src/librustc_errors/emitter.rs

   1 use Destination::*;
   2
   3 use syntax_pos::{SourceFile, Span, MultiSpan};
   4
   5 use crate::{
   6     Level, CodeSuggestion, DiagnosticBuilder, SubDiagnostic,
   7     SuggestionStyle, SourceMapperDyn, DiagnosticId,
   8 };
   9 use crate::Level::Error;
  10 use crate::snippet::{Annotation, AnnotationType, Line, MultilineAnnotation, StyledString, Style};
  11 use crate::styled_buffer::StyledBuffer;
  12
  13 use rustc_data_structures::fx::FxHashMap;
  14 use rustc_data_structures::sync::Lrc;
  15 use std::borrow::Cow;
  16 use std::io::prelude::*;
  17 use std::io;
  18 use std::cmp::{min, Reverse};
  19 use std::path::Path;
  20 use termcolor::{StandardStream, ColorChoice, ColorSpec, BufferWriter, Ansi};
  21 use termcolor::{WriteColor, Color, Buffer};
  22
  23 /// Describes the way the content of the `rendered` field of the json output is generated
  24 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
  25 pub enum HumanReadableErrorType {
  26     Default(ColorConfig),
  27     Short(ColorConfig),
  28 }
  29
  30 impl HumanReadableErrorType {
  31     /// Returns a (`short`, `color`) tuple
  32     pub fn unzip(self) -> (bool, ColorConfig) {
  33         match self {
  34             HumanReadableErrorType::Default(cc) => (false, cc),
  35             HumanReadableErrorType::Short(cc) => (true, cc),
  36         }
  37     }
  38     pub fn new_emitter(
  39         self,
  40         dst: Box<dyn Write + Send>,
  41         source_map: Option<Lrc<SourceMapperDyn>>,
  42         teach: bool,
  43     ) -> EmitterWriter {
  44         let (short, color_config) = self.unzip();
  45         EmitterWriter::new(dst, source_map, short, teach, color_config.suggests_using_colors())
  46     }
  47 }
  48
  49 const ANONYMIZED_LINE_NUM: &str = "LL";
  50
  51 /// Emitter trait for emitting errors.
  52 pub trait Emitter {
  53     /// Emit a structured diagnostic.
  54     fn emit_diagnostic(&mut self, db: &DiagnosticBuilder<'_>);
  55
  56     /// Emit a notification that an artifact has been output.
  57     /// This is currently only supported for the JSON format,
  58     /// other formats can, and will, simply ignore it.
  59     fn emit_artifact_notification(&mut self, _path: &Path, _artifact_type: &str) {}
  60
  61     /// Checks if should show explanations about "rustc --explain"
  62     fn should_show_explain(&self) -> bool {
  63         true
  64     }
  65 }
  66
  67 impl Emitter for EmitterWriter {
  68     fn emit_diagnostic(&mut self, db: &DiagnosticBuilder<'_>) {
  69         let mut primary_span = db.span.clone();
  70         let mut children = db.children.clone();
  71         let mut suggestions: &[_] = &[];
  72
  73         if let Some((sugg, rest)) = db.suggestions.split_first() {
  74             if rest.is_empty() &&
  75                // don't display multi-suggestions as labels
  76                sugg.substitutions.len() == 1 &&
  77                // don't display multipart suggestions as labels
  78                sugg.substitutions[0].parts.len() == 1 &&
  79                // don't display long messages as labels
  80                sugg.msg.split_whitespace().count() < 10 &&
  81                // don't display multiline suggestions as labels
  82                !sugg.substitutions[0].parts[0].snippet.contains('\n') &&
  83                // when this style is set we want the suggestion to be a message, not inline
  84                sugg.style != SuggestionStyle::HideCodeAlways &&
  85                // trivial suggestion for tooling's sake, never shown
  86                sugg.style != SuggestionStyle::CompletelyHidden
  87             {
  88                 let substitution = &sugg.substitutions[0].parts[0].snippet.trim();
  89                 let msg = if substitution.len() == 0 || sugg.style.hide_inline() {
  90                     // This substitution is only removal or we explicitly don't want to show the
  91                     // code inline, don't show it
  92                     format!("help: {}", sugg.msg)
  93                 } else {
  94                     format!("help: {}: `{}`", sugg.msg, substitution)
  95                 };
  96                 primary_span.push_span_label(sugg.substitutions[0].parts[0].span, msg);
  97             } else {
  98                 // if there are multiple suggestions, print them all in full
  99                 // to be consistent. We could try to figure out if we can
 100                 // make one (or the first one) inline, but that would give
 101                 // undue importance to a semi-random suggestion
 102                 suggestions = &db.suggestions;
 103             }
 104         }
 105
 106         self.fix_multispans_in_std_macros(&mut primary_span,
 107                                           &mut children,
 108                                           &db.level,
 109                                           db.handler.flags.external_macro_backtrace);
 110
 111         self.emit_messages_default(&db.level,
 112                                    &db.styled_message(),
 113                                    &db.code,
 114                                    &primary_span,
 115                                    &children,
 116                                    &suggestions);
 117     }
 118
 119     fn should_show_explain(&self) -> bool {
 120         !self.short_message
 121     }
 122 }
 123
 124 /// maximum number of lines we will print for each error; arbitrary.
 125 pub const MAX_HIGHLIGHT_LINES: usize = 6;
 126 /// maximum number of suggestions to be shown
 127 ///
 128 /// Arbitrary, but taken from trait import suggestion limit
 129 pub const MAX_SUGGESTIONS: usize = 4;
 130
 131 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 132 pub enum ColorConfig {
 133     Auto,
 134     Always,
 135     Never,
 136 }
 137
 138 impl ColorConfig {
 139     fn to_color_choice(self) -> ColorChoice {
 140         match self {
 141             ColorConfig::Always => {
 142                 if atty::is(atty::Stream::Stderr) {
 143                     ColorChoice::Always
 144                 } else {
 145                     ColorChoice::AlwaysAnsi
 146                 }
 147             }
 148             ColorConfig::Never => ColorChoice::Never,
 149             ColorConfig::Auto if atty::is(atty::Stream::Stderr) => {
 150                 ColorChoice::Auto
 151             }
 152             ColorConfig::Auto => ColorChoice::Never,
 153         }
 154     }
 155     fn suggests_using_colors(self) -> bool {
 156         match self {
 157             | ColorConfig::Always
 158             | ColorConfig::Auto
 159             => true,
 160             ColorConfig::Never => false,
 161         }
 162     }
 163 }
 164
 165 pub struct EmitterWriter {
 166     dst: Destination,
 167     sm: Option<Lrc<SourceMapperDyn>>,
 168     short_message: bool,
 169     teach: bool,
 170     ui_testing: bool,
 171 }
 172
 173 struct FileWithAnnotatedLines {
 174     file: Lrc<SourceFile>,
 175     lines: Vec<Line>,
 176     multiline_depth: usize,
 177 }
 178
 179 impl EmitterWriter {
 180     pub fn stderr(color_config: ColorConfig,
 181                   source_map: Option<Lrc<SourceMapperDyn>>,
 182                   short_message: bool,
 183                   teach: bool)
 184                   -> EmitterWriter {
 185         let dst = Destination::from_stderr(color_config);
 186         EmitterWriter {
 187             dst,
 188             sm: source_map,
 189             short_message,
 190             teach,
 191             ui_testing: false,
 192         }
 193     }
 194
 195     pub fn new(
 196         dst: Box<dyn Write + Send>,
 197         source_map: Option<Lrc<SourceMapperDyn>>,
 198         short_message: bool,
 199         teach: bool,
 200         colored: bool,
 201     ) -> EmitterWriter {
 202         EmitterWriter {
 203             dst: Raw(dst, colored),
 204             sm: source_map,
 205             short_message,
 206             teach,
 207             ui_testing: false,
 208         }
 209     }
 210
 211     pub fn ui_testing(mut self, ui_testing: bool) -> Self {
 212         self.ui_testing = ui_testing;
 213         self
 214     }
 215
 216     fn maybe_anonymized(&self, line_num: usize) -> String {
 217         if self.ui_testing {
 218             ANONYMIZED_LINE_NUM.to_string()
 219         } else {
 220             line_num.to_string()
 221         }
 222     }
 223
 224     fn preprocess_annotations(&mut self, msp: &MultiSpan) -> Vec<FileWithAnnotatedLines> {
 225         fn add_annotation_to_file(file_vec: &mut Vec<FileWithAnnotatedLines>,
 226                                   file: Lrc<SourceFile>,
 227                                   line_index: usize,
 228                                   ann: Annotation) {
 229
 230             for slot in file_vec.iter_mut() {
 231                 // Look through each of our files for the one we're adding to
 232                 if slot.file.name == file.name {
 233                     // See if we already have a line for it
 234                     for line_slot in &mut slot.lines {
 235                         if line_slot.line_index == line_index {
 236                             line_slot.annotations.push(ann);
 237                             return;
 238                         }
 239                     }
 240                     // We don't have a line yet, create one
 241                     slot.lines.push(Line {
 242                         line_index,
 243                         annotations: vec![ann],
 244                     });
 245                     slot.lines.sort();
 246                     return;
 247                 }
 248             }
 249             // This is the first time we're seeing the file
 250             file_vec.push(FileWithAnnotatedLines {
 251                 file,
 252                 lines: vec![Line {
 253                                 line_index,
 254                                 annotations: vec![ann],
 255                             }],
 256                 multiline_depth: 0,
 257             });
 258         }
 259
 260         let mut output = vec![];
 261         let mut multiline_annotations = vec![];
 262
 263         if let Some(ref sm) = self.sm {
 264             for span_label in msp.span_labels() {
 265                 if span_label.span.is_dummy() {
 266                     continue;
 267                 }
 268
 269                 let lo = sm.lookup_char_pos(span_label.span.lo());
 270                 let mut hi = sm.lookup_char_pos(span_label.span.hi());
 271
 272                 // Watch out for "empty spans". If we get a span like 6..6, we
 273                 // want to just display a `^` at 6, so convert that to
 274                 // 6..7. This is degenerate input, but it's best to degrade
 275                 // gracefully -- and the parser likes to supply a span like
 276                 // that for EOF, in particular.
 277
 278                 if lo.col_display == hi.col_display && lo.line == hi.line {
 279                     hi.col_display += 1;
 280                 }
 281
 282                 let ann_type = if lo.line != hi.line {
 283                     let ml = MultilineAnnotation {
 284                         depth: 1,
 285                         line_start: lo.line,
 286                         line_end: hi.line,
 287                         start_col: lo.col_display,
 288                         end_col: hi.col_display,
 289                         is_primary: span_label.is_primary,
 290                         label: span_label.label.clone(),
 291                         overlaps_exactly: false,
 292                     };
 293                     multiline_annotations.push((lo.file.clone(), ml.clone()));
 294                     AnnotationType::Multiline(ml)
 295                 } else {
 296                     AnnotationType::Singleline
 297                 };
 298                 let ann = Annotation {
 299                     start_col: lo.col_display,
 300                     end_col: hi.col_display,
 301                     is_primary: span_label.is_primary,
 302                     label: span_label.label.clone(),
 303                     annotation_type: ann_type,
 304                 };
 305
 306                 if !ann.is_multiline() {
 307                     add_annotation_to_file(&mut output, lo.file, lo.line, ann);
 308                 }
 309             }
 310         }
 311
 312         // Find overlapping multiline annotations, put them at different depths
 313         multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, ml.line_end));
 314         for item in multiline_annotations.clone() {
 315             let ann = item.1;
 316             for item in multiline_annotations.iter_mut() {
 317                 let ref mut a = item.1;
 318                 // Move all other multiline annotations overlapping with this one
 319                 // one level to the right.
 320                 if !(ann.same_span(a)) &&
 321                     num_overlap(ann.line_start, ann.line_end, a.line_start, a.line_end, true)
 322                 {
 323                     a.increase_depth();
 324                 } else if ann.same_span(a) && &ann != a {
 325                     a.overlaps_exactly = true;
 326                 } else {
 327                     break;
 328                 }
 329             }
 330         }
 331
 332         let mut max_depth = 0;  // max overlapping multiline spans
 333         for (file, ann) in multiline_annotations {
 334             if ann.depth > max_depth {
 335                 max_depth = ann.depth;
 336             }
 337             let mut end_ann = ann.as_end();
 338             if !ann.overlaps_exactly {
 339                 // avoid output like
 340                 //
 341                 //  |        foo(
 342                 //  |   _____^
 343                 //  |  |_____|
 344                 //  | ||         bar,
 345                 //  | ||     );
 346                 //  | ||      ^
 347                 //  | ||______|
 348                 //  |  |______foo
 349                 //  |         baz
 350                 //
 351                 // and instead get
 352                 //
 353                 //  |       foo(
 354                 //  |  _____^
 355                 //  | |         bar,
 356                 //  | |     );
 357                 //  | |      ^
 358                 //  | |      |
 359                 //  | |______foo
 360                 //  |        baz
 361                 add_annotation_to_file(&mut output, file.clone(), ann.line_start, ann.as_start());
 362                 // 4 is the minimum vertical length of a multiline span when presented: two lines
 363                 // of code and two lines of underline. This is not true for the special case where
 364                 // the beginning doesn't have an underline, but the current logic seems to be
 365                 // working correctly.
 366                 let middle = min(ann.line_start + 4, ann.line_end);
 367                 for line in ann.line_start + 1..middle {
 368                     // Every `|` that joins the beginning of the span (`___^`) to the end (`|__^`).
 369                     add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
 370                 }
 371                 if middle < ann.line_end - 1 {
 372                     for line in ann.line_end - 1..ann.line_end {
 373                         add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
 374                     }
 375                 }
 376             } else {
 377                 end_ann.annotation_type = AnnotationType::Singleline;
 378             }
 379             add_annotation_to_file(&mut output, file, ann.line_end, end_ann);
 380         }
 381         for file_vec in output.iter_mut() {
 382             file_vec.multiline_depth = max_depth;
 383         }
 384         output
 385     }
 386
 387     fn render_source_line(&self,
 388                           buffer: &mut StyledBuffer,
 389                           file: Lrc<SourceFile>,
 390                           line: &Line,
 391                           width_offset: usize,
 392                           code_offset: usize) -> Vec<(usize, Style)> {
 393         if line.line_index == 0 {
 394             return Vec::new();
 395         }
 396
 397         let source_string = match file.get_line(line.line_index - 1) {
 398             Some(s) => s,
 399             None => return Vec::new(),
 400         };
 401
 402         let line_offset = buffer.num_lines();
 403
 404         // First create the source line we will highlight.
 405         buffer.puts(line_offset, code_offset, &source_string, Style::Quotation);
 406         buffer.puts(line_offset,
 407                     0,
 408                     &self.maybe_anonymized(line.line_index),
 409                     Style::LineNumber);
 410
 411         draw_col_separator(buffer, line_offset, width_offset - 2);
 412
 413         // Special case when there's only one annotation involved, it is the start of a multiline
 414         // span and there's no text at the beginning of the code line. Instead of doing the whole
 415         // graph:
 416         //
 417         // 2 |   fn foo() {
 418         //   |  _^
 419         // 3 | |
 420         // 4 | | }
 421         //   | |_^ test
 422         //
 423         // we simplify the output to:
 424         //
 425         // 2 | / fn foo() {
 426         // 3 | |
 427         // 4 | | }
 428         //   | |_^ test
 429         if line.annotations.len() == 1 {
 430             if let Some(ref ann) = line.annotations.get(0) {
 431                 if let AnnotationType::MultilineStart(depth) = ann.annotation_type {
 432                     if source_string.chars()
 433                                     .take(ann.start_col)
 434                                     .all(|c| c.is_whitespace()) {
 435                         let style = if ann.is_primary {
 436                             Style::UnderlinePrimary
 437                         } else {
 438                             Style::UnderlineSecondary
 439                         };
 440                         buffer.putc(line_offset,
 441                                     width_offset + depth - 1,
 442                                     '/',
 443                                     style);
 444                         return vec![(depth, style)];
 445                     }
 446                 }
 447             }
 448         }
 449
 450         // We want to display like this:
 451         //
 452         //      vec.push(vec.pop().unwrap());
 453         //      ---      ^^^               - previous borrow ends here
 454         //      |        |
 455         //      |        error occurs here
 456         //      previous borrow of `vec` occurs here
 457         //
 458         // But there are some weird edge cases to be aware of:
 459         //
 460         //      vec.push(vec.pop().unwrap());
 461         //      --------                    - previous borrow ends here
 462         //      ||
 463         //      |this makes no sense
 464         //      previous borrow of `vec` occurs here
 465         //
 466         // For this reason, we group the lines into "highlight lines"
 467         // and "annotations lines", where the highlight lines have the `^`.
 468
 469         // Sort the annotations by (start, end col)
 470         // The labels are reversed, sort and then reversed again.
 471         // Consider a list of annotations (A1, A2, C1, C2, B1, B2) where
 472         // the letter signifies the span. Here we are only sorting by the
 473         // span and hence, the order of the elements with the same span will
 474         // not change. On reversing the ordering (|a, b| but b.cmp(a)), you get
 475         // (C1, C2, B1, B2, A1, A2). All the elements with the same span are
 476         // still ordered first to last, but all the elements with different
 477         // spans are ordered by their spans in last to first order. Last to
 478         // first order is important, because the jiggly lines and | are on
 479         // the left, so the rightmost span needs to be rendered first,
 480         // otherwise the lines would end up needing to go over a message.
 481
 482         let mut annotations = line.annotations.clone();
 483         annotations.sort_by_key(|a| Reverse(a.start_col));
 484
 485         // First, figure out where each label will be positioned.
 486         //
 487         // In the case where you have the following annotations:
 488         //
 489         //      vec.push(vec.pop().unwrap());
 490         //      --------                    - previous borrow ends here [C]
 491         //      ||
 492         //      |this makes no sense [B]
 493         //      previous borrow of `vec` occurs here [A]
 494         //
 495         // `annotations_position` will hold [(2, A), (1, B), (0, C)].
 496         //
 497         // We try, when possible, to stick the rightmost annotation at the end
 498         // of the highlight line:
 499         //
 500         //      vec.push(vec.pop().unwrap());
 501         //      ---      ---               - previous borrow ends here
 502         //
 503         // But sometimes that's not possible because one of the other
 504         // annotations overlaps it. For example, from the test
 505         // `span_overlap_label`, we have the following annotations
 506         // (written on distinct lines for clarity):
 507         //
 508         //      fn foo(x: u32) {
 509         //      --------------
 510         //             -
 511         //
 512         // In this case, we can't stick the rightmost-most label on
 513         // the highlight line, or we would get:
 514         //
 515         //      fn foo(x: u32) {
 516         //      -------- x_span
 517         //      |
 518         //      fn_span
 519         //
 520         // which is totally weird. Instead we want:
 521         //
 522         //      fn foo(x: u32) {
 523         //      --------------
 524         //      |      |
 525         //      |      x_span
 526         //      fn_span
 527         //
 528         // which is...less weird, at least. In fact, in general, if
 529         // the rightmost span overlaps with any other span, we should
 530         // use the "hang below" version, so we can at least make it
 531         // clear where the span *starts*. There's an exception for this
 532         // logic, when the labels do not have a message:
 533         //
 534         //      fn foo(x: u32) {
 535         //      --------------
 536         //             |
 537         //             x_span
 538         //
 539         // instead of:
 540         //
 541         //      fn foo(x: u32) {
 542         //      --------------
 543         //      |      |
 544         //      |      x_span
 545         //      <EMPTY LINE>
 546         //
 547         let mut annotations_position = vec![];
 548         let mut line_len = 0;
 549         let mut p = 0;
 550         for (i, annotation) in annotations.iter().enumerate() {
 551             for (j, next) in annotations.iter().enumerate() {
 552                 if overlaps(next, annotation, 0)  // This label overlaps with another one and both
 553                     && annotation.has_label()     // take space (they have text and are not
 554                     && j > i                      // multiline lines).
 555                     && p == 0  // We're currently on the first line, move the label one line down
 556                 {
 557                     // If we're overlapping with an un-labelled annotation with the same span
 558                     // we can just merge them in the output
 559                     if next.start_col == annotation.start_col
 560                     && next.end_col == annotation.end_col
 561                     && !next.has_label()
 562                     {
 563                         continue;
 564                     }
 565
 566                     // This annotation needs a new line in the output.
 567                     p += 1;
 568                     break;
 569                 }
 570             }
 571             annotations_position.push((p, annotation));
 572             for (j, next) in annotations.iter().enumerate() {
 573                 if j > i  {
 574                     let l = if let Some(ref label) = next.label {
 575                         label.len() + 2
 576                     } else {
 577                         0
 578                     };
 579                     if (overlaps(next, annotation, l) // Do not allow two labels to be in the same
 580                                                      // line if they overlap including padding, to
 581                                                      // avoid situations like:
 582                                                      //
 583                                                      //      fn foo(x: u32) {
 584                                                      //      -------^------
 585                                                      //      |      |
 586                                                      //      fn_spanx_span
 587                                                      //
 588                         && annotation.has_label()    // Both labels must have some text, otherwise
 589                         && next.has_label())         // they are not overlapping.
 590                                                      // Do not add a new line if this annotation
 591                                                      // or the next are vertical line placeholders.
 592                         || (annotation.takes_space() // If either this or the next annotation is
 593                             && next.has_label())     // multiline start/end, move it to a new line
 594                         || (annotation.has_label()   // so as not to overlap the orizontal lines.
 595                             && next.takes_space())
 596                         || (annotation.takes_space() && next.takes_space())
 597                         || (overlaps(next, annotation, l)
 598                             && next.end_col <= annotation.end_col
 599                             && next.has_label()
 600                             && p == 0)  // Avoid #42595.
 601                     {
 602                         // This annotation needs a new line in the output.
 603                         p += 1;
 604                         break;
 605                     }
 606                 }
 607             }
 608             if line_len < p {
 609                 line_len = p;
 610             }
 611         }
 612
 613         if line_len != 0 {
 614             line_len += 1;
 615         }
 616
 617         // If there are no annotations or the only annotations on this line are
 618         // MultilineLine, then there's only code being shown, stop processing.
 619         if line.annotations.iter().all(|a| a.is_line()) {
 620             return vec![];
 621         }
 622
 623         // Write the colunmn separator.
 624         //
 625         // After this we will have:
 626         //
 627         // 2 |   fn foo() {
 628         //   |
 629         //   |
 630         //   |
 631         // 3 |
 632         // 4 |   }
 633         //   |
 634         for pos in 0..=line_len {
 635             draw_col_separator(buffer, line_offset + pos + 1, width_offset - 2);
 636             buffer.putc(line_offset + pos + 1,
 637                         width_offset - 2,
 638                         '|',
 639                         Style::LineNumber);
 640         }
 641
 642         // Write the horizontal lines for multiline annotations
 643         // (only the first and last lines need this).
 644         //
 645         // After this we will have:
 646         //
 647         // 2 |   fn foo() {
 648         //   |  __________
 649         //   |
 650         //   |
 651         // 3 |
 652         // 4 |   }
 653         //   |  _
 654         for &(pos, annotation) in &annotations_position {
 655             let style = if annotation.is_primary {
 656                 Style::UnderlinePrimary
 657             } else {
 658                 Style::UnderlineSecondary
 659             };
 660             let pos = pos + 1;
 661             match annotation.annotation_type {
 662                 AnnotationType::MultilineStart(depth) |
 663                 AnnotationType::MultilineEnd(depth) => {
 664                     draw_range(buffer,
 665                                '_',
 666                                line_offset + pos,
 667                                width_offset + depth,
 668                                code_offset + annotation.start_col,
 669                                style);
 670                 }
 671                 _ if self.teach => {
 672                     buffer.set_style_range(line_offset,
 673                                            code_offset + annotation.start_col,
 674                                            code_offset + annotation.end_col,
 675                                            style,
 676                                            annotation.is_primary);
 677                 }
 678                 _ => {}
 679             }
 680         }
 681
 682         // Write the vertical lines for labels that are on a different line as the underline.
 683         //
 684         // After this we will have:
 685         //
 686         // 2 |   fn foo() {
 687         //   |  __________
 688         //   | |    |
 689         //   | |
 690         // 3 |
 691         // 4 | | }
 692         //   | |_
 693         for &(pos, annotation) in &annotations_position {
 694             let style = if annotation.is_primary {
 695                 Style::UnderlinePrimary
 696             } else {
 697                 Style::UnderlineSecondary
 698             };
 699             let pos = pos + 1;
 700
 701             if pos > 1 && (annotation.has_label() || annotation.takes_space()) {
 702                 for p in line_offset + 1..=line_offset + pos {
 703                     buffer.putc(p,
 704                                 code_offset + annotation.start_col,
 705                                 '|',
 706                                 style);
 707                 }
 708             }
 709             match annotation.annotation_type {
 710                 AnnotationType::MultilineStart(depth) => {
 711                     for p in line_offset + pos + 1..line_offset + line_len + 2 {
 712                         buffer.putc(p,
 713                                     width_offset + depth - 1,
 714                                     '|',
 715                                     style);
 716                     }
 717                 }
 718                 AnnotationType::MultilineEnd(depth) => {
 719                     for p in line_offset..=line_offset + pos {
 720                         buffer.putc(p,
 721                                     width_offset + depth - 1,
 722                                     '|',
 723                                     style);
 724                     }
 725                 }
 726                 _ => (),
 727             }
 728         }
 729
 730         // Write the labels on the annotations that actually have a label.
 731         //
 732         // After this we will have:
 733         //
 734         // 2 |   fn foo() {
 735         //   |  __________
 736         //   |      |
 737         //   |      something about `foo`
 738         // 3 |
 739         // 4 |   }
 740         //   |  _  test
 741         for &(pos, annotation) in &annotations_position {
 742             let style = if annotation.is_primary {
 743                 Style::LabelPrimary
 744             } else {
 745                 Style::LabelSecondary
 746             };
 747             let (pos, col) = if pos == 0 {
 748                 (pos + 1, annotation.end_col + 1)
 749             } else {
 750                 (pos + 2, annotation.start_col)
 751             };
 752             if let Some(ref label) = annotation.label {
 753                 buffer.puts(line_offset + pos,
 754                             code_offset + col,
 755                             &label,
 756                             style);
 757             }
 758         }
 759
 760         // Sort from biggest span to smallest span so that smaller spans are
 761         // represented in the output:
 762         //
 763         // x | fn foo()
 764         //   | ^^^---^^
 765         //   | |  |
 766         //   | |  something about `foo`
 767         //   | something about `fn foo()`
 768         annotations_position.sort_by(|a, b| {
 769             // Decreasing order. When `a` and `b` are the same length, prefer `Primary`.
 770             (a.1.len(), !a.1.is_primary).cmp(&(b.1.len(), !b.1.is_primary)).reverse()
 771         });
 772
 773         // Write the underlines.
 774         //
 775         // After this we will have:
 776         //
 777         // 2 |   fn foo() {
 778         //   |  ____-_____^
 779         //   |      |
 780         //   |      something about `foo`
 781         // 3 |
 782         // 4 |   }
 783         //   |  _^  test
 784         for &(_, annotation) in &annotations_position {
 785             let (underline, style) = if annotation.is_primary {
 786                 ('^', Style::UnderlinePrimary)
 787             } else {
 788                 ('-', Style::UnderlineSecondary)
 789             };
 790             for p in annotation.start_col..annotation.end_col {
 791                 buffer.putc(line_offset + 1,
 792                             code_offset + p,
 793                             underline,
 794                             style);
 795             }
 796         }
 797         annotations_position.iter().filter_map(|&(_, annotation)| {
 798             match annotation.annotation_type {
 799                 AnnotationType::MultilineStart(p) | AnnotationType::MultilineEnd(p) => {
 800                     let style = if annotation.is_primary {
 801                         Style::LabelPrimary
 802                     } else {
 803                         Style::LabelSecondary
 804                     };
 805                     Some((p, style))
 806                 }
 807                 _ => None
 808             }
 809
 810         }).collect::<Vec<_>>()
 811     }
 812
 813     fn get_multispan_max_line_num(&mut self, msp: &MultiSpan) -> usize {
 814         let mut max = 0;
 815         if let Some(ref sm) = self.sm {
 816             for primary_span in msp.primary_spans() {
 817                 if !primary_span.is_dummy() {
 818                     let hi = sm.lookup_char_pos(primary_span.hi());
 819                     if hi.line > max {
 820                         max = hi.line;
 821                     }
 822                 }
 823             }
 824             if !self.short_message {
 825                 for span_label in msp.span_labels() {
 826                     if !span_label.span.is_dummy() {
 827                         let hi = sm.lookup_char_pos(span_label.span.hi());
 828                         if hi.line > max {
 829                             max = hi.line;
 830                         }
 831                     }
 832                 }
 833             }
 834         }
 835         max
 836     }
 837
 838     fn get_max_line_num(&mut self, span: &MultiSpan, children: &[SubDiagnostic]) -> usize {
 839         let mut max = 0;
 840
 841         let primary = self.get_multispan_max_line_num(span);
 842         max = if primary > max { primary } else { max };
 843
 844         for sub in children {
 845             let sub_result = self.get_multispan_max_line_num(&sub.span);
 846             max = if sub_result > max { primary } else { max };
 847         }
 848         max
 849     }
 850
 851     // This "fixes" MultiSpans that contain Spans that are pointing to locations inside of
 852     // <*macros>. Since these locations are often difficult to read, we move these Spans from
 853     // <*macros> to their corresponding use site.
 854     fn fix_multispan_in_std_macros(&mut self,
 855                                    span: &mut MultiSpan,
 856                                    always_backtrace: bool) -> bool {
 857         let mut spans_updated = false;
 858
 859         if let Some(ref sm) = self.sm {
 860             let mut before_after: Vec<(Span, Span)> = vec![];
 861             let mut new_labels: Vec<(Span, String)> = vec![];
 862
 863             // First, find all the spans in <*macros> and point instead at their use site
 864             for sp in span.primary_spans() {
 865                 if sp.is_dummy() {
 866                     continue;
 867                 }
 868                 let call_sp = sm.call_span_if_macro(*sp);
 869                 if call_sp != *sp && !always_backtrace {
 870                     before_after.push((*sp, call_sp));
 871                 }
 872                 let backtrace_len = sp.macro_backtrace().len();
 873                 for (i, trace) in sp.macro_backtrace().iter().rev().enumerate() {
 874                     // Only show macro locations that are local
 875                     // and display them like a span_note
 876                     if let Some(def_site) = trace.def_site_span {
 877                         if def_site.is_dummy() {
 878                             continue;
 879                         }
 880                         if always_backtrace {
 881                             new_labels.push((def_site,
 882                                              format!("in this expansion of `{}`{}",
 883                                                      trace.macro_decl_name,
 884                                                      if backtrace_len > 2 {
 885                                                          // if backtrace_len == 1 it'll be pointed
 886                                                          // at by "in this macro invocation"
 887                                                          format!(" (#{})", i + 1)
 888                                                      } else {
 889                                                          String::new()
 890                                                      })));
 891                         }
 892                         // Check to make sure we're not in any <*macros>
 893                         if !sm.span_to_filename(def_site).is_macros() &&
 894                            !trace.macro_decl_name.starts_with("desugaring of ") &&
 895                            !trace.macro_decl_name.starts_with("#[") ||
 896                            always_backtrace {
 897                             new_labels.push((trace.call_site,
 898                                              format!("in this macro invocation{}",
 899                                                      if backtrace_len > 2 && always_backtrace {
 900                                                          // only specify order when the macro
 901                                                          // backtrace is multiple levels deep
 902                                                          format!(" (#{})", i + 1)
 903                                                      } else {
 904                                                          String::new()
 905                                                      })));
 906                             if !always_backtrace {
 907                                 break;
 908                             }
 909                         }
 910                     }
 911                 }
 912             }
 913             for (label_span, label_text) in new_labels {
 914                 span.push_span_label(label_span, label_text);
 915             }
 916             for sp_label in span.span_labels() {
 917                 if sp_label.span.is_dummy() {
 918                     continue;
 919                 }
 920                 if sm.span_to_filename(sp_label.span.clone()).is_macros() &&
 921                     !always_backtrace
 922                 {
 923                     let v = sp_label.span.macro_backtrace();
 924                     if let Some(use_site) = v.last() {
 925                         before_after.push((sp_label.span.clone(), use_site.call_site.clone()));
 926                     }
 927                 }
 928             }
 929             // After we have them, make sure we replace these 'bad' def sites with their use sites
 930             for (before, after) in before_after {
 931                 span.replace(before, after);
 932                 spans_updated = true;
 933             }
 934         }
 935
 936         spans_updated
 937     }
 938
 939     // This does a small "fix" for multispans by looking to see if it can find any that
 940     // point directly at <*macros>. Since these are often difficult to read, this
 941     // will change the span to point at the use site.
 942     fn fix_multispans_in_std_macros(&mut self,
 943                                     span: &mut MultiSpan,
 944                                     children: &mut Vec<SubDiagnostic>,
 945                                     level: &Level,
 946                                     backtrace: bool) {
 947         let mut spans_updated = self.fix_multispan_in_std_macros(span, backtrace);
 948         for child in children.iter_mut() {
 949             spans_updated |= self.fix_multispan_in_std_macros(&mut child.span, backtrace);
 950         }
 951         let msg = if level == &Error {
 952             "this error originates in a macro outside of the current crate \
 953              (in Nightly builds, run with -Z external-macro-backtrace \
 954               for more info)".to_string()
 955         } else {
 956             "this warning originates in a macro outside of the current crate \
 957              (in Nightly builds, run with -Z external-macro-backtrace \
 958               for more info)".to_string()
 959         };
 960
 961         if spans_updated {
 962             children.push(SubDiagnostic {
 963                 level: Level::Note,
 964                 message: vec![
 965                     (msg,
 966                      Style::NoStyle),
 967                 ],
 968                 span: MultiSpan::new(),
 969                 render_span: None,
 970             });
 971         }
 972     }
 973
 974     /// Adds a left margin to every line but the first, given a padding length and the label being
 975     /// displayed, keeping the provided highlighting.
 976     fn msg_to_buffer(&self,
 977                      buffer: &mut StyledBuffer,
 978                      msg: &[(String, Style)],
 979                      padding: usize,
 980                      label: &str,
 981                      override_style: Option<Style>) {
 982
 983         // The extra 5 ` ` is padding that's always needed to align to the `note: `:
 984         //
 985         //   error: message
 986         //     --> file.rs:13:20
 987         //      |
 988         //   13 |     <CODE>
 989         //      |      ^^^^
 990         //      |
 991         //      = note: multiline
 992         //              message
 993         //   ++^^^----xx
 994         //    |  |   | |
 995         //    |  |   | magic `2`
 996         //    |  |   length of label
 997         //    |  magic `3`
 998         //    `max_line_num_len`
 999         let padding = " ".repeat(padding + label.len() + 5);
1000
1001         /// Returns `true` if `style`, or the override if present and the style is `NoStyle`.
1002         fn style_or_override(style: Style, override_style: Option<Style>) -> Style {
1003             if let Some(o) = override_style {
1004                 if style == Style::NoStyle {
1005                     return o;
1006                 }
1007             }
1008             style
1009         }
1010
1011         let mut line_number = 0;
1012
1013         // Provided the following diagnostic message:
1014         //
1015         //     let msg = vec![
1016         //       ("
1017         //       ("highlighted multiline\nstring to\nsee how it ", Style::NoStyle),
1018         //       ("looks", Style::Highlight),
1019         //       ("with\nvery ", Style::NoStyle),
1020         //       ("weird", Style::Highlight),
1021         //       (" formats\n", Style::NoStyle),
1022         //       ("see?", Style::Highlight),
1023         //     ];
1024         //
1025         // the expected output on a note is (* surround the highlighted text)
1026         //
1027         //        = note: highlighted multiline
1028         //                string to
1029         //                see how it *looks* with
1030         //                very *weird* formats
1031         //                see?
1032         for &(ref text, ref style) in msg.iter() {
1033             let lines = text.split('\n').collect::<Vec<_>>();
1034             if lines.len() > 1 {
1035                 for (i, line) in lines.iter().enumerate() {
1036                     if i != 0 {
1037                         line_number += 1;
1038                         buffer.append(line_number, &padding, Style::NoStyle);
1039                     }
1040                     buffer.append(line_number, line, style_or_override(*style, override_style));
1041                 }
1042             } else {
1043                 buffer.append(line_number, text, style_or_override(*style, override_style));
1044             }
1045         }
1046     }
1047
1048     fn emit_message_default(
1049         &mut self,
1050         msp: &MultiSpan,
1051         msg: &[(String, Style)],
1052         code: &Option<DiagnosticId>,
1053         level: &Level,
1054         max_line_num_len: usize,
1055         is_secondary: bool,
1056     ) -> io::Result<()> {
1057         let mut buffer = StyledBuffer::new();
1058         let header_style = if is_secondary {
1059             Style::HeaderMsg
1060         } else {
1061             Style::MainHeaderMsg
1062         };
1063
1064         if !msp.has_primary_spans() && !msp.has_span_labels() && is_secondary
1065            && !self.short_message {
1066             // This is a secondary message with no span info
1067             for _ in 0..max_line_num_len {
1068                 buffer.prepend(0, " ", Style::NoStyle);
1069             }
1070             draw_note_separator(&mut buffer, 0, max_line_num_len + 1);
1071             let level_str = level.to_string();
1072             if !level_str.is_empty() {
1073                 buffer.append(0, &level_str, Style::MainHeaderMsg);
1074                 buffer.append(0, ": ", Style::NoStyle);
1075             }
1076             self.msg_to_buffer(&mut buffer, msg, max_line_num_len, "note", None);
1077         } else {
1078             let level_str = level.to_string();
1079             if !level_str.is_empty() {
1080                 buffer.append(0, &level_str, Style::Level(level.clone()));
1081             }
1082             // only render error codes, not lint codes
1083             if let Some(DiagnosticId::Error(ref code)) = *code {
1084                 buffer.append(0, "[", Style::Level(level.clone()));
1085                 buffer.append(0, &code, Style::Level(level.clone()));
1086                 buffer.append(0, "]", Style::Level(level.clone()));
1087             }
1088             if !level_str.is_empty() {
1089                 buffer.append(0, ": ", header_style);
1090             }
1091             for &(ref text, _) in msg.iter() {
1092                 buffer.append(0, text, header_style);
1093             }
1094         }
1095
1096         // Preprocess all the annotations so that they are grouped by file and by line number
1097         // This helps us quickly iterate over the whole message (including secondary file spans)
1098         let mut annotated_files = self.preprocess_annotations(msp);
1099
1100         // Make sure our primary file comes first
1101         let (primary_lo, sm) = if let (Some(sm), Some(ref primary_span)) =
1102             (self.sm.as_ref(), msp.primary_span().as_ref()) {
1103             if !primary_span.is_dummy() {
1104                 (sm.lookup_char_pos(primary_span.lo()), sm)
1105             } else {
1106                 emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1107                 return Ok(());
1108             }
1109         } else {
1110             // If we don't have span information, emit and exit
1111             emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1112             return Ok(());
1113         };
1114         if let Ok(pos) =
1115             annotated_files.binary_search_by(|x| x.file.name.cmp(&primary_lo.file.name)) {
1116             annotated_files.swap(0, pos);
1117         }
1118
1119         // Print out the annotate source lines that correspond with the error
1120         for annotated_file in annotated_files {
1121             // we can't annotate anything if the source is unavailable.
1122             if !sm.ensure_source_file_source_present(annotated_file.file.clone()) {
1123                 continue;
1124             }
1125
1126             // print out the span location and spacer before we print the annotated source
1127             // to do this, we need to know if this span will be primary
1128             let is_primary = primary_lo.file.name == annotated_file.file.name;
1129             if is_primary {
1130                 let loc = primary_lo.clone();
1131                 if !self.short_message {
1132                     // remember where we are in the output buffer for easy reference
1133                     let buffer_msg_line_offset = buffer.num_lines();
1134
1135                     buffer.prepend(buffer_msg_line_offset, "--> ", Style::LineNumber);
1136                     buffer.append(buffer_msg_line_offset,
1137                                   &format!("{}:{}:{}",
1138                                            loc.file.name,
1139                                            sm.doctest_offset_line(&loc.file.name, loc.line),
1140                                            loc.col.0 + 1),
1141                                   Style::LineAndColumn);
1142                     for _ in 0..max_line_num_len {
1143                         buffer.prepend(buffer_msg_line_offset, " ", Style::NoStyle);
1144                     }
1145                 } else {
1146                     buffer.prepend(0,
1147                                    &format!("{}:{}:{}: ",
1148                                             loc.file.name,
1149                                             sm.doctest_offset_line(&loc.file.name, loc.line),
1150                                             loc.col.0 + 1),
1151                                    Style::LineAndColumn);
1152                 }
1153             } else if !self.short_message {
1154                 // remember where we are in the output buffer for easy reference
1155                 let buffer_msg_line_offset = buffer.num_lines();
1156
1157                 // Add spacing line
1158                 draw_col_separator(&mut buffer, buffer_msg_line_offset, max_line_num_len + 1);
1159
1160                 // Then, the secondary file indicator
1161                 buffer.prepend(buffer_msg_line_offset + 1, "::: ", Style::LineNumber);
1162                 let loc = if let Some(first_line) = annotated_file.lines.first() {
1163                     let col = if let Some(first_annotation) = first_line.annotations.first() {
1164                         format!(":{}", first_annotation.start_col + 1)
1165                     } else {
1166                         String::new()
1167                     };
1168                     format!("{}:{}{}",
1169                             annotated_file.file.name,
1170                             sm.doctest_offset_line(
1171                                 &annotated_file.file.name, first_line.line_index),
1172                             col)
1173                 } else {
1174                     annotated_file.file.name.to_string()
1175                 };
1176                 buffer.append(buffer_msg_line_offset + 1,
1177                               &loc,
1178                               Style::LineAndColumn);
1179                 for _ in 0..max_line_num_len {
1180                     buffer.prepend(buffer_msg_line_offset + 1, " ", Style::NoStyle);
1181                 }
1182             }
1183
1184             if !self.short_message {
1185                 // Put in the spacer between the location and annotated source
1186                 let buffer_msg_line_offset = buffer.num_lines();
1187                 draw_col_separator_no_space(&mut buffer,
1188                                             buffer_msg_line_offset,
1189                                             max_line_num_len + 1);
1190
1191                 // Contains the vertical lines' positions for active multiline annotations
1192                 let mut multilines = FxHashMap::default();
1193
1194                 // Next, output the annotate source for this file
1195                 for line_idx in 0..annotated_file.lines.len() {
1196                     let previous_buffer_line = buffer.num_lines();
1197
1198                     let width_offset = 3 + max_line_num_len;
1199                     let code_offset = if annotated_file.multiline_depth == 0 {
1200                         width_offset
1201                     } else {
1202                         width_offset + annotated_file.multiline_depth + 1
1203                     };
1204
1205                     let depths = self.render_source_line(&mut buffer,
1206                                                          annotated_file.file.clone(),
1207                                                          &annotated_file.lines[line_idx],
1208                                                          width_offset,
1209                                                          code_offset);
1210
1211                     let mut to_add = FxHashMap::default();
1212
1213                     for (depth, style) in depths {
1214                         if multilines.get(&depth).is_some() {
1215                             multilines.remove(&depth);
1216                         } else {
1217                             to_add.insert(depth, style);
1218                         }
1219                     }
1220
1221                     // Set the multiline annotation vertical lines to the left of
1222                     // the code in this line.
1223                     for (depth, style) in &multilines {
1224                         for line in previous_buffer_line..buffer.num_lines() {
1225                             draw_multiline_line(&mut buffer,
1226                                                 line,
1227                                                 width_offset,
1228                                                 *depth,
1229                                                 *style);
1230                         }
1231                     }
1232                     // check to see if we need to print out or elide lines that come between
1233                     // this annotated line and the next one.
1234                     if line_idx < (annotated_file.lines.len() - 1) {
1235                         let line_idx_delta = annotated_file.lines[line_idx + 1].line_index -
1236                                              annotated_file.lines[line_idx].line_index;
1237                         if line_idx_delta > 2 {
1238                             let last_buffer_line_num = buffer.num_lines();
1239                             buffer.puts(last_buffer_line_num, 0, "...", Style::LineNumber);
1240
1241                             // Set the multiline annotation vertical lines on `...` bridging line.
1242                             for (depth, style) in &multilines {
1243                                 draw_multiline_line(&mut buffer,
1244                                                     last_buffer_line_num,
1245                                                     width_offset,
1246                                                     *depth,
1247                                                     *style);
1248                             }
1249                         } else if line_idx_delta == 2 {
1250                             let unannotated_line = annotated_file.file
1251                                 .get_line(annotated_file.lines[line_idx].line_index)
1252                                 .unwrap_or_else(|| Cow::from(""));
1253
1254                             let last_buffer_line_num = buffer.num_lines();
1255
1256                             buffer.puts(last_buffer_line_num,
1257                                         0,
1258                                         &self.maybe_anonymized(annotated_file.lines[line_idx + 1]
1259                                                                              .line_index - 1),
1260                                         Style::LineNumber);
1261                             draw_col_separator(&mut buffer,
1262                                                last_buffer_line_num,
1263                                                1 + max_line_num_len);
1264                             buffer.puts(last_buffer_line_num,
1265                                         code_offset,
1266                                         &unannotated_line,
1267                                         Style::Quotation);
1268
1269                             for (depth, style) in &multilines {
1270                                 draw_multiline_line(&mut buffer,
1271                                                     last_buffer_line_num,
1272                                                     width_offset,
1273                                                     *depth,
1274                                                     *style);
1275                             }
1276                         }
1277                     }
1278
1279                     multilines.extend(&to_add);
1280                 }
1281             }
1282         }
1283
1284         // final step: take our styled buffer, render it, then output it
1285         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1286
1287         Ok(())
1288
1289     }
1290
1291     fn emit_suggestion_default(
1292         &mut self,
1293         suggestion: &CodeSuggestion,
1294         level: &Level,
1295         max_line_num_len: usize,
1296     ) -> io::Result<()> {
1297         if let Some(ref sm) = self.sm {
1298             let mut buffer = StyledBuffer::new();
1299
1300             // Render the suggestion message
1301             let level_str = level.to_string();
1302             if !level_str.is_empty() {
1303                 buffer.append(0, &level_str, Style::Level(level.clone()));
1304                 buffer.append(0, ": ", Style::HeaderMsg);
1305             }
1306             self.msg_to_buffer(
1307                 &mut buffer,
1308                 &[(suggestion.msg.to_owned(), Style::NoStyle)],
1309                 max_line_num_len,
1310                 "suggestion",
1311                 Some(Style::HeaderMsg),
1312             );
1313
1314             // Render the replacements for each suggestion
1315             let suggestions = suggestion.splice_lines(&**sm);
1316
1317             let mut row_num = 2;
1318             for &(ref complete, ref parts) in suggestions.iter().take(MAX_SUGGESTIONS) {
1319                 // Only show underline if the suggestion spans a single line and doesn't cover the
1320                 // entirety of the code output. If you have multiple replacements in the same line
1321                 // of code, show the underline.
1322                 let show_underline = !(parts.len() == 1
1323                     && parts[0].snippet.trim() == complete.trim())
1324                     && complete.lines().count() == 1;
1325
1326                 let lines = sm.span_to_lines(parts[0].span).unwrap();
1327
1328                 assert!(!lines.lines.is_empty());
1329
1330                 let line_start = sm.lookup_char_pos(parts[0].span.lo()).line;
1331                 draw_col_separator_no_space(&mut buffer, 1, max_line_num_len + 1);
1332                 let mut line_pos = 0;
1333                 let mut lines = complete.lines();
1334                 for line in lines.by_ref().take(MAX_HIGHLIGHT_LINES) {
1335                     // Print the span column to avoid confusion
1336                     buffer.puts(row_num,
1337                                 0,
1338                                 &self.maybe_anonymized(line_start + line_pos),
1339                                 Style::LineNumber);
1340                     // print the suggestion
1341                     draw_col_separator(&mut buffer, row_num, max_line_num_len + 1);
1342                     buffer.append(row_num, line, Style::NoStyle);
1343                     line_pos += 1;
1344                     row_num += 1;
1345                 }
1346
1347                 // This offset and the ones below need to be signed to account for replacement code
1348                 // that is shorter than the original code.
1349                 let mut offset: isize = 0;
1350                 // Only show an underline in the suggestions if the suggestion is not the
1351                 // entirety of the code being shown and the displayed code is not multiline.
1352                 if show_underline {
1353                     draw_col_separator(&mut buffer, row_num, max_line_num_len + 1);
1354                     for part in parts {
1355                         let span_start_pos = sm.lookup_char_pos(part.span.lo()).col_display;
1356                         let span_end_pos = sm.lookup_char_pos(part.span.hi()).col_display;
1357
1358                         // Do not underline the leading...
1359                         let start = part.snippet.len()
1360                             .saturating_sub(part.snippet.trim_start().len());
1361                         // ...or trailing spaces. Account for substitutions containing unicode
1362                         // characters.
1363                         let sub_len = part.snippet.trim().chars().fold(0, |acc, ch| {
1364                             acc + unicode_width::UnicodeWidthChar::width(ch).unwrap_or(0)
1365                         });
1366
1367                         let underline_start = (span_start_pos + start) as isize + offset;
1368                         let underline_end = (span_start_pos + start + sub_len) as isize + offset;
1369                         for p in underline_start..underline_end {
1370                             buffer.putc(row_num,
1371                                         max_line_num_len + 3 + p as usize,
1372                                         '^',
1373                                         Style::UnderlinePrimary);
1374                         }
1375                         // underline removals too
1376                         if underline_start == underline_end {
1377                             for p in underline_start-1..underline_start+1 {
1378                                 buffer.putc(row_num,
1379                                             max_line_num_len + 3 + p as usize,
1380                                             '-',
1381                                             Style::UnderlineSecondary);
1382                             }
1383                         }
1384
1385                         // length of the code after substitution
1386                         let full_sub_len = part.snippet.chars().fold(0, |acc, ch| {
1387                             acc + unicode_width::UnicodeWidthChar::width(ch).unwrap_or(0) as isize
1388                         });
1389
1390                         // length of the code to be substituted
1391                         let snippet_len = span_end_pos as isize - span_start_pos as isize;
1392                         // For multiple substitutions, use the position *after* the previous
1393                         // substitutions have happened.
1394                         offset += full_sub_len - snippet_len;
1395                     }
1396                     row_num += 1;
1397                 }
1398
1399                 // if we elided some lines, add an ellipsis
1400                 if lines.next().is_some() {
1401                     buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
1402                 } else if !show_underline {
1403                     draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
1404                     row_num += 1;
1405                 }
1406             }
1407             if suggestions.len() > MAX_SUGGESTIONS {
1408                 let msg = format!("and {} other candidates", suggestions.len() - MAX_SUGGESTIONS);
1409                 buffer.puts(row_num, 0, &msg, Style::NoStyle);
1410             }
1411             emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1412         }
1413         Ok(())
1414     }
1415
1416     fn emit_messages_default(&mut self,
1417                              level: &Level,
1418                              message: &[(String, Style)],
1419                              code: &Option<DiagnosticId>,
1420                              span: &MultiSpan,
1421                              children: &[SubDiagnostic],
1422                              suggestions: &[CodeSuggestion]) {
1423         let max_line_num_len = if self.ui_testing {
1424             ANONYMIZED_LINE_NUM.len()
1425         } else {
1426             self.get_max_line_num(span, children).to_string().len()
1427         };
1428
1429         match self.emit_message_default(span,
1430                                         message,
1431                                         code,
1432                                         level,
1433                                         max_line_num_len,
1434                                         false) {
1435             Ok(()) => {
1436                 if !children.is_empty() {
1437                     let mut buffer = StyledBuffer::new();
1438                     if !self.short_message {
1439                         draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
1440                     }
1441                     match emit_to_destination(&buffer.render(), level, &mut self.dst,
1442                                               self.short_message) {
1443                         Ok(()) => (),
1444                         Err(e) => panic!("failed to emit error: {}", e)
1445                     }
1446                 }
1447                 if !self.short_message {
1448                     for child in children {
1449                         let span = child.render_span.as_ref().unwrap_or(&child.span);
1450                         match self.emit_message_default(
1451                             &span,
1452                             &child.styled_message(),
1453                             &None,
1454                             &child.level,
1455                             max_line_num_len,
1456                             true,
1457                         ) {
1458                             Err(e) => panic!("failed to emit error: {}", e),
1459                             _ => ()
1460                         }
1461                     }
1462                     for sugg in suggestions {
1463                         if sugg.style == SuggestionStyle::CompletelyHidden {
1464                             // do not display this suggestion, it is meant only for tools
1465                         } else if sugg.style == SuggestionStyle::HideCodeAlways {
1466                             match self.emit_message_default(
1467                                 &MultiSpan::new(),
1468                                 &[(sugg.msg.to_owned(), Style::HeaderMsg)],
1469                                 &None,
1470                                 &Level::Help,
1471                                 max_line_num_len,
1472                                 true,
1473                             ) {
1474                                 Err(e) => panic!("failed to emit error: {}", e),
1475                                 _ => ()
1476                             }
1477                         } else {
1478                             match self.emit_suggestion_default(
1479                                 sugg,
1480                                 &Level::Help,
1481                                 max_line_num_len,
1482                             ) {
1483                                 Err(e) => panic!("failed to emit error: {}", e),
1484                                 _ => ()
1485                             }
1486                         }
1487                     }
1488                 }
1489             }
1490             Err(e) => panic!("failed to emit error: {}", e),
1491         }
1492
1493         let mut dst = self.dst.writable();
1494         match write!(dst, "\n") {
1495             Err(e) => panic!("failed to emit error: {}", e),
1496             _ => {
1497                 match dst.flush() {
1498                     Err(e) => panic!("failed to emit error: {}", e),
1499                     _ => (),
1500                 }
1501             }
1502         }
1503     }
1504 }
1505
1506 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
1507     buffer.puts(line, col, "| ", Style::LineNumber);
1508 }
1509
1510 fn draw_col_separator_no_space(buffer: &mut StyledBuffer, line: usize, col: usize) {
1511     draw_col_separator_no_space_with_style(buffer, line, col, Style::LineNumber);
1512 }
1513
1514 fn draw_col_separator_no_space_with_style(buffer: &mut StyledBuffer,
1515                                           line: usize,
1516                                           col: usize,
1517                                           style: Style) {
1518     buffer.putc(line, col, '|', style);
1519 }
1520
1521 fn draw_range(buffer: &mut StyledBuffer, symbol: char, line: usize,
1522               col_from: usize, col_to: usize, style: Style) {
1523     for col in col_from..col_to {
1524         buffer.putc(line, col, symbol, style);
1525     }
1526 }
1527
1528 fn draw_note_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
1529     buffer.puts(line, col, "= ", Style::LineNumber);
1530 }
1531
1532 fn draw_multiline_line(buffer: &mut StyledBuffer,
1533                        line: usize,
1534                        offset: usize,
1535                        depth: usize,
1536                        style: Style)
1537 {
1538     buffer.putc(line, offset + depth - 1, '|', style);
1539 }
1540
1541 fn num_overlap(a_start: usize, a_end: usize, b_start: usize, b_end:usize, inclusive: bool) -> bool {
1542     let extra = if inclusive {
1543         1
1544     } else {
1545         0
1546     };
1547     (b_start..b_end + extra).contains(&a_start) ||
1548     (a_start..a_end + extra).contains(&b_start)
1549 }
1550 fn overlaps(a1: &Annotation, a2: &Annotation, padding: usize) -> bool {
1551     num_overlap(a1.start_col, a1.end_col + padding, a2.start_col, a2.end_col, false)
1552 }
1553
1554 fn emit_to_destination(rendered_buffer: &[Vec<StyledString>],
1555                        lvl: &Level,
1556                        dst: &mut Destination,
1557                        short_message: bool)
1558                        -> io::Result<()> {
1559     use crate::lock;
1560
1561     let mut dst = dst.writable();
1562
1563     // In order to prevent error message interleaving, where multiple error lines get intermixed
1564     // when multiple compiler processes error simultaneously, we emit errors with additional
1565     // steps.
1566     //
1567     // On Unix systems, we write into a buffered terminal rather than directly to a terminal. When
1568     // the .flush() is called we take the buffer created from the buffered writes and write it at
1569     // one shot.  Because the Unix systems use ANSI for the colors, which is a text-based styling
1570     // scheme, this buffered approach works and maintains the styling.
1571     //
1572     // On Windows, styling happens through calls to a terminal API. This prevents us from using the
1573     // same buffering approach.  Instead, we use a global Windows mutex, which we acquire long
1574     // enough to output the full error message, then we release.
1575     let _buffer_lock = lock::acquire_global_lock("rustc_errors");
1576     for (pos, line) in rendered_buffer.iter().enumerate() {
1577         for part in line {
1578             dst.apply_style(lvl.clone(), part.style)?;
1579             write!(dst, "{}", part.text)?;
1580             dst.reset()?;
1581         }
1582         if !short_message && (!lvl.is_failure_note() || pos != rendered_buffer.len() - 1) {
1583             write!(dst, "\n")?;
1584         }
1585     }
1586     dst.flush()?;
1587     Ok(())
1588 }
1589
1590 pub enum Destination {
1591     Terminal(StandardStream),
1592     Buffered(BufferWriter),
1593     // The bool denotes whether we should be emitting ansi color codes or not
1594     Raw(Box<(dyn Write + Send)>, bool),
1595 }
1596
1597 pub enum WritableDst<'a> {
1598     Terminal(&'a mut StandardStream),
1599     Buffered(&'a mut BufferWriter, Buffer),
1600     Raw(&'a mut (dyn Write + Send)),
1601     ColoredRaw(Ansi<&'a mut (dyn Write + Send)>),
1602 }
1603
1604 impl Destination {
1605     fn from_stderr(color: ColorConfig) -> Destination {
1606         let choice = color.to_color_choice();
1607         // On Windows we'll be performing global synchronization on the entire
1608         // system for emitting rustc errors, so there's no need to buffer
1609         // anything.
1610         //
1611         // On non-Windows we rely on the atomicity of `write` to ensure errors
1612         // don't get all jumbled up.
1613         if cfg!(windows) {
1614             Terminal(StandardStream::stderr(choice))
1615         } else {
1616             Buffered(BufferWriter::stderr(choice))
1617         }
1618     }
1619
1620     fn writable<'a>(&'a mut self) -> WritableDst<'a> {
1621         match *self {
1622             Destination::Terminal(ref mut t) => WritableDst::Terminal(t),
1623             Destination::Buffered(ref mut t) => {
1624                 let buf = t.buffer();
1625                 WritableDst::Buffered(t, buf)
1626             }
1627             Destination::Raw(ref mut t, false) => WritableDst::Raw(t),
1628             Destination::Raw(ref mut t, true) => WritableDst::ColoredRaw(Ansi::new(t)),
1629         }
1630     }
1631 }
1632
1633 impl<'a> WritableDst<'a> {
1634     fn apply_style(&mut self, lvl: Level, style: Style) -> io::Result<()> {
1635         let mut spec = ColorSpec::new();
1636         match style {
1637             Style::LineAndColumn => {}
1638             Style::LineNumber => {
1639                 spec.set_bold(true);
1640                 spec.set_intense(true);
1641                 if cfg!(windows) {
1642                     spec.set_fg(Some(Color::Cyan));
1643                 } else {
1644                     spec.set_fg(Some(Color::Blue));
1645                 }
1646             }
1647             Style::Quotation => {}
1648             Style::OldSchoolNoteText | Style::MainHeaderMsg => {
1649                 spec.set_bold(true);
1650                 if cfg!(windows) {
1651                     spec.set_intense(true)
1652                         .set_fg(Some(Color::White));
1653                 }
1654             }
1655             Style::UnderlinePrimary | Style::LabelPrimary => {
1656                 spec = lvl.color();
1657                 spec.set_bold(true);
1658             }
1659             Style::UnderlineSecondary |
1660             Style::LabelSecondary => {
1661                 spec.set_bold(true)
1662                     .set_intense(true);
1663                 if cfg!(windows) {
1664                     spec.set_fg(Some(Color::Cyan));
1665                 } else {
1666                     spec.set_fg(Some(Color::Blue));
1667                 }
1668             }
1669             Style::HeaderMsg |
1670             Style::NoStyle => {}
1671             Style::Level(lvl) => {
1672                 spec = lvl.color();
1673                 spec.set_bold(true);
1674             }
1675             Style::Highlight => {
1676                 spec.set_bold(true);
1677             }
1678         }
1679         self.set_color(&spec)
1680     }
1681
1682     fn set_color(&mut self, color: &ColorSpec) -> io::Result<()> {
1683         match *self {
1684             WritableDst::Terminal(ref mut t) => t.set_color(color),
1685             WritableDst::Buffered(_, ref mut t) => t.set_color(color),
1686             WritableDst::ColoredRaw(ref mut t) => t.set_color(color),
1687             WritableDst::Raw(_) => Ok(())
1688         }
1689     }
1690
1691     fn reset(&mut self) -> io::Result<()> {
1692         match *self {
1693             WritableDst::Terminal(ref mut t) => t.reset(),
1694             WritableDst::Buffered(_, ref mut t) => t.reset(),
1695             WritableDst::ColoredRaw(ref mut t) => t.reset(),
1696             WritableDst::Raw(_) => Ok(()),
1697         }
1698     }
1699 }
1700
1701 impl<'a> Write for WritableDst<'a> {
1702     fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
1703         match *self {
1704             WritableDst::Terminal(ref mut t) => t.write(bytes),
1705             WritableDst::Buffered(_, ref mut buf) => buf.write(bytes),
1706             WritableDst::Raw(ref mut w) => w.write(bytes),
1707             WritableDst::ColoredRaw(ref mut t) => t.write(bytes),
1708         }
1709     }
1710
1711     fn flush(&mut self) -> io::Result<()> {
1712         match *self {
1713             WritableDst::Terminal(ref mut t) => t.flush(),
1714             WritableDst::Buffered(_, ref mut buf) => buf.flush(),
1715             WritableDst::Raw(ref mut w) => w.flush(),
1716             WritableDst::ColoredRaw(ref mut w) => w.flush(),
1717         }
1718     }
1719 }
1720
1721 impl<'a> Drop for WritableDst<'a> {
1722     fn drop(&mut self) {
1723         match *self {
1724             WritableDst::Buffered(ref mut dst, ref mut buf) => {
1725                 drop(dst.print(buf));
1726             }
1727             _ => {}
1728         }
1729     }
1730 }