src/librustc_errors/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 `librustc::session::config::ErrorOutputType`.
   9
  10 use Destination::*;
  11
  12 use syntax_pos::{SourceFile, Span, MultiSpan};
  13
  14 use crate::{
  15     Level, CodeSuggestion, Diagnostic, SubDiagnostic, pluralize,
  16     SuggestionStyle, SourceMapper, SourceMapperDyn, DiagnosticId,
  17 };
  18 use crate::Level::Error;
  19 use crate::snippet::{Annotation, AnnotationType, Line, MultilineAnnotation, StyledString, Style};
  20 use crate::styled_buffer::StyledBuffer;
  21
  22 use rustc_data_structures::fx::FxHashMap;
  23 use rustc_data_structures::sync::Lrc;
  24 use std::borrow::Cow;
  25 use std::io::prelude::*;
  26 use std::io;
  27 use std::cmp::{min, max, Reverse};
  28 use std::path::Path;
  29 use termcolor::{StandardStream, ColorChoice, ColorSpec, BufferWriter, Ansi};
  30 use termcolor::{WriteColor, Color, Buffer};
  31
  32 /// Describes the way the content of the `rendered` field of the json output is generated
  33 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
  34 pub enum HumanReadableErrorType {
  35     Default(ColorConfig),
  36     AnnotateSnippet(ColorConfig),
  37     Short(ColorConfig),
  38 }
  39
  40 impl HumanReadableErrorType {
  41     /// Returns a (`short`, `color`) tuple
  42     pub fn unzip(self) -> (bool, ColorConfig) {
  43         match self {
  44             HumanReadableErrorType::Default(cc) => (false, cc),
  45             HumanReadableErrorType::Short(cc) => (true, cc),
  46             HumanReadableErrorType::AnnotateSnippet(cc) => (false, cc),
  47         }
  48     }
  49     pub fn new_emitter(
  50         self,
  51         dst: Box<dyn Write + Send>,
  52         source_map: Option<Lrc<SourceMapperDyn>>,
  53         teach: bool,
  54         terminal_width: Option<usize>,
  55         external_macro_backtrace: bool,
  56     ) -> EmitterWriter {
  57         let (short, color_config) = self.unzip();
  58         let color = color_config.suggests_using_colors();
  59         EmitterWriter::new(dst, source_map, short, teach, color, terminal_width,
  60             external_macro_backtrace)
  61     }
  62 }
  63
  64 #[derive(Clone, Copy, Debug)]
  65 struct Margin {
  66     /// The available whitespace in the left that can be consumed when centering.
  67     pub whitespace_left: usize,
  68     /// The column of the beginning of left-most span.
  69     pub span_left: usize,
  70     /// The column of the end of right-most span.
  71     pub span_right: usize,
  72     /// The beginning of the line to be displayed.
  73     pub computed_left: usize,
  74     /// The end of the line to be displayed.
  75     pub computed_right: usize,
  76     /// The current width of the terminal. 140 by default and in tests.
  77     pub column_width: usize,
  78     /// The end column of a span label, including the span. Doesn't account for labels not in the
  79     /// same line as the span.
  80     pub label_right: usize,
  81 }
  82
  83 impl Margin {
  84     fn new(
  85         whitespace_left: usize,
  86         span_left: usize,
  87         span_right: usize,
  88         label_right: usize,
  89         column_width: usize,
  90         max_line_len: usize,
  91     ) -> Self {
  92         // The 6 is padding to give a bit of room for `...` when displaying:
  93         // ```
  94         // error: message
  95         //   --> file.rs:16:58
  96         //    |
  97         // 16 | ... fn foo(self) -> Self::Bar {
  98         //    |                     ^^^^^^^^^
  99         // ```
 100
 101         let mut m = Margin {
 102             whitespace_left: whitespace_left.saturating_sub(6),
 103             span_left: span_left.saturating_sub(6),
 104             span_right: span_right + 6,
 105             computed_left: 0,
 106             computed_right: 0,
 107             column_width,
 108             label_right: label_right + 6,
 109         };
 110         m.compute(max_line_len);
 111         m
 112     }
 113
 114     fn was_cut_left(&self) -> bool {
 115         self.computed_left > 0
 116     }
 117
 118     fn was_cut_right(&self, line_len: usize) -> bool {
 119         let right = if self.computed_right == self.span_right ||
 120             self.computed_right == self.label_right
 121         {
 122             // Account for the "..." padding given above. Otherwise we end up with code lines that
 123             // do fit but end in "..." as if they were trimmed.
 124             self.computed_right - 6
 125         } else {
 126             self.computed_right
 127         };
 128         right < line_len && self.computed_left + self.column_width < line_len
 129     }
 130
 131     fn compute(&mut self, max_line_len: usize) {
 132         // When there's a lot of whitespace (>20), we want to trim it as it is useless.
 133         self.computed_left = if self.whitespace_left > 20 {
 134             self.whitespace_left - 16 // We want some padding.
 135         } else {
 136             0
 137         };
 138         // We want to show as much as possible, max_line_len is the right-most boundary for the
 139         // relevant code.
 140         self.computed_right = max(max_line_len, self.computed_left);
 141
 142         if self.computed_right - self.computed_left > self.column_width {
 143             // Trimming only whitespace isn't enough, let's get craftier.
 144             if self.label_right - self.whitespace_left <= self.column_width {
 145                 // Attempt to fit the code window only trimming whitespace.
 146                 self.computed_left = self.whitespace_left;
 147                 self.computed_right = self.computed_left + self.column_width;
 148             } else if self.label_right - self.span_left <= self.column_width {
 149                 // Attempt to fit the code window considering only the spans and labels.
 150                 let padding_left = (self.column_width - (self.label_right - self.span_left)) / 2;
 151                 self.computed_left = self.span_left.saturating_sub(padding_left);
 152                 self.computed_right = self.computed_left + self.column_width;
 153             } else if self.span_right - self.span_left <= self.column_width {
 154                 // Attempt to fit the code window considering the spans and labels plus padding.
 155                 let padding_left = (self.column_width - (self.span_right - self.span_left)) / 5 * 2;
 156                 self.computed_left = self.span_left.saturating_sub(padding_left);
 157                 self.computed_right = self.computed_left + self.column_width;
 158             } else { // Mostly give up but still don't show the full line.
 159                 self.computed_left = self.span_left;
 160                 self.computed_right = self.span_right;
 161             }
 162         }
 163     }
 164
 165     fn left(&self, line_len: usize) -> usize {
 166         min(self.computed_left, line_len)
 167     }
 168
 169     fn right(&self, line_len: usize) -> usize {
 170         if line_len.saturating_sub(self.computed_left) <= self.column_width {
 171             line_len
 172         } else {
 173             min(line_len, self.computed_right)
 174         }
 175     }
 176 }
 177
 178 const ANONYMIZED_LINE_NUM: &str = "LL";
 179
 180 /// Emitter trait for emitting errors.
 181 pub trait Emitter {
 182     /// Emit a structured diagnostic.
 183     fn emit_diagnostic(&mut self, diag: &Diagnostic);
 184
 185     /// Emit a notification that an artifact has been output.
 186     /// This is currently only supported for the JSON format,
 187     /// other formats can, and will, simply ignore it.
 188     fn emit_artifact_notification(&mut self, _path: &Path, _artifact_type: &str) {}
 189
 190     /// Checks if should show explanations about "rustc --explain"
 191     fn should_show_explain(&self) -> bool {
 192         true
 193     }
 194
 195     fn source_map(&self) -> Option<&Lrc<SourceMapperDyn>>;
 196
 197     /// Formats the substitutions of the primary_span
 198     ///
 199     /// The are a lot of conditions to this method, but in short:
 200     ///
 201     /// * If the current `Diagnostic` has only one visible `CodeSuggestion`,
 202     ///   we format the `help` suggestion depending on the content of the
 203     ///   substitutions. In that case, we return the modified span only.
 204     ///
 205     /// * If the current `Diagnostic` has multiple suggestions,
 206     ///   we return the original `primary_span` and the original suggestions.
 207     fn primary_span_formatted<'a>(
 208         &mut self,
 209         diag: &'a Diagnostic,
 210     ) -> (MultiSpan, &'a [CodeSuggestion]) {
 211         let mut primary_span = diag.span.clone();
 212         if let Some((sugg, rest)) = diag.suggestions.split_first() {
 213             if rest.is_empty() &&
 214                // ^ if there is only one suggestion
 215                // don't display multi-suggestions as labels
 216                sugg.substitutions.len() == 1 &&
 217                // don't display multipart suggestions as labels
 218                sugg.substitutions[0].parts.len() == 1 &&
 219                // don't display long messages as labels
 220                sugg.msg.split_whitespace().count() < 10 &&
 221                // don't display multiline suggestions as labels
 222                !sugg.substitutions[0].parts[0].snippet.contains('\n') &&
 223                ![
 224                     // when this style is set we want the suggestion to be a message, not inline
 225                     SuggestionStyle::HideCodeAlways,
 226                     // trivial suggestion for tooling's sake, never shown
 227                     SuggestionStyle::CompletelyHidden,
 228                     // subtle suggestion, never shown inline
 229                     SuggestionStyle::ShowAlways,
 230                ].contains(&sugg.style)
 231             {
 232                 let substitution = &sugg.substitutions[0].parts[0].snippet.trim();
 233                 let msg = if substitution.len() == 0 || sugg.style.hide_inline() {
 234                     // This substitution is only removal OR we explicitly don't want to show the
 235                     // code inline (`hide_inline`). Therefore, we don't show the substitution.
 236                     format!("help: {}", sugg.msg)
 237                 } else {
 238                     // Show the default suggestion text with the substitution
 239                     format!(
 240                         "help: {}{}: `{}`",
 241                         sugg.msg,
 242                         if self.source_map().map(|sm| is_case_difference(
 243                             &**sm,
 244                             substitution,
 245                             sugg.substitutions[0].parts[0].span,
 246                         )).unwrap_or(false) {
 247                             " (notice the capitalization)"
 248                         } else {
 249                             ""
 250                         },
 251                         substitution,
 252                     )
 253                 };
 254                 primary_span.push_span_label(sugg.substitutions[0].parts[0].span, msg);
 255
 256                 // We return only the modified primary_span
 257                 (primary_span, &[])
 258             } else {
 259                 // if there are multiple suggestions, print them all in full
 260                 // to be consistent. We could try to figure out if we can
 261                 // make one (or the first one) inline, but that would give
 262                 // undue importance to a semi-random suggestion
 263                 (primary_span, &diag.suggestions)
 264             }
 265         } else {
 266             (primary_span, &diag.suggestions)
 267         }
 268     }
 269
 270     // This does a small "fix" for multispans by looking to see if it can find any that
 271     // point directly at <*macros>. Since these are often difficult to read, this
 272     // will change the span to point at the use site.
 273     fn fix_multispans_in_std_macros(&self,
 274                                     source_map: &Option<Lrc<SourceMapperDyn>>,
 275                                     span: &mut MultiSpan,
 276                                     children: &mut Vec<SubDiagnostic>,
 277                                     level: &Level,
 278                                     backtrace: bool) {
 279         let mut spans_updated = self.fix_multispan_in_std_macros(source_map, span, backtrace);
 280         for child in children.iter_mut() {
 281             spans_updated |= self.fix_multispan_in_std_macros(
 282                                  source_map,
 283                                  &mut child.span,
 284                                  backtrace
 285                              );
 286         }
 287         let msg = if level == &Error {
 288             "this error originates in a macro outside of the current crate \
 289              (in Nightly builds, run with -Z external-macro-backtrace \
 290               for more info)".to_string()
 291         } else {
 292             "this warning originates in a macro outside of the current crate \
 293              (in Nightly builds, run with -Z external-macro-backtrace \
 294               for more info)".to_string()
 295         };
 296
 297         if spans_updated {
 298             children.push(SubDiagnostic {
 299                 level: Level::Note,
 300                 message: vec![
 301                     (msg,
 302                      Style::NoStyle),
 303                 ],
 304                 span: MultiSpan::new(),
 305                 render_span: None,
 306             });
 307         }
 308     }
 309
 310     // This "fixes" MultiSpans that contain Spans that are pointing to locations inside of
 311     // <*macros>. Since these locations are often difficult to read, we move these Spans from
 312     // <*macros> to their corresponding use site.
 313     fn fix_multispan_in_std_macros(&self,
 314                                    source_map: &Option<Lrc<SourceMapperDyn>>,
 315                                    span: &mut MultiSpan,
 316                                    always_backtrace: bool) -> bool {
 317         let sm = match source_map {
 318             Some(ref sm) => sm,
 319             None => return false,
 320         };
 321
 322         let mut before_after: Vec<(Span, Span)> = vec![];
 323         let mut new_labels: Vec<(Span, String)> = vec![];
 324
 325         // First, find all the spans in <*macros> and point instead at their use site
 326         for sp in span.primary_spans() {
 327             if sp.is_dummy() {
 328                 continue;
 329             }
 330             let call_sp = sm.call_span_if_macro(*sp);
 331             if call_sp != *sp && !always_backtrace {
 332                 before_after.push((*sp, call_sp));
 333             }
 334             let backtrace_len = sp.macro_backtrace().len();
 335             for (i, trace) in sp.macro_backtrace().iter().rev().enumerate() {
 336                 // Only show macro locations that are local
 337                 // and display them like a span_note
 338                 if trace.def_site_span.is_dummy() {
 339                     continue;
 340                 }
 341                 if always_backtrace {
 342                     new_labels.push((trace.def_site_span,
 343                                         format!("in this expansion of `{}`{}",
 344                                                 trace.macro_decl_name,
 345                                                 if backtrace_len > 2 {
 346                                                     // if backtrace_len == 1 it'll be pointed
 347                                                     // at by "in this macro invocation"
 348                                                     format!(" (#{})", i + 1)
 349                                                 } else {
 350                                                     String::new()
 351                                                 })));
 352                 }
 353                 // Check to make sure we're not in any <*macros>
 354                 if !sm.span_to_filename(trace.def_site_span).is_macros() &&
 355                     !trace.macro_decl_name.starts_with("desugaring of ") &&
 356                     !trace.macro_decl_name.starts_with("#[") ||
 357                     always_backtrace {
 358                     new_labels.push((trace.call_site,
 359                                         format!("in this macro invocation{}",
 360                                                 if backtrace_len > 2 && always_backtrace {
 361                                                     // only specify order when the macro
 362                                                     // backtrace is multiple levels deep
 363                                                     format!(" (#{})", i + 1)
 364                                                 } else {
 365                                                     String::new()
 366                                                 })));
 367                     if !always_backtrace {
 368                         break;
 369                     }
 370                 }
 371             }
 372         }
 373         for (label_span, label_text) in new_labels {
 374             span.push_span_label(label_span, label_text);
 375         }
 376         for sp_label in span.span_labels() {
 377             if sp_label.span.is_dummy() {
 378                 continue;
 379             }
 380             if sm.span_to_filename(sp_label.span.clone()).is_macros() &&
 381                 !always_backtrace
 382             {
 383                 let v = sp_label.span.macro_backtrace();
 384                 if let Some(use_site) = v.last() {
 385                     before_after.push((sp_label.span.clone(), use_site.call_site.clone()));
 386                 }
 387             }
 388         }
 389         // After we have them, make sure we replace these 'bad' def sites with their use sites
 390         let spans_updated = !before_after.is_empty();
 391         for (before, after) in before_after {
 392             span.replace(before, after);
 393         }
 394
 395         spans_updated
 396     }
 397 }
 398
 399 impl Emitter for EmitterWriter {
 400     fn source_map(&self) -> Option<&Lrc<SourceMapperDyn>> {
 401         self.sm.as_ref()
 402     }
 403
 404     fn emit_diagnostic(&mut self, diag: &Diagnostic) {
 405         let mut children = diag.children.clone();
 406         let (mut primary_span, suggestions) = self.primary_span_formatted(&diag);
 407
 408         self.fix_multispans_in_std_macros(&self.sm,
 409                                           &mut primary_span,
 410                                           &mut children,
 411                                           &diag.level,
 412                                           self.external_macro_backtrace);
 413
 414         self.emit_messages_default(&diag.level,
 415                                    &diag.styled_message(),
 416                                    &diag.code,
 417                                    &primary_span,
 418                                    &children,
 419                                    &suggestions);
 420     }
 421
 422     fn should_show_explain(&self) -> bool {
 423         !self.short_message
 424     }
 425 }
 426
 427 /// An emitter that does nothing when emitting a diagnostic.
 428 pub struct SilentEmitter;
 429
 430 impl Emitter for SilentEmitter {
 431     fn source_map(&self) -> Option<&Lrc<SourceMapperDyn>> { None }
 432     fn emit_diagnostic(&mut self, _: &Diagnostic) {}
 433 }
 434
 435 /// maximum number of lines we will print for each error; arbitrary.
 436 pub const MAX_HIGHLIGHT_LINES: usize = 6;
 437 /// maximum number of suggestions to be shown
 438 ///
 439 /// Arbitrary, but taken from trait import suggestion limit
 440 pub const MAX_SUGGESTIONS: usize = 4;
 441
 442 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 443 pub enum ColorConfig {
 444     Auto,
 445     Always,
 446     Never,
 447 }
 448
 449 impl ColorConfig {
 450     fn to_color_choice(self) -> ColorChoice {
 451         match self {
 452             ColorConfig::Always => {
 453                 if atty::is(atty::Stream::Stderr) {
 454                     ColorChoice::Always
 455                 } else {
 456                     ColorChoice::AlwaysAnsi
 457                 }
 458             }
 459             ColorConfig::Never => ColorChoice::Never,
 460             ColorConfig::Auto if atty::is(atty::Stream::Stderr) => {
 461                 ColorChoice::Auto
 462             }
 463             ColorConfig::Auto => ColorChoice::Never,
 464         }
 465     }
 466     fn suggests_using_colors(self) -> bool {
 467         match self {
 468             | ColorConfig::Always
 469             | ColorConfig::Auto
 470             => true,
 471             ColorConfig::Never => false,
 472         }
 473     }
 474 }
 475
 476 /// Handles the writing of `HumanReadableErrorType::Default` and `HumanReadableErrorType::Short`
 477 pub struct EmitterWriter {
 478     dst: Destination,
 479     sm: Option<Lrc<SourceMapperDyn>>,
 480     short_message: bool,
 481     teach: bool,
 482     ui_testing: bool,
 483     terminal_width: Option<usize>,
 484
 485     external_macro_backtrace: bool,
 486 }
 487
 488 #[derive(Debug)]
 489 pub struct FileWithAnnotatedLines {
 490     pub file: Lrc<SourceFile>,
 491     pub lines: Vec<Line>,
 492     multiline_depth: usize,
 493 }
 494
 495 impl EmitterWriter {
 496     pub fn stderr(
 497         color_config: ColorConfig,
 498         source_map: Option<Lrc<SourceMapperDyn>>,
 499         short_message: bool,
 500         teach: bool,
 501         terminal_width: Option<usize>,
 502         external_macro_backtrace: bool,
 503     ) -> EmitterWriter {
 504         let dst = Destination::from_stderr(color_config);
 505         EmitterWriter {
 506             dst,
 507             sm: source_map,
 508             short_message,
 509             teach,
 510             ui_testing: false,
 511             terminal_width,
 512             external_macro_backtrace,
 513         }
 514     }
 515
 516     pub fn new(
 517         dst: Box<dyn Write + Send>,
 518         source_map: Option<Lrc<SourceMapperDyn>>,
 519         short_message: bool,
 520         teach: bool,
 521         colored: bool,
 522         terminal_width: Option<usize>,
 523         external_macro_backtrace: bool,
 524     ) -> EmitterWriter {
 525         EmitterWriter {
 526             dst: Raw(dst, colored),
 527             sm: source_map,
 528             short_message,
 529             teach,
 530             ui_testing: false,
 531             terminal_width,
 532             external_macro_backtrace,
 533         }
 534     }
 535
 536     pub fn ui_testing(mut self, ui_testing: bool) -> Self {
 537         self.ui_testing = ui_testing;
 538         self
 539     }
 540
 541     fn maybe_anonymized(&self, line_num: usize) -> String {
 542         if self.ui_testing {
 543             ANONYMIZED_LINE_NUM.to_string()
 544         } else {
 545             line_num.to_string()
 546         }
 547     }
 548
 549     fn draw_line(
 550         &self,
 551         buffer: &mut StyledBuffer,
 552         source_string: &str,
 553         line_index: usize,
 554         line_offset: usize,
 555         width_offset: usize,
 556         code_offset: usize,
 557         margin: Margin,
 558     ) {
 559         let line_len = source_string.len();
 560         // Create the source line we will highlight.
 561         let left = margin.left(line_len);
 562         let right = margin.right(line_len);
 563         // On long lines, we strip the source line, accounting for unicode.
 564         let mut taken = 0;
 565         let code: String = source_string.chars().skip(left).take_while(|ch| {
 566             // Make sure that the trimming on the right will fall within the terminal width.
 567             // FIXME: `unicode_width` sometimes disagrees with terminals on how wide a `char` is.
 568             // For now, just accept that sometimes the code line will be longer than desired.
 569             let next = unicode_width::UnicodeWidthChar::width(*ch).unwrap_or(1);
 570             if taken + next > right - left {
 571                 return false;
 572             }
 573             taken += next;
 574             true
 575         }).collect();
 576         buffer.puts(line_offset, code_offset, &code, Style::Quotation);
 577         if margin.was_cut_left() {
 578             // We have stripped some code/whitespace from the beginning, make it clear.
 579             buffer.puts(line_offset, code_offset, "...", Style::LineNumber);
 580         }
 581         if margin.was_cut_right(line_len) {
 582             // We have stripped some code after the right-most span end, make it clear we did so.
 583             buffer.puts(line_offset, code_offset + taken - 3, "...", Style::LineNumber);
 584         }
 585         buffer.puts(line_offset, 0, &self.maybe_anonymized(line_index), Style::LineNumber);
 586
 587         draw_col_separator(buffer, line_offset, width_offset - 2);
 588     }
 589
 590     fn render_source_line(
 591         &self,
 592         buffer: &mut StyledBuffer,
 593         file: Lrc<SourceFile>,
 594         line: &Line,
 595         width_offset: usize,
 596         code_offset: usize,
 597         margin: Margin,
 598     ) -> Vec<(usize, Style)> {
 599         // Draw:
 600         //
 601         //   LL | ... code ...
 602         //      |     ^^-^ span label
 603         //      |       |
 604         //      |       secondary span label
 605         //
 606         //   ^^ ^ ^^^ ^^^^ ^^^ we don't care about code too far to the right of a span, we trim it
 607         //   |  | |   |
 608         //   |  | |   actual code found in your source code and the spans we use to mark it
 609         //   |  | when there's too much wasted space to the left, trim it
 610         //   |  vertical divider between the column number and the code
 611         //   column number
 612
 613         if line.line_index == 0 {
 614             return Vec::new();
 615         }
 616
 617         let source_string = match file.get_line(line.line_index - 1) {
 618             Some(s) => s,
 619             None => return Vec::new(),
 620         };
 621
 622         let line_offset = buffer.num_lines();
 623
 624         let left = margin.left(source_string.len()); // Left trim
 625         // Account for unicode characters of width !=0 that were removed.
 626         let left = source_string.chars().take(left)
 627             .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
 628             .sum();
 629
 630         self.draw_line(
 631             buffer,
 632             &source_string,
 633             line.line_index,
 634             line_offset,
 635             width_offset,
 636             code_offset,
 637             margin,
 638         );
 639
 640         // Special case when there's only one annotation involved, it is the start of a multiline
 641         // span and there's no text at the beginning of the code line. Instead of doing the whole
 642         // graph:
 643         //
 644         // 2 |   fn foo() {
 645         //   |  _^
 646         // 3 | |
 647         // 4 | | }
 648         //   | |_^ test
 649         //
 650         // we simplify the output to:
 651         //
 652         // 2 | / fn foo() {
 653         // 3 | |
 654         // 4 | | }
 655         //   | |_^ test
 656         if let [ann] = &line.annotations[..] {
 657             if let AnnotationType::MultilineStart(depth) = ann.annotation_type {
 658                 if source_string.chars().take(ann.start_col).all(|c| c.is_whitespace()) {
 659                     let style = if ann.is_primary {
 660                         Style::UnderlinePrimary
 661                     } else {
 662                         Style::UnderlineSecondary
 663                     };
 664                     buffer.putc(line_offset, width_offset + depth - 1, '/', style);
 665                     return vec![(depth, style)];
 666                 }
 667             }
 668         }
 669
 670         // We want to display like this:
 671         //
 672         //      vec.push(vec.pop().unwrap());
 673         //      ---      ^^^               - previous borrow ends here
 674         //      |        |
 675         //      |        error occurs here
 676         //      previous borrow of `vec` occurs here
 677         //
 678         // But there are some weird edge cases to be aware of:
 679         //
 680         //      vec.push(vec.pop().unwrap());
 681         //      --------                    - previous borrow ends here
 682         //      ||
 683         //      |this makes no sense
 684         //      previous borrow of `vec` occurs here
 685         //
 686         // For this reason, we group the lines into "highlight lines"
 687         // and "annotations lines", where the highlight lines have the `^`.
 688
 689         // Sort the annotations by (start, end col)
 690         // The labels are reversed, sort and then reversed again.
 691         // Consider a list of annotations (A1, A2, C1, C2, B1, B2) where
 692         // the letter signifies the span. Here we are only sorting by the
 693         // span and hence, the order of the elements with the same span will
 694         // not change. On reversing the ordering (|a, b| but b.cmp(a)), you get
 695         // (C1, C2, B1, B2, A1, A2). All the elements with the same span are
 696         // still ordered first to last, but all the elements with different
 697         // spans are ordered by their spans in last to first order. Last to
 698         // first order is important, because the jiggly lines and | are on
 699         // the left, so the rightmost span needs to be rendered first,
 700         // otherwise the lines would end up needing to go over a message.
 701
 702         let mut annotations = line.annotations.clone();
 703         annotations.sort_by_key(|a| Reverse(a.start_col));
 704
 705         // First, figure out where each label will be positioned.
 706         //
 707         // In the case where you have the following annotations:
 708         //
 709         //      vec.push(vec.pop().unwrap());
 710         //      --------                    - previous borrow ends here [C]
 711         //      ||
 712         //      |this makes no sense [B]
 713         //      previous borrow of `vec` occurs here [A]
 714         //
 715         // `annotations_position` will hold [(2, A), (1, B), (0, C)].
 716         //
 717         // We try, when possible, to stick the rightmost annotation at the end
 718         // of the highlight line:
 719         //
 720         //      vec.push(vec.pop().unwrap());
 721         //      ---      ---               - previous borrow ends here
 722         //
 723         // But sometimes that's not possible because one of the other
 724         // annotations overlaps it. For example, from the test
 725         // `span_overlap_label`, we have the following annotations
 726         // (written on distinct lines for clarity):
 727         //
 728         //      fn foo(x: u32) {
 729         //      --------------
 730         //             -
 731         //
 732         // In this case, we can't stick the rightmost-most label on
 733         // the highlight line, or we would get:
 734         //
 735         //      fn foo(x: u32) {
 736         //      -------- x_span
 737         //      |
 738         //      fn_span
 739         //
 740         // which is totally weird. Instead we want:
 741         //
 742         //      fn foo(x: u32) {
 743         //      --------------
 744         //      |      |
 745         //      |      x_span
 746         //      fn_span
 747         //
 748         // which is...less weird, at least. In fact, in general, if
 749         // the rightmost span overlaps with any other span, we should
 750         // use the "hang below" version, so we can at least make it
 751         // clear where the span *starts*. There's an exception for this
 752         // logic, when the labels do not have a message:
 753         //
 754         //      fn foo(x: u32) {
 755         //      --------------
 756         //             |
 757         //             x_span
 758         //
 759         // instead of:
 760         //
 761         //      fn foo(x: u32) {
 762         //      --------------
 763         //      |      |
 764         //      |      x_span
 765         //      <EMPTY LINE>
 766         //
 767         let mut annotations_position = vec![];
 768         let mut line_len = 0;
 769         let mut p = 0;
 770         for (i, annotation) in annotations.iter().enumerate() {
 771             for (j, next) in annotations.iter().enumerate() {
 772                 if overlaps(next, annotation, 0)  // This label overlaps with another one and both
 773                     && annotation.has_label()     // take space (they have text and are not
 774                     && j > i                      // multiline lines).
 775                     && p == 0  // We're currently on the first line, move the label one line down
 776                 {
 777                     // If we're overlapping with an un-labelled annotation with the same span
 778                     // we can just merge them in the output
 779                     if next.start_col == annotation.start_col
 780                     && next.end_col == annotation.end_col
 781                     && !next.has_label()
 782                     {
 783                         continue;
 784                     }
 785
 786                     // This annotation needs a new line in the output.
 787                     p += 1;
 788                     break;
 789                 }
 790             }
 791             annotations_position.push((p, annotation));
 792             for (j, next) in annotations.iter().enumerate() {
 793                 if j > i  {
 794                     let l = next.label.as_ref().map_or(0, |label| label.len() + 2);
 795                     if (overlaps(next, annotation, l) // Do not allow two labels to be in the same
 796                                                      // line if they overlap including padding, to
 797                                                      // avoid situations like:
 798                                                      //
 799                                                      //      fn foo(x: u32) {
 800                                                      //      -------^------
 801                                                      //      |      |
 802                                                      //      fn_spanx_span
 803                                                      //
 804                         && annotation.has_label()    // Both labels must have some text, otherwise
 805                         && next.has_label())         // they are not overlapping.
 806                                                      // Do not add a new line if this annotation
 807                                                      // or the next are vertical line placeholders.
 808                         || (annotation.takes_space() // If either this or the next annotation is
 809                             && next.has_label())     // multiline start/end, move it to a new line
 810                         || (annotation.has_label()   // so as not to overlap the orizontal lines.
 811                             && next.takes_space())
 812                         || (annotation.takes_space() && next.takes_space())
 813                         || (overlaps(next, annotation, l)
 814                             && next.end_col <= annotation.end_col
 815                             && next.has_label()
 816                             && p == 0)  // Avoid #42595.
 817                     {
 818                         // This annotation needs a new line in the output.
 819                         p += 1;
 820                         break;
 821                     }
 822                 }
 823             }
 824             line_len = max(line_len, p);
 825         }
 826
 827         if line_len != 0 {
 828             line_len += 1;
 829         }
 830
 831         // If there are no annotations or the only annotations on this line are
 832         // MultilineLine, then there's only code being shown, stop processing.
 833         if line.annotations.iter().all(|a| a.is_line()) {
 834             return vec![];
 835         }
 836
 837         // Write the colunmn separator.
 838         //
 839         // After this we will have:
 840         //
 841         // 2 |   fn foo() {
 842         //   |
 843         //   |
 844         //   |
 845         // 3 |
 846         // 4 |   }
 847         //   |
 848         for pos in 0..=line_len {
 849             draw_col_separator(buffer, line_offset + pos + 1, width_offset - 2);
 850             buffer.putc(line_offset + pos + 1,
 851                         width_offset - 2,
 852                         '|',
 853                         Style::LineNumber);
 854         }
 855
 856         // Write the horizontal lines for multiline annotations
 857         // (only the first and last lines need this).
 858         //
 859         // After this we will have:
 860         //
 861         // 2 |   fn foo() {
 862         //   |  __________
 863         //   |
 864         //   |
 865         // 3 |
 866         // 4 |   }
 867         //   |  _
 868         for &(pos, annotation) in &annotations_position {
 869             let style = if annotation.is_primary {
 870                 Style::UnderlinePrimary
 871             } else {
 872                 Style::UnderlineSecondary
 873             };
 874             let pos = pos + 1;
 875             match annotation.annotation_type {
 876                 AnnotationType::MultilineStart(depth) |
 877                 AnnotationType::MultilineEnd(depth) => {
 878                     draw_range(
 879                         buffer,
 880                         '_',
 881                         line_offset + pos,
 882                         width_offset + depth,
 883                         code_offset + annotation.start_col - left,
 884                         style,
 885                     );
 886                 }
 887                 _ if self.teach => {
 888                     buffer.set_style_range(
 889                         line_offset,
 890                         code_offset + annotation.start_col - left,
 891                         code_offset + annotation.end_col - left,
 892                         style,
 893                         annotation.is_primary,
 894                     );
 895                 }
 896                 _ => {}
 897             }
 898         }
 899
 900         // Write the vertical lines for labels that are on a different line as the underline.
 901         //
 902         // After this we will have:
 903         //
 904         // 2 |   fn foo() {
 905         //   |  __________
 906         //   | |    |
 907         //   | |
 908         // 3 |
 909         // 4 | | }
 910         //   | |_
 911         for &(pos, annotation) in &annotations_position {
 912             let style = if annotation.is_primary {
 913                 Style::UnderlinePrimary
 914             } else {
 915                 Style::UnderlineSecondary
 916             };
 917             let pos = pos + 1;
 918
 919             if pos > 1 && (annotation.has_label() || annotation.takes_space()) {
 920                 for p in line_offset + 1..=line_offset + pos {
 921                     buffer.putc(p,
 922                                 code_offset + annotation.start_col - margin.computed_left,
 923                                 '|',
 924                                 style);
 925                 }
 926             }
 927             match annotation.annotation_type {
 928                 AnnotationType::MultilineStart(depth) => {
 929                     for p in line_offset + pos + 1..line_offset + line_len + 2 {
 930                         buffer.putc(p,
 931                                     width_offset + depth - 1,
 932                                     '|',
 933                                     style);
 934                     }
 935                 }
 936                 AnnotationType::MultilineEnd(depth) => {
 937                     for p in line_offset..=line_offset + pos {
 938                         buffer.putc(p,
 939                                     width_offset + depth - 1,
 940                                     '|',
 941                                     style);
 942                     }
 943                 }
 944                 _ => (),
 945             }
 946         }
 947
 948         // Write the labels on the annotations that actually have a label.
 949         //
 950         // After this we will have:
 951         //
 952         // 2 |   fn foo() {
 953         //   |  __________
 954         //   |      |
 955         //   |      something about `foo`
 956         // 3 |
 957         // 4 |   }
 958         //   |  _  test
 959         for &(pos, annotation) in &annotations_position {
 960             let style = if annotation.is_primary {
 961                 Style::LabelPrimary
 962             } else {
 963                 Style::LabelSecondary
 964             };
 965             let (pos, col) = if pos == 0 {
 966                 (pos + 1, (annotation.end_col + 1).saturating_sub(left))
 967             } else {
 968                 (pos + 2, annotation.start_col.saturating_sub(left))
 969             };
 970             if let Some(ref label) = annotation.label {
 971                 buffer.puts(line_offset + pos, code_offset + col, &label, style);
 972             }
 973         }
 974
 975         // Sort from biggest span to smallest span so that smaller spans are
 976         // represented in the output:
 977         //
 978         // x | fn foo()
 979         //   | ^^^---^^
 980         //   | |  |
 981         //   | |  something about `foo`
 982         //   | something about `fn foo()`
 983         annotations_position.sort_by_key(|(_, ann)| {
 984             // Decreasing order. When annotations share the same length, prefer `Primary`.
 985             (Reverse(ann.len()), ann.is_primary)
 986         });
 987
 988         // Write the underlines.
 989         //
 990         // After this we will have:
 991         //
 992         // 2 |   fn foo() {
 993         //   |  ____-_____^
 994         //   |      |
 995         //   |      something about `foo`
 996         // 3 |
 997         // 4 |   }
 998         //   |  _^  test
 999         for &(_, annotation) in &annotations_position {
1000             let (underline, style) = if annotation.is_primary {
1001                 ('^', Style::UnderlinePrimary)
1002             } else {
1003                 ('-', Style::UnderlineSecondary)
1004             };
1005             for p in annotation.start_col..annotation.end_col {
1006                 buffer.putc(
1007                     line_offset + 1,
1008                     (code_offset + p).saturating_sub(left),
1009                     underline,
1010                     style,
1011                 );
1012             }
1013         }
1014         annotations_position.iter().filter_map(|&(_, annotation)| {
1015             match annotation.annotation_type {
1016                 AnnotationType::MultilineStart(p) | AnnotationType::MultilineEnd(p) => {
1017                     let style = if annotation.is_primary {
1018                         Style::LabelPrimary
1019                     } else {
1020                         Style::LabelSecondary
1021                     };
1022                     Some((p, style))
1023                 }
1024                 _ => None
1025             }
1026
1027         }).collect::<Vec<_>>()
1028     }
1029
1030     fn get_multispan_max_line_num(&mut self, msp: &MultiSpan) -> usize {
1031         let sm = match self.sm {
1032             Some(ref sm) => sm,
1033             None => return 0,
1034         };
1035
1036         let mut max = 0;
1037         for primary_span in msp.primary_spans() {
1038             if !primary_span.is_dummy() {
1039                 let hi = sm.lookup_char_pos(primary_span.hi());
1040                 max = (hi.line).max(max);
1041             }
1042         }
1043         if !self.short_message {
1044             for span_label in msp.span_labels() {
1045                 if !span_label.span.is_dummy() {
1046                     let hi = sm.lookup_char_pos(span_label.span.hi());
1047                     max = (hi.line).max(max);
1048                 }
1049             }
1050         }
1051
1052         max
1053     }
1054
1055     fn get_max_line_num(&mut self, span: &MultiSpan, children: &[SubDiagnostic]) -> usize {
1056         let primary = self.get_multispan_max_line_num(span);
1057         children.iter()
1058             .map(|sub| self.get_multispan_max_line_num(&sub.span))
1059             .max()
1060             .unwrap_or(0)
1061             .max(primary)
1062     }
1063
1064     /// Adds a left margin to every line but the first, given a padding length and the label being
1065     /// displayed, keeping the provided highlighting.
1066     fn msg_to_buffer(&self,
1067                      buffer: &mut StyledBuffer,
1068                      msg: &[(String, Style)],
1069                      padding: usize,
1070                      label: &str,
1071                      override_style: Option<Style>) {
1072
1073         // The extra 5 ` ` is padding that's always needed to align to the `note: `:
1074         //
1075         //   error: message
1076         //     --> file.rs:13:20
1077         //      |
1078         //   13 |     <CODE>
1079         //      |      ^^^^
1080         //      |
1081         //      = note: multiline
1082         //              message
1083         //   ++^^^----xx
1084         //    |  |   | |
1085         //    |  |   | magic `2`
1086         //    |  |   length of label
1087         //    |  magic `3`
1088         //    `max_line_num_len`
1089         let padding = " ".repeat(padding + label.len() + 5);
1090
1091         /// Returns `override` if it is present and `style` is `NoStyle` or `style` otherwise
1092         fn style_or_override(style: Style, override_: Option<Style>) -> Style {
1093             match (style, override_) {
1094                 (Style::NoStyle, Some(override_)) => override_,
1095                 _ => style,
1096             }
1097         }
1098
1099         let mut line_number = 0;
1100
1101         // Provided the following diagnostic message:
1102         //
1103         //     let msg = vec![
1104         //       ("
1105         //       ("highlighted multiline\nstring to\nsee how it ", Style::NoStyle),
1106         //       ("looks", Style::Highlight),
1107         //       ("with\nvery ", Style::NoStyle),
1108         //       ("weird", Style::Highlight),
1109         //       (" formats\n", Style::NoStyle),
1110         //       ("see?", Style::Highlight),
1111         //     ];
1112         //
1113         // the expected output on a note is (* surround the highlighted text)
1114         //
1115         //        = note: highlighted multiline
1116         //                string to
1117         //                see how it *looks* with
1118         //                very *weird* formats
1119         //                see?
1120         for &(ref text, ref style) in msg.iter() {
1121             let lines = text.split('\n').collect::<Vec<_>>();
1122             if lines.len() > 1 {
1123                 for (i, line) in lines.iter().enumerate() {
1124                     if i != 0 {
1125                         line_number += 1;
1126                         buffer.append(line_number, &padding, Style::NoStyle);
1127                     }
1128                     buffer.append(line_number, line, style_or_override(*style, override_style));
1129                 }
1130             } else {
1131                 buffer.append(line_number, text, style_or_override(*style, override_style));
1132             }
1133         }
1134     }
1135
1136     fn emit_message_default(
1137         &mut self,
1138         msp: &MultiSpan,
1139         msg: &[(String, Style)],
1140         code: &Option<DiagnosticId>,
1141         level: &Level,
1142         max_line_num_len: usize,
1143         is_secondary: bool,
1144     ) -> io::Result<()> {
1145         let mut buffer = StyledBuffer::new();
1146         let header_style = if is_secondary {
1147             Style::HeaderMsg
1148         } else {
1149             Style::MainHeaderMsg
1150         };
1151
1152         if !msp.has_primary_spans() && !msp.has_span_labels() && is_secondary
1153            && !self.short_message {
1154             // This is a secondary message with no span info
1155             for _ in 0..max_line_num_len {
1156                 buffer.prepend(0, " ", Style::NoStyle);
1157             }
1158             draw_note_separator(&mut buffer, 0, max_line_num_len + 1);
1159             if *level != Level::FailureNote {
1160                 let level_str = level.to_string();
1161                 if !level_str.is_empty() {
1162                     buffer.append(0, &level_str, Style::MainHeaderMsg);
1163                     buffer.append(0, ": ", Style::NoStyle);
1164                 }
1165             }
1166             self.msg_to_buffer(&mut buffer, msg, max_line_num_len, "note", None);
1167         } else {
1168             let level_str = level.to_string();
1169             // The failure note level itself does not provide any useful diagnostic information
1170             if *level != Level::FailureNote && !level_str.is_empty() {
1171                 buffer.append(0, &level_str, Style::Level(level.clone()));
1172             }
1173             // only render error codes, not lint codes
1174             if let Some(DiagnosticId::Error(ref code)) = *code {
1175                 buffer.append(0, "[", Style::Level(level.clone()));
1176                 buffer.append(0, &code, Style::Level(level.clone()));
1177                 buffer.append(0, "]", Style::Level(level.clone()));
1178             }
1179             if *level != Level::FailureNote && !level_str.is_empty() {
1180                 buffer.append(0, ": ", header_style);
1181             }
1182             for &(ref text, _) in msg.iter() {
1183                 buffer.append(0, text, header_style);
1184             }
1185         }
1186
1187         let mut annotated_files = FileWithAnnotatedLines::collect_annotations(msp, &self.sm);
1188
1189         // Make sure our primary file comes first
1190         let (primary_lo, sm) = if let (Some(sm), Some(ref primary_span)) =
1191             (self.sm.as_ref(), msp.primary_span().as_ref()) {
1192             if !primary_span.is_dummy() {
1193                 (sm.lookup_char_pos(primary_span.lo()), sm)
1194             } else {
1195                 emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1196                 return Ok(());
1197             }
1198         } else {
1199             // If we don't have span information, emit and exit
1200             emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1201             return Ok(());
1202         };
1203         if let Ok(pos) =
1204             annotated_files.binary_search_by(|x| x.file.name.cmp(&primary_lo.file.name)) {
1205             annotated_files.swap(0, pos);
1206         }
1207
1208         // Print out the annotate source lines that correspond with the error
1209         for annotated_file in annotated_files {
1210             // we can't annotate anything if the source is unavailable.
1211             if !sm.ensure_source_file_source_present(annotated_file.file.clone()) {
1212                 continue;
1213             }
1214
1215             // print out the span location and spacer before we print the annotated source
1216             // to do this, we need to know if this span will be primary
1217             let is_primary = primary_lo.file.name == annotated_file.file.name;
1218             if is_primary {
1219                 let loc = primary_lo.clone();
1220                 if !self.short_message {
1221                     // remember where we are in the output buffer for easy reference
1222                     let buffer_msg_line_offset = buffer.num_lines();
1223
1224                     buffer.prepend(buffer_msg_line_offset, "--> ", Style::LineNumber);
1225                     buffer.append(
1226                         buffer_msg_line_offset,
1227                         &format!(
1228                             "{}:{}:{}",
1229                             loc.file.name,
1230                             sm.doctest_offset_line(&loc.file.name, loc.line),
1231                             loc.col.0 + 1,
1232                         ),
1233                         Style::LineAndColumn,
1234                     );
1235                     for _ in 0..max_line_num_len {
1236                         buffer.prepend(buffer_msg_line_offset, " ", Style::NoStyle);
1237                     }
1238                 } else {
1239                     buffer.prepend(
1240                         0,
1241                         &format!(
1242                             "{}:{}:{}: ",
1243                             loc.file.name,
1244                             sm.doctest_offset_line(&loc.file.name, loc.line),
1245                             loc.col.0 + 1,
1246                         ),
1247                         Style::LineAndColumn,
1248                     );
1249                 }
1250             } else if !self.short_message {
1251                 // remember where we are in the output buffer for easy reference
1252                 let buffer_msg_line_offset = buffer.num_lines();
1253
1254                 // Add spacing line
1255                 draw_col_separator(&mut buffer, buffer_msg_line_offset, max_line_num_len + 1);
1256
1257                 // Then, the secondary file indicator
1258                 buffer.prepend(buffer_msg_line_offset + 1, "::: ", Style::LineNumber);
1259                 let loc = if let Some(first_line) = annotated_file.lines.first() {
1260                     let col = if let Some(first_annotation) = first_line.annotations.first() {
1261                         format!(":{}", first_annotation.start_col + 1)
1262                     } else {
1263                         String::new()
1264                     };
1265                     format!("{}:{}{}",
1266                             annotated_file.file.name,
1267                             sm.doctest_offset_line(
1268                                 &annotated_file.file.name, first_line.line_index),
1269                             col)
1270                 } else {
1271                     annotated_file.file.name.to_string()
1272                 };
1273                 buffer.append(buffer_msg_line_offset + 1,
1274                               &loc,
1275                               Style::LineAndColumn);
1276                 for _ in 0..max_line_num_len {
1277                     buffer.prepend(buffer_msg_line_offset + 1, " ", Style::NoStyle);
1278                 }
1279             }
1280
1281             if !self.short_message {
1282                 // Put in the spacer between the location and annotated source
1283                 let buffer_msg_line_offset = buffer.num_lines();
1284                 draw_col_separator_no_space(&mut buffer,
1285                                             buffer_msg_line_offset,
1286                                             max_line_num_len + 1);
1287
1288                 // Contains the vertical lines' positions for active multiline annotations
1289                 let mut multilines = FxHashMap::default();
1290
1291                 // Get the left-side margin to remove it
1292                 let mut whitespace_margin = std::usize::MAX;
1293                 for line_idx in 0..annotated_file.lines.len() {
1294                     let file = annotated_file.file.clone();
1295                     let line = &annotated_file.lines[line_idx];
1296                     if let Some(source_string) = file.get_line(line.line_index - 1) {
1297                         let leading_whitespace = source_string
1298                             .chars()
1299                             .take_while(|c| c.is_whitespace())
1300                             .count();
1301                         if source_string.chars().any(|c| !c.is_whitespace()) {
1302                             whitespace_margin = min(
1303                                 whitespace_margin,
1304                                 leading_whitespace,
1305                             );
1306                         }
1307                     }
1308                 }
1309                 if whitespace_margin == std::usize::MAX {
1310                     whitespace_margin = 0;
1311                 }
1312
1313                 // Left-most column any visible span points at.
1314                 let mut span_left_margin = std::usize::MAX;
1315                 for line in &annotated_file.lines {
1316                     for ann in &line.annotations {
1317                         span_left_margin = min(span_left_margin, ann.start_col);
1318                         span_left_margin = min(span_left_margin, ann.end_col);
1319                     }
1320                 }
1321                 if span_left_margin == std::usize::MAX {
1322                     span_left_margin = 0;
1323                 }
1324
1325                 // Right-most column any visible span points at.
1326                 let mut span_right_margin = 0;
1327                 let mut label_right_margin = 0;
1328                 let mut max_line_len = 0;
1329                 for line in &annotated_file.lines {
1330                     max_line_len = max(max_line_len, annotated_file.file
1331                         .get_line(line.line_index - 1)
1332                         .map_or(0, |s| s.len()));
1333                     for ann in &line.annotations {
1334                         span_right_margin = max(span_right_margin, ann.start_col);
1335                         span_right_margin = max(span_right_margin, ann.end_col);
1336                         // FIXME: account for labels not in the same line
1337                         let label_right = ann.label.as_ref().map_or(0, |l| l.len() + 1);
1338                         label_right_margin = max(label_right_margin, ann.end_col + label_right);
1339                     }
1340                 }
1341
1342                 let width_offset = 3 + max_line_num_len;
1343                 let code_offset = if annotated_file.multiline_depth == 0 {
1344                     width_offset
1345                 } else {
1346                     width_offset + annotated_file.multiline_depth + 1
1347                 };
1348
1349                 let column_width = if let Some(width) = self.terminal_width {
1350                     width.saturating_sub(code_offset)
1351                 } else if self.ui_testing {
1352                     140
1353                 } else {
1354                     term_size::dimensions()
1355                         .map(|(w, _)| w.saturating_sub(code_offset))
1356                         .unwrap_or(std::usize::MAX)
1357                 };
1358
1359                 let margin = Margin::new(
1360                     whitespace_margin,
1361                     span_left_margin,
1362                     span_right_margin,
1363                     label_right_margin,
1364                     column_width,
1365                     max_line_len,
1366                 );
1367
1368                 // Next, output the annotate source for this file
1369                 for line_idx in 0..annotated_file.lines.len() {
1370                     let previous_buffer_line = buffer.num_lines();
1371
1372                     let depths = self.render_source_line(
1373                         &mut buffer,
1374                         annotated_file.file.clone(),
1375                         &annotated_file.lines[line_idx],
1376                         width_offset,
1377                         code_offset,
1378                         margin,
1379                     );
1380
1381                     let mut to_add = FxHashMap::default();
1382
1383                     for (depth, style) in depths {
1384                         if multilines.get(&depth).is_some() {
1385                             multilines.remove(&depth);
1386                         } else {
1387                             to_add.insert(depth, style);
1388                         }
1389                     }
1390
1391                     // Set the multiline annotation vertical lines to the left of
1392                     // the code in this line.
1393                     for (depth, style) in &multilines {
1394                         for line in previous_buffer_line..buffer.num_lines() {
1395                             draw_multiline_line(&mut buffer,
1396                                                 line,
1397                                                 width_offset,
1398                                                 *depth,
1399                                                 *style);
1400                         }
1401                     }
1402                     // check to see if we need to print out or elide lines that come between
1403                     // this annotated line and the next one.
1404                     if line_idx < (annotated_file.lines.len() - 1) {
1405                         let line_idx_delta = annotated_file.lines[line_idx + 1].line_index -
1406                                              annotated_file.lines[line_idx].line_index;
1407                         if line_idx_delta > 2 {
1408                             let last_buffer_line_num = buffer.num_lines();
1409                             buffer.puts(last_buffer_line_num, 0, "...", Style::LineNumber);
1410
1411                             // Set the multiline annotation vertical lines on `...` bridging line.
1412                             for (depth, style) in &multilines {
1413                                 draw_multiline_line(&mut buffer,
1414                                                     last_buffer_line_num,
1415                                                     width_offset,
1416                                                     *depth,
1417                                                     *style);
1418                             }
1419                         } else if line_idx_delta == 2 {
1420                             let unannotated_line = annotated_file.file
1421                                 .get_line(annotated_file.lines[line_idx].line_index)
1422                                 .unwrap_or_else(|| Cow::from(""));
1423
1424                             let last_buffer_line_num = buffer.num_lines();
1425
1426                             self.draw_line(
1427                                 &mut buffer,
1428                                 &unannotated_line,
1429                                 annotated_file.lines[line_idx + 1].line_index - 1,
1430                                 last_buffer_line_num,
1431                                 width_offset,
1432                                 code_offset,
1433                                 margin,
1434                             );
1435
1436                             for (depth, style) in &multilines {
1437                                 draw_multiline_line(
1438                                     &mut buffer,
1439                                     last_buffer_line_num,
1440                                     width_offset,
1441                                     *depth,
1442                                     *style,
1443                                 );
1444                             }
1445                         }
1446                     }
1447
1448                     multilines.extend(&to_add);
1449                 }
1450             }
1451         }
1452
1453         // final step: take our styled buffer, render it, then output it
1454         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1455
1456         Ok(())
1457
1458     }
1459
1460     fn emit_suggestion_default(
1461         &mut self,
1462         suggestion: &CodeSuggestion,
1463         level: &Level,
1464         max_line_num_len: usize,
1465     ) -> io::Result<()> {
1466         let sm = match self.sm {
1467             Some(ref sm) => sm,
1468             None => return Ok(())
1469         };
1470
1471         let mut buffer = StyledBuffer::new();
1472
1473         // Render the suggestion message
1474         let level_str = level.to_string();
1475         if !level_str.is_empty() {
1476             buffer.append(0, &level_str, Style::Level(level.clone()));
1477             buffer.append(0, ": ", Style::HeaderMsg);
1478         }
1479         self.msg_to_buffer(
1480             &mut buffer,
1481             &[(suggestion.msg.to_owned(), Style::NoStyle)],
1482             max_line_num_len,
1483             "suggestion",
1484             Some(Style::HeaderMsg),
1485         );
1486
1487         // Render the replacements for each suggestion
1488         let suggestions = suggestion.splice_lines(&**sm);
1489
1490         let mut row_num = 2;
1491         let mut notice_capitalization = false;
1492         for (complete, parts, only_capitalization) in suggestions.iter().take(MAX_SUGGESTIONS) {
1493             notice_capitalization |= only_capitalization;
1494             // Only show underline if the suggestion spans a single line and doesn't cover the
1495             // entirety of the code output. If you have multiple replacements in the same line
1496             // of code, show the underline.
1497             let show_underline = !(parts.len() == 1
1498                 && parts[0].snippet.trim() == complete.trim())
1499                 && complete.lines().count() == 1;
1500
1501             let lines = sm.span_to_lines(parts[0].span).unwrap();
1502
1503             assert!(!lines.lines.is_empty());
1504
1505             let line_start = sm.lookup_char_pos(parts[0].span.lo()).line;
1506             draw_col_separator_no_space(&mut buffer, 1, max_line_num_len + 1);
1507             let mut line_pos = 0;
1508             let mut lines = complete.lines();
1509             for line in lines.by_ref().take(MAX_HIGHLIGHT_LINES) {
1510                 // Print the span column to avoid confusion
1511                 buffer.puts(row_num,
1512                             0,
1513                             &self.maybe_anonymized(line_start + line_pos),
1514                             Style::LineNumber);
1515                 // print the suggestion
1516                 draw_col_separator(&mut buffer, row_num, max_line_num_len + 1);
1517                 buffer.append(row_num, line, Style::NoStyle);
1518                 line_pos += 1;
1519                 row_num += 1;
1520             }
1521
1522             // This offset and the ones below need to be signed to account for replacement code
1523             // that is shorter than the original code.
1524             let mut offset: isize = 0;
1525             // Only show an underline in the suggestions if the suggestion is not the
1526             // entirety of the code being shown and the displayed code is not multiline.
1527             if show_underline {
1528                 draw_col_separator(&mut buffer, row_num, max_line_num_len + 1);
1529                 for part in parts {
1530                     let span_start_pos = sm.lookup_char_pos(part.span.lo()).col_display;
1531                     let span_end_pos = sm.lookup_char_pos(part.span.hi()).col_display;
1532
1533                     // Do not underline the leading...
1534                     let start = part.snippet.len()
1535                         .saturating_sub(part.snippet.trim_start().len());
1536                     // ...or trailing spaces. Account for substitutions containing unicode
1537                     // characters.
1538                     let sub_len: usize = part.snippet.trim().chars()
1539                         .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
1540                         .sum();
1541
1542                     let underline_start = (span_start_pos + start) as isize + offset;
1543                     let underline_end = (span_start_pos + start + sub_len) as isize + offset;
1544                     for p in underline_start..underline_end {
1545                         buffer.putc(row_num,
1546                                     max_line_num_len + 3 + p as usize,
1547                                     '^',
1548                                     Style::UnderlinePrimary);
1549                     }
1550                     // underline removals too
1551                     if underline_start == underline_end {
1552                         for p in underline_start-1..underline_start+1 {
1553                             buffer.putc(row_num,
1554                                         max_line_num_len + 3 + p as usize,
1555                                         '-',
1556                                         Style::UnderlineSecondary);
1557                         }
1558                     }
1559
1560                     // length of the code after substitution
1561                     let full_sub_len = part.snippet.chars()
1562                         .map(|ch| unicode_width::UnicodeWidthChar::width(ch).unwrap_or(1))
1563                         .sum::<usize>() as isize;
1564
1565                     // length of the code to be substituted
1566                     let snippet_len = span_end_pos as isize - span_start_pos as isize;
1567                     // For multiple substitutions, use the position *after* the previous
1568                     // substitutions have happened.
1569                     offset += full_sub_len - snippet_len;
1570                 }
1571                 row_num += 1;
1572             }
1573
1574             // if we elided some lines, add an ellipsis
1575             if lines.next().is_some() {
1576                 buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
1577             } else if !show_underline {
1578                 draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
1579                 row_num += 1;
1580             }
1581         }
1582         if suggestions.len() > MAX_SUGGESTIONS {
1583             let others = suggestions.len() - MAX_SUGGESTIONS;
1584             let msg = format!("and {} other candidate{}", others, pluralize!(others));
1585             buffer.puts(row_num, max_line_num_len + 3, &msg, Style::NoStyle);
1586         } else if notice_capitalization {
1587             let msg = "notice the capitalization difference";
1588             buffer.puts(row_num, max_line_num_len + 3, &msg, Style::NoStyle);
1589         }
1590         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1591         Ok(())
1592     }
1593
1594     fn emit_messages_default(
1595         &mut self,
1596         level: &Level,
1597         message: &[(String, Style)],
1598         code: &Option<DiagnosticId>,
1599         span: &MultiSpan,
1600         children: &[SubDiagnostic],
1601         suggestions: &[CodeSuggestion],
1602     ) {
1603         let max_line_num_len = if self.ui_testing {
1604             ANONYMIZED_LINE_NUM.len()
1605         } else {
1606             self.get_max_line_num(span, children).to_string().len()
1607         };
1608
1609         match self.emit_message_default(span, message, code, level, max_line_num_len, false) {
1610             Ok(()) => {
1611                 if !children.is_empty() || suggestions.iter().any(|s| {
1612                     s.style != SuggestionStyle::CompletelyHidden
1613                 }) {
1614                     let mut buffer = StyledBuffer::new();
1615                     if !self.short_message {
1616                         draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
1617                     }
1618                     match emit_to_destination(&buffer.render(), level, &mut self.dst,
1619                                               self.short_message) {
1620                         Ok(()) => (),
1621                         Err(e) => panic!("failed to emit error: {}", e)
1622                     }
1623                 }
1624                 if !self.short_message {
1625                     for child in children {
1626                         let span = child.render_span.as_ref().unwrap_or(&child.span);
1627                         match self.emit_message_default(
1628                             &span,
1629                             &child.styled_message(),
1630                             &None,
1631                             &child.level,
1632                             max_line_num_len,
1633                             true,
1634                         ) {
1635                             Err(e) => panic!("failed to emit error: {}", e),
1636                             _ => ()
1637                         }
1638                     }
1639                     for sugg in suggestions {
1640                         if sugg.style == SuggestionStyle::CompletelyHidden {
1641                             // do not display this suggestion, it is meant only for tools
1642                         } else if sugg.style == SuggestionStyle::HideCodeAlways {
1643                             match self.emit_message_default(
1644                                 &MultiSpan::new(),
1645                                 &[(sugg.msg.to_owned(), Style::HeaderMsg)],
1646                                 &None,
1647                                 &Level::Help,
1648                                 max_line_num_len,
1649                                 true,
1650                             ) {
1651                                 Err(e) => panic!("failed to emit error: {}", e),
1652                                 _ => ()
1653                             }
1654                         } else {
1655                             match self.emit_suggestion_default(
1656                                 sugg,
1657                                 &Level::Help,
1658                                 max_line_num_len,
1659                             ) {
1660                                 Err(e) => panic!("failed to emit error: {}", e),
1661                                 _ => ()
1662                             }
1663                         }
1664                     }
1665                 }
1666             }
1667             Err(e) => panic!("failed to emit error: {}", e),
1668         }
1669
1670         let mut dst = self.dst.writable();
1671         match writeln!(dst) {
1672             Err(e) => panic!("failed to emit error: {}", e),
1673             _ => {
1674                 match dst.flush() {
1675                     Err(e) => panic!("failed to emit error: {}", e),
1676                     _ => (),
1677                 }
1678             }
1679         }
1680     }
1681 }
1682
1683 impl FileWithAnnotatedLines {
1684     /// Preprocess all the annotations so that they are grouped by file and by line number
1685     /// This helps us quickly iterate over the whole message (including secondary file spans)
1686     pub fn collect_annotations(
1687         msp: &MultiSpan,
1688         source_map: &Option<Lrc<SourceMapperDyn>>
1689     ) -> Vec<FileWithAnnotatedLines> {
1690         fn add_annotation_to_file(file_vec: &mut Vec<FileWithAnnotatedLines>,
1691                                   file: Lrc<SourceFile>,
1692                                   line_index: usize,
1693                                   ann: Annotation) {
1694
1695             for slot in file_vec.iter_mut() {
1696                 // Look through each of our files for the one we're adding to
1697                 if slot.file.name == file.name {
1698                     // See if we already have a line for it
1699                     for line_slot in &mut slot.lines {
1700                         if line_slot.line_index == line_index {
1701                             line_slot.annotations.push(ann);
1702                             return;
1703                         }
1704                     }
1705                     // We don't have a line yet, create one
1706                     slot.lines.push(Line {
1707                         line_index,
1708                         annotations: vec![ann],
1709                     });
1710                     slot.lines.sort();
1711                     return;
1712                 }
1713             }
1714             // This is the first time we're seeing the file
1715             file_vec.push(FileWithAnnotatedLines {
1716                 file,
1717                 lines: vec![Line {
1718                                 line_index,
1719                                 annotations: vec![ann],
1720                             }],
1721                 multiline_depth: 0,
1722             });
1723         }
1724
1725         let mut output = vec![];
1726         let mut multiline_annotations = vec![];
1727
1728         if let Some(ref sm) = source_map {
1729             for span_label in msp.span_labels() {
1730                 if span_label.span.is_dummy() {
1731                     continue;
1732                 }
1733
1734                 let lo = sm.lookup_char_pos(span_label.span.lo());
1735                 let mut hi = sm.lookup_char_pos(span_label.span.hi());
1736
1737                 // Watch out for "empty spans". If we get a span like 6..6, we
1738                 // want to just display a `^` at 6, so convert that to
1739                 // 6..7. This is degenerate input, but it's best to degrade
1740                 // gracefully -- and the parser likes to supply a span like
1741                 // that for EOF, in particular.
1742
1743                 if lo.col_display == hi.col_display && lo.line == hi.line {
1744                     hi.col_display += 1;
1745                 }
1746
1747                 if lo.line != hi.line {
1748                     let ml = MultilineAnnotation {
1749                         depth: 1,
1750                         line_start: lo.line,
1751                         line_end: hi.line,
1752                         start_col: lo.col_display,
1753                         end_col: hi.col_display,
1754                         is_primary: span_label.is_primary,
1755                         label: span_label.label,
1756                         overlaps_exactly: false,
1757                     };
1758                     multiline_annotations.push((lo.file, ml));
1759                 } else {
1760                     let ann = Annotation {
1761                         start_col: lo.col_display,
1762                         end_col: hi.col_display,
1763                         is_primary: span_label.is_primary,
1764                         label: span_label.label,
1765                         annotation_type: AnnotationType::Singleline,
1766                     };
1767                     add_annotation_to_file(&mut output, lo.file, lo.line, ann);
1768                 };
1769             }
1770         }
1771
1772         // Find overlapping multiline annotations, put them at different depths
1773         multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, ml.line_end));
1774         for (_, ann) in multiline_annotations.clone() {
1775             for (_, a) in multiline_annotations.iter_mut() {
1776                 // Move all other multiline annotations overlapping with this one
1777                 // one level to the right.
1778                 if !(ann.same_span(a)) &&
1779                     num_overlap(ann.line_start, ann.line_end, a.line_start, a.line_end, true)
1780                 {
1781                     a.increase_depth();
1782                 } else if ann.same_span(a) && &ann != a {
1783                     a.overlaps_exactly = true;
1784                 } else {
1785                     break;
1786                 }
1787             }
1788         }
1789
1790         let mut max_depth = 0;  // max overlapping multiline spans
1791         for (file, ann) in multiline_annotations {
1792             max_depth = max(max_depth, ann.depth);
1793             let mut end_ann = ann.as_end();
1794             if !ann.overlaps_exactly {
1795                 // avoid output like
1796                 //
1797                 //  |        foo(
1798                 //  |   _____^
1799                 //  |  |_____|
1800                 //  | ||         bar,
1801                 //  | ||     );
1802                 //  | ||      ^
1803                 //  | ||______|
1804                 //  |  |______foo
1805                 //  |         baz
1806                 //
1807                 // and instead get
1808                 //
1809                 //  |       foo(
1810                 //  |  _____^
1811                 //  | |         bar,
1812                 //  | |     );
1813                 //  | |      ^
1814                 //  | |      |
1815                 //  | |______foo
1816                 //  |        baz
1817                 add_annotation_to_file(&mut output, file.clone(), ann.line_start, ann.as_start());
1818                 // 4 is the minimum vertical length of a multiline span when presented: two lines
1819                 // of code and two lines of underline. This is not true for the special case where
1820                 // the beginning doesn't have an underline, but the current logic seems to be
1821                 // working correctly.
1822                 let middle = min(ann.line_start + 4, ann.line_end);
1823                 for line in ann.line_start + 1..middle {
1824                     // Every `|` that joins the beginning of the span (`___^`) to the end (`|__^`).
1825                     add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
1826                 }
1827                 let line_end = ann.line_end - 1;
1828                 if middle < line_end {
1829                     add_annotation_to_file(&mut output, file.clone(), line_end, ann.as_line());
1830                 }
1831             } else {
1832                 end_ann.annotation_type = AnnotationType::Singleline;
1833             }
1834             add_annotation_to_file(&mut output, file, ann.line_end, end_ann);
1835         }
1836         for file_vec in output.iter_mut() {
1837             file_vec.multiline_depth = max_depth;
1838         }
1839         output
1840     }
1841 }
1842
1843 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
1844     buffer.puts(line, col, "| ", Style::LineNumber);
1845 }
1846
1847 fn draw_col_separator_no_space(buffer: &mut StyledBuffer, line: usize, col: usize) {
1848     draw_col_separator_no_space_with_style(buffer, line, col, Style::LineNumber);
1849 }
1850
1851 fn draw_col_separator_no_space_with_style(buffer: &mut StyledBuffer,
1852                                           line: usize,
1853                                           col: usize,
1854                                           style: Style) {
1855     buffer.putc(line, col, '|', style);
1856 }
1857
1858 fn draw_range(buffer: &mut StyledBuffer, symbol: char, line: usize,
1859               col_from: usize, col_to: usize, style: Style) {
1860     for col in col_from..col_to {
1861         buffer.putc(line, col, symbol, style);
1862     }
1863 }
1864
1865 fn draw_note_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
1866     buffer.puts(line, col, "= ", Style::LineNumber);
1867 }
1868
1869 fn draw_multiline_line(buffer: &mut StyledBuffer,
1870                        line: usize,
1871                        offset: usize,
1872                        depth: usize,
1873                        style: Style)
1874 {
1875     buffer.putc(line, offset + depth - 1, '|', style);
1876 }
1877
1878 fn num_overlap(a_start: usize, a_end: usize, b_start: usize, b_end:usize, inclusive: bool) -> bool {
1879     let extra = if inclusive {
1880         1
1881     } else {
1882         0
1883     };
1884     (b_start..b_end + extra).contains(&a_start) ||
1885     (a_start..a_end + extra).contains(&b_start)
1886 }
1887 fn overlaps(a1: &Annotation, a2: &Annotation, padding: usize) -> bool {
1888     num_overlap(a1.start_col, a1.end_col + padding, a2.start_col, a2.end_col, false)
1889 }
1890
1891 fn emit_to_destination(rendered_buffer: &[Vec<StyledString>],
1892                        lvl: &Level,
1893                        dst: &mut Destination,
1894                        short_message: bool)
1895                        -> io::Result<()> {
1896     use crate::lock;
1897
1898     let mut dst = dst.writable();
1899
1900     // In order to prevent error message interleaving, where multiple error lines get intermixed
1901     // when multiple compiler processes error simultaneously, we emit errors with additional
1902     // steps.
1903     //
1904     // On Unix systems, we write into a buffered terminal rather than directly to a terminal. When
1905     // the .flush() is called we take the buffer created from the buffered writes and write it at
1906     // one shot.  Because the Unix systems use ANSI for the colors, which is a text-based styling
1907     // scheme, this buffered approach works and maintains the styling.
1908     //
1909     // On Windows, styling happens through calls to a terminal API. This prevents us from using the
1910     // same buffering approach.  Instead, we use a global Windows mutex, which we acquire long
1911     // enough to output the full error message, then we release.
1912     let _buffer_lock = lock::acquire_global_lock("rustc_errors");
1913     for (pos, line) in rendered_buffer.iter().enumerate() {
1914         for part in line {
1915             dst.apply_style(lvl.clone(), part.style)?;
1916             write!(dst, "{}", part.text)?;
1917             dst.reset()?;
1918         }
1919         if !short_message && (!lvl.is_failure_note() || pos != rendered_buffer.len() - 1) {
1920             writeln!(dst)?;
1921         }
1922     }
1923     dst.flush()?;
1924     Ok(())
1925 }
1926
1927 pub enum Destination {
1928     Terminal(StandardStream),
1929     Buffered(BufferWriter),
1930     // The bool denotes whether we should be emitting ansi color codes or not
1931     Raw(Box<(dyn Write + Send)>, bool),
1932 }
1933
1934 pub enum WritableDst<'a> {
1935     Terminal(&'a mut StandardStream),
1936     Buffered(&'a mut BufferWriter, Buffer),
1937     Raw(&'a mut (dyn Write + Send)),
1938     ColoredRaw(Ansi<&'a mut (dyn Write + Send)>),
1939 }
1940
1941 impl Destination {
1942     fn from_stderr(color: ColorConfig) -> Destination {
1943         let choice = color.to_color_choice();
1944         // On Windows we'll be performing global synchronization on the entire
1945         // system for emitting rustc errors, so there's no need to buffer
1946         // anything.
1947         //
1948         // On non-Windows we rely on the atomicity of `write` to ensure errors
1949         // don't get all jumbled up.
1950         if cfg!(windows) {
1951             Terminal(StandardStream::stderr(choice))
1952         } else {
1953             Buffered(BufferWriter::stderr(choice))
1954         }
1955     }
1956
1957     fn writable(&mut self) -> WritableDst<'_> {
1958         match *self {
1959             Destination::Terminal(ref mut t) => WritableDst::Terminal(t),
1960             Destination::Buffered(ref mut t) => {
1961                 let buf = t.buffer();
1962                 WritableDst::Buffered(t, buf)
1963             }
1964             Destination::Raw(ref mut t, false) => WritableDst::Raw(t),
1965             Destination::Raw(ref mut t, true) => WritableDst::ColoredRaw(Ansi::new(t)),
1966         }
1967     }
1968 }
1969
1970 impl<'a> WritableDst<'a> {
1971     fn apply_style(&mut self, lvl: Level, style: Style) -> io::Result<()> {
1972         let mut spec = ColorSpec::new();
1973         match style {
1974             Style::LineAndColumn => {}
1975             Style::LineNumber => {
1976                 spec.set_bold(true);
1977                 spec.set_intense(true);
1978                 if cfg!(windows) {
1979                     spec.set_fg(Some(Color::Cyan));
1980                 } else {
1981                     spec.set_fg(Some(Color::Blue));
1982                 }
1983             }
1984             Style::Quotation => {}
1985             Style::MainHeaderMsg => {
1986                 spec.set_bold(true);
1987                 if cfg!(windows) {
1988                     spec.set_intense(true)
1989                         .set_fg(Some(Color::White));
1990                 }
1991             }
1992             Style::UnderlinePrimary | Style::LabelPrimary => {
1993                 spec = lvl.color();
1994                 spec.set_bold(true);
1995             }
1996             Style::UnderlineSecondary |
1997             Style::LabelSecondary => {
1998                 spec.set_bold(true)
1999                     .set_intense(true);
2000                 if cfg!(windows) {
2001                     spec.set_fg(Some(Color::Cyan));
2002                 } else {
2003                     spec.set_fg(Some(Color::Blue));
2004                 }
2005             }
2006             Style::HeaderMsg |
2007             Style::NoStyle => {}
2008             Style::Level(lvl) => {
2009                 spec = lvl.color();
2010                 spec.set_bold(true);
2011             }
2012             Style::Highlight => {
2013                 spec.set_bold(true);
2014             }
2015         }
2016         self.set_color(&spec)
2017     }
2018
2019     fn set_color(&mut self, color: &ColorSpec) -> io::Result<()> {
2020         match *self {
2021             WritableDst::Terminal(ref mut t) => t.set_color(color),
2022             WritableDst::Buffered(_, ref mut t) => t.set_color(color),
2023             WritableDst::ColoredRaw(ref mut t) => t.set_color(color),
2024             WritableDst::Raw(_) => Ok(())
2025         }
2026     }
2027
2028     fn reset(&mut self) -> io::Result<()> {
2029         match *self {
2030             WritableDst::Terminal(ref mut t) => t.reset(),
2031             WritableDst::Buffered(_, ref mut t) => t.reset(),
2032             WritableDst::ColoredRaw(ref mut t) => t.reset(),
2033             WritableDst::Raw(_) => Ok(()),
2034         }
2035     }
2036 }
2037
2038 impl<'a> Write for WritableDst<'a> {
2039     fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
2040         match *self {
2041             WritableDst::Terminal(ref mut t) => t.write(bytes),
2042             WritableDst::Buffered(_, ref mut buf) => buf.write(bytes),
2043             WritableDst::Raw(ref mut w) => w.write(bytes),
2044             WritableDst::ColoredRaw(ref mut t) => t.write(bytes),
2045         }
2046     }
2047
2048     fn flush(&mut self) -> io::Result<()> {
2049         match *self {
2050             WritableDst::Terminal(ref mut t) => t.flush(),
2051             WritableDst::Buffered(_, ref mut buf) => buf.flush(),
2052             WritableDst::Raw(ref mut w) => w.flush(),
2053             WritableDst::ColoredRaw(ref mut w) => w.flush(),
2054         }
2055     }
2056 }
2057
2058 impl<'a> Drop for WritableDst<'a> {
2059     fn drop(&mut self) {
2060         match *self {
2061             WritableDst::Buffered(ref mut dst, ref mut buf) => {
2062                 drop(dst.print(buf));
2063             }
2064             _ => {}
2065         }
2066     }
2067 }
2068
2069 /// Whether the original and suggested code are visually similar enough to warrant extra wording.
2070 pub fn is_case_difference(sm: &dyn SourceMapper, suggested: &str, sp: Span) -> bool {
2071     // FIXME: this should probably be extended to also account for `FO0` → `FOO` and unicode.
2072     let found = sm.span_to_snippet(sp).unwrap();
2073     let ascii_confusables = &['c', 'f', 'i', 'k', 'o', 's', 'u', 'v', 'w', 'x', 'y', 'z'];
2074     // All the chars that differ in capitalization are confusable (above):
2075     let confusable = found.chars().zip(suggested.chars()).filter(|(f, s)| f != s).all(|(f, s)| {
2076         (ascii_confusables.contains(&f) || ascii_confusables.contains(&s))
2077     });
2078     confusable && found.to_lowercase() == suggested.to_lowercase()
2079             // FIXME: We sometimes suggest the same thing we already have, which is a
2080             //        bug, but be defensive against that here.
2081             && found != suggested
2082 }