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, SpanLabel};
  28 use rustc_span::hygiene::{ExpnKind, MacroKind};
  29 use std::borrow::Cow;
  30 use std::cmp::{max, min, Reverse};
  31 use std::error::Report;
  32 use std::io::prelude::*;
  33 use std::io::{self, IsTerminal};
  34 use std::iter;
  35 use std::path::Path;
  36 use termcolor::{Ansi, BufferWriter, ColorChoice, ColorSpec, StandardStream};
  37 use termcolor::{Buffer, Color, WriteColor};
  38
  39 /// Default column width, used in tests and when terminal dimensions cannot be determined.
  40 const DEFAULT_COLUMN_WIDTH: usize = 140;
  41
  42 /// Describes the way the content of the `rendered` field of the json output is generated
  43 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
  44 pub enum HumanReadableErrorType {
  45     Default(ColorConfig),
  46     AnnotateSnippet(ColorConfig),
  47     Short(ColorConfig),
  48 }
  49
  50 impl HumanReadableErrorType {
  51     /// Returns a (`short`, `color`) tuple
  52     pub fn unzip(self) -> (bool, ColorConfig) {
  53         match self {
  54             HumanReadableErrorType::Default(cc) => (false, cc),
  55             HumanReadableErrorType::Short(cc) => (true, cc),
  56             HumanReadableErrorType::AnnotateSnippet(cc) => (false, cc),
  57         }
  58     }
  59     pub fn new_emitter(
  60         self,
  61         dst: Box<dyn Write + Send>,
  62         source_map: Option<Lrc<SourceMap>>,
  63         bundle: Option<Lrc<FluentBundle>>,
  64         fallback_bundle: LazyFallbackBundle,
  65         teach: bool,
  66         diagnostic_width: Option<usize>,
  67         macro_backtrace: bool,
  68         track_diagnostics: bool,
  69     ) -> EmitterWriter {
  70         let (short, color_config) = self.unzip();
  71         let color = color_config.suggests_using_colors();
  72         EmitterWriter::new(
  73             dst,
  74             source_map,
  75             bundle,
  76             fallback_bundle,
  77             short,
  78             teach,
  79             color,
  80             diagnostic_width,
  81             macro_backtrace,
  82             track_diagnostics,
  83         )
  84     }
  85 }
  86
  87 #[derive(Clone, Copy, Debug)]
  88 struct Margin {
  89     /// The available whitespace in the left that can be consumed when centering.
  90     pub whitespace_left: usize,
  91     /// The column of the beginning of left-most span.
  92     pub span_left: usize,
  93     /// The column of the end of right-most span.
  94     pub span_right: usize,
  95     /// The beginning of the line to be displayed.
  96     pub computed_left: usize,
  97     /// The end of the line to be displayed.
  98     pub computed_right: usize,
  99     /// The current width of the terminal. Uses value of `DEFAULT_COLUMN_WIDTH` constant by default
 100     /// and in tests.
 101     pub column_width: usize,
 102     /// The end column of a span label, including the span. Doesn't account for labels not in the
 103     /// same line as the span.
 104     pub label_right: usize,
 105 }
 106
 107 impl Margin {
 108     fn new(
 109         whitespace_left: usize,
 110         span_left: usize,
 111         span_right: usize,
 112         label_right: usize,
 113         column_width: usize,
 114         max_line_len: usize,
 115     ) -> Self {
 116         // The 6 is padding to give a bit of room for `...` when displaying:
 117         // ```
 118         // error: message
 119         //   --> file.rs:16:58
 120         //    |
 121         // 16 | ... fn foo(self) -> Self::Bar {
 122         //    |                     ^^^^^^^^^
 123         // ```
 124
 125         let mut m = Margin {
 126             whitespace_left: whitespace_left.saturating_sub(6),
 127             span_left: span_left.saturating_sub(6),
 128             span_right: span_right + 6,
 129             computed_left: 0,
 130             computed_right: 0,
 131             column_width,
 132             label_right: label_right + 6,
 133         };
 134         m.compute(max_line_len);
 135         m
 136     }
 137
 138     fn was_cut_left(&self) -> bool {
 139         self.computed_left > 0
 140     }
 141
 142     fn was_cut_right(&self, line_len: usize) -> bool {
 143         let right =
 144             if self.computed_right == self.span_right || self.computed_right == self.label_right {
 145                 // Account for the "..." padding given above. Otherwise we end up with code lines that
 146                 // do fit but end in "..." as if they were trimmed.
 147                 self.computed_right - 6
 148             } else {
 149                 self.computed_right
 150             };
 151         right < line_len && self.computed_left + self.column_width < line_len
 152     }
 153
 154     fn compute(&mut self, max_line_len: usize) {
 155         // When there's a lot of whitespace (>20), we want to trim it as it is useless.
 156         self.computed_left = if self.whitespace_left > 20 {
 157             self.whitespace_left - 16 // We want some padding.
 158         } else {
 159             0
 160         };
 161         // We want to show as much as possible, max_line_len is the right-most boundary for the
 162         // relevant code.
 163         self.computed_right = max(max_line_len, self.computed_left);
 164
 165         if self.computed_right - self.computed_left > self.column_width {
 166             // Trimming only whitespace isn't enough, let's get craftier.
 167             if self.label_right - self.whitespace_left <= self.column_width {
 168                 // Attempt to fit the code window only trimming whitespace.
 169                 self.computed_left = self.whitespace_left;
 170                 self.computed_right = self.computed_left + self.column_width;
 171             } else if self.label_right - self.span_left <= self.column_width {
 172                 // Attempt to fit the code window considering only the spans and labels.
 173                 let padding_left = (self.column_width - (self.label_right - self.span_left)) / 2;
 174                 self.computed_left = self.span_left.saturating_sub(padding_left);
 175                 self.computed_right = self.computed_left + self.column_width;
 176             } else if self.span_right - self.span_left <= self.column_width {
 177                 // Attempt to fit the code window considering the spans and labels plus padding.
 178                 let padding_left = (self.column_width - (self.span_right - self.span_left)) / 5 * 2;
 179                 self.computed_left = self.span_left.saturating_sub(padding_left);
 180                 self.computed_right = self.computed_left + self.column_width;
 181             } else {
 182                 // Mostly give up but still don't show the full line.
 183                 self.computed_left = self.span_left;
 184                 self.computed_right = self.span_right;
 185             }
 186         }
 187     }
 188
 189     fn left(&self, line_len: usize) -> usize {
 190         min(self.computed_left, line_len)
 191     }
 192
 193     fn right(&self, line_len: usize) -> usize {
 194         if line_len.saturating_sub(self.computed_left) <= self.column_width {
 195             line_len
 196         } else {
 197             min(line_len, self.computed_right)
 198         }
 199     }
 200 }
 201
 202 const ANONYMIZED_LINE_NUM: &str = "LL";
 203
 204 /// Emitter trait for emitting errors.
 205 pub trait Emitter: Translate {
 206     /// Emit a structured diagnostic.
 207     fn emit_diagnostic(&mut self, diag: &Diagnostic);
 208
 209     /// Emit a notification that an artifact has been output.
 210     /// This is currently only supported for the JSON format,
 211     /// other formats can, and will, simply ignore it.
 212     fn emit_artifact_notification(&mut self, _path: &Path, _artifact_type: &str) {}
 213
 214     fn emit_future_breakage_report(&mut self, _diags: Vec<Diagnostic>) {}
 215
 216     /// Emit list of unused externs
 217     fn emit_unused_externs(
 218         &mut self,
 219         _lint_level: rustc_lint_defs::Level,
 220         _unused_externs: &[&str],
 221     ) {
 222     }
 223
 224     /// Checks if should show explanations about "rustc --explain"
 225     fn should_show_explain(&self) -> bool {
 226         true
 227     }
 228
 229     /// Checks if we can use colors in the current output stream.
 230     fn supports_color(&self) -> bool {
 231         false
 232     }
 233
 234     fn source_map(&self) -> Option<&Lrc<SourceMap>>;
 235
 236     /// Formats the substitutions of the primary_span
 237     ///
 238     /// There are a lot of conditions to this method, but in short:
 239     ///
 240     /// * If the current `Diagnostic` has only one visible `CodeSuggestion`,
 241     ///   we format the `help` suggestion depending on the content of the
 242     ///   substitutions. In that case, we return the modified span only.
 243     ///
 244     /// * If the current `Diagnostic` has multiple suggestions,
 245     ///   we return the original `primary_span` and the original suggestions.
 246     fn primary_span_formatted<'a>(
 247         &mut self,
 248         diag: &'a Diagnostic,
 249         fluent_args: &FluentArgs<'_>,
 250     ) -> (MultiSpan, &'a [CodeSuggestion]) {
 251         let mut primary_span = diag.span.clone();
 252         let suggestions = diag.suggestions.as_deref().unwrap_or(&[]);
 253         if let Some((sugg, rest)) = suggestions.split_first() {
 254             let msg = self.translate_message(&sugg.msg, fluent_args).map_err(Report::new).unwrap();
 255             if rest.is_empty() &&
 256                // ^ if there is only one suggestion
 257                // don't display multi-suggestions as labels
 258                sugg.substitutions.len() == 1 &&
 259                // don't display multipart suggestions as labels
 260                sugg.substitutions[0].parts.len() == 1 &&
 261                // don't display long messages as labels
 262                msg.split_whitespace().count() < 10 &&
 263                // don't display multiline suggestions as labels
 264                !sugg.substitutions[0].parts[0].snippet.contains('\n') &&
 265                ![
 266                     // when this style is set we want the suggestion to be a message, not inline
 267                     SuggestionStyle::HideCodeAlways,
 268                     // trivial suggestion for tooling's sake, never shown
 269                     SuggestionStyle::CompletelyHidden,
 270                     // subtle suggestion, never shown inline
 271                     SuggestionStyle::ShowAlways,
 272                ].contains(&sugg.style)
 273             {
 274                 let substitution = &sugg.substitutions[0].parts[0].snippet.trim();
 275                 let msg = if substitution.is_empty() || sugg.style.hide_inline() {
 276                     // This substitution is only removal OR we explicitly don't want to show the
 277                     // code inline (`hide_inline`). Therefore, we don't show the substitution.
 278                     format!("help: {}", &msg)
 279                 } else {
 280                     // Show the default suggestion text with the substitution
 281                     format!(
 282                         "help: {}{}: `{}`",
 283                         &msg,
 284                         if self
 285                             .source_map()
 286                             .map(|sm| is_case_difference(
 287                                 sm,
 288                                 substitution,
 289                                 sugg.substitutions[0].parts[0].span,
 290                             ))
 291                             .unwrap_or(false)
 292                         {
 293                             " (notice the capitalization)"
 294                         } else {
 295                             ""
 296                         },
 297                         substitution,
 298                     )
 299                 };
 300                 primary_span.push_span_label(sugg.substitutions[0].parts[0].span, msg);
 301
 302                 // We return only the modified primary_span
 303                 (primary_span, &[])
 304             } else {
 305                 // if there are multiple suggestions, print them all in full
 306                 // to be consistent. We could try to figure out if we can
 307                 // make one (or the first one) inline, but that would give
 308                 // undue importance to a semi-random suggestion
 309                 (primary_span, suggestions)
 310             }
 311         } else {
 312             (primary_span, suggestions)
 313         }
 314     }
 315
 316     fn fix_multispans_in_extern_macros_and_render_macro_backtrace(
 317         &self,
 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(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         span: &mut MultiSpan,
 484         children: &mut Vec<SubDiagnostic>,
 485     ) {
 486         debug!("fix_multispans_in_extern_macros: before: span={:?} children={:?}", span, children);
 487         self.fix_multispan_in_extern_macros(span);
 488         for child in children.iter_mut() {
 489             self.fix_multispan_in_extern_macros(&mut child.span);
 490         }
 491         debug!("fix_multispans_in_extern_macros: after: span={:?} children={:?}", span, children);
 492     }
 493
 494     // This "fixes" MultiSpans that contain `Span`s pointing to locations inside of external macros.
 495     // Since these locations are often difficult to read,
 496     // we move these spans from the external macros to their corresponding use site.
 497     fn fix_multispan_in_extern_macros(&self, span: &mut MultiSpan) {
 498         let Some(source_map) = self.source_map() else { return };
 499         // First, find all the spans in external macros and point instead at their use site.
 500         let replacements: Vec<(Span, Span)> = span
 501             .primary_spans()
 502             .iter()
 503             .copied()
 504             .chain(span.span_labels().iter().map(|sp_label| sp_label.span))
 505             .filter_map(|sp| {
 506                 if !sp.is_dummy() && source_map.is_imported(sp) {
 507                     let maybe_callsite = sp.source_callsite();
 508                     if sp != maybe_callsite {
 509                         return Some((sp, maybe_callsite));
 510                     }
 511                 }
 512                 None
 513             })
 514             .collect();
 515
 516         // After we have them, make sure we replace these 'bad' def sites with their use sites.
 517         for (from, to) in replacements {
 518             span.replace(from, to);
 519         }
 520     }
 521 }
 522
 523 impl Translate for EmitterWriter {
 524     fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
 525         self.fluent_bundle.as_ref()
 526     }
 527
 528     fn fallback_fluent_bundle(&self) -> &FluentBundle {
 529         &self.fallback_bundle
 530     }
 531 }
 532
 533 impl Emitter for EmitterWriter {
 534     fn source_map(&self) -> Option<&Lrc<SourceMap>> {
 535         self.sm.as_ref()
 536     }
 537
 538     fn emit_diagnostic(&mut self, diag: &Diagnostic) {
 539         let fluent_args = to_fluent_args(diag.args());
 540
 541         let mut children = diag.children.clone();
 542         let (mut primary_span, suggestions) = self.primary_span_formatted(diag, &fluent_args);
 543         debug!("emit_diagnostic: suggestions={:?}", suggestions);
 544
 545         self.fix_multispans_in_extern_macros_and_render_macro_backtrace(
 546             &mut primary_span,
 547             &mut children,
 548             &diag.level,
 549             self.macro_backtrace,
 550         );
 551
 552         self.emit_messages_default(
 553             &diag.level,
 554             &diag.message,
 555             &fluent_args,
 556             &diag.code,
 557             &primary_span,
 558             &children,
 559             suggestions,
 560             self.track_diagnostics.then_some(&diag.emitted_at),
 561         );
 562     }
 563
 564     fn should_show_explain(&self) -> bool {
 565         !self.short_message
 566     }
 567
 568     fn supports_color(&self) -> bool {
 569         self.dst.supports_color()
 570     }
 571 }
 572
 573 /// An emitter that does nothing when emitting a non-fatal diagnostic.
 574 /// Fatal diagnostics are forwarded to `fatal_handler` to avoid silent
 575 /// failures of rustc, as witnessed e.g. in issue #89358.
 576 pub struct SilentEmitter {
 577     pub fatal_handler: Handler,
 578     pub fatal_note: Option<String>,
 579 }
 580
 581 impl Translate for SilentEmitter {
 582     fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
 583         None
 584     }
 585
 586     fn fallback_fluent_bundle(&self) -> &FluentBundle {
 587         panic!("silent emitter attempted to translate message")
 588     }
 589 }
 590
 591 impl Emitter for SilentEmitter {
 592     fn source_map(&self) -> Option<&Lrc<SourceMap>> {
 593         None
 594     }
 595
 596     fn emit_diagnostic(&mut self, d: &Diagnostic) {
 597         if d.level == Level::Fatal {
 598             let mut d = d.clone();
 599             if let Some(ref note) = self.fatal_note {
 600                 d.note(note);
 601             }
 602             self.fatal_handler.emit_diagnostic(&mut d);
 603         }
 604     }
 605 }
 606
 607 /// Maximum number of suggestions to be shown
 608 ///
 609 /// Arbitrary, but taken from trait import suggestion limit
 610 pub const MAX_SUGGESTIONS: usize = 4;
 611
 612 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 613 pub enum ColorConfig {
 614     Auto,
 615     Always,
 616     Never,
 617 }
 618
 619 impl ColorConfig {
 620     fn to_color_choice(self) -> ColorChoice {
 621         match self {
 622             ColorConfig::Always => {
 623                 if io::stderr().is_terminal() {
 624                     ColorChoice::Always
 625                 } else {
 626                     ColorChoice::AlwaysAnsi
 627                 }
 628             }
 629             ColorConfig::Never => ColorChoice::Never,
 630             ColorConfig::Auto if io::stderr().is_terminal() => ColorChoice::Auto,
 631             ColorConfig::Auto => ColorChoice::Never,
 632         }
 633     }
 634     fn suggests_using_colors(self) -> bool {
 635         match self {
 636             ColorConfig::Always | ColorConfig::Auto => true,
 637             ColorConfig::Never => false,
 638         }
 639     }
 640 }
 641
 642 /// Handles the writing of `HumanReadableErrorType::Default` and `HumanReadableErrorType::Short`
 643 pub struct EmitterWriter {
 644     dst: Destination,
 645     sm: Option<Lrc<SourceMap>>,
 646     fluent_bundle: Option<Lrc<FluentBundle>>,
 647     fallback_bundle: LazyFallbackBundle,
 648     short_message: bool,
 649     teach: bool,
 650     ui_testing: bool,
 651     diagnostic_width: Option<usize>,
 652
 653     macro_backtrace: bool,
 654     track_diagnostics: bool,
 655 }
 656
 657 #[derive(Debug)]
 658 pub struct FileWithAnnotatedLines {
 659     pub file: Lrc<SourceFile>,
 660     pub lines: Vec<Line>,
 661     multiline_depth: usize,
 662 }
 663
 664 impl EmitterWriter {
 665     pub fn stderr(
 666         color_config: ColorConfig,
 667         source_map: Option<Lrc<SourceMap>>,
 668         fluent_bundle: Option<Lrc<FluentBundle>>,
 669         fallback_bundle: LazyFallbackBundle,
 670         short_message: bool,
 671         teach: bool,
 672         diagnostic_width: Option<usize>,
 673         macro_backtrace: bool,
 674         track_diagnostics: bool,
 675     ) -> EmitterWriter {
 676         let dst = Destination::from_stderr(color_config);
 677         EmitterWriter {
 678             dst,
 679             sm: source_map,
 680             fluent_bundle,
 681             fallback_bundle,
 682             short_message,
 683             teach,
 684             ui_testing: false,
 685             diagnostic_width,
 686             macro_backtrace,
 687             track_diagnostics,
 688         }
 689     }
 690
 691     pub fn new(
 692         dst: Box<dyn Write + Send>,
 693         source_map: Option<Lrc<SourceMap>>,
 694         fluent_bundle: Option<Lrc<FluentBundle>>,
 695         fallback_bundle: LazyFallbackBundle,
 696         short_message: bool,
 697         teach: bool,
 698         colored: bool,
 699         diagnostic_width: Option<usize>,
 700         macro_backtrace: bool,
 701         track_diagnostics: bool,
 702     ) -> EmitterWriter {
 703         EmitterWriter {
 704             dst: Raw(dst, colored),
 705             sm: source_map,
 706             fluent_bundle,
 707             fallback_bundle,
 708             short_message,
 709             teach,
 710             ui_testing: false,
 711             diagnostic_width,
 712             macro_backtrace,
 713             track_diagnostics,
 714         }
 715     }
 716
 717     pub fn ui_testing(mut self, ui_testing: bool) -> Self {
 718         self.ui_testing = ui_testing;
 719         self
 720     }
 721
 722     fn maybe_anonymized(&self, line_num: usize) -> Cow<'static, str> {
 723         if self.ui_testing {
 724             Cow::Borrowed(ANONYMIZED_LINE_NUM)
 725         } else {
 726             Cow::Owned(line_num.to_string())
 727         }
 728     }
 729
 730     fn draw_line(
 731         &self,
 732         buffer: &mut StyledBuffer,
 733         source_string: &str,
 734         line_index: usize,
 735         line_offset: usize,
 736         width_offset: usize,
 737         code_offset: usize,
 738         margin: Margin,
 739     ) {
 740         // Tabs are assumed to have been replaced by spaces in calling code.
 741         debug_assert!(!source_string.contains('\t'));
 742         let line_len = source_string.len();
 743         // Create the source line we will highlight.
 744         let left = margin.left(line_len);
 745         let right = margin.right(line_len);
 746         // On long lines, we strip the source line, accounting for unicode.
 747         let mut taken = 0;
 748         let code: String = source_string
 749             .chars()
 750             .skip(left)
 751             .take_while(|ch| {
 752                 // Make sure that the trimming on the right will fall within the terminal width.
 753                 // FIXME: `unicode_width` sometimes disagrees with terminals on how wide a `char` is.
 754                 // For now, just accept that sometimes the code line will be longer than desired.
 755                 let next = unicode_width::UnicodeWidthChar::width(*ch).unwrap_or(1);
 756                 if taken + next > right - left {
 757                     return false;
 758                 }
 759                 taken += next;
 760                 true
 761             })
 762             .collect();
 763         buffer.puts(line_offset, code_offset, &code, Style::Quotation);
 764         if margin.was_cut_left() {
 765             // We have stripped some code/whitespace from the beginning, make it clear.
 766             buffer.puts(line_offset, code_offset, "...", Style::LineNumber);
 767         }
 768         if margin.was_cut_right(line_len) {
 769             // We have stripped some code after the right-most span end, make it clear we did so.
 770             buffer.puts(line_offset, code_offset + taken - 3, "...", Style::LineNumber);
 771         }
 772         buffer.puts(line_offset, 0, &self.maybe_anonymized(line_index), Style::LineNumber);
 773
 774         draw_col_separator_no_space(buffer, line_offset, width_offset - 2);
 775     }
 776
 777     #[instrument(level = "trace", skip(self), ret)]
 778     fn render_source_line(
 779         &self,
 780         buffer: &mut StyledBuffer,
 781         file: Lrc<SourceFile>,
 782         line: &Line,
 783         width_offset: usize,
 784         code_offset: usize,
 785         margin: Margin,
 786     ) -> Vec<(usize, Style)> {
 787         // Draw:
 788         //
 789         //   LL | ... code ...
 790         //      |     ^^-^ span label
 791         //      |       |
 792         //      |       secondary span label
 793         //
 794         //   ^^ ^ ^^^ ^^^^ ^^^ we don't care about code too far to the right of a span, we trim it
 795         //   |  | |   |
 796         //   |  | |   actual code found in your source code and the spans we use to mark it
 797         //   |  | when there's too much wasted space to the left, trim it
 798         //   |  vertical divider between the column number and the code
 799         //   column number
 800
 801         if line.line_index == 0 {
 802             return Vec::new();
 803         }
 804
 805         let source_string = match file.get_line(line.line_index - 1) {
 806             Some(s) => normalize_whitespace(&s),
 807             None => return Vec::new(),
 808         };
 809         trace!(?source_string);
 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         let mut buffer_ops = vec![];
 850         let mut annotations = vec![];
 851         let mut short_start = true;
 852         for ann in &line.annotations {
 853             if let AnnotationType::MultilineStart(depth) = ann.annotation_type {
 854                 if source_string.chars().take(ann.start_col).all(|c| c.is_whitespace()) {
 855                     let style = if ann.is_primary {
 856                         Style::UnderlinePrimary
 857                     } else {
 858                         Style::UnderlineSecondary
 859                     };
 860                     annotations.push((depth, style));
 861                     buffer_ops.push((line_offset, width_offset + depth - 1, '/', style));
 862                 } else {
 863                     short_start = false;
 864                     break;
 865                 }
 866             } else if let AnnotationType::MultilineLine(_) = ann.annotation_type {
 867             } else {
 868                 short_start = false;
 869                 break;
 870             }
 871         }
 872         if short_start {
 873             for (y, x, c, s) in buffer_ops {
 874                 buffer.putc(y, x, c, s);
 875             }
 876             return annotations;
 877         }
 878
 879         // We want to display like this:
 880         //
 881         //      vec.push(vec.pop().unwrap());
 882         //      ---      ^^^               - previous borrow ends here
 883         //      |        |
 884         //      |        error occurs here
 885         //      previous borrow of `vec` occurs here
 886         //
 887         // But there are some weird edge cases to be aware of:
 888         //
 889         //      vec.push(vec.pop().unwrap());
 890         //      --------                    - previous borrow ends here
 891         //      ||
 892         //      |this makes no sense
 893         //      previous borrow of `vec` occurs here
 894         //
 895         // For this reason, we group the lines into "highlight lines"
 896         // and "annotations lines", where the highlight lines have the `^`.
 897
 898         // Sort the annotations by (start, end col)
 899         // The labels are reversed, sort and then reversed again.
 900         // Consider a list of annotations (A1, A2, C1, C2, B1, B2) where
 901         // the letter signifies the span. Here we are only sorting by the
 902         // span and hence, the order of the elements with the same span will
 903         // not change. On reversing the ordering (|a, b| but b.cmp(a)), you get
 904         // (C1, C2, B1, B2, A1, A2). All the elements with the same span are
 905         // still ordered first to last, but all the elements with different
 906         // spans are ordered by their spans in last to first order. Last to
 907         // first order is important, because the jiggly lines and | are on
 908         // the left, so the rightmost span needs to be rendered first,
 909         // otherwise the lines would end up needing to go over a message.
 910
 911         let mut annotations = line.annotations.clone();
 912         annotations.sort_by_key(|a| Reverse(a.start_col));
 913
 914         // First, figure out where each label will be positioned.
 915         //
 916         // In the case where you have the following annotations:
 917         //
 918         //      vec.push(vec.pop().unwrap());
 919         //      --------                    - previous borrow ends here [C]
 920         //      ||
 921         //      |this makes no sense [B]
 922         //      previous borrow of `vec` occurs here [A]
 923         //
 924         // `annotations_position` will hold [(2, A), (1, B), (0, C)].
 925         //
 926         // We try, when possible, to stick the rightmost annotation at the end
 927         // of the highlight line:
 928         //
 929         //      vec.push(vec.pop().unwrap());
 930         //      ---      ---               - previous borrow ends here
 931         //
 932         // But sometimes that's not possible because one of the other
 933         // annotations overlaps it. For example, from the test
 934         // `span_overlap_label`, we have the following annotations
 935         // (written on distinct lines for clarity):
 936         //
 937         //      fn foo(x: u32) {
 938         //      --------------
 939         //             -
 940         //
 941         // In this case, we can't stick the rightmost-most label on
 942         // the highlight line, or we would get:
 943         //
 944         //      fn foo(x: u32) {
 945         //      -------- x_span
 946         //      |
 947         //      fn_span
 948         //
 949         // which is totally weird. Instead we want:
 950         //
 951         //      fn foo(x: u32) {
 952         //      --------------
 953         //      |      |
 954         //      |      x_span
 955         //      fn_span
 956         //
 957         // which is...less weird, at least. In fact, in general, if
 958         // the rightmost span overlaps with any other span, we should
 959         // use the "hang below" version, so we can at least make it
 960         // clear where the span *starts*. There's an exception for this
 961         // logic, when the labels do not have a message:
 962         //
 963         //      fn foo(x: u32) {
 964         //      --------------
 965         //             |
 966         //             x_span
 967         //
 968         // instead of:
 969         //
 970         //      fn foo(x: u32) {
 971         //      --------------
 972         //      |      |
 973         //      |      x_span
 974         //      <EMPTY LINE>
 975         //
 976         let mut annotations_position = vec![];
 977         let mut line_len = 0;
 978         let mut p = 0;
 979         for (i, annotation) in annotations.iter().enumerate() {
 980             for (j, next) in annotations.iter().enumerate() {
 981                 if overlaps(next, annotation, 0)  // This label overlaps with another one and both
 982                     && annotation.has_label()     // take space (they have text and are not
 983                     && j > i                      // multiline lines).
 984                     && p == 0
 985                 // We're currently on the first line, move the label one line down
 986                 {
 987                     // If we're overlapping with an un-labelled annotation with the same span
 988                     // we can just merge them in the output
 989                     if next.start_col == annotation.start_col
 990                         && next.end_col == annotation.end_col
 991                         && !next.has_label()
 992                     {
 993                         continue;
 994                     }
 995
 996                     // This annotation needs a new line in the output.
 997                     p += 1;
 998                     break;
 999                 }
1000             }
1001             annotations_position.push((p, annotation));
1002             for (j, next) in annotations.iter().enumerate() {
1003                 if j > i {
1004                     let l = next.label.as_ref().map_or(0, |label| label.len() + 2);
1005                     if (overlaps(next, annotation, l) // Do not allow two labels to be in the same
1006                                                      // line if they overlap including padding, to
1007                                                      // avoid situations like:
1008                                                      //
1009                                                      //      fn foo(x: u32) {
1010                                                      //      -------^------
1011                                                      //      |      |
1012                                                      //      fn_spanx_span
1013                                                      //
1014                         && annotation.has_label()    // Both labels must have some text, otherwise
1015                         && next.has_label())         // they are not overlapping.
1016                                                      // Do not add a new line if this annotation
1017                                                      // or the next are vertical line placeholders.
1018                         || (annotation.takes_space() // If either this or the next annotation is
1019                             && next.has_label())     // multiline start/end, move it to a new line
1020                         || (annotation.has_label()   // so as not to overlap the horizontal lines.
1021                             && next.takes_space())
1022                         || (annotation.takes_space() && next.takes_space())
1023                         || (overlaps(next, annotation, l)
1024                             && next.end_col <= annotation.end_col
1025                             && next.has_label()
1026                             && p == 0)
1027                     // Avoid #42595.
1028                     {
1029                         // This annotation needs a new line in the output.
1030                         p += 1;
1031                         break;
1032                     }
1033                 }
1034             }
1035             line_len = max(line_len, p);
1036         }
1037
1038         if line_len != 0 {
1039             line_len += 1;
1040         }
1041
1042         // If there are no annotations or the only annotations on this line are
1043         // MultilineLine, then there's only code being shown, stop processing.
1044         if line.annotations.iter().all(|a| a.is_line()) {
1045             return vec![];
1046         }
1047
1048         // Write the column separator.
1049         //
1050         // After this we will have:
1051         //
1052         // 2 |   fn foo() {
1053         //   |
1054         //   |
1055         //   |
1056         // 3 |
1057         // 4 |   }
1058         //   |
1059         for pos in 0..=line_len {
1060             draw_col_separator(buffer, line_offset + pos + 1, width_offset - 2);
1061         }
1062
1063         // Write the horizontal lines for multiline annotations
1064         // (only the first and last lines need this).
1065         //
1066         // After this we will have:
1067         //
1068         // 2 |   fn foo() {
1069         //   |  __________
1070         //   |
1071         //   |
1072         // 3 |
1073         // 4 |   }
1074         //   |  _
1075         for &(pos, annotation) in &annotations_position {
1076             let style = if annotation.is_primary {
1077                 Style::UnderlinePrimary
1078             } else {
1079                 Style::UnderlineSecondary
1080             };
1081             let pos = pos + 1;
1082             match annotation.annotation_type {
1083                 AnnotationType::MultilineStart(depth) | AnnotationType::MultilineEnd(depth) => {
1084                     draw_range(
1085                         buffer,
1086                         '_',
1087                         line_offset + pos,
1088                         width_offset + depth,
1089                         (code_offset + annotation.start_col).saturating_sub(left),
1090                         style,
1091                     );
1092                 }
1093                 _ if self.teach => {
1094                     buffer.set_style_range(
1095                         line_offset,
1096                         (code_offset + annotation.start_col).saturating_sub(left),
1097                         (code_offset + annotation.end_col).saturating_sub(left),
1098                         style,
1099                         annotation.is_primary,
1100                     );
1101                 }
1102                 _ => {}
1103             }
1104         }
1105
1106         // Write the vertical lines for labels that are on a different line as the underline.
1107         //
1108         // After this we will have:
1109         //
1110         // 2 |   fn foo() {
1111         //   |  __________
1112         //   | |    |
1113         //   | |
1114         // 3 | |
1115         // 4 | | }
1116         //   | |_
1117         for &(pos, annotation) in &annotations_position {
1118             let style = if annotation.is_primary {
1119                 Style::UnderlinePrimary
1120             } else {
1121                 Style::UnderlineSecondary
1122             };
1123             let pos = pos + 1;
1124
1125             if pos > 1 && (annotation.has_label() || annotation.takes_space()) {
1126                 for p in line_offset + 1..=line_offset + pos {
1127                     buffer.putc(
1128                         p,
1129                         (code_offset + annotation.start_col).saturating_sub(left),
1130                         '|',
1131                         style,
1132                     );
1133                 }
1134             }
1135             match annotation.annotation_type {
1136                 AnnotationType::MultilineStart(depth) => {
1137                     for p in line_offset + pos + 1..line_offset + line_len + 2 {
1138                         buffer.putc(p, width_offset + depth - 1, '|', style);
1139                     }
1140                 }
1141                 AnnotationType::MultilineEnd(depth) => {
1142                     for p in line_offset..=line_offset + pos {
1143                         buffer.putc(p, width_offset + depth - 1, '|', style);
1144                     }
1145                 }
1146                 _ => (),
1147             }
1148         }
1149
1150         // Write the labels on the annotations that actually have a label.
1151         //
1152         // After this we will have:
1153         //
1154         // 2 |   fn foo() {
1155         //   |  __________
1156         //   |      |
1157         //   |      something about `foo`
1158         // 3 |
1159         // 4 |   }
1160         //   |  _  test
1161         for &(pos, annotation) in &annotations_position {
1162             let style =
1163                 if annotation.is_primary { Style::LabelPrimary } else { Style::LabelSecondary };
1164             let (pos, col) = if pos == 0 {
1165                 (pos + 1, (annotation.end_col + 1).saturating_sub(left))
1166             } else {
1167                 (pos + 2, annotation.start_col.saturating_sub(left))
1168             };
1169             if let Some(ref label) = annotation.label {
1170                 buffer.puts(line_offset + pos, code_offset + col, label, style);
1171             }
1172         }
1173
1174         // Sort from biggest span to smallest span so that smaller spans are
1175         // represented in the output:
1176         //
1177         // x | fn foo()
1178         //   | ^^^---^^
1179         //   | |  |
1180         //   | |  something about `foo`
1181         //   | something about `fn foo()`
1182         annotations_position.sort_by_key(|(_, ann)| {
1183             // Decreasing order. When annotations share the same length, prefer `Primary`.
1184             (Reverse(ann.len()), ann.is_primary)
1185         });
1186
1187         // Write the underlines.
1188         //
1189         // After this we will have:
1190         //
1191         // 2 |   fn foo() {
1192         //   |  ____-_____^
1193         //   |      |
1194         //   |      something about `foo`
1195         // 3 |
1196         // 4 |   }
1197         //   |  _^  test
1198         for &(_, annotation) in &annotations_position {
1199             let (underline, style) = if annotation.is_primary {
1200                 ('^', Style::UnderlinePrimary)
1201             } else {
1202                 ('-', Style::UnderlineSecondary)
1203             };
1204             for p in annotation.start_col..annotation.end_col {
1205                 buffer.putc(
1206                     line_offset + 1,
1207                     (code_offset + p).saturating_sub(left),
1208                     underline,
1209                     style,
1210                 );
1211             }
1212         }
1213         annotations_position
1214             .iter()
1215             .filter_map(|&(_, annotation)| match annotation.annotation_type {
1216                 AnnotationType::MultilineStart(p) | AnnotationType::MultilineEnd(p) => {
1217                     let style = if annotation.is_primary {
1218                         Style::LabelPrimary
1219                     } else {
1220                         Style::LabelSecondary
1221                     };
1222                     Some((p, style))
1223                 }
1224                 _ => None,
1225             })
1226             .collect::<Vec<_>>()
1227     }
1228
1229     fn get_multispan_max_line_num(&mut self, msp: &MultiSpan) -> usize {
1230         let Some(ref sm) = self.sm else {
1231             return 0;
1232         };
1233
1234         let will_be_emitted = |span: Span| {
1235             !span.is_dummy() && {
1236                 let file = sm.lookup_source_file(span.hi());
1237                 sm.ensure_source_file_source_present(file)
1238             }
1239         };
1240
1241         let mut max = 0;
1242         for primary_span in msp.primary_spans() {
1243             if will_be_emitted(*primary_span) {
1244                 let hi = sm.lookup_char_pos(primary_span.hi());
1245                 max = (hi.line).max(max);
1246             }
1247         }
1248         if !self.short_message {
1249             for span_label in msp.span_labels() {
1250                 if will_be_emitted(span_label.span) {
1251                     let hi = sm.lookup_char_pos(span_label.span.hi());
1252                     max = (hi.line).max(max);
1253                 }
1254             }
1255         }
1256
1257         max
1258     }
1259
1260     fn get_max_line_num(&mut self, span: &MultiSpan, children: &[SubDiagnostic]) -> usize {
1261         let primary = self.get_multispan_max_line_num(span);
1262         children
1263             .iter()
1264             .map(|sub| self.get_multispan_max_line_num(&sub.span))
1265             .max()
1266             .unwrap_or(0)
1267             .max(primary)
1268     }
1269
1270     /// Adds a left margin to every line but the first, given a padding length and the label being
1271     /// displayed, keeping the provided highlighting.
1272     fn msg_to_buffer(
1273         &self,
1274         buffer: &mut StyledBuffer,
1275         msg: &[(DiagnosticMessage, Style)],
1276         args: &FluentArgs<'_>,
1277         padding: usize,
1278         label: &str,
1279         override_style: Option<Style>,
1280     ) {
1281         // The extra 5 ` ` is padding that's always needed to align to the `note: `:
1282         //
1283         //   error: message
1284         //     --> file.rs:13:20
1285         //      |
1286         //   13 |     <CODE>
1287         //      |      ^^^^
1288         //      |
1289         //      = note: multiline
1290         //              message
1291         //   ++^^^----xx
1292         //    |  |   | |
1293         //    |  |   | magic `2`
1294         //    |  |   length of label
1295         //    |  magic `3`
1296         //    `max_line_num_len`
1297         let padding = " ".repeat(padding + label.len() + 5);
1298
1299         /// Returns `override` if it is present and `style` is `NoStyle` or `style` otherwise
1300         fn style_or_override(style: Style, override_: Option<Style>) -> Style {
1301             match (style, override_) {
1302                 (Style::NoStyle, Some(override_)) => override_,
1303                 _ => style,
1304             }
1305         }
1306
1307         let mut line_number = 0;
1308
1309         // Provided the following diagnostic message:
1310         //
1311         //     let msg = vec![
1312         //       ("
1313         //       ("highlighted multiline\nstring to\nsee how it ", Style::NoStyle),
1314         //       ("looks", Style::Highlight),
1315         //       ("with\nvery ", Style::NoStyle),
1316         //       ("weird", Style::Highlight),
1317         //       (" formats\n", Style::NoStyle),
1318         //       ("see?", Style::Highlight),
1319         //     ];
1320         //
1321         // the expected output on a note is (* surround the highlighted text)
1322         //
1323         //        = note: highlighted multiline
1324         //                string to
1325         //                see how it *looks* with
1326         //                very *weird* formats
1327         //                see?
1328         for (text, style) in msg.iter() {
1329             let text = self.translate_message(text, args).map_err(Report::new).unwrap();
1330             let lines = text.split('\n').collect::<Vec<_>>();
1331             if lines.len() > 1 {
1332                 for (i, line) in lines.iter().enumerate() {
1333                     if i != 0 {
1334                         line_number += 1;
1335                         buffer.append(line_number, &padding, Style::NoStyle);
1336                     }
1337                     buffer.append(line_number, line, style_or_override(*style, override_style));
1338                 }
1339             } else {
1340                 buffer.append(line_number, &text, style_or_override(*style, override_style));
1341             }
1342         }
1343     }
1344
1345     #[instrument(level = "trace", skip(self, args), ret)]
1346     fn emit_message_default(
1347         &mut self,
1348         msp: &MultiSpan,
1349         msg: &[(DiagnosticMessage, Style)],
1350         args: &FluentArgs<'_>,
1351         code: &Option<DiagnosticId>,
1352         level: &Level,
1353         max_line_num_len: usize,
1354         is_secondary: bool,
1355         emitted_at: Option<&DiagnosticLocation>,
1356     ) -> io::Result<()> {
1357         let mut buffer = StyledBuffer::new();
1358
1359         if !msp.has_primary_spans() && !msp.has_span_labels() && is_secondary && !self.short_message
1360         {
1361             // This is a secondary message with no span info
1362             for _ in 0..max_line_num_len {
1363                 buffer.prepend(0, " ", Style::NoStyle);
1364             }
1365             draw_note_separator(&mut buffer, 0, max_line_num_len + 1);
1366             if *level != Level::FailureNote {
1367                 buffer.append(0, level.to_str(), Style::MainHeaderMsg);
1368                 buffer.append(0, ": ", Style::NoStyle);
1369             }
1370             self.msg_to_buffer(&mut buffer, msg, args, max_line_num_len, "note", None);
1371         } else {
1372             let mut label_width = 0;
1373             // The failure note level itself does not provide any useful diagnostic information
1374             if *level != Level::FailureNote {
1375                 buffer.append(0, level.to_str(), Style::Level(*level));
1376                 label_width += level.to_str().len();
1377             }
1378             // only render error codes, not lint codes
1379             if let Some(DiagnosticId::Error(ref code)) = *code {
1380                 buffer.append(0, "[", Style::Level(*level));
1381                 buffer.append(0, code, Style::Level(*level));
1382                 buffer.append(0, "]", Style::Level(*level));
1383                 label_width += 2 + code.len();
1384             }
1385             let header_style = if is_secondary { Style::HeaderMsg } else { Style::MainHeaderMsg };
1386             if *level != Level::FailureNote {
1387                 buffer.append(0, ": ", header_style);
1388                 label_width += 2;
1389             }
1390             for (text, _) in msg.iter() {
1391                 let text = self.translate_message(text, args).map_err(Report::new).unwrap();
1392                 // Account for newlines to align output to its label.
1393                 for (line, text) in normalize_whitespace(&text).lines().enumerate() {
1394                     buffer.append(
1395                         0 + line,
1396                         &format!(
1397                             "{}{}",
1398                             if line == 0 { String::new() } else { " ".repeat(label_width) },
1399                             text
1400                         ),
1401                         header_style,
1402                     );
1403                 }
1404             }
1405         }
1406         let mut annotated_files = FileWithAnnotatedLines::collect_annotations(self, args, msp);
1407         trace!("{annotated_files:#?}");
1408
1409         // Make sure our primary file comes first
1410         let primary_span = msp.primary_span().unwrap_or_default();
1411         let (Some(sm), false) = (self.sm.as_ref(), primary_span.is_dummy()) else {
1412             // If we don't have span information, emit and exit
1413             return emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message);
1414         };
1415         let primary_lo = sm.lookup_char_pos(primary_span.lo());
1416         if let Ok(pos) =
1417             annotated_files.binary_search_by(|x| x.file.name.cmp(&primary_lo.file.name))
1418         {
1419             annotated_files.swap(0, pos);
1420         }
1421
1422         // Print out the annotate source lines that correspond with the error
1423         for annotated_file in annotated_files {
1424             // we can't annotate anything if the source is unavailable.
1425             if !sm.ensure_source_file_source_present(annotated_file.file.clone()) {
1426                 if !self.short_message {
1427                     // We'll just print an unannotated message.
1428                     for (annotation_id, line) in annotated_file.lines.iter().enumerate() {
1429                         let mut annotations = line.annotations.clone();
1430                         annotations.sort_by_key(|a| Reverse(a.start_col));
1431                         let mut line_idx = buffer.num_lines();
1432
1433                         let labels: Vec<_> = annotations
1434                             .iter()
1435                             .filter_map(|a| Some((a.label.as_ref()?, a.is_primary)))
1436                             .filter(|(l, _)| !l.is_empty())
1437                             .collect();
1438
1439                         if annotation_id == 0 || !labels.is_empty() {
1440                             buffer.append(
1441                                 line_idx,
1442                                 &format!(
1443                                     "{}:{}:{}",
1444                                     sm.filename_for_diagnostics(&annotated_file.file.name),
1445                                     sm.doctest_offset_line(
1446                                         &annotated_file.file.name,
1447                                         line.line_index
1448                                     ),
1449                                     annotations[0].start_col + 1,
1450                                 ),
1451                                 Style::LineAndColumn,
1452                             );
1453                             if annotation_id == 0 {
1454                                 buffer.prepend(line_idx, "--> ", Style::LineNumber);
1455                             } else {
1456                                 buffer.prepend(line_idx, "::: ", Style::LineNumber);
1457                             }
1458                             for _ in 0..max_line_num_len {
1459                                 buffer.prepend(line_idx, " ", Style::NoStyle);
1460                             }
1461                             line_idx += 1;
1462                         }
1463                         for (label, is_primary) in labels.into_iter() {
1464                             let style = if is_primary {
1465                                 Style::LabelPrimary
1466                             } else {
1467                                 Style::LabelSecondary
1468                             };
1469                             buffer.prepend(line_idx, " |", Style::LineNumber);
1470                             for _ in 0..max_line_num_len {
1471                                 buffer.prepend(line_idx, " ", Style::NoStyle);
1472                             }
1473                             line_idx += 1;
1474                             buffer.append(line_idx, " = note: ", style);
1475                             for _ in 0..max_line_num_len {
1476                                 buffer.prepend(line_idx, " ", Style::NoStyle);
1477                             }
1478                             buffer.append(line_idx, label, style);
1479                             line_idx += 1;
1480                         }
1481                     }
1482                 }
1483                 continue;
1484             }
1485
1486             // print out the span location and spacer before we print the annotated source
1487             // to do this, we need to know if this span will be primary
1488             let is_primary = primary_lo.file.name == annotated_file.file.name;
1489             if is_primary {
1490                 let loc = primary_lo.clone();
1491                 if !self.short_message {
1492                     // remember where we are in the output buffer for easy reference
1493                     let buffer_msg_line_offset = buffer.num_lines();
1494
1495                     buffer.prepend(buffer_msg_line_offset, "--> ", Style::LineNumber);
1496                     buffer.append(
1497                         buffer_msg_line_offset,
1498                         &format!(
1499                             "{}:{}:{}",
1500                             sm.filename_for_diagnostics(&loc.file.name),
1501                             sm.doctest_offset_line(&loc.file.name, loc.line),
1502                             loc.col.0 + 1,
1503                         ),
1504                         Style::LineAndColumn,
1505                     );
1506                     for _ in 0..max_line_num_len {
1507                         buffer.prepend(buffer_msg_line_offset, " ", Style::NoStyle);
1508                     }
1509                 } else {
1510                     buffer.prepend(
1511                         0,
1512                         &format!(
1513                             "{}:{}:{}: ",
1514                             sm.filename_for_diagnostics(&loc.file.name),
1515                             sm.doctest_offset_line(&loc.file.name, loc.line),
1516                             loc.col.0 + 1,
1517                         ),
1518                         Style::LineAndColumn,
1519                     );
1520                 }
1521             } else if !self.short_message {
1522                 // remember where we are in the output buffer for easy reference
1523                 let buffer_msg_line_offset = buffer.num_lines();
1524
1525                 // Add spacing line
1526                 draw_col_separator_no_space(
1527                     &mut buffer,
1528                     buffer_msg_line_offset,
1529                     max_line_num_len + 1,
1530                 );
1531
1532                 // Then, the secondary file indicator
1533                 buffer.prepend(buffer_msg_line_offset + 1, "::: ", Style::LineNumber);
1534                 let loc = if let Some(first_line) = annotated_file.lines.first() {
1535                     let col = if let Some(first_annotation) = first_line.annotations.first() {
1536                         format!(":{}", first_annotation.start_col + 1)
1537                     } else {
1538                         String::new()
1539                     };
1540                     format!(
1541                         "{}:{}{}",
1542                         sm.filename_for_diagnostics(&annotated_file.file.name),
1543                         sm.doctest_offset_line(&annotated_file.file.name, first_line.line_index),
1544                         col
1545                     )
1546                 } else {
1547                     format!("{}", sm.filename_for_diagnostics(&annotated_file.file.name))
1548                 };
1549                 buffer.append(buffer_msg_line_offset + 1, &loc, Style::LineAndColumn);
1550                 for _ in 0..max_line_num_len {
1551                     buffer.prepend(buffer_msg_line_offset + 1, " ", Style::NoStyle);
1552                 }
1553             }
1554
1555             if !self.short_message {
1556                 // Put in the spacer between the location and annotated source
1557                 let buffer_msg_line_offset = buffer.num_lines();
1558                 draw_col_separator_no_space(
1559                     &mut buffer,
1560                     buffer_msg_line_offset,
1561                     max_line_num_len + 1,
1562                 );
1563
1564                 // Contains the vertical lines' positions for active multiline annotations
1565                 let mut multilines = FxIndexMap::default();
1566
1567                 // Get the left-side margin to remove it
1568                 let mut whitespace_margin = usize::MAX;
1569                 for line_idx in 0..annotated_file.lines.len() {
1570                     let file = annotated_file.file.clone();
1571                     let line = &annotated_file.lines[line_idx];
1572                     if let Some(source_string) = file.get_line(line.line_index - 1) {
1573                         let leading_whitespace = source_string
1574                             .chars()
1575                             .take_while(|c| c.is_whitespace())
1576                             .map(|c| {
1577                                 match c {
1578                                     // Tabs are displayed as 4 spaces
1579                                     '\t' => 4,
1580                                     _ => 1,
1581                                 }
1582                             })
1583                             .sum();
1584                         if source_string.chars().any(|c| !c.is_whitespace()) {
1585                             whitespace_margin = min(whitespace_margin, leading_whitespace);
1586                         }
1587                     }
1588                 }
1589                 if whitespace_margin == usize::MAX {
1590                     whitespace_margin = 0;
1591                 }
1592
1593                 // Left-most column any visible span points at.
1594                 let mut span_left_margin = usize::MAX;
1595                 for line in &annotated_file.lines {
1596                     for ann in &line.annotations {
1597                         span_left_margin = min(span_left_margin, ann.start_col);
1598                         span_left_margin = min(span_left_margin, ann.end_col);
1599                     }
1600                 }
1601                 if span_left_margin == usize::MAX {
1602                     span_left_margin = 0;
1603                 }
1604
1605                 // Right-most column any visible span points at.
1606                 let mut span_right_margin = 0;
1607                 let mut label_right_margin = 0;
1608                 let mut max_line_len = 0;
1609                 for line in &annotated_file.lines {
1610                     max_line_len = max(
1611                         max_line_len,
1612                         annotated_file.file.get_line(line.line_index - 1).map_or(0, |s| s.len()),
1613                     );
1614                     for ann in &line.annotations {
1615                         span_right_margin = max(span_right_margin, ann.start_col);
1616                         span_right_margin = max(span_right_margin, ann.end_col);
1617                         // FIXME: account for labels not in the same line
1618                         let label_right = ann.label.as_ref().map_or(0, |l| l.len() + 1);
1619                         label_right_margin = max(label_right_margin, ann.end_col + label_right);
1620                     }
1621                 }
1622
1623                 let width_offset = 3 + max_line_num_len;
1624                 let code_offset = if annotated_file.multiline_depth == 0 {
1625                     width_offset
1626                 } else {
1627                     width_offset + annotated_file.multiline_depth + 1
1628                 };
1629
1630                 let column_width = if let Some(width) = self.diagnostic_width {
1631                     width.saturating_sub(code_offset)
1632                 } else if self.ui_testing {
1633                     DEFAULT_COLUMN_WIDTH
1634                 } else {
1635                     termize::dimensions()
1636                         .map(|(w, _)| w.saturating_sub(code_offset))
1637                         .unwrap_or(DEFAULT_COLUMN_WIDTH)
1638                 };
1639
1640                 let margin = Margin::new(
1641                     whitespace_margin,
1642                     span_left_margin,
1643                     span_right_margin,
1644                     label_right_margin,
1645                     column_width,
1646                     max_line_len,
1647                 );
1648
1649                 // Next, output the annotate source for this file
1650                 for line_idx in 0..annotated_file.lines.len() {
1651                     let previous_buffer_line = buffer.num_lines();
1652
1653                     let depths = self.render_source_line(
1654                         &mut buffer,
1655                         annotated_file.file.clone(),
1656                         &annotated_file.lines[line_idx],
1657                         width_offset,
1658                         code_offset,
1659                         margin,
1660                     );
1661
1662                     let mut to_add = FxHashMap::default();
1663
1664                     for (depth, style) in depths {
1665                         if multilines.remove(&depth).is_none() {
1666                             to_add.insert(depth, style);
1667                         }
1668                     }
1669
1670                     // Set the multiline annotation vertical lines to the left of
1671                     // the code in this line.
1672                     for (depth, style) in &multilines {
1673                         for line in previous_buffer_line..buffer.num_lines() {
1674                             draw_multiline_line(&mut buffer, line, width_offset, *depth, *style);
1675                         }
1676                     }
1677                     // check to see if we need to print out or elide lines that come between
1678                     // this annotated line and the next one.
1679                     if line_idx < (annotated_file.lines.len() - 1) {
1680                         let line_idx_delta = annotated_file.lines[line_idx + 1].line_index
1681                             - annotated_file.lines[line_idx].line_index;
1682                         if line_idx_delta > 2 {
1683                             let last_buffer_line_num = buffer.num_lines();
1684                             buffer.puts(last_buffer_line_num, 0, "...", Style::LineNumber);
1685
1686                             // Set the multiline annotation vertical lines on `...` bridging line.
1687                             for (depth, style) in &multilines {
1688                                 draw_multiline_line(
1689                                     &mut buffer,
1690                                     last_buffer_line_num,
1691                                     width_offset,
1692                                     *depth,
1693                                     *style,
1694                                 );
1695                             }
1696                         } else if line_idx_delta == 2 {
1697                             let unannotated_line = annotated_file
1698                                 .file
1699                                 .get_line(annotated_file.lines[line_idx].line_index)
1700                                 .unwrap_or_else(|| Cow::from(""));
1701
1702                             let last_buffer_line_num = buffer.num_lines();
1703
1704                             self.draw_line(
1705                                 &mut buffer,
1706                                 &normalize_whitespace(&unannotated_line),
1707                                 annotated_file.lines[line_idx + 1].line_index - 1,
1708                                 last_buffer_line_num,
1709                                 width_offset,
1710                                 code_offset,
1711                                 margin,
1712                             );
1713
1714                             for (depth, style) in &multilines {
1715                                 draw_multiline_line(
1716                                     &mut buffer,
1717                                     last_buffer_line_num,
1718                                     width_offset,
1719                                     *depth,
1720                                     *style,
1721                                 );
1722                             }
1723                         }
1724                     }
1725
1726                     multilines.extend(&to_add);
1727                 }
1728             }
1729             trace!("buffer: {:#?}", buffer.render());
1730         }
1731
1732         if let Some(tracked) = emitted_at {
1733             let track = format!("-Ztrack-diagnostics: created at {tracked}");
1734             let len = buffer.num_lines();
1735             buffer.append(len, &track, Style::NoStyle);
1736         }
1737
1738         // final step: take our styled buffer, render it, then output it
1739         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1740
1741         Ok(())
1742     }
1743
1744     fn emit_suggestion_default(
1745         &mut self,
1746         span: &MultiSpan,
1747         suggestion: &CodeSuggestion,
1748         args: &FluentArgs<'_>,
1749         level: &Level,
1750         max_line_num_len: usize,
1751     ) -> io::Result<()> {
1752         let Some(ref sm) = self.sm else {
1753             return Ok(());
1754         };
1755
1756         // Render the replacements for each suggestion
1757         let suggestions = suggestion.splice_lines(sm);
1758         debug!("emit_suggestion_default: suggestions={:?}", suggestions);
1759
1760         if suggestions.is_empty() {
1761             // Suggestions coming from macros can have malformed spans. This is a heavy handed
1762             // approach to avoid ICEs by ignoring the suggestion outright.
1763             return Ok(());
1764         }
1765
1766         let mut buffer = StyledBuffer::new();
1767
1768         // Render the suggestion message
1769         buffer.append(0, level.to_str(), Style::Level(*level));
1770         buffer.append(0, ": ", Style::HeaderMsg);
1771
1772         self.msg_to_buffer(
1773             &mut buffer,
1774             &[(suggestion.msg.to_owned(), Style::NoStyle)],
1775             args,
1776             max_line_num_len,
1777             "suggestion",
1778             Some(Style::HeaderMsg),
1779         );
1780
1781         let mut row_num = 2;
1782         draw_col_separator_no_space(&mut buffer, 1, max_line_num_len + 1);
1783         let mut notice_capitalization = false;
1784         for (complete, parts, highlights, only_capitalization) in
1785             suggestions.iter().take(MAX_SUGGESTIONS)
1786         {
1787             notice_capitalization |= only_capitalization;
1788
1789             let has_deletion = parts.iter().any(|p| p.is_deletion(sm));
1790             let is_multiline = complete.lines().count() > 1;
1791
1792             if let Some(span) = span.primary_span() {
1793                 // Compare the primary span of the diagnostic with the span of the suggestion
1794                 // being emitted.  If they belong to the same file, we don't *need* to show the
1795                 // file name, saving in verbosity, but if it *isn't* we do need it, otherwise we're
1796                 // telling users to make a change but not clarifying *where*.
1797                 let loc = sm.lookup_char_pos(parts[0].span.lo());
1798                 if loc.file.name != sm.span_to_filename(span) && loc.file.name.is_real() {
1799                     buffer.puts(row_num - 1, 0, "--> ", Style::LineNumber);
1800                     buffer.append(
1801                         row_num - 1,
1802                         &format!(
1803                             "{}:{}:{}",
1804                             sm.filename_for_diagnostics(&loc.file.name),
1805                             sm.doctest_offset_line(&loc.file.name, loc.line),
1806                             loc.col.0 + 1,
1807                         ),
1808                         Style::LineAndColumn,
1809                     );
1810                     for _ in 0..max_line_num_len {
1811                         buffer.prepend(row_num - 1, " ", Style::NoStyle);
1812                     }
1813                     row_num += 1;
1814                 }
1815             }
1816             let show_code_change = if has_deletion && !is_multiline {
1817                 DisplaySuggestion::Diff
1818             } else if (parts.len() != 1 || parts[0].snippet.trim() != complete.trim())
1819                 && !is_multiline
1820             {
1821                 DisplaySuggestion::Underline
1822             } else {
1823                 DisplaySuggestion::None
1824             };
1825
1826             if let DisplaySuggestion::Diff = show_code_change {
1827                 row_num += 1;
1828             }
1829
1830             let file_lines = sm
1831                 .span_to_lines(parts[0].span)
1832                 .expect("span_to_lines failed when emitting suggestion");
1833
1834             assert!(!file_lines.lines.is_empty() || parts[0].span.is_dummy());
1835
1836             let line_start = sm.lookup_char_pos(parts[0].span.lo()).line;
1837             draw_col_separator_no_space(&mut buffer, row_num - 1, max_line_num_len + 1);
1838             let mut lines = complete.lines();
1839             if lines.clone().next().is_none() {
1840                 // Account for a suggestion to completely remove a line(s) with whitespace (#94192).
1841                 let line_end = sm.lookup_char_pos(parts[0].span.hi()).line;
1842                 for line in line_start..=line_end {
1843                     buffer.puts(
1844                         row_num - 1 + line - line_start,
1845                         0,
1846                         &self.maybe_anonymized(line),
1847                         Style::LineNumber,
1848                     );
1849                     buffer.puts(
1850                         row_num - 1 + line - line_start,
1851                         max_line_num_len + 1,
1852                         "- ",
1853                         Style::Removal,
1854                     );
1855                     buffer.puts(
1856                         row_num - 1 + line - line_start,
1857                         max_line_num_len + 3,
1858                         &normalize_whitespace(&file_lines.file.get_line(line - 1).unwrap()),
1859                         Style::Removal,
1860                     );
1861                 }
1862                 row_num += line_end - line_start;
1863             }
1864             let mut unhighlighted_lines = Vec::new();
1865             for (line_pos, (line, highlight_parts)) in lines.by_ref().zip(highlights).enumerate() {
1866                 debug!(%line_pos, %line, ?highlight_parts);
1867
1868                 // Remember lines that are not highlighted to hide them if needed
1869                 if highlight_parts.is_empty() {
1870                     unhighlighted_lines.push((line_pos, line));
1871                     continue;
1872                 }
1873
1874                 match unhighlighted_lines.len() {
1875                     0 => (),
1876                     // Since we show first line, "..." line and last line,
1877                     // There is no reason to hide if there are 3 or less lines
1878                     // (because then we just replace a line with ... which is
1879                     // not helpful)
1880                     n if n <= 3 => unhighlighted_lines.drain(..).for_each(|(p, l)| {
1881                         self.draw_code_line(
1882                             &mut buffer,
1883                             &mut row_num,
1884                             &Vec::new(),
1885                             p,
1886                             l,
1887                             line_start,
1888                             show_code_change,
1889                             max_line_num_len,
1890                             &file_lines,
1891                             is_multiline,
1892                         )
1893                     }),
1894                     // Print first unhighlighted line, "..." and last unhighlighted line, like so:
1895                     //
1896                     // LL | this line was highlighted
1897                     // LL | this line is just for context
1898                     //   ...
1899                     // LL | this line is just for context
1900                     // LL | this line was highlighted
1901                     _ => {
1902                         let last_line = unhighlighted_lines.pop();
1903                         let first_line = unhighlighted_lines.drain(..).next();
1904
1905                         first_line.map(|(p, l)| {
1906                             self.draw_code_line(
1907                                 &mut buffer,
1908                                 &mut row_num,
1909                                 &Vec::new(),
1910                                 p,
1911                                 l,
1912                                 line_start,
1913                                 show_code_change,
1914                                 max_line_num_len,
1915                                 &file_lines,
1916                                 is_multiline,
1917                             )
1918                         });
1919
1920                         buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
1921                         row_num += 1;
1922
1923                         last_line.map(|(p, l)| {
1924                             self.draw_code_line(
1925                                 &mut buffer,
1926                                 &mut row_num,
1927                                 &Vec::new(),
1928                                 p,
1929                                 l,
1930                                 line_start,
1931                                 show_code_change,
1932                                 max_line_num_len,
1933                                 &file_lines,
1934                                 is_multiline,
1935                             )
1936                         });
1937                     }
1938                 }
1939
1940                 self.draw_code_line(
1941                     &mut buffer,
1942                     &mut row_num,
1943                     highlight_parts,
1944                     line_pos,
1945                     line,
1946                     line_start,
1947                     show_code_change,
1948                     max_line_num_len,
1949                     &file_lines,
1950                     is_multiline,
1951                 )
1952             }
1953
1954             // This offset and the ones below need to be signed to account for replacement code
1955             // that is shorter than the original code.
1956             let mut offsets: Vec<(usize, isize)> = Vec::new();
1957             // Only show an underline in the suggestions if the suggestion is not the
1958             // entirety of the code being shown and the displayed code is not multiline.
1959             if let DisplaySuggestion::Diff | DisplaySuggestion::Underline = show_code_change {
1960                 draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
1961                 for part in parts {
1962                     let span_start_pos = sm.lookup_char_pos(part.span.lo()).col_display;
1963                     let span_end_pos = sm.lookup_char_pos(part.span.hi()).col_display;
1964
1965                     // If this addition is _only_ whitespace, then don't trim it,
1966                     // or else we're just not rendering anything.
1967                     let is_whitespace_addition = part.snippet.trim().is_empty();
1968
1969                     // Do not underline the leading...
1970                     let start = if is_whitespace_addition {
1971                         0
1972                     } else {
1973                         part.snippet.len().saturating_sub(part.snippet.trim_start().len())
1974                     };
1975                     // ...or trailing spaces. Account for substitutions containing unicode
1976                     // characters.
1977                     let sub_len: usize =
1978                         if is_whitespace_addition { &part.snippet } else { part.snippet.trim() }
1979                             .chars()
1980                             .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
1981                             .sum();
1982
1983                     let offset: isize = offsets
1984                         .iter()
1985                         .filter_map(
1986                             |(start, v)| if span_start_pos <= *start { None } else { Some(v) },
1987                         )
1988                         .sum();
1989                     let underline_start = (span_start_pos + start) as isize + offset;
1990                     let underline_end = (span_start_pos + start + sub_len) as isize + offset;
1991                     assert!(underline_start >= 0 && underline_end >= 0);
1992                     let padding: usize = max_line_num_len + 3;
1993                     for p in underline_start..underline_end {
1994                         if let DisplaySuggestion::Underline = show_code_change {
1995                             // If this is a replacement, underline with `^`, if this is an addition
1996                             // underline with `+`.
1997                             buffer.putc(
1998                                 row_num,
1999                                 (padding as isize + p) as usize,
2000                                 if part.is_addition(sm) { '+' } else { '~' },
2001                                 Style::Addition,
2002                             );
2003                         }
2004                     }
2005                     if let DisplaySuggestion::Diff = show_code_change {
2006                         // Colorize removal with red in diff format.
2007                         buffer.set_style_range(
2008                             row_num - 2,
2009                             (padding as isize + span_start_pos as isize) as usize,
2010                             (padding as isize + span_end_pos as isize) as usize,
2011                             Style::Removal,
2012                             true,
2013                         );
2014                     }
2015
2016                     // length of the code after substitution
2017                     let full_sub_len = part
2018                         .snippet
2019                         .chars()
2020                         .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
2021                         .sum::<usize>() as isize;
2022
2023                     // length of the code to be substituted
2024                     let snippet_len = span_end_pos as isize - span_start_pos as isize;
2025                     // For multiple substitutions, use the position *after* the previous
2026                     // substitutions have happened, only when further substitutions are
2027                     // located strictly after.
2028                     offsets.push((span_end_pos, full_sub_len - snippet_len));
2029                 }
2030                 row_num += 1;
2031             }
2032
2033             // if we elided some lines, add an ellipsis
2034             if lines.next().is_some() {
2035                 buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
2036             } else if let DisplaySuggestion::None = show_code_change {
2037                 draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
2038                 row_num += 1;
2039             }
2040         }
2041         if suggestions.len() > MAX_SUGGESTIONS {
2042             let others = suggestions.len() - MAX_SUGGESTIONS;
2043             let msg = format!("and {} other candidate{}", others, pluralize!(others));
2044             buffer.puts(row_num, max_line_num_len + 3, &msg, Style::NoStyle);
2045         } else if notice_capitalization {
2046             let msg = "notice the capitalization difference";
2047             buffer.puts(row_num, max_line_num_len + 3, msg, Style::NoStyle);
2048         }
2049         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
2050         Ok(())
2051     }
2052
2053     #[instrument(level = "trace", skip(self, args, code, children, suggestions))]
2054     fn emit_messages_default(
2055         &mut self,
2056         level: &Level,
2057         message: &[(DiagnosticMessage, Style)],
2058         args: &FluentArgs<'_>,
2059         code: &Option<DiagnosticId>,
2060         span: &MultiSpan,
2061         children: &[SubDiagnostic],
2062         suggestions: &[CodeSuggestion],
2063         emitted_at: Option<&DiagnosticLocation>,
2064     ) {
2065         let max_line_num_len = if self.ui_testing {
2066             ANONYMIZED_LINE_NUM.len()
2067         } else {
2068             let n = self.get_max_line_num(span, children);
2069             num_decimal_digits(n)
2070         };
2071
2072         match self.emit_message_default(
2073             span,
2074             message,
2075             args,
2076             code,
2077             level,
2078             max_line_num_len,
2079             false,
2080             emitted_at,
2081         ) {
2082             Ok(()) => {
2083                 if !children.is_empty()
2084                     || suggestions.iter().any(|s| s.style != SuggestionStyle::CompletelyHidden)
2085                 {
2086                     let mut buffer = StyledBuffer::new();
2087                     if !self.short_message {
2088                         draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
2089                     }
2090                     if let Err(e) = emit_to_destination(
2091                         &buffer.render(),
2092                         level,
2093                         &mut self.dst,
2094                         self.short_message,
2095                     ) {
2096                         panic!("failed to emit error: {}", e)
2097                     }
2098                 }
2099                 if !self.short_message {
2100                     for child in children {
2101                         let span = child.render_span.as_ref().unwrap_or(&child.span);
2102                         if let Err(err) = self.emit_message_default(
2103                             span,
2104                             &child.message,
2105                             args,
2106                             &None,
2107                             &child.level,
2108                             max_line_num_len,
2109                             true,
2110                             None,
2111                         ) {
2112                             panic!("failed to emit error: {}", err);
2113                         }
2114                     }
2115                     for sugg in suggestions {
2116                         if sugg.style == SuggestionStyle::CompletelyHidden {
2117                             // do not display this suggestion, it is meant only for tools
2118                         } else if sugg.style == SuggestionStyle::HideCodeAlways {
2119                             if let Err(e) = self.emit_message_default(
2120                                 &MultiSpan::new(),
2121                                 &[(sugg.msg.to_owned(), Style::HeaderMsg)],
2122                                 args,
2123                                 &None,
2124                                 &Level::Help,
2125                                 max_line_num_len,
2126                                 true,
2127                                 None,
2128                             ) {
2129                                 panic!("failed to emit error: {}", e);
2130                             }
2131                         } else if let Err(e) = self.emit_suggestion_default(
2132                             span,
2133                             sugg,
2134                             args,
2135                             &Level::Help,
2136                             max_line_num_len,
2137                         ) {
2138                             panic!("failed to emit error: {}", e);
2139                         };
2140                     }
2141                 }
2142             }
2143             Err(e) => panic!("failed to emit error: {}", e),
2144         }
2145
2146         let mut dst = self.dst.writable();
2147         match writeln!(dst) {
2148             Err(e) => panic!("failed to emit error: {}", e),
2149             _ => {
2150                 if let Err(e) = dst.flush() {
2151                     panic!("failed to emit error: {}", e)
2152                 }
2153             }
2154         }
2155     }
2156
2157     fn draw_code_line(
2158         &self,
2159         buffer: &mut StyledBuffer,
2160         row_num: &mut usize,
2161         highlight_parts: &Vec<SubstitutionHighlight>,
2162         line_pos: usize,
2163         line: &str,
2164         line_start: usize,
2165         show_code_change: DisplaySuggestion,
2166         max_line_num_len: usize,
2167         file_lines: &FileLines,
2168         is_multiline: bool,
2169     ) {
2170         // Print the span column to avoid confusion
2171         buffer.puts(*row_num, 0, &self.maybe_anonymized(line_start + line_pos), Style::LineNumber);
2172         if let DisplaySuggestion::Diff = show_code_change {
2173             // Add the line number for both addition and removal to drive the point home.
2174             //
2175             // N - fn foo<A: T>(bar: A) {
2176             // N + fn foo(bar: impl T) {
2177             buffer.puts(
2178                 *row_num - 1,
2179                 0,
2180                 &self.maybe_anonymized(line_start + line_pos),
2181                 Style::LineNumber,
2182             );
2183             buffer.puts(*row_num - 1, max_line_num_len + 1, "- ", Style::Removal);
2184             buffer.puts(
2185                 *row_num - 1,
2186                 max_line_num_len + 3,
2187                 &normalize_whitespace(
2188                     &file_lines.file.get_line(file_lines.lines[line_pos].line_index).unwrap(),
2189                 ),
2190                 Style::NoStyle,
2191             );
2192             buffer.puts(*row_num, max_line_num_len + 1, "+ ", Style::Addition);
2193         } else if is_multiline {
2194             match &highlight_parts[..] {
2195                 [SubstitutionHighlight { start: 0, end }] if *end == line.len() => {
2196                     buffer.puts(*row_num, max_line_num_len + 1, "+ ", Style::Addition);
2197                 }
2198                 [] => {
2199                     draw_col_separator(buffer, *row_num, max_line_num_len + 1);
2200                 }
2201                 _ => {
2202                     buffer.puts(*row_num, max_line_num_len + 1, "~ ", Style::Addition);
2203                 }
2204             }
2205         } else {
2206             draw_col_separator(buffer, *row_num, max_line_num_len + 1);
2207         }
2208
2209         // print the suggestion
2210         buffer.append(*row_num, &normalize_whitespace(line), Style::NoStyle);
2211
2212         // Colorize addition/replacements with green.
2213         for &SubstitutionHighlight { start, end } in highlight_parts {
2214             // Account for tabs when highlighting (#87972).
2215             let tabs: usize = line
2216                 .chars()
2217                 .take(start)
2218                 .map(|ch| match ch {
2219                     '\t' => 3,
2220                     _ => 0,
2221                 })
2222                 .sum();
2223             buffer.set_style_range(
2224                 *row_num,
2225                 max_line_num_len + 3 + start + tabs,
2226                 max_line_num_len + 3 + end + tabs,
2227                 Style::Addition,
2228                 true,
2229             );
2230         }
2231         *row_num += 1;
2232     }
2233 }
2234
2235 #[derive(Clone, Copy, Debug)]
2236 enum DisplaySuggestion {
2237     Underline,
2238     Diff,
2239     None,
2240 }
2241
2242 impl FileWithAnnotatedLines {
2243     /// Preprocess all the annotations so that they are grouped by file and by line number
2244     /// This helps us quickly iterate over the whole message (including secondary file spans)
2245     pub fn collect_annotations(
2246         emitter: &dyn Emitter,
2247         args: &FluentArgs<'_>,
2248         msp: &MultiSpan,
2249     ) -> Vec<FileWithAnnotatedLines> {
2250         fn add_annotation_to_file(
2251             file_vec: &mut Vec<FileWithAnnotatedLines>,
2252             file: Lrc<SourceFile>,
2253             line_index: usize,
2254             ann: Annotation,
2255         ) {
2256             for slot in file_vec.iter_mut() {
2257                 // Look through each of our files for the one we're adding to
2258                 if slot.file.name == file.name {
2259                     // See if we already have a line for it
2260                     for line_slot in &mut slot.lines {
2261                         if line_slot.line_index == line_index {
2262                             line_slot.annotations.push(ann);
2263                             return;
2264                         }
2265                     }
2266                     // We don't have a line yet, create one
2267                     slot.lines.push(Line { line_index, annotations: vec![ann] });
2268                     slot.lines.sort();
2269                     return;
2270                 }
2271             }
2272             // This is the first time we're seeing the file
2273             file_vec.push(FileWithAnnotatedLines {
2274                 file,
2275                 lines: vec![Line { line_index, annotations: vec![ann] }],
2276                 multiline_depth: 0,
2277             });
2278         }
2279
2280         let mut output = vec![];
2281         let mut multiline_annotations = vec![];
2282
2283         if let Some(ref sm) = emitter.source_map() {
2284             for SpanLabel { span, is_primary, label } in msp.span_labels() {
2285                 // If we don't have a useful span, pick the primary span if that exists.
2286                 // Worst case we'll just print an error at the top of the main file.
2287                 let span = match (span.is_dummy(), msp.primary_span()) {
2288                     (_, None) | (false, _) => span,
2289                     (true, Some(span)) => span,
2290                 };
2291
2292                 let lo = sm.lookup_char_pos(span.lo());
2293                 let mut hi = sm.lookup_char_pos(span.hi());
2294
2295                 // Watch out for "empty spans". If we get a span like 6..6, we
2296                 // want to just display a `^` at 6, so convert that to
2297                 // 6..7. This is degenerate input, but it's best to degrade
2298                 // gracefully -- and the parser likes to supply a span like
2299                 // that for EOF, in particular.
2300
2301                 if lo.col_display == hi.col_display && lo.line == hi.line {
2302                     hi.col_display += 1;
2303                 }
2304
2305                 let label = label.as_ref().map(|m| {
2306                     emitter.translate_message(m, args).map_err(Report::new).unwrap().to_string()
2307                 });
2308
2309                 if lo.line != hi.line {
2310                     let ml = MultilineAnnotation {
2311                         depth: 1,
2312                         line_start: lo.line,
2313                         line_end: hi.line,
2314                         start_col: lo.col_display,
2315                         end_col: hi.col_display,
2316                         is_primary,
2317                         label,
2318                         overlaps_exactly: false,
2319                     };
2320                     multiline_annotations.push((lo.file, ml));
2321                 } else {
2322                     let ann = Annotation {
2323                         start_col: lo.col_display,
2324                         end_col: hi.col_display,
2325                         is_primary,
2326                         label,
2327                         annotation_type: AnnotationType::Singleline,
2328                     };
2329                     add_annotation_to_file(&mut output, lo.file, lo.line, ann);
2330                 };
2331             }
2332         }
2333
2334         // Find overlapping multiline annotations, put them at different depths
2335         multiline_annotations.sort_by_key(|(_, ml)| (ml.line_start, usize::MAX - ml.line_end));
2336         for (_, ann) in multiline_annotations.clone() {
2337             for (_, a) in multiline_annotations.iter_mut() {
2338                 // Move all other multiline annotations overlapping with this one
2339                 // one level to the right.
2340                 if !(ann.same_span(a))
2341                     && num_overlap(ann.line_start, ann.line_end, a.line_start, a.line_end, true)
2342                 {
2343                     a.increase_depth();
2344                 } else if ann.same_span(a) && &ann != a {
2345                     a.overlaps_exactly = true;
2346                 } else {
2347                     break;
2348                 }
2349             }
2350         }
2351
2352         let mut max_depth = 0; // max overlapping multiline spans
2353         for (_, ann) in &multiline_annotations {
2354             max_depth = max(max_depth, ann.depth);
2355         }
2356         // Change order of multispan depth to minimize the number of overlaps in the ASCII art.
2357         for (_, a) in multiline_annotations.iter_mut() {
2358             a.depth = max_depth - a.depth + 1;
2359         }
2360         for (file, ann) in multiline_annotations {
2361             let mut end_ann = ann.as_end();
2362             if !ann.overlaps_exactly {
2363                 // avoid output like
2364                 //
2365                 //  |        foo(
2366                 //  |   _____^
2367                 //  |  |_____|
2368                 //  | ||         bar,
2369                 //  | ||     );
2370                 //  | ||      ^
2371                 //  | ||______|
2372                 //  |  |______foo
2373                 //  |         baz
2374                 //
2375                 // and instead get
2376                 //
2377                 //  |       foo(
2378                 //  |  _____^
2379                 //  | |         bar,
2380                 //  | |     );
2381                 //  | |      ^
2382                 //  | |      |
2383                 //  | |______foo
2384                 //  |        baz
2385                 add_annotation_to_file(&mut output, file.clone(), ann.line_start, ann.as_start());
2386                 // 4 is the minimum vertical length of a multiline span when presented: two lines
2387                 // of code and two lines of underline. This is not true for the special case where
2388                 // the beginning doesn't have an underline, but the current logic seems to be
2389                 // working correctly.
2390                 let middle = min(ann.line_start + 4, ann.line_end);
2391                 for line in ann.line_start + 1..middle {
2392                     // Every `|` that joins the beginning of the span (`___^`) to the end (`|__^`).
2393                     add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
2394                 }
2395                 let line_end = ann.line_end - 1;
2396                 if middle < line_end {
2397                     add_annotation_to_file(&mut output, file.clone(), line_end, ann.as_line());
2398                 }
2399             } else {
2400                 end_ann.annotation_type = AnnotationType::Singleline;
2401             }
2402             add_annotation_to_file(&mut output, file, ann.line_end, end_ann);
2403         }
2404         for file_vec in output.iter_mut() {
2405             file_vec.multiline_depth = max_depth;
2406         }
2407         output
2408     }
2409 }
2410
2411 // instead of taking the String length or dividing by 10 while > 0, we multiply a limit by 10 until
2412 // we're higher. If the loop isn't exited by the `return`, the last multiplication will wrap, which
2413 // is OK, because while we cannot fit a higher power of 10 in a usize, the loop will end anyway.
2414 // This is also why we need the max number of decimal digits within a `usize`.
2415 fn num_decimal_digits(num: usize) -> usize {
2416     #[cfg(target_pointer_width = "64")]
2417     const MAX_DIGITS: usize = 20;
2418
2419     #[cfg(target_pointer_width = "32")]
2420     const MAX_DIGITS: usize = 10;
2421
2422     #[cfg(target_pointer_width = "16")]
2423     const MAX_DIGITS: usize = 5;
2424
2425     let mut lim = 10;
2426     for num_digits in 1..MAX_DIGITS {
2427         if num < lim {
2428             return num_digits;
2429         }
2430         lim = lim.wrapping_mul(10);
2431     }
2432     MAX_DIGITS
2433 }
2434
2435 // We replace some characters so the CLI output is always consistent and underlines aligned.
2436 const OUTPUT_REPLACEMENTS: &[(char, &str)] = &[
2437     ('\t', "    "),   // We do our own tab replacement
2438     ('\u{200D}', ""), // Replace ZWJ with nothing for consistent terminal output of grapheme clusters.
2439     ('\u{202A}', ""), // The following unicode text flow control characters are inconsistently
2440     ('\u{202B}', ""), // supported across CLIs and can cause confusion due to the bytes on disk
2441     ('\u{202D}', ""), // not corresponding to the visible source code, so we replace them always.
2442     ('\u{202E}', ""),
2443     ('\u{2066}', ""),
2444     ('\u{2067}', ""),
2445     ('\u{2068}', ""),
2446     ('\u{202C}', ""),
2447     ('\u{2069}', ""),
2448 ];
2449
2450 fn normalize_whitespace(str: &str) -> String {
2451     let mut s = str.to_string();
2452     for (c, replacement) in OUTPUT_REPLACEMENTS {
2453         s = s.replace(*c, replacement);
2454     }
2455     s
2456 }
2457
2458 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
2459     buffer.puts(line, col, "| ", Style::LineNumber);
2460 }
2461
2462 fn draw_col_separator_no_space(buffer: &mut StyledBuffer, line: usize, col: usize) {
2463     draw_col_separator_no_space_with_style(buffer, line, col, Style::LineNumber);
2464 }
2465
2466 fn draw_col_separator_no_space_with_style(
2467     buffer: &mut StyledBuffer,
2468     line: usize,
2469     col: usize,
2470     style: Style,
2471 ) {
2472     buffer.putc(line, col, '|', style);
2473 }
2474
2475 fn draw_range(
2476     buffer: &mut StyledBuffer,
2477     symbol: char,
2478     line: usize,
2479     col_from: usize,
2480     col_to: usize,
2481     style: Style,
2482 ) {
2483     for col in col_from..col_to {
2484         buffer.putc(line, col, symbol, style);
2485     }
2486 }
2487
2488 fn draw_note_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
2489     buffer.puts(line, col, "= ", Style::LineNumber);
2490 }
2491
2492 fn draw_multiline_line(
2493     buffer: &mut StyledBuffer,
2494     line: usize,
2495     offset: usize,
2496     depth: usize,
2497     style: Style,
2498 ) {
2499     buffer.putc(line, offset + depth - 1, '|', style);
2500 }
2501
2502 fn num_overlap(
2503     a_start: usize,
2504     a_end: usize,
2505     b_start: usize,
2506     b_end: usize,
2507     inclusive: bool,
2508 ) -> bool {
2509     let extra = if inclusive { 1 } else { 0 };
2510     (b_start..b_end + extra).contains(&a_start) || (a_start..a_end + extra).contains(&b_start)
2511 }
2512 fn overlaps(a1: &Annotation, a2: &Annotation, padding: usize) -> bool {
2513     num_overlap(a1.start_col, a1.end_col + padding, a2.start_col, a2.end_col, false)
2514 }
2515
2516 fn emit_to_destination(
2517     rendered_buffer: &[Vec<StyledString>],
2518     lvl: &Level,
2519     dst: &mut Destination,
2520     short_message: bool,
2521 ) -> io::Result<()> {
2522     use crate::lock;
2523
2524     let mut dst = dst.writable();
2525
2526     // In order to prevent error message interleaving, where multiple error lines get intermixed
2527     // when multiple compiler processes error simultaneously, we emit errors with additional
2528     // steps.
2529     //
2530     // On Unix systems, we write into a buffered terminal rather than directly to a terminal. When
2531     // the .flush() is called we take the buffer created from the buffered writes and write it at
2532     // one shot.  Because the Unix systems use ANSI for the colors, which is a text-based styling
2533     // scheme, this buffered approach works and maintains the styling.
2534     //
2535     // On Windows, styling happens through calls to a terminal API. This prevents us from using the
2536     // same buffering approach.  Instead, we use a global Windows mutex, which we acquire long
2537     // enough to output the full error message, then we release.
2538     let _buffer_lock = lock::acquire_global_lock("rustc_errors");
2539     for (pos, line) in rendered_buffer.iter().enumerate() {
2540         for part in line {
2541             dst.apply_style(*lvl, part.style)?;
2542             write!(dst, "{}", part.text)?;
2543             dst.reset()?;
2544         }
2545         if !short_message && (!lvl.is_failure_note() || pos != rendered_buffer.len() - 1) {
2546             writeln!(dst)?;
2547         }
2548     }
2549     dst.flush()?;
2550     Ok(())
2551 }
2552
2553 pub enum Destination {
2554     Terminal(StandardStream),
2555     Buffered(BufferWriter),
2556     // The bool denotes whether we should be emitting ansi color codes or not
2557     Raw(Box<(dyn Write + Send)>, bool),
2558 }
2559
2560 pub enum WritableDst<'a> {
2561     Terminal(&'a mut StandardStream),
2562     Buffered(&'a mut BufferWriter, Buffer),
2563     Raw(&'a mut (dyn Write + Send)),
2564     ColoredRaw(Ansi<&'a mut (dyn Write + Send)>),
2565 }
2566
2567 impl Destination {
2568     fn from_stderr(color: ColorConfig) -> Destination {
2569         let choice = color.to_color_choice();
2570         // On Windows we'll be performing global synchronization on the entire
2571         // system for emitting rustc errors, so there's no need to buffer
2572         // anything.
2573         //
2574         // On non-Windows we rely on the atomicity of `write` to ensure errors
2575         // don't get all jumbled up.
2576         if cfg!(windows) {
2577             Terminal(StandardStream::stderr(choice))
2578         } else {
2579             Buffered(BufferWriter::stderr(choice))
2580         }
2581     }
2582
2583     fn writable(&mut self) -> WritableDst<'_> {
2584         match *self {
2585             Destination::Terminal(ref mut t) => WritableDst::Terminal(t),
2586             Destination::Buffered(ref mut t) => {
2587                 let buf = t.buffer();
2588                 WritableDst::Buffered(t, buf)
2589             }
2590             Destination::Raw(ref mut t, false) => WritableDst::Raw(t),
2591             Destination::Raw(ref mut t, true) => WritableDst::ColoredRaw(Ansi::new(t)),
2592         }
2593     }
2594
2595     fn supports_color(&self) -> bool {
2596         match *self {
2597             Self::Terminal(ref stream) => stream.supports_color(),
2598             Self::Buffered(ref buffer) => buffer.buffer().supports_color(),
2599             Self::Raw(_, supports_color) => supports_color,
2600         }
2601     }
2602 }
2603
2604 impl<'a> WritableDst<'a> {
2605     fn apply_style(&mut self, lvl: Level, style: Style) -> io::Result<()> {
2606         let mut spec = ColorSpec::new();
2607         match style {
2608             Style::Addition => {
2609                 spec.set_fg(Some(Color::Green)).set_intense(true);
2610             }
2611             Style::Removal => {
2612                 spec.set_fg(Some(Color::Red)).set_intense(true);
2613             }
2614             Style::LineAndColumn => {}
2615             Style::LineNumber => {
2616                 spec.set_bold(true);
2617                 spec.set_intense(true);
2618                 if cfg!(windows) {
2619                     spec.set_fg(Some(Color::Cyan));
2620                 } else {
2621                     spec.set_fg(Some(Color::Blue));
2622                 }
2623             }
2624             Style::Quotation => {}
2625             Style::MainHeaderMsg => {
2626                 spec.set_bold(true);
2627                 if cfg!(windows) {
2628                     spec.set_intense(true).set_fg(Some(Color::White));
2629                 }
2630             }
2631             Style::UnderlinePrimary | Style::LabelPrimary => {
2632                 spec = lvl.color();
2633                 spec.set_bold(true);
2634             }
2635             Style::UnderlineSecondary | Style::LabelSecondary => {
2636                 spec.set_bold(true).set_intense(true);
2637                 if cfg!(windows) {
2638                     spec.set_fg(Some(Color::Cyan));
2639                 } else {
2640                     spec.set_fg(Some(Color::Blue));
2641                 }
2642             }
2643             Style::HeaderMsg | Style::NoStyle => {}
2644             Style::Level(lvl) => {
2645                 spec = lvl.color();
2646                 spec.set_bold(true);
2647             }
2648             Style::Highlight => {
2649                 spec.set_bold(true);
2650             }
2651         }
2652         self.set_color(&spec)
2653     }
2654
2655     fn set_color(&mut self, color: &ColorSpec) -> io::Result<()> {
2656         match *self {
2657             WritableDst::Terminal(ref mut t) => t.set_color(color),
2658             WritableDst::Buffered(_, ref mut t) => t.set_color(color),
2659             WritableDst::ColoredRaw(ref mut t) => t.set_color(color),
2660             WritableDst::Raw(_) => Ok(()),
2661         }
2662     }
2663
2664     fn reset(&mut self) -> io::Result<()> {
2665         match *self {
2666             WritableDst::Terminal(ref mut t) => t.reset(),
2667             WritableDst::Buffered(_, ref mut t) => t.reset(),
2668             WritableDst::ColoredRaw(ref mut t) => t.reset(),
2669             WritableDst::Raw(_) => Ok(()),
2670         }
2671     }
2672 }
2673
2674 impl<'a> Write for WritableDst<'a> {
2675     fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
2676         match *self {
2677             WritableDst::Terminal(ref mut t) => t.write(bytes),
2678             WritableDst::Buffered(_, ref mut buf) => buf.write(bytes),
2679             WritableDst::Raw(ref mut w) => w.write(bytes),
2680             WritableDst::ColoredRaw(ref mut t) => t.write(bytes),
2681         }
2682     }
2683
2684     fn flush(&mut self) -> io::Result<()> {
2685         match *self {
2686             WritableDst::Terminal(ref mut t) => t.flush(),
2687             WritableDst::Buffered(_, ref mut buf) => buf.flush(),
2688             WritableDst::Raw(ref mut w) => w.flush(),
2689             WritableDst::ColoredRaw(ref mut w) => w.flush(),
2690         }
2691     }
2692 }
2693
2694 impl<'a> Drop for WritableDst<'a> {
2695     fn drop(&mut self) {
2696         if let WritableDst::Buffered(ref mut dst, ref mut buf) = self {
2697             drop(dst.print(buf));
2698         }
2699     }
2700 }
2701
2702 /// Whether the original and suggested code are visually similar enough to warrant extra wording.
2703 pub fn is_case_difference(sm: &SourceMap, suggested: &str, sp: Span) -> bool {
2704     // FIXME: this should probably be extended to also account for `FO0` → `FOO` and unicode.
2705     let found = match sm.span_to_snippet(sp) {
2706         Ok(snippet) => snippet,
2707         Err(e) => {
2708             warn!(error = ?e, "Invalid span {:?}", sp);
2709             return false;
2710         }
2711     };
2712     let ascii_confusables = &['c', 'f', 'i', 'k', 'o', 's', 'u', 'v', 'w', 'x', 'y', 'z'];
2713     // All the chars that differ in capitalization are confusable (above):
2714     let confusable = iter::zip(found.chars(), suggested.chars())
2715         .filter(|(f, s)| f != s)
2716         .all(|(f, s)| (ascii_confusables.contains(&f) || ascii_confusables.contains(&s)));
2717     confusable && found.to_lowercase() == suggested.to_lowercase()
2718             // FIXME: We sometimes suggest the same thing we already have, which is a
2719             //        bug, but be defensive against that here.
2720             && found != suggested
2721 }