file_lines = sm
1763                 .span_to_lines(parts[0].span)
1764                 .expect("span_to_lines failed when emitting suggestion");
1765
1766             assert!(!file_lines.lines.is_empty() || parts[0].span.is_dummy());
1767
1768             let line_start = sm.lookup_char_pos(parts[0].span.lo()).line;
1769             draw_col_separator_no_space(&mut buffer, row_num - 1, max_line_num_len + 1);
1770             let mut lines = complete.lines();
1771             if lines.clone().next().is_none() {
1772                 // Account for a suggestion to completely remove a line(s) with whitespace (#94192).
1773                 let line_end = sm.lookup_char_pos(parts[0].span.hi()).line;
1774                 for line in line_start..=line_end {
1775                     buffer.puts(
1776                         row_num - 1 + line - line_start,
1777                         0,
1778                         &self.maybe_anonymized(line),
1779                         Style::LineNumber,
1780                     );
1781                     buffer.puts(
1782                         row_num - 1 + line - line_start,
1783                         max_line_num_len + 1,
1784                         "- ",
1785                         Style::Removal,
1786                     );
1787                     buffer.puts(
1788                         row_num - 1 + line - line_start,
1789                         max_line_num_len + 3,
1790                         &normalize_whitespace(&*file_lines.file.get_line(line - 1).unwrap()),
1791                         Style::Removal,
1792                     );
1793                 }
1794                 row_num += line_end - line_start;
1795             }
1796             let mut unhighlighted_lines = Vec::new();
1797             for (line_pos, (line, highlight_parts)) in lines.by_ref().zip(highlights).enumerate() {
1798                 debug!(%line_pos, %line, ?highlight_parts);
1799
1800                 // Remember lines that are not highlighted to hide them if needed
1801                 if highlight_parts.is_empty() {
1802                     unhighlighted_lines.push((line_pos, line));
1803                     continue;
1804                 }
1805
1806                 match unhighlighted_lines.len() {
1807                     0 => (),
1808                     // Since we show first line, "..." line and last line,
1809                     // There is no reason to hide if there are 3 or less lines
1810                     // (because then we just replace a line with ... which is
1811                     // not helpful)
1812                     n if n <= 3 => unhighlighted_lines.drain(..).for_each(|(p, l)| {
1813                         self.draw_code_line(
1814                             &mut buffer,
1815                             &mut row_num,
1816                             &Vec::new(),
1817                             p,
1818                             l,
1819                             line_start,
1820                             show_code_change,
1821                             max_line_num_len,
1822                             &file_lines,
1823                             is_multiline,
1824                         )
1825                     }),
1826                     // Print first unhighlighted line, "..." and last unhighlighted line, like so:
1827                     //
1828                     // LL | this line was highlighted
1829                     // LL | this line is just for context
1830                     //   ...
1831                     // LL | this line is just for context
1832                     // LL | this line was highlighted
1833                     _ => {
1834                         let last_line = unhighlighted_lines.pop();
1835                         let first_line = unhighlighted_lines.drain(..).next();
1836
1837                         first_line.map(|(p, l)| {
1838                             self.draw_code_line(
1839                                 &mut buffer,
1840                                 &mut row_num,
1841                                 &Vec::new(),
1842                                 p,
1843                                 l,
1844                                 line_start,
1845                                 show_code_change,
1846                                 max_line_num_len,
1847                                 &file_lines,
1848                                 is_multiline,
1849                             )
1850                         });
1851
1852                         buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
1853                         row_num += 1;
1854
1855                         last_line.map(|(p, l)| {
1856                             self.draw_code_line(
1857                                 &mut buffer,
1858                                 &mut row_num,
1859                                 &Vec::new(),
1860                                 p,
1861                                 l,
1862                                 line_start,
1863                                 show_code_change,
1864                                 max_line_num_len,
1865                                 &file_lines,
1866                                 is_multiline,
1867                             )
1868                         });
1869                     }
1870                 }
1871
1872                 self.draw_code_line(
1873                     &mut buffer,
1874                     &mut row_num,
1875                     highlight_parts,
1876                     line_pos,
1877                     line,
1878                     line_start,
1879                     show_code_change,
1880                     max_line_num_len,
1881                     &file_lines,
1882                     is_multiline,
1883                 )
1884             }
1885
1886             // This offset and the ones below need to be signed to account for replacement code
1887             // that is shorter than the original code.
1888             let mut offsets: Vec<(usize, isize)> = Vec::new();
1889             // Only show an underline in the suggestions if the suggestion is not the
1890             // entirety of the code being shown and the displayed code is not multiline.
1891             if let DisplaySuggestion::Diff | DisplaySuggestion::Underline = show_code_change {
1892                 draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
1893                 for part in parts {
1894                     let span_start_pos = sm.lookup_char_pos(part.span.lo()).col_display;
1895                     let span_end_pos = sm.lookup_char_pos(part.span.hi()).col_display;
1896
1897                     // If this addition is _only_ whitespace, then don't trim it,
1898                     // or else we're just not rendering anything.
1899                     let is_whitespace_addition = part.snippet.trim().is_empty();
1900
1901                     // Do not underline the leading...
1902                     let start = if is_whitespace_addition {
1903                         0
1904                     } else {
1905                         part.snippet.len().saturating_sub(part.snippet.trim_start().len())
1906                     };
1907                     // ...or trailing spaces. Account for substitutions containing unicode
1908                     // characters.
1909                     let sub_len: usize =
1910                         if is_whitespace_addition { &part.snippet } else { part.snippet.trim() }
1911                             .chars()
1912                             .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
1913                             .sum();
1914
1915                     let offset: isize = offsets
1916                         .iter()
1917                         .filter_map(
1918                             |(start, v)| if span_start_pos <= *start { None } else { Some(v) },
1919                         )
1920                         .sum();
1921                     let underline_start = (span_start_pos + start) as isize + offset;
1922                     let underline_end = (span_start_pos + start + sub_len) as isize + offset;
1923                     assert!(underline_start >= 0 && underline_end >= 0);
1924                     let padding: usize = max_line_num_len + 3;
1925                     for p in underline_start..underline_end {
1926                         if let DisplaySuggestion::Underline = show_code_change {
1927                             // If this is a replacement, underline with `^`, if this is an addition
1928                             // underline with `+`.
1929                             buffer.putc(
1930                                 row_num,
1931                                 (padding as isize + p) as usize,
1932                                 if part.is_addition(&sm) { '+' } else { '~' },
1933                                 Style::Addition,
1934                             );
1935                         }
1936                     }
1937                     if let DisplaySuggestion::Diff = show_code_change {
1938                         // Colorize removal with red in diff format.
1939                         buffer.set_style_range(
1940                             row_num - 2,
1941                             (padding as isize + span_start_pos as isize) as usize,
1942                             (padding as isize + span_end_pos as isize) as usize,
1943                             Style::Removal,
1944                             true,
1945                         );
1946                     }
1947
1948                     // length of the code after substitution
1949                     let full_sub_len = part
1950                         .snippet
1951                         .chars()
1952                         .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
1953                         .sum::<usize>() as isize;
1954
1955                     // length of the code to be substituted
1956                     let snippet_len = span_end_pos as isize - span_start_pos as isize;
1957                     // For multiple substitutions, use the position *after* the previous
1958                     // substitutions have happened, only when further substitutions are
1959                     // located strictly after.
1960                     offsets.push((span_end_pos, full_sub_len - snippet_len));
1961                 }
1962                 row_num += 1;
1963             }
1964
1965             // if we elided some lines, add an ellipsis
1966             if lines.next().is_some() {
1967                 buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
1968             } else if let DisplaySuggestion::None = show_code_change {
1969                 draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
1970                 row_num += 1;
1971             }
1972         }
1973         if suggestions.len() > MAX_SUGGESTIONS {
1974             let others = suggestions.len() - MAX_SUGGESTIONS;
1975             let msg = format!("and {} other candidate{}", others, pluralize!(others));
1976             buffer.puts(row_num, max_line_num_len + 3, &msg, Style::NoStyle);
1977         } else if notice_capitalization {
1978             let msg = "notice the capitalization difference";
1979             buffer.puts(row_num, max_line_num_len + 3, &msg, Style::NoStyle);
1980         }
1981         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1982         Ok(())
1983     }
1984
1985     fn emit_messages_default(
1986         &mut self,
1987         level: &Level,
1988         message: &[(DiagnosticMessage, Style)],
1989         args: &FluentArgs<'_>,
1990         code: &Option<DiagnosticId>,
1991         span: &MultiSpan,
1992         children: &[SubDiagnostic],
1993         suggestions: &[CodeSuggestion],
1994         emitted_at: Option<&DiagnosticLocation>,
1995     ) {
1996         let max_line_num_len = if self.ui_testing {
1997             ANONYMIZED_LINE_NUM.len()
1998         } else {
1999             let n = self.get_max_line_num(span, children);
2000             num_decimal_digits(n)
2001         };
2002
2003         match self.emit_message_default(
2004             span,
2005             message,
2006             args,
2007             code,
2008             level,
2009             max_line_num_len,
2010             false,
2011             emitted_at,
2012         ) {
2013             Ok(()) => {
2014                 if !children.is_empty()
2015                     || suggestions.iter().any(|s| s.style != SuggestionStyle::CompletelyHidden)
2016                 {
2017                     let mut buffer = StyledBuffer::new();
2018                     if !self.short_message {
2019                         draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
2020                     }
2021                     if let Err(e) = emit_to_destination(
2022                         &buffer.render(),
2023                         level,
2024                         &mut self.dst,
2025                         self.short_message,
2026                     ) {
2027                         panic!("failed to emit error: {}", e)
2028                     }
2029                 }
2030                 if !self.short_message {
2031                     for child in children {
2032                         let span = child.render_span.as_ref().unwrap_or(&child.span);
2033                         if let Err(err) = self.emit_message_default(
2034                             &span,
2035                             &child.message,
2036                             args,
2037                             &None,
2038                             &child.level,
2039                             max_line_num_len,
2040                             true,
2041                             None,
2042                         ) {
2043                             panic!("failed to emit error: {}", err);
2044                         }
2045                     }
2046                     for sugg in suggestions {
2047                         if sugg.style == SuggestionStyle::CompletelyHidden {
2048                             // do not display this suggestion, it is meant only for tools
2049                         } else if sugg.style == SuggestionStyle::HideCodeAlways {
2050                             if let Err(e) = self.emit_message_default(
2051                                 &MultiSpan::new(),
2052                                 &[(sugg.msg.to_owned(), Style::HeaderMsg)],
2053                                 args,
2054                                 &None,
2055                                 &Level::Help,
2056                                 max_line_num_len,
2057                                 true,
2058                                 None,
2059                             ) {
2060                                 panic!("failed to emit error: {}", e);
2061                             }
2062                         } else if let Err(e) = self.emit_suggestion_default(
2063                             span,
2064                             sugg,
2065                             args,
2066                             &Level::Help,
2067                             max_line_num_len,
2068                         ) {
2069                             panic!("failed to emit error: {}", e);
2070                         };
2071                     }
2072                 }
2073             }
2074             Err(e) => panic!("failed to emit error: {}", e),
2075         }
2076
2077         let mut dst = self.dst.writable();
2078         match writeln!(dst) {
2079             Err(e) => panic!("failed to emit error: {}", e),
2080             _ => {
2081                 if let Err(e) = dst.flush() {
2082                     panic!("failed to emit error: {}", e)
2083                 }
2084             }
2085         }
2086     }
2087
2088     fn draw_code_line(
2089         &self,
2090         buffer: &mut StyledBuffer,
2091         row_num: &mut usize,
2092         highlight_parts: &Vec<SubstitutionHighlight>,
2093         line_pos: usize,
2094         line: &str,
2095         line_start: usize,
2096         show_code_change: DisplaySuggestion,
2097         max_line_num_len: usize,
2098         file_lines: &FileLines,
2099         is_multiline: bool,
2100     ) {
2101         // Print the span column to avoid confusion
2102         buffer.puts(*row_num, 0, &self.maybe_anonymized(line_start + line_pos), Style::LineNumber);
2103         if let DisplaySuggestion::Diff = show_code_change {
2104             // Add the line number for both addition and removal to drive the point home.
2105             //
2106             // N - fn foo<A: T>(bar: A) {
2107             // N + fn foo(bar: impl T) {
2108             buffer.puts(
2109                 *row_num - 1,
2110                 0,
2111                 &self.maybe_anonymized(line_start + line_pos),
2112                 Style::LineNumber,
2113             );
2114             buffer.puts(*row_num - 1, max_line_num_len + 1, "- ", Style::Removal);
2115             buffer.puts(
2116                 *row_num - 1,
2117                 max_line_num_len + 3,
2118                 &normalize_whitespace(
2119                     &*file_lines.file.get_line(file_lines.lines[line_pos].line_index).unwrap(),
2120                 ),
2121                 Style::NoStyle,
2122             );
2123             buffer.puts(*row_num, max_line_num_len + 1, "+ ", Style::Addition);
2124         } else if is_multiline {
2125             match &highlight_parts[..] {
2126                 [SubstitutionHighlight { start: 0, end }] if *end == line.len() => {
2127                     buffer.puts(*row_num, max_line_num_len + 1, "+ ", Style::Addition);
2128                 }
2129                 [] => {
2130                     draw_col_separator(buffer, *row_num, max_line_num_len + 1);
2131                 }
2132                 _ => {
2133                     buffer.puts(*row_num, max_line_num_len + 1, "~ ", Style::Addition);
2134                 }
2135             }
2136         } else {
2137             draw_col_separator(buffer, *row_num, max_line_num_len + 1);
2138         }
2139
2140         // print the suggestion
2141         buffer.append(*row_num, &normalize_whitespace(line), Style::NoStyle);
2142
2143         // Colorize addition/replacements with green.
2144         for &SubstitutionHighlight { start, end } in highlight_parts {
2145             // Account for tabs when highlighting (#87972).
2146             let tabs: usize = line
2147                 .chars()
2148                 .take(start)
2149                 .map(|ch| match ch {
2150                     '\t' => 3,
2151                     _ => 0,
2152                 })
2153                 .sum();
2154             buffer.set_style_range(
2155                 *row_num,
2156                 max_line_num_len + 3 + start + tabs,
2157                 max_line_num_len + 3 + end + tabs,
2158                 Style::Addition,
2159                 true,
2160             );
2161         }
2162         *row_num += 1;
2163     }
2164 }
2165
2166 #[derive(Clone, Copy, Debug)]
2167 enum DisplaySuggestion {
2168     Underline,
2169     Diff,
2170     None,
2171 }
2172
2173 impl FileWithAnnotatedLines {
2174     /// Preprocess all the annotations so that they are grouped by file and by line number
2175     /// This helps us quickly iterate over the whole message (including secondary file spans)
2176     pub fn collect_annotations(
2177         emitter: &dyn Emitter,
2178         args: &FluentArgs<'_>,
2179         msp: &MultiSpan,
2180     ) -> Vec<FileWithAnnotatedLines> {
2181         fn add_annotation_to_file(
2182             file_vec: &mut Vec<FileWithAnnotatedLines>,
2183             file: Lrc<SourceFile>,
2184             line_index: usize,
2185             ann: Annotation,
2186         ) {
2187             for slot in file_vec.iter_mut() {
2188                 // Look through each of our files for the one we're adding to
2189                 if slot.file.name == file.name {
2190                     // See if we already have a line for it
2191                     for line_slot in &mut slot.lines {
2192                         if line_slot.line_index == line_index {
2193                             line_slot.annotations.push(ann);
2194                             return;
2195                         }
2196                     }
2197                     // We don't have a line yet, create one
2198                     slot.lines.push(Line { line_index, annotations: vec![ann] });
2199                     slot.lines.sort();
2200                     return;
2201                 }
2202             }
2203             // This is the first time we're seeing the file
2204             file_vec.push(FileWithAnnotatedLines {
2205                 file,
2206                 lines: vec![Line { line_index, annotations: vec![ann] }],
2207                 multiline_depth: 0,
2208             });
2209         }
2210
2211         let mut output = vec![];
2212         let mut multiline_annotations = vec![];
2213
2214         if let Some(ref sm) = emitter.source_map() {
2215             for span_label in msp.span_labels() {
2216                 if span_label.span.is_dummy() {
2217                     continue;
2218                 }
2219
2220                 let lo = sm.lookup_char_pos(span_label.span.lo());
2221                 let mut hi = sm.lookup_char_pos(span_label.span.hi());
2222
2223                 // Watch out for "empty spans". If we get a span like 6..6, we
2224                 // want to just display a `^` at 6, so convert that to
2225                 // 6..7. This is degenerate input, but it's best to degrade
2226                 // gracefully -- and the parser likes to supply a span like
2227                 // that for EOF, in particular.
2228
2229                 if lo.col_display == hi.col_display && lo.line == hi.line {
2230                     hi.col_display += 1;
2231                 }
2232
2233                 if lo.line != hi.line {
2234                     let ml = MultilineAnnotation {
2235                         depth: 1,
2236                         line_start: lo.line,
2237                         line_end: hi.line,
2238                         start_col: lo.col_display,
2239                         end_col: hi.col_display,
2240                         is_primary: span_label.is_primary,
2241                         label: span_label
2242                             .label
2243                             .as_ref()
2244                             .map(|m| emitter.translate_message(m, args).to_string()),
2245                         overlaps_exactly: false,
2246                     };
2247                     multiline_annotations.push((lo.file, ml));
2248                 } else {
2249                     let ann = Annotation {
2250                         start_col: lo.col_display,
2251                         end_col: hi.col_display,
2252                         is_primary: span_label.is_primary,
2253                         label: span_label
2254                             .label
2255                             .as_ref()
2256                             .map(|m| emitter.translate_message(m, args).to_string()),
2257                         annotation_type: AnnotationType::Singleline,
2258                     };
2259                     add_annotation_to_file(&mut output, lo.file, lo.line, ann);
2260                 };
2261             }
2262         }
2263
2264         // Find overlapping multiline annotations, put them at different depths
2265         multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, ml.line_end));
2266         for (_, ann) in multiline_annotations.clone() {
2267             for (_, a) in multiline_annotations.iter_mut() {
2268                 // Move all other multiline annotations overlapping with this one
2269                 // one level to the right.
2270                 if !(ann.same_span(a))
2271                     && num_overlap(ann.line_start, ann.line_end, a.line_start, a.line_end, true)
2272                 {
2273                     a.increase_depth();
2274                 } else if ann.same_span(a) && &ann != a {
2275                     a.overlaps_exactly = true;
2276                 } else {
2277                     break;
2278                 }
2279             }
2280         }
2281
2282         let mut max_depth = 0; // max overlapping multiline spans
2283         for (file, ann) in multiline_annotations {
2284             max_depth = max(max_depth, ann.depth);
2285             let mut end_ann = ann.as_end();
2286             if !ann.overlaps_exactly {
2287                 // avoid output like
2288                 //
2289                 //  |        foo(
2290                 //  |   _____^
2291                 //  |  |_____|
2292                 //  | ||         bar,
2293                 //  | ||     );
2294                 //  | ||      ^
2295                 //  | ||______|
2296                 //  |  |______foo
2297                 //  |         baz
2298                 //
2299                 // and instead get
2300                 //
2301                 //  |       foo(
2302                 //  |  _____^
2303                 //  | |         bar,
2304                 //  | |     );
2305                 //  | |      ^
2306                 //  | |      |
2307                 //  | |______foo
2308                 //  |        baz
2309                 add_annotation_to_file(&mut output, file.clone(), ann.line_start, ann.as_start());
2310                 // 4 is the minimum vertical length of a multiline span when presented: two lines
2311                 // of code and two lines of underline. This is not true for the special case where
2312                 // the beginning doesn't have an underline, but the current logic seems to be
2313                 // working correctly.
2314                 let middle = min(ann.line_start + 4, ann.line_end);
2315                 for line in ann.line_start + 1..middle {
2316                     // Every `|` that joins the beginning of the span (`___^`) to the end (`|__^`).
2317                     add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
2318                 }
2319                 let line_end = ann.line_end - 1;
2320                 if middle < line_end {
2321                     add_annotation_to_file(&mut output, file.clone(), line_end, ann.as_line());
2322                 }
2323             } else {
2324                 end_ann.annotation_type = AnnotationType::Singleline;
2325             }
2326             add_annotation_to_file(&mut output, file, ann.line_end, end_ann);
2327         }
2328         for file_vec in output.iter_mut() {
2329             file_vec.multiline_depth = max_depth;
2330         }
2331         output
2332     }
2333 }
2334
2335 // instead of taking the String length or dividing by 10 while > 0, we multiply a limit by 10 until
2336 // we're higher. If the loop isn't exited by the `return`, the last multiplication will wrap, which
2337 // is OK, because while we cannot fit a higher power of 10 in a usize, the loop will end anyway.
2338 // This is also why we need the max number of decimal digits within a `usize`.
2339 fn num_decimal_digits(num: usize) -> usize {
2340     #[cfg(target_pointer_width = "64")]
2341     const MAX_DIGITS: usize = 20;
2342
2343     #[cfg(target_pointer_width = "32")]
2344     const MAX_DIGITS: usize = 10;
2345
2346     #[cfg(target_pointer_width = "16")]
2347     const MAX_DIGITS: usize = 5;
2348
2349     let mut lim = 10;
2350     for num_digits in 1..MAX_DIGITS {
2351         if num < lim {
2352             return num_digits;
2353         }
2354         lim = lim.wrapping_mul(10);
2355     }
2356     MAX_DIGITS
2357 }
2358
2359 // We replace some characters so the CLI output is always consistent and underlines aligned.
2360 const OUTPUT_REPLACEMENTS: &[(char, &str)] = &[
2361     ('\t', "    "),   // We do our own tab replacement
2362     ('\u{200D}', ""), // Replace ZWJ with nothing for consistent terminal output of grapheme clusters.
2363     ('\u{202A}', ""), // The following unicode text flow control characters are inconsistently
2364     ('\u{202B}', ""), // supported across CLIs and can cause confusion due to the bytes on disk
2365     ('\u{202D}', ""), // not corresponding to the visible source code, so we replace them always.
2366     ('\u{202E}', ""),
2367     ('\u{2066}', ""),
2368     ('\u{2067}', ""),
2369     ('\u{2068}', ""),
2370     ('\u{202C}', ""),
2371     ('\u{2069}', ""),
2372 ];
2373
2374 fn normalize_whitespace(str: &str) -> String {
2375     let mut s = str.to_string();
2376     for (c, replacement) in OUTPUT_REPLACEMENTS {
2377         s = s.replace(*c, replacement);
2378     }
2379     s
2380 }
2381
2382 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
2383     buffer.puts(line, col, "| ", Style::LineNumber);
2384 }
2385
2386 fn draw_col_separator_no_space(buffer: &mut StyledBuffer, line: usize, col: usize) {
2387     draw_col_separator_no_space_with_style(buffer, line, col, Style::LineNumber);
2388 }
2389
2390 fn draw_col_separator_no_space_with_style(
2391     buffer: &mut StyledBuffer,
2392     line: usize,
2393     col: usize,
2394     style: Style,
2395 ) {
2396     buffer.putc(line, col, '|', style);
2397 }
2398
2399 fn draw_range(
2400     buffer: &mut StyledBuffer,
2401     symbol: char,
2402     line: usize,
2403     col_from: usize,
2404     col_to: usize,
2405     style: Style,
2406 ) {
2407     for col in col_from..col_to {
2408         buffer.putc(line, col, symbol, style);
2409     }
2410 }
2411
2412 fn draw_note_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
2413     buffer.puts(line, col, "= ", Style::LineNumber);
2414 }
2415
2416 fn draw_multiline_line(
2417     buffer: &mut StyledBuffer,
2418     line: usize,
2419     offset: usize,
2420     depth: usize,
2421     style: Style,
2422 ) {
2423     buffer.putc(line, offset + depth - 1, '|', style);
2424 }
2425
2426 fn num_overlap(
2427     a_start: usize,
2428     a_end: usize,
2429     b_start: usize,
2430     b_end: usize,
2431     inclusive: bool,
2432 ) -> bool {
2433     let extra = if inclusive { 1 } else { 0 };
2434     (b_start..b_end + extra).contains(&a_start) || (a_start..a_end + extra).contains(&b_start)
2435 }
2436 fn overlaps(a1: &Annotation, a2: &Annotation, padding: usize) -> bool {
2437     num_overlap(a1.start_col, a1.end_col + padding, a2.start_col, a2.end_col, false)
2438 }
2439
2440 fn emit_to_destination(
2441     rendered_buffer: &[Vec<StyledString>],
2442     lvl: &Level,
2443     dst: &mut Destination,
2444     short_message: bool,
2445 ) -> io::Result<()> {
2446     use crate::lock;
2447
2448     let mut dst = dst.writable();
2449
2450     // In order to prevent error message interleaving, where multiple error lines get intermixed
2451     // when multiple compiler processes error simultaneously, we emit errors with additional
2452     // steps.
2453     //
2454     // On Unix systems, we write into a buffered terminal rather than directly to a terminal. When
2455     // the .flush() is called we take the buffer created from the buffered writes and write it at
2456     // one shot.  Because the Unix systems use ANSI for the colors, which is a text-based styling
2457     // scheme, this buffered approach works and maintains the styling.
2458     //
2459     // On Windows, styling happens through calls to a terminal API. This prevents us from using the
2460     // same buffering approach.  Instead, we use a global Windows mutex, which we acquire long
2461     // enough to output the full error message, then we release.
2462     let _buffer_lock = lock::acquire_global_lock("rustc_errors");
2463     for (pos, line) in rendered_buffer.iter().enumerate() {
2464         for part in line {
2465             dst.apply_style(*lvl, part.style)?;
2466             write!(dst, "{}", part.text)?;
2467             dst.reset()?;
2468         }
2469         if !short_message && (!lvl.is_failure_note() || pos != rendered_buffer.len() - 1) {
2470             writeln!(dst)?;
2471         }
2472     }
2473     dst.flush()?;
2474     Ok(())
2475 }
2476
2477 pub enum Destination {
2478     Terminal(StandardStream),
2479     Buffered(BufferWriter),
2480     // The bool denotes whether we should be emitting ansi color codes or not
2481     Raw(Box<(dyn Write + Send)>, bool),
2482 }
2483
2484 pub enum WritableDst<'a> {
2485     Terminal(&'a mut StandardStream),
2486     Buffered(&'a mut BufferWriter, Buffer),
2487     Raw(&'a mut (dyn Write + Send)),
2488     ColoredRaw(Ansi<&'a mut (dyn Write + Send)>),
2489 }
2490
2491 impl Destination {
2492     fn from_stderr(color: ColorConfig) -> Destination {
2493         let choice = color.to_color_choice();
2494         // On Windows we'll be performing global synchronization on the entire
2495         // system for emitting rustc errors, so there's no need to buffer
2496         // anything.
2497         //
2498         // On non-Windows we rely on the atomicity of `write` to ensure errors
2499         // don't get all jumbled up.
2500         if cfg!(windows) {
2501             Terminal(StandardStream::stderr(choice))
2502         } else {
2503             Buffered(BufferWriter::stderr(choice))
2504         }
2505     }
2506
2507     fn writable(&mut self) -> WritableDst<'_> {
2508         match *self {
2509             Destination::Terminal(ref mut t) => WritableDst::Terminal(t),
2510             Destination::Buffered(ref mut t) => {
2511                 let buf = t.buffer();
2512                 WritableDst::Buffered(t, buf)
2513             }
2514             Destination::Raw(ref mut t, false) => WritableDst::Raw(t),
2515             Destination::Raw(ref mut t, true) => WritableDst::ColoredRaw(Ansi::new(t)),
2516         }
2517     }
2518
2519     fn supports_color(&self) -> bool {
2520         match *self {
2521             Self::Terminal(ref stream) => stream.supports_color(),
2522             Self::Buffered(ref buffer) => buffer.buffer().supports_color(),
2523             Self::Raw(_, supports_color) => supports_color,
2524         }
2525     }
2526 }
2527
2528 impl<'a> WritableDst<'a> {
2529     fn apply_style(&mut self, lvl: Level, style: Style) -> io::Result<()> {
2530         let mut spec = ColorSpec::new();
2531         match style {
2532             Style::Addition => {
2533                 spec.set_fg(Some(Color::Green)).set_intense(true);
2534             }
2535             Style::Removal => {
2536                 spec.set_fg(Some(Color::Red)).set_intense(true);
2537             }
2538             Style::LineAndColumn => {}
2539             Style::LineNumber => {
2540                 spec.set_bold(true);
2541                 spec.set_intense(true);
2542                 if cfg!(windows) {
2543                     spec.set_fg(Some(Color::Cyan));
2544                 } else {
2545                     spec.set_fg(Some(Color::Blue));
2546                 }
2547             }
2548             Style::Quotation => {}
2549             Style::MainHeaderMsg => {
2550                 spec.set_bold(true);
2551                 if cfg!(windows) {
2552                     spec.set_intense(true).set_fg(Some(Color::White));
2553                 }
2554             }
2555             Style::UnderlinePrimary | Style::LabelPrimary => {
2556                 spec = lvl.color();
2557                 spec.set_bold(true);
2558             }
2559             Style::UnderlineSecondary | Style::LabelSecondary => {
2560                 spec.set_bold(true).set_intense(true);
2561                 if cfg!(windows) {
2562                     spec.set_fg(Some(Color::Cyan));
2563                 } else {
2564                     spec.set_fg(Some(Color::Blue));
2565                 }
2566             }
2567             Style::HeaderMsg | Style::NoStyle => {}
2568             Style::Level(lvl) => {
2569                 spec = lvl.color();
2570                 spec.set_bold(true);
2571             }
2572             Style::Highlight => {
2573                 spec.set_bold(true);
2574             }
2575         }
2576         self.set_color(&spec)
2577     }
2578
2579     fn set_color(&mut self, color: &ColorSpec) -> io::Result<()> {
2580         match *self {
2581             WritableDst::Terminal(ref mut t) => t.set_color(color),
2582             WritableDst::Buffered(_, ref mut t) => t.set_color(color),
2583             WritableDst::ColoredRaw(ref mut t) => t.set_color(color),
2584             WritableDst::Raw(_) => Ok(()),
2585         }
2586     }
2587
2588     fn reset(&mut self) -> io::Result<()> {
2589         match *self {
2590             WritableDst::Terminal(ref mut t) => t.reset(),
2591             WritableDst::Buffered(_, ref mut t) => t.reset(),
2592             WritableDst::ColoredRaw(ref mut t) => t.reset(),
2593             WritableDst::Raw(_) => Ok(()),
2594         }
2595     }
2596 }
2597
2598 impl<'a> Write for WritableDst<'a> {
2599     fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
2600         match *self {
2601             WritableDst::Terminal(ref mut t) => t.write(bytes),
2602             WritableDst::Buffered(_, ref mut buf) => buf.write(bytes),
2603             WritableDst::Raw(ref mut w) => w.write(bytes),
2604             WritableDst::ColoredRaw(ref mut t) => t.write(bytes),
2605         }
2606     }
2607
2608     fn flush(&mut self) -> io::Result<()> {
2609         match *self {
2610             WritableDst::Terminal(ref mut t) => t.flush(),
2611             WritableDst::Buffered(_, ref mut buf) => buf.flush(),
2612             WritableDst::Raw(ref mut w) => w.flush(),
2613             WritableDst::ColoredRaw(ref mut w) => w.flush(),
2614         }
2615     }
2616 }
2617
2618 impl<'a> Drop for WritableDst<'a> {
2619     fn drop(&mut self) {
2620         if let WritableDst::Buffered(ref mut dst, ref mut buf) = self {
2621             drop(dst.print(buf));
2622         }
2623     }
2624 }
2625
2626 /// Whether the original and suggested code are visually similar enough to warrant extra wording.
2627 pub fn is_case_difference(sm: &SourceMap, suggested: &str, sp: Span) -> bool {
2628     // FIXME: this should probably be extended to also account for `FO0` → `FOO` and unicode.
2629     let found = match sm.span_to_snippet(sp) {
2630         Ok(snippet) => snippet,
2631         Err(e) => {
2632             warn!(error = ?e, "Invalid span {:?}", sp);
2633             return false;
2634         }
2635     };
2636     let ascii_confusables = &['c', 'f', 'i', 'k', 'o', 's', 'u', 'v', 'w', 'x', 'y', 'z'];
2637     // All the chars that differ in capitalization are confusable (above):
2638     let confusable = iter::zip(found.chars(), suggested.chars())
2639         .filter(|(f, s)| f != s)
2640         .all(|(f, s)| (ascii_confusables.contains(&f) || ascii_confusables.contains(&s)));
2641     confusable && found.to_lowercase() == suggested.to_lowercase()
2642             // FIXME: We sometimes suggest the same thing we already have, which is a
2643             //        bug, but be defensive against that here.
2644             && found != suggested
2645 }