src/librustc_errors/emitter.rs

   1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use self::Destination::*;
  12
  13 use syntax_pos::{FileMap, Span, MultiSpan};
  14
  15 use {Level, CodeSuggestion, DiagnosticBuilder, SubDiagnostic, CodeMapperDyn, DiagnosticId};
  16 use snippet::{Annotation, AnnotationType, Line, MultilineAnnotation, StyledString, Style};
  17 use styled_buffer::StyledBuffer;
  18
  19 use rustc_data_structures::sync::Lrc;
  20 use atty;
  21 use std::borrow::Cow;
  22 use std::io::prelude::*;
  23 use std::io;
  24 use std::collections::HashMap;
  25 use std::cmp::{min, Reverse};
  26 use termcolor::{StandardStream, ColorChoice, ColorSpec, BufferWriter};
  27 use termcolor::{WriteColor, Color, Buffer};
  28 use unicode_width;
  29
  30 const ANONYMIZED_LINE_NUM: &str = "LL";
  31
  32 /// Emitter trait for emitting errors.
  33 pub trait Emitter {
  34     /// Emit a structured diagnostic.
  35     fn emit(&mut self, db: &DiagnosticBuilder);
  36
  37     /// Check if should show explanations about "rustc --explain"
  38     fn should_show_explain(&self) -> bool {
  39         true
  40     }
  41 }
  42
  43 impl Emitter for EmitterWriter {
  44     fn emit(&mut self, db: &DiagnosticBuilder) {
  45         let mut primary_span = db.span.clone();
  46         let mut children = db.children.clone();
  47         let mut suggestions: &[_] = &[];
  48
  49         if let Some((sugg, rest)) = db.suggestions.split_first() {
  50             if rest.is_empty() &&
  51                // don't display multi-suggestions as labels
  52                sugg.substitutions.len() == 1 &&
  53                // don't display multipart suggestions as labels
  54                sugg.substitutions[0].parts.len() == 1 &&
  55                // don't display long messages as labels
  56                sugg.msg.split_whitespace().count() < 10 &&
  57                // don't display multiline suggestions as labels
  58                !sugg.substitutions[0].parts[0].snippet.contains('\n') {
  59                 let substitution = &sugg.substitutions[0].parts[0].snippet.trim();
  60                 let msg = if substitution.len() == 0 || !sugg.show_code_when_inline {
  61                     // This substitution is only removal or we explicitly don't want to show the
  62                     // code inline, don't show it
  63                     format!("help: {}", sugg.msg)
  64                 } else {
  65                     format!("help: {}: `{}`", sugg.msg, substitution)
  66                 };
  67                 primary_span.push_span_label(sugg.substitutions[0].parts[0].span, msg);
  68             } else {
  69                 // if there are multiple suggestions, print them all in full
  70                 // to be consistent. We could try to figure out if we can
  71                 // make one (or the first one) inline, but that would give
  72                 // undue importance to a semi-random suggestion
  73                 suggestions = &db.suggestions;
  74             }
  75         }
  76
  77         self.fix_multispans_in_std_macros(&mut primary_span,
  78                                           &mut children,
  79                                           db.handler.flags.external_macro_backtrace);
  80
  81         self.emit_messages_default(&db.level,
  82                                    &db.styled_message(),
  83                                    &db.code,
  84                                    &primary_span,
  85                                    &children,
  86                                    &suggestions);
  87     }
  88
  89     fn should_show_explain(&self) -> bool {
  90         !self.short_message
  91     }
  92 }
  93
  94 /// maximum number of lines we will print for each error; arbitrary.
  95 pub const MAX_HIGHLIGHT_LINES: usize = 6;
  96 /// maximum number of suggestions to be shown
  97 ///
  98 /// Arbitrary, but taken from trait import suggestion limit
  99 pub const MAX_SUGGESTIONS: usize = 4;
 100
 101 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 102 pub enum ColorConfig {
 103     Auto,
 104     Always,
 105     Never,
 106 }
 107
 108 impl ColorConfig {
 109     fn to_color_choice(&self) -> ColorChoice {
 110         match *self {
 111             ColorConfig::Always => ColorChoice::Always,
 112             ColorConfig::Never => ColorChoice::Never,
 113             ColorConfig::Auto if atty::is(atty::Stream::Stderr) => {
 114                 ColorChoice::Auto
 115             }
 116             ColorConfig::Auto => ColorChoice::Never,
 117         }
 118     }
 119 }
 120
 121 pub struct EmitterWriter {
 122     dst: Destination,
 123     cm: Option<Lrc<CodeMapperDyn>>,
 124     short_message: bool,
 125     teach: bool,
 126     ui_testing: bool,
 127 }
 128
 129 struct FileWithAnnotatedLines {
 130     file: Lrc<FileMap>,
 131     lines: Vec<Line>,
 132     multiline_depth: usize,
 133 }
 134
 135 impl EmitterWriter {
 136     pub fn stderr(color_config: ColorConfig,
 137                   code_map: Option<Lrc<CodeMapperDyn>>,
 138                   short_message: bool,
 139                   teach: bool)
 140                   -> EmitterWriter {
 141         let dst = Destination::from_stderr(color_config);
 142         EmitterWriter {
 143             dst,
 144             cm: code_map,
 145             short_message,
 146             teach,
 147             ui_testing: false,
 148         }
 149     }
 150
 151     pub fn new(dst: Box<dyn Write + Send>,
 152                code_map: Option<Lrc<CodeMapperDyn>>,
 153                short_message: bool,
 154                teach: bool)
 155                -> EmitterWriter {
 156         EmitterWriter {
 157             dst: Raw(dst),
 158             cm: code_map,
 159             short_message,
 160             teach,
 161             ui_testing: false,
 162         }
 163     }
 164
 165     pub fn ui_testing(mut self, ui_testing: bool) -> Self {
 166         self.ui_testing = ui_testing;
 167         self
 168     }
 169
 170     fn maybe_anonymized(&self, line_num: usize) -> String {
 171         if self.ui_testing {
 172             ANONYMIZED_LINE_NUM.to_string()
 173         } else {
 174             line_num.to_string()
 175         }
 176     }
 177
 178     fn preprocess_annotations(&mut self, msp: &MultiSpan) -> Vec<FileWithAnnotatedLines> {
 179         fn add_annotation_to_file(file_vec: &mut Vec<FileWithAnnotatedLines>,
 180                                   file: Lrc<FileMap>,
 181                                   line_index: usize,
 182                                   ann: Annotation) {
 183
 184             for slot in file_vec.iter_mut() {
 185                 // Look through each of our files for the one we're adding to
 186                 if slot.file.name == file.name {
 187                     // See if we already have a line for it
 188                     for line_slot in &mut slot.lines {
 189                         if line_slot.line_index == line_index {
 190                             line_slot.annotations.push(ann);
 191                             return;
 192                         }
 193                     }
 194                     // We don't have a line yet, create one
 195                     slot.lines.push(Line {
 196                         line_index,
 197                         annotations: vec![ann],
 198                     });
 199                     slot.lines.sort();
 200                     return;
 201                 }
 202             }
 203             // This is the first time we're seeing the file
 204             file_vec.push(FileWithAnnotatedLines {
 205                 file,
 206                 lines: vec![Line {
 207                                 line_index,
 208                                 annotations: vec![ann],
 209                             }],
 210                 multiline_depth: 0,
 211             });
 212         }
 213
 214         let mut output = vec![];
 215         let mut multiline_annotations = vec![];
 216
 217         if let Some(ref cm) = self.cm {
 218             for span_label in msp.span_labels() {
 219                 if span_label.span.is_dummy() {
 220                     continue;
 221                 }
 222
 223                 let lo = cm.lookup_char_pos(span_label.span.lo());
 224                 let mut hi = cm.lookup_char_pos(span_label.span.hi());
 225
 226                 // Watch out for "empty spans". If we get a span like 6..6, we
 227                 // want to just display a `^` at 6, so convert that to
 228                 // 6..7. This is degenerate input, but it's best to degrade
 229                 // gracefully -- and the parser likes to supply a span like
 230                 // that for EOF, in particular.
 231                 if lo.col_display == hi.col_display && lo.line == hi.line {
 232                     hi.col_display += 1;
 233                 }
 234
 235                 let ann_type = if lo.line != hi.line {
 236                     let ml = MultilineAnnotation {
 237                         depth: 1,
 238                         line_start: lo.line,
 239                         line_end: hi.line,
 240                         start_col: lo.col_display,
 241                         end_col: hi.col_display,
 242                         is_primary: span_label.is_primary,
 243                         label: span_label.label.clone(),
 244                     };
 245                     multiline_annotations.push((lo.file.clone(), ml.clone()));
 246                     AnnotationType::Multiline(ml)
 247                 } else {
 248                     AnnotationType::Singleline
 249                 };
 250                 let ann = Annotation {
 251                     start_col: lo.col_display,
 252                     end_col: hi.col_display,
 253                     is_primary: span_label.is_primary,
 254                     label: span_label.label.clone(),
 255                     annotation_type: ann_type,
 256                 };
 257
 258                 if !ann.is_multiline() {
 259                     add_annotation_to_file(&mut output,
 260                                            lo.file,
 261                                            lo.line,
 262                                            ann);
 263                 }
 264             }
 265         }
 266
 267         // Find overlapping multiline annotations, put them at different depths
 268         multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, ml.line_end));
 269         for item in multiline_annotations.clone() {
 270             let ann = item.1;
 271             for item in multiline_annotations.iter_mut() {
 272                 let ref mut a = item.1;
 273                 // Move all other multiline annotations overlapping with this one
 274                 // one level to the right.
 275                 if &ann != a &&
 276                     num_overlap(ann.line_start, ann.line_end, a.line_start, a.line_end, true)
 277                 {
 278                     a.increase_depth();
 279                 } else {
 280                     break;
 281                 }
 282             }
 283         }
 284
 285         let mut max_depth = 0;  // max overlapping multiline spans
 286         for (file, ann) in multiline_annotations {
 287             if ann.depth > max_depth {
 288                 max_depth = ann.depth;
 289             }
 290             add_annotation_to_file(&mut output, file.clone(), ann.line_start, ann.as_start());
 291             let middle = min(ann.line_start + 4, ann.line_end);
 292             for line in ann.line_start + 1..middle {
 293                 add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
 294             }
 295             if middle < ann.line_end - 1 {
 296                 for line in ann.line_end - 1..ann.line_end {
 297                     add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
 298                 }
 299             }
 300             add_annotation_to_file(&mut output, file, ann.line_end, ann.as_end());
 301         }
 302         for file_vec in output.iter_mut() {
 303             file_vec.multiline_depth = max_depth;
 304         }
 305         output
 306     }
 307
 308     fn render_source_line(&self,
 309                           buffer: &mut StyledBuffer,
 310                           file: Lrc<FileMap>,
 311                           line: &Line,
 312                           width_offset: usize,
 313                           code_offset: usize) -> Vec<(usize, Style)> {
 314         if line.line_index == 0 {
 315             return Vec::new();
 316         }
 317
 318         let source_string = match file.get_line(line.line_index - 1) {
 319             Some(s) => s,
 320             None => return Vec::new(),
 321         };
 322
 323         let line_offset = buffer.num_lines();
 324
 325         // First create the source line we will highlight.
 326         buffer.puts(line_offset, code_offset, &source_string, Style::Quotation);
 327         buffer.puts(line_offset,
 328                     0,
 329                     &self.maybe_anonymized(line.line_index),
 330                     Style::LineNumber);
 331
 332         draw_col_separator(buffer, line_offset, width_offset - 2);
 333
 334         // Special case when there's only one annotation involved, it is the start of a multiline
 335         // span and there's no text at the beginning of the code line. Instead of doing the whole
 336         // graph:
 337         //
 338         // 2 |   fn foo() {
 339         //   |  _^
 340         // 3 | |
 341         // 4 | | }
 342         //   | |_^ test
 343         //
 344         // we simplify the output to:
 345         //
 346         // 2 | / fn foo() {
 347         // 3 | |
 348         // 4 | | }
 349         //   | |_^ test
 350         if line.annotations.len() == 1 {
 351             if let Some(ref ann) = line.annotations.get(0) {
 352                 if let AnnotationType::MultilineStart(depth) = ann.annotation_type {
 353                     if source_string.chars()
 354                                     .take(ann.start_col)
 355                                     .all(|c| c.is_whitespace()) {
 356                         let style = if ann.is_primary {
 357                             Style::UnderlinePrimary
 358                         } else {
 359                             Style::UnderlineSecondary
 360                         };
 361                         buffer.putc(line_offset,
 362                                     width_offset + depth - 1,
 363                                     '/',
 364                                     style);
 365                         return vec![(depth, style)];
 366                     }
 367                 }
 368             }
 369         }
 370
 371         // We want to display like this:
 372         //
 373         //      vec.push(vec.pop().unwrap());
 374         //      ---      ^^^               - previous borrow ends here
 375         //      |        |
 376         //      |        error occurs here
 377         //      previous borrow of `vec` occurs here
 378         //
 379         // But there are some weird edge cases to be aware of:
 380         //
 381         //      vec.push(vec.pop().unwrap());
 382         //      --------                    - previous borrow ends here
 383         //      ||
 384         //      |this makes no sense
 385         //      previous borrow of `vec` occurs here
 386         //
 387         // For this reason, we group the lines into "highlight lines"
 388         // and "annotations lines", where the highlight lines have the `^`.
 389
 390         // Sort the annotations by (start, end col)
 391         // The labels are reversed, sort and then reversed again.
 392         // Consider a list of annotations (A1, A2, C1, C2, B1, B2) where
 393         // the letter signifies the span. Here we are only sorting by the
 394         // span and hence, the order of the elements with the same span will
 395         // not change. On reversing the ordering (|a, b| but b.cmp(a)), you get
 396         // (C1, C2, B1, B2, A1, A2). All the elements with the same span are
 397         // still ordered first to last, but all the elements with different
 398         // spans are ordered by their spans in last to first order. Last to
 399         // first order is important, because the jiggly lines and | are on
 400         // the left, so the rightmost span needs to be rendered first,
 401         // otherwise the lines would end up needing to go over a message.
 402
 403         let mut annotations = line.annotations.clone();
 404         annotations.sort_by_key(|a| Reverse(a.start_col));
 405
 406         // First, figure out where each label will be positioned.
 407         //
 408         // In the case where you have the following annotations:
 409         //
 410         //      vec.push(vec.pop().unwrap());
 411         //      --------                    - previous borrow ends here [C]
 412         //      ||
 413         //      |this makes no sense [B]
 414         //      previous borrow of `vec` occurs here [A]
 415         //
 416         // `annotations_position` will hold [(2, A), (1, B), (0, C)].
 417         //
 418         // We try, when possible, to stick the rightmost annotation at the end
 419         // of the highlight line:
 420         //
 421         //      vec.push(vec.pop().unwrap());
 422         //      ---      ---               - previous borrow ends here
 423         //
 424         // But sometimes that's not possible because one of the other
 425         // annotations overlaps it. For example, from the test
 426         // `span_overlap_label`, we have the following annotations
 427         // (written on distinct lines for clarity):
 428         //
 429         //      fn foo(x: u32) {
 430         //      --------------
 431         //             -
 432         //
 433         // In this case, we can't stick the rightmost-most label on
 434         // the highlight line, or we would get:
 435         //
 436         //      fn foo(x: u32) {
 437         //      -------- x_span
 438         //      |
 439         //      fn_span
 440         //
 441         // which is totally weird. Instead we want:
 442         //
 443         //      fn foo(x: u32) {
 444         //      --------------
 445         //      |      |
 446         //      |      x_span
 447         //      fn_span
 448         //
 449         // which is...less weird, at least. In fact, in general, if
 450         // the rightmost span overlaps with any other span, we should
 451         // use the "hang below" version, so we can at least make it
 452         // clear where the span *starts*. There's an exception for this
 453         // logic, when the labels do not have a message:
 454         //
 455         //      fn foo(x: u32) {
 456         //      --------------
 457         //             |
 458         //             x_span
 459         //
 460         // instead of:
 461         //
 462         //      fn foo(x: u32) {
 463         //      --------------
 464         //      |      |
 465         //      |      x_span
 466         //      <EMPTY LINE>
 467         //
 468         let mut annotations_position = vec![];
 469         let mut line_len = 0;
 470         let mut p = 0;
 471         for (i, annotation) in annotations.iter().enumerate() {
 472             for (j, next) in annotations.iter().enumerate() {
 473                 if overlaps(next, annotation, 0)  // This label overlaps with another one and both
 474                     && annotation.has_label()     // take space (they have text and are not
 475                     && j > i                      // multiline lines).
 476                     && p == 0  // We're currently on the first line, move the label one line down
 477                 {
 478                     // This annotation needs a new line in the output.
 479                     p += 1;
 480                     break;
 481                 }
 482             }
 483             annotations_position.push((p, annotation));
 484             for (j, next) in annotations.iter().enumerate() {
 485                 if j > i  {
 486                     let l = if let Some(ref label) = next.label {
 487                         label.len() + 2
 488                     } else {
 489                         0
 490                     };
 491                     if (overlaps(next, annotation, l) // Do not allow two labels to be in the same
 492                                                      // line if they overlap including padding, to
 493                                                      // avoid situations like:
 494                                                      //
 495                                                      //      fn foo(x: u32) {
 496                                                      //      -------^------
 497                                                      //      |      |
 498                                                      //      fn_spanx_span
 499                                                      //
 500                         && annotation.has_label()    // Both labels must have some text, otherwise
 501                         && next.has_label())         // they are not overlapping.
 502                                                      // Do not add a new line if this annotation
 503                                                      // or the next are vertical line placeholders.
 504                         || (annotation.takes_space() // If either this or the next annotation is
 505                             && next.has_label())     // multiline start/end, move it to a new line
 506                         || (annotation.has_label()   // so as not to overlap the orizontal lines.
 507                             && next.takes_space())
 508                         || (annotation.takes_space() && next.takes_space())
 509                         || (overlaps(next, annotation, l)
 510                             && next.end_col <= annotation.end_col
 511                             && next.has_label()
 512                             && p == 0)  // Avoid #42595.
 513                     {
 514                         // This annotation needs a new line in the output.
 515                         p += 1;
 516                         break;
 517                     }
 518                 }
 519             }
 520             if line_len < p {
 521                 line_len = p;
 522             }
 523         }
 524
 525         if line_len != 0 {
 526             line_len += 1;
 527         }
 528
 529         // If there are no annotations or the only annotations on this line are
 530         // MultilineLine, then there's only code being shown, stop processing.
 531         if line.annotations.is_empty() || line.annotations.iter()
 532             .filter(|a| !a.is_line()).collect::<Vec<_>>().len() == 0
 533         {
 534             return vec![];
 535         }
 536
 537         // Write the colunmn separator.
 538         //
 539         // After this we will have:
 540         //
 541         // 2 |   fn foo() {
 542         //   |
 543         //   |
 544         //   |
 545         // 3 |
 546         // 4 |   }
 547         //   |
 548         for pos in 0..line_len + 1 {
 549             draw_col_separator(buffer, line_offset + pos + 1, width_offset - 2);
 550             buffer.putc(line_offset + pos + 1,
 551                         width_offset - 2,
 552                         '|',
 553                         Style::LineNumber);
 554         }
 555
 556         // Write the horizontal lines for multiline annotations
 557         // (only the first and last lines need this).
 558         //
 559         // After this we will have:
 560         //
 561         // 2 |   fn foo() {
 562         //   |  __________
 563         //   |
 564         //   |
 565         // 3 |
 566         // 4 |   }
 567         //   |  _
 568         for &(pos, annotation) in &annotations_position {
 569             let style = if annotation.is_primary {
 570                 Style::UnderlinePrimary
 571             } else {
 572                 Style::UnderlineSecondary
 573             };
 574             let pos = pos + 1;
 575             match annotation.annotation_type {
 576                 AnnotationType::MultilineStart(depth) |
 577                 AnnotationType::MultilineEnd(depth) => {
 578                     draw_range(buffer,
 579                                '_',
 580                                line_offset + pos,
 581                                width_offset + depth,
 582                                code_offset + annotation.start_col,
 583                                style);
 584                 }
 585                 _ if self.teach => {
 586                     buffer.set_style_range(line_offset,
 587                                            code_offset + annotation.start_col,
 588                                            code_offset + annotation.end_col,
 589                                            style,
 590                                            annotation.is_primary);
 591                 }
 592                 _ => {}
 593             }
 594         }
 595
 596         // Write the vertical lines for labels that are on a different line as the underline.
 597         //
 598         // After this we will have:
 599         //
 600         // 2 |   fn foo() {
 601         //   |  __________
 602         //   | |    |
 603         //   | |
 604         // 3 |
 605         // 4 | | }
 606         //   | |_
 607         for &(pos, annotation) in &annotations_position {
 608             let style = if annotation.is_primary {
 609                 Style::UnderlinePrimary
 610             } else {
 611                 Style::UnderlineSecondary
 612             };
 613             let pos = pos + 1;
 614
 615             if pos > 1 && (annotation.has_label() || annotation.takes_space()) {
 616                 for p in line_offset + 1..line_offset + pos + 1 {
 617                     buffer.putc(p,
 618                                 code_offset + annotation.start_col,
 619                                 '|',
 620                                 style);
 621                 }
 622             }
 623             match annotation.annotation_type {
 624                 AnnotationType::MultilineStart(depth) => {
 625                     for p in line_offset + pos + 1..line_offset + line_len + 2 {
 626                         buffer.putc(p,
 627                                     width_offset + depth - 1,
 628                                     '|',
 629                                     style);
 630                     }
 631                 }
 632                 AnnotationType::MultilineEnd(depth) => {
 633                     for p in line_offset..line_offset + pos + 1 {
 634                         buffer.putc(p,
 635                                     width_offset + depth - 1,
 636                                     '|',
 637                                     style);
 638                     }
 639                 }
 640                 _ => (),
 641             }
 642         }
 643
 644         // Write the labels on the annotations that actually have a label.
 645         //
 646         // After this we will have:
 647         //
 648         // 2 |   fn foo() {
 649         //   |  __________
 650         //   |      |
 651         //   |      something about `foo`
 652         // 3 |
 653         // 4 |   }
 654         //   |  _  test
 655         for &(pos, annotation) in &annotations_position {
 656             let style = if annotation.is_primary {
 657                 Style::LabelPrimary
 658             } else {
 659                 Style::LabelSecondary
 660             };
 661             let (pos, col) = if pos == 0 {
 662                 (pos + 1, annotation.end_col + 1)
 663             } else {
 664                 (pos + 2, annotation.start_col)
 665             };
 666             if let Some(ref label) = annotation.label {
 667                 buffer.puts(line_offset + pos,
 668                             code_offset + col,
 669                             &label,
 670                             style);
 671             }
 672         }
 673
 674         // Sort from biggest span to smallest span so that smaller spans are
 675         // represented in the output:
 676         //
 677         // x | fn foo()
 678         //   | ^^^---^^
 679         //   | |  |
 680         //   | |  something about `foo`
 681         //   | something about `fn foo()`
 682         annotations_position.sort_by(|a, b| {
 683             // Decreasing order
 684             a.1.len().cmp(&b.1.len()).reverse()
 685         });
 686
 687         // Write the underlines.
 688         //
 689         // After this we will have:
 690         //
 691         // 2 |   fn foo() {
 692         //   |  ____-_____^
 693         //   |      |
 694         //   |      something about `foo`
 695         // 3 |
 696         // 4 |   }
 697         //   |  _^  test
 698         for &(_, annotation) in &annotations_position {
 699             let (underline, style) = if annotation.is_primary {
 700                 ('^', Style::UnderlinePrimary)
 701             } else {
 702                 ('-', Style::UnderlineSecondary)
 703             };
 704             for p in annotation.start_col..annotation.end_col {
 705                 buffer.putc(line_offset + 1,
 706                             code_offset + p,
 707                             underline,
 708                             style);
 709             }
 710         }
 711         annotations_position.iter().filter_map(|&(_, annotation)| {
 712             match annotation.annotation_type {
 713                 AnnotationType::MultilineStart(p) | AnnotationType::MultilineEnd(p) => {
 714                     let style = if annotation.is_primary {
 715                         Style::LabelPrimary
 716                     } else {
 717                         Style::LabelSecondary
 718                     };
 719                     Some((p, style))
 720                 }
 721                 _ => None
 722             }
 723
 724         }).collect::<Vec<_>>()
 725     }
 726
 727     fn get_multispan_max_line_num(&mut self, msp: &MultiSpan) -> usize {
 728         let mut max = 0;
 729         if let Some(ref cm) = self.cm {
 730             for primary_span in msp.primary_spans() {
 731                 if !primary_span.is_dummy() {
 732                     let hi = cm.lookup_char_pos(primary_span.hi());
 733                     if hi.line > max {
 734                         max = hi.line;
 735                     }
 736                 }
 737             }
 738             if !self.short_message {
 739                 for span_label in msp.span_labels() {
 740                     if !span_label.span.is_dummy() {
 741                         let hi = cm.lookup_char_pos(span_label.span.hi());
 742                         if hi.line > max {
 743                             max = hi.line;
 744                         }
 745                     }
 746                 }
 747             }
 748         }
 749         max
 750     }
 751
 752     fn get_max_line_num(&mut self, span: &MultiSpan, children: &Vec<SubDiagnostic>) -> usize {
 753         let mut max = 0;
 754
 755         let primary = self.get_multispan_max_line_num(span);
 756         max = if primary > max { primary } else { max };
 757
 758         for sub in children {
 759             let sub_result = self.get_multispan_max_line_num(&sub.span);
 760             max = if sub_result > max { primary } else { max };
 761         }
 762         max
 763     }
 764
 765     // This "fixes" MultiSpans that contain Spans that are pointing to locations inside of
 766     // <*macros>. Since these locations are often difficult to read, we move these Spans from
 767     // <*macros> to their corresponding use site.
 768     fn fix_multispan_in_std_macros(&mut self,
 769                                    span: &mut MultiSpan,
 770                                    always_backtrace: bool) -> bool {
 771         let mut spans_updated = false;
 772
 773         if let Some(ref cm) = self.cm {
 774             let mut before_after: Vec<(Span, Span)> = vec![];
 775             let mut new_labels: Vec<(Span, String)> = vec![];
 776
 777             // First, find all the spans in <*macros> and point instead at their use site
 778             for sp in span.primary_spans() {
 779                 if sp.is_dummy() {
 780                     continue;
 781                 }
 782                 let call_sp = cm.call_span_if_macro(*sp);
 783                 if call_sp != *sp && !always_backtrace {
 784                     before_after.push((*sp, call_sp));
 785                 }
 786                 let backtrace_len = sp.macro_backtrace().len();
 787                 for (i, trace) in sp.macro_backtrace().iter().rev().enumerate() {
 788                     // Only show macro locations that are local
 789                     // and display them like a span_note
 790                     if let Some(def_site) = trace.def_site_span {
 791                         if def_site.is_dummy() {
 792                             continue;
 793                         }
 794                         if always_backtrace {
 795                             new_labels.push((def_site,
 796                                              format!("in this expansion of `{}`{}",
 797                                                      trace.macro_decl_name,
 798                                                      if backtrace_len > 2 {
 799                                                          // if backtrace_len == 1 it'll be pointed
 800                                                          // at by "in this macro invocation"
 801                                                          format!(" (#{})", i + 1)
 802                                                      } else {
 803                                                          "".to_string()
 804                                                      })));
 805                         }
 806                         // Check to make sure we're not in any <*macros>
 807                         if !cm.span_to_filename(def_site).is_macros() &&
 808                            !trace.macro_decl_name.starts_with("desugaring of ") &&
 809                            !trace.macro_decl_name.starts_with("#[") ||
 810                            always_backtrace {
 811                             new_labels.push((trace.call_site,
 812                                              format!("in this macro invocation{}",
 813                                                      if backtrace_len > 2 && always_backtrace {
 814                                                          // only specify order when the macro
 815                                                          // backtrace is multiple levels deep
 816                                                          format!(" (#{})", i + 1)
 817                                                      } else {
 818                                                          "".to_string()
 819                                                      })));
 820                             if !always_backtrace {
 821                                 break;
 822                             }
 823                         }
 824                     }
 825                 }
 826             }
 827             for (label_span, label_text) in new_labels {
 828                 span.push_span_label(label_span, label_text);
 829             }
 830             for sp_label in span.span_labels() {
 831                 if sp_label.span.is_dummy() {
 832                     continue;
 833                 }
 834                 if cm.span_to_filename(sp_label.span.clone()).is_macros() &&
 835                     !always_backtrace
 836                 {
 837                     let v = sp_label.span.macro_backtrace();
 838                     if let Some(use_site) = v.last() {
 839                         before_after.push((sp_label.span.clone(), use_site.call_site.clone()));
 840                     }
 841                 }
 842             }
 843             // After we have them, make sure we replace these 'bad' def sites with their use sites
 844             for (before, after) in before_after {
 845                 span.replace(before, after);
 846                 spans_updated = true;
 847             }
 848         }
 849
 850         spans_updated
 851     }
 852
 853     // This does a small "fix" for multispans by looking to see if it can find any that
 854     // point directly at <*macros>. Since these are often difficult to read, this
 855     // will change the span to point at the use site.
 856     fn fix_multispans_in_std_macros(&mut self,
 857                                     span: &mut MultiSpan,
 858                                     children: &mut Vec<SubDiagnostic>,
 859                                     backtrace: bool) {
 860         let mut spans_updated = self.fix_multispan_in_std_macros(span, backtrace);
 861         for child in children.iter_mut() {
 862             spans_updated |= self.fix_multispan_in_std_macros(&mut child.span, backtrace);
 863         }
 864         if spans_updated {
 865             children.push(SubDiagnostic {
 866                 level: Level::Note,
 867                 message: vec![
 868                     ("this error originates in a macro outside of the current crate \
 869                       (in Nightly builds, run with -Z external-macro-backtrace \
 870                        for more info)".to_string(),
 871                      Style::NoStyle),
 872                 ],
 873                 span: MultiSpan::new(),
 874                 render_span: None,
 875             });
 876         }
 877     }
 878
 879     /// Add a left margin to every line but the first, given a padding length and the label being
 880     /// displayed, keeping the provided highlighting.
 881     fn msg_to_buffer(&self,
 882                      buffer: &mut StyledBuffer,
 883                      msg: &[(String, Style)],
 884                      padding: usize,
 885                      label: &str,
 886                      override_style: Option<Style>) {
 887
 888         // The extra 5 ` ` is padding that's always needed to align to the `note: `:
 889         //
 890         //   error: message
 891         //     --> file.rs:13:20
 892         //      |
 893         //   13 |     <CODE>
 894         //      |      ^^^^
 895         //      |
 896         //      = note: multiline
 897         //              message
 898         //   ++^^^----xx
 899         //    |  |   | |
 900         //    |  |   | magic `2`
 901         //    |  |   length of label
 902         //    |  magic `3`
 903         //    `max_line_num_len`
 904         let padding = (0..padding + label.len() + 5)
 905             .map(|_| " ")
 906             .collect::<String>();
 907
 908         /// Return whether `style`, or the override if present and the style is `NoStyle`.
 909         fn style_or_override(style: Style, override_style: Option<Style>) -> Style {
 910             if let Some(o) = override_style {
 911                 if style == Style::NoStyle {
 912                     return o;
 913                 }
 914             }
 915             style
 916         }
 917
 918         let mut line_number = 0;
 919
 920         // Provided the following diagnostic message:
 921         //
 922         //     let msg = vec![
 923         //       ("
 924         //       ("highlighted multiline\nstring to\nsee how it ", Style::NoStyle),
 925         //       ("looks", Style::Highlight),
 926         //       ("with\nvery ", Style::NoStyle),
 927         //       ("weird", Style::Highlight),
 928         //       (" formats\n", Style::NoStyle),
 929         //       ("see?", Style::Highlight),
 930         //     ];
 931         //
 932         // the expected output on a note is (* surround the highlighted text)
 933         //
 934         //        = note: highlighted multiline
 935         //                string to
 936         //                see how it *looks* with
 937         //                very *weird* formats
 938         //                see?
 939         for &(ref text, ref style) in msg.iter() {
 940             let lines = text.split('\n').collect::<Vec<_>>();
 941             if lines.len() > 1 {
 942                 for (i, line) in lines.iter().enumerate() {
 943                     if i != 0 {
 944                         line_number += 1;
 945                         buffer.append(line_number, &padding, Style::NoStyle);
 946                     }
 947                     buffer.append(line_number, line, style_or_override(*style, override_style));
 948                 }
 949             } else {
 950                 buffer.append(line_number, text, style_or_override(*style, override_style));
 951             }
 952         }
 953     }
 954
 955     fn emit_message_default(&mut self,
 956                             msp: &MultiSpan,
 957                             msg: &Vec<(String, Style)>,
 958                             code: &Option<DiagnosticId>,
 959                             level: &Level,
 960                             max_line_num_len: usize,
 961                             is_secondary: bool)
 962                             -> io::Result<()> {
 963         let mut buffer = StyledBuffer::new();
 964         let header_style = if is_secondary {
 965             Style::HeaderMsg
 966         } else {
 967             Style::MainHeaderMsg
 968         };
 969
 970         if msp.primary_spans().is_empty() && msp.span_labels().is_empty() && is_secondary
 971            && !self.short_message {
 972             // This is a secondary message with no span info
 973             for _ in 0..max_line_num_len {
 974                 buffer.prepend(0, " ", Style::NoStyle);
 975             }
 976             draw_note_separator(&mut buffer, 0, max_line_num_len + 1);
 977             let level_str = level.to_string();
 978             if !level_str.is_empty() {
 979                 buffer.append(0, &level_str, Style::MainHeaderMsg);
 980                 buffer.append(0, ": ", Style::NoStyle);
 981             }
 982             self.msg_to_buffer(&mut buffer, msg, max_line_num_len, "note", None);
 983         } else {
 984             let level_str = level.to_string();
 985             if !level_str.is_empty() {
 986                 buffer.append(0, &level_str, Style::Level(level.clone()));
 987             }
 988             // only render error codes, not lint codes
 989             if let Some(DiagnosticId::Error(ref code)) = *code {
 990                 buffer.append(0, "[", Style::Level(level.clone()));
 991                 buffer.append(0, &code, Style::Level(level.clone()));
 992                 buffer.append(0, "]", Style::Level(level.clone()));
 993             }
 994             if !level_str.is_empty() {
 995                 buffer.append(0, ": ", header_style);
 996             }
 997             for &(ref text, _) in msg.iter() {
 998                 buffer.append(0, text, header_style);
 999             }
1000         }
1001
1002         // Preprocess all the annotations so that they are grouped by file and by line number
1003         // This helps us quickly iterate over the whole message (including secondary file spans)
1004         let mut annotated_files = self.preprocess_annotations(msp);
1005
1006         // Make sure our primary file comes first
1007         let (primary_lo, cm) = if let (Some(cm), Some(ref primary_span)) =
1008             (self.cm.as_ref(), msp.primary_span().as_ref()) {
1009             if !primary_span.is_dummy() {
1010                 (cm.lookup_char_pos(primary_span.lo()), cm)
1011             } else {
1012                 emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1013                 return Ok(());
1014             }
1015         } else {
1016             // If we don't have span information, emit and exit
1017             emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1018             return Ok(());
1019         };
1020         if let Ok(pos) =
1021             annotated_files.binary_search_by(|x| x.file.name.cmp(&primary_lo.file.name)) {
1022             annotated_files.swap(0, pos);
1023         }
1024
1025         // Print out the annotate source lines that correspond with the error
1026         for annotated_file in annotated_files {
1027             // we can't annotate anything if the source is unavailable.
1028             if !cm.ensure_filemap_source_present(annotated_file.file.clone()) {
1029                 continue;
1030             }
1031
1032             // print out the span location and spacer before we print the annotated source
1033             // to do this, we need to know if this span will be primary
1034             let is_primary = primary_lo.file.name == annotated_file.file.name;
1035             if is_primary {
1036                 let loc = primary_lo.clone();
1037                 if !self.short_message {
1038                     // remember where we are in the output buffer for easy reference
1039                     let buffer_msg_line_offset = buffer.num_lines();
1040
1041                     buffer.prepend(buffer_msg_line_offset, "--> ", Style::LineNumber);
1042                     buffer.append(buffer_msg_line_offset,
1043                                   &format!("{}:{}:{}",
1044                                            loc.file.name,
1045                                            cm.doctest_offset_line(loc.line),
1046                                            loc.col.0 + 1),
1047                                   Style::LineAndColumn);
1048                     for _ in 0..max_line_num_len {
1049                         buffer.prepend(buffer_msg_line_offset, " ", Style::NoStyle);
1050                     }
1051                 } else {
1052                     buffer.prepend(0,
1053                                    &format!("{}:{}:{}: ",
1054                                             loc.file.name,
1055                                             cm.doctest_offset_line(loc.line),
1056                                             loc.col.0 + 1),
1057                                    Style::LineAndColumn);
1058                 }
1059             } else if !self.short_message {
1060                 // remember where we are in the output buffer for easy reference
1061                 let buffer_msg_line_offset = buffer.num_lines();
1062
1063                 // Add spacing line
1064                 draw_col_separator(&mut buffer, buffer_msg_line_offset, max_line_num_len + 1);
1065
1066                 // Then, the secondary file indicator
1067                 buffer.prepend(buffer_msg_line_offset + 1, "::: ", Style::LineNumber);
1068                 let loc = if let Some(first_line) = annotated_file.lines.first() {
1069                     let col = if let Some(first_annotation) = first_line.annotations.first() {
1070                         format!(":{}", first_annotation.start_col + 1)
1071                     } else {
1072                         "".to_string()
1073                     };
1074                     format!("{}:{}{}",
1075                             annotated_file.file.name,
1076                             cm.doctest_offset_line(first_line.line_index),
1077                             col)
1078                 } else {
1079                     annotated_file.file.name.to_string()
1080                 };
1081                 buffer.append(buffer_msg_line_offset + 1,
1082                               &loc,
1083                               Style::LineAndColumn);
1084                 for _ in 0..max_line_num_len {
1085                     buffer.prepend(buffer_msg_line_offset + 1, " ", Style::NoStyle);
1086                 }
1087             }
1088
1089             if !self.short_message {
1090                 // Put in the spacer between the location and annotated source
1091                 let buffer_msg_line_offset = buffer.num_lines();
1092                 draw_col_separator_no_space(&mut buffer,
1093                                             buffer_msg_line_offset,
1094                                             max_line_num_len + 1);
1095
1096                 // Contains the vertical lines' positions for active multiline annotations
1097                 let mut multilines = HashMap::new();
1098
1099                 // Next, output the annotate source for this file
1100                 for line_idx in 0..annotated_file.lines.len() {
1101                     let previous_buffer_line = buffer.num_lines();
1102
1103                     let width_offset = 3 + max_line_num_len;
1104                     let code_offset = if annotated_file.multiline_depth == 0 {
1105                         width_offset
1106                     } else {
1107                         width_offset + annotated_file.multiline_depth + 1
1108                     };
1109
1110                     let depths = self.render_source_line(&mut buffer,
1111                                                          annotated_file.file.clone(),
1112                                                          &annotated_file.lines[line_idx],
1113                                                          width_offset,
1114                                                          code_offset);
1115
1116                     let mut to_add = HashMap::new();
1117
1118                     for (depth, style) in depths {
1119                         if multilines.get(&depth).is_some() {
1120                             multilines.remove(&depth);
1121                         } else {
1122                             to_add.insert(depth, style);
1123                         }
1124                     }
1125
1126                     // Set the multiline annotation vertical lines to the left of
1127                     // the code in this line.
1128                     for (depth, style) in &multilines {
1129                         for line in previous_buffer_line..buffer.num_lines() {
1130                             draw_multiline_line(&mut buffer,
1131                                                 line,
1132                                                 width_offset,
1133                                                 *depth,
1134                                                 *style);
1135                         }
1136                     }
1137                     // check to see if we need to print out or elide lines that come between
1138                     // this annotated line and the next one.
1139                     if line_idx < (annotated_file.lines.len() - 1) {
1140                         let line_idx_delta = annotated_file.lines[line_idx + 1].line_index -
1141                                              annotated_file.lines[line_idx].line_index;
1142                         if line_idx_delta > 2 {
1143                             let last_buffer_line_num = buffer.num_lines();
1144                             buffer.puts(last_buffer_line_num, 0, "...", Style::LineNumber);
1145
1146                             // Set the multiline annotation vertical lines on `...` bridging line.
1147                             for (depth, style) in &multilines {
1148                                 draw_multiline_line(&mut buffer,
1149                                                     last_buffer_line_num,
1150                                                     width_offset,
1151                                                     *depth,
1152                                                     *style);
1153                             }
1154                         } else if line_idx_delta == 2 {
1155                             let unannotated_line = annotated_file.file
1156                                 .get_line(annotated_file.lines[line_idx].line_index)
1157                                 .unwrap_or_else(|| Cow::from(""));
1158
1159                             let last_buffer_line_num = buffer.num_lines();
1160
1161                             buffer.puts(last_buffer_line_num,
1162                                         0,
1163                                         &self.maybe_anonymized(annotated_file.lines[line_idx + 1]
1164                                                                              .line_index - 1),
1165                                         Style::LineNumber);
1166                             draw_col_separator(&mut buffer,
1167                                                last_buffer_line_num,
1168                                                1 + max_line_num_len);
1169                             buffer.puts(last_buffer_line_num,
1170                                         code_offset,
1171                                         &unannotated_line,
1172                                         Style::Quotation);
1173
1174                             for (depth, style) in &multilines {
1175                                 draw_multiline_line(&mut buffer,
1176                                                     last_buffer_line_num,
1177                                                     width_offset,
1178                                                     *depth,
1179                                                     *style);
1180                             }
1181                         }
1182                     }
1183
1184                     multilines.extend(&to_add);
1185                 }
1186             }
1187         }
1188
1189         // final step: take our styled buffer, render it, then output it
1190         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1191
1192         Ok(())
1193
1194     }
1195
1196     fn emit_suggestion_default(&mut self,
1197                                suggestion: &CodeSuggestion,
1198                                level: &Level,
1199                                max_line_num_len: usize)
1200                                -> io::Result<()> {
1201         if let Some(ref cm) = self.cm {
1202             let mut buffer = StyledBuffer::new();
1203
1204             // Render the suggestion message
1205             let level_str = level.to_string();
1206             if !level_str.is_empty() {
1207                 buffer.append(0, &level_str, Style::Level(level.clone()));
1208                 buffer.append(0, ": ", Style::HeaderMsg);
1209             }
1210             self.msg_to_buffer(&mut buffer,
1211                                &[(suggestion.msg.to_owned(), Style::NoStyle)],
1212                                max_line_num_len,
1213                                "suggestion",
1214                                Some(Style::HeaderMsg));
1215
1216             // Render the replacements for each suggestion
1217             let suggestions = suggestion.splice_lines(&**cm);
1218
1219             let mut row_num = 2;
1220             for &(ref complete, ref parts) in suggestions.iter().take(MAX_SUGGESTIONS) {
1221                 // Only show underline if the suggestion spans a single line and doesn't cover the
1222                 // entirety of the code output. If you have multiple replacements in the same line
1223                 // of code, show the underline.
1224                 let show_underline = !(parts.len() == 1
1225                     && parts[0].snippet.trim() == complete.trim())
1226                     && complete.lines().count() == 1;
1227
1228                 let lines = cm.span_to_lines(parts[0].span).unwrap();
1229
1230                 assert!(!lines.lines.is_empty());
1231
1232                 let line_start = cm.lookup_char_pos(parts[0].span.lo()).line;
1233                 draw_col_separator_no_space(&mut buffer, 1, max_line_num_len + 1);
1234                 let mut line_pos = 0;
1235                 let mut lines = complete.lines();
1236                 for line in lines.by_ref().take(MAX_HIGHLIGHT_LINES) {
1237                     // Print the span column to avoid confusion
1238                     buffer.puts(row_num,
1239                                 0,
1240                                 &self.maybe_anonymized(line_start + line_pos),
1241                                 Style::LineNumber);
1242                     // print the suggestion
1243                     draw_col_separator(&mut buffer, row_num, max_line_num_len + 1);
1244                     buffer.append(row_num, line, Style::NoStyle);
1245                     line_pos += 1;
1246                     row_num += 1;
1247                 }
1248
1249                 // This offset and the ones below need to be signed to account for replacement code
1250                 // that is shorter than the original code.
1251                 let mut offset: isize = 0;
1252                 // Only show an underline in the suggestions if the suggestion is not the
1253                 // entirety of the code being shown and the displayed code is not multiline.
1254                 if show_underline {
1255                     draw_col_separator(&mut buffer, row_num, max_line_num_len + 1);
1256                     for part in parts {
1257                         let span_start_pos = cm.lookup_char_pos(part.span.lo()).col_display;
1258                         let span_end_pos = cm.lookup_char_pos(part.span.hi()).col_display;
1259
1260                         // Do not underline the leading...
1261                         let start = part.snippet.len()
1262                             .saturating_sub(part.snippet.trim_left().len());
1263                         // ...or trailing spaces. Account for substitutions containing unicode
1264                         // characters.
1265                         let sub_len = part.snippet.trim().chars().fold(0, |acc, ch| {
1266                             acc + unicode_width::UnicodeWidthChar::width(ch).unwrap_or(0)
1267                         });
1268
1269                         let underline_start = (span_start_pos + start) as isize + offset;
1270                         let underline_end = (span_start_pos + start + sub_len) as isize + offset;
1271                         for p in underline_start..underline_end {
1272                             buffer.putc(row_num,
1273                                         max_line_num_len + 3 + p as usize,
1274                                         '^',
1275                                         Style::UnderlinePrimary);
1276                         }
1277                         // underline removals too
1278                         if underline_start == underline_end {
1279                             for p in underline_start-1..underline_start+1 {
1280                                 buffer.putc(row_num,
1281                                             max_line_num_len + 3 + p as usize,
1282                                             '-',
1283                                             Style::UnderlineSecondary);
1284                             }
1285                         }
1286
1287                         // length of the code after substitution
1288                         let full_sub_len = part.snippet.chars().fold(0, |acc, ch| {
1289                             acc + unicode_width::UnicodeWidthChar::width(ch).unwrap_or(0) as isize
1290                         });
1291
1292                         // length of the code to be substituted
1293                         let snippet_len = span_end_pos as isize - span_start_pos as isize;
1294                         // For multiple substitutions, use the position *after* the previous
1295                         // substitutions have happened.
1296                         offset += full_sub_len - snippet_len;
1297                     }
1298                     row_num += 1;
1299                 }
1300
1301                 // if we elided some lines, add an ellipsis
1302                 if let Some(_) = lines.next() {
1303                     buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
1304                 } else if !show_underline {
1305                     draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
1306                     row_num += 1;
1307                 }
1308             }
1309             if suggestions.len() > MAX_SUGGESTIONS {
1310                 let msg = format!("and {} other candidates", suggestions.len() - MAX_SUGGESTIONS);
1311                 buffer.puts(row_num, 0, &msg, Style::NoStyle);
1312             }
1313             emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
1314         }
1315         Ok(())
1316     }
1317
1318     fn emit_messages_default(&mut self,
1319                              level: &Level,
1320                              message: &Vec<(String, Style)>,
1321                              code: &Option<DiagnosticId>,
1322                              span: &MultiSpan,
1323                              children: &Vec<SubDiagnostic>,
1324                              suggestions: &[CodeSuggestion]) {
1325         let max_line_num_len = if self.ui_testing {
1326             ANONYMIZED_LINE_NUM.len()
1327         } else {
1328             self.get_max_line_num(span, children).to_string().len()
1329         };
1330
1331         match self.emit_message_default(span,
1332                                         message,
1333                                         code,
1334                                         level,
1335                                         max_line_num_len,
1336                                         false) {
1337             Ok(()) => {
1338                 if !children.is_empty() {
1339                     let mut buffer = StyledBuffer::new();
1340                     if !self.short_message {
1341                         draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
1342                     }
1343                     match emit_to_destination(&buffer.render(), level, &mut self.dst,
1344                                               self.short_message) {
1345                         Ok(()) => (),
1346                         Err(e) => panic!("failed to emit error: {}", e)
1347                     }
1348                 }
1349                 if !self.short_message {
1350                     for child in children {
1351                         let span = child.render_span.as_ref().unwrap_or(&child.span);
1352                         match self.emit_message_default(&span,
1353                                                         &child.styled_message(),
1354                                                         &None,
1355                                                         &child.level,
1356                                                         max_line_num_len,
1357                                                         true) {
1358                             Err(e) => panic!("failed to emit error: {}", e),
1359                             _ => ()
1360                         }
1361                     }
1362                     for sugg in suggestions {
1363                         match self.emit_suggestion_default(sugg,
1364                                                            &Level::Help,
1365                                                            max_line_num_len) {
1366                             Err(e) => panic!("failed to emit error: {}", e),
1367                             _ => ()
1368                         }
1369                     }
1370                 }
1371             }
1372             Err(e) => panic!("failed to emit error: {}", e),
1373         }
1374
1375         let mut dst = self.dst.writable();
1376         match write!(dst, "\n") {
1377             Err(e) => panic!("failed to emit error: {}", e),
1378             _ => {
1379                 match dst.flush() {
1380                     Err(e) => panic!("failed to emit error: {}", e),
1381                     _ => (),
1382                 }
1383             }
1384         }
1385     }
1386 }
1387
1388 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
1389     buffer.puts(line, col, "| ", Style::LineNumber);
1390 }
1391
1392 fn draw_col_separator_no_space(buffer: &mut StyledBuffer, line: usize, col: usize) {
1393     draw_col_separator_no_space_with_style(buffer, line, col, Style::LineNumber);
1394 }
1395
1396 fn draw_col_separator_no_space_with_style(buffer: &mut StyledBuffer,
1397                                           line: usize,
1398                                           col: usize,
1399                                           style: Style) {
1400     buffer.putc(line, col, '|', style);
1401 }
1402
1403 fn draw_range(buffer: &mut StyledBuffer, symbol: char, line: usize,
1404               col_from: usize, col_to: usize, style: Style) {
1405     for col in col_from..col_to {
1406         buffer.putc(line, col, symbol, style);
1407     }
1408 }
1409
1410 fn draw_note_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
1411     buffer.puts(line, col, "= ", Style::LineNumber);
1412 }
1413
1414 fn draw_multiline_line(buffer: &mut StyledBuffer,
1415                        line: usize,
1416                        offset: usize,
1417                        depth: usize,
1418                        style: Style)
1419 {
1420     buffer.putc(line, offset + depth - 1, '|', style);
1421 }
1422
1423 fn num_overlap(a_start: usize, a_end: usize, b_start: usize, b_end:usize, inclusive: bool) -> bool {
1424     let extra = if inclusive {
1425         1
1426     } else {
1427         0
1428     };
1429     (b_start..b_end + extra).contains(&a_start) ||
1430     (a_start..a_end + extra).contains(&b_start)
1431 }
1432 fn overlaps(a1: &Annotation, a2: &Annotation, padding: usize) -> bool {
1433     num_overlap(a1.start_col, a1.end_col + padding, a2.start_col, a2.end_col, false)
1434 }
1435
1436 fn emit_to_destination(rendered_buffer: &Vec<Vec<StyledString>>,
1437                        lvl: &Level,
1438                        dst: &mut Destination,
1439                        short_message: bool)
1440                        -> io::Result<()> {
1441     use lock;
1442
1443     let mut dst = dst.writable();
1444
1445     // In order to prevent error message interleaving, where multiple error lines get intermixed
1446     // when multiple compiler processes error simultaneously, we emit errors with additional
1447     // steps.
1448     //
1449     // On Unix systems, we write into a buffered terminal rather than directly to a terminal. When
1450     // the .flush() is called we take the buffer created from the buffered writes and write it at
1451     // one shot.  Because the Unix systems use ANSI for the colors, which is a text-based styling
1452     // scheme, this buffered approach works and maintains the styling.
1453     //
1454     // On Windows, styling happens through calls to a terminal API. This prevents us from using the
1455     // same buffering approach.  Instead, we use a global Windows mutex, which we acquire long
1456     // enough to output the full error message, then we release.
1457     let _buffer_lock = lock::acquire_global_lock("rustc_errors");
1458     for (pos, line) in rendered_buffer.iter().enumerate() {
1459         for part in line {
1460             dst.apply_style(lvl.clone(), part.style)?;
1461             write!(dst, "{}", part.text)?;
1462             dst.reset()?;
1463         }
1464         if !short_message && (!lvl.is_failure_note() || pos != rendered_buffer.len() - 1) {
1465             write!(dst, "\n")?;
1466         }
1467     }
1468     dst.flush()?;
1469     Ok(())
1470 }
1471
1472 pub enum Destination {
1473     Terminal(StandardStream),
1474     Buffered(BufferWriter),
1475     Raw(Box<dyn Write + Send>),
1476 }
1477
1478 pub enum WritableDst<'a> {
1479     Terminal(&'a mut StandardStream),
1480     Buffered(&'a mut BufferWriter, Buffer),
1481     Raw(&'a mut Box<dyn Write + Send>),
1482 }
1483
1484 impl Destination {
1485     fn from_stderr(color: ColorConfig) -> Destination {
1486         let choice = color.to_color_choice();
1487         // On Windows we'll be performing global synchronization on the entire
1488         // system for emitting rustc errors, so there's no need to buffer
1489         // anything.
1490         //
1491         // On non-Windows we rely on the atomicity of `write` to ensure errors
1492         // don't get all jumbled up.
1493         if cfg!(windows) {
1494             Terminal(StandardStream::stderr(choice))
1495         } else {
1496             Buffered(BufferWriter::stderr(choice))
1497         }
1498     }
1499
1500     fn writable<'a>(&'a mut self) -> WritableDst<'a> {
1501         match *self {
1502             Destination::Terminal(ref mut t) => WritableDst::Terminal(t),
1503             Destination::Buffered(ref mut t) => {
1504                 let buf = t.buffer();
1505                 WritableDst::Buffered(t, buf)
1506             }
1507             Destination::Raw(ref mut t) => WritableDst::Raw(t),
1508         }
1509     }
1510 }
1511
1512 impl<'a> WritableDst<'a> {
1513     fn apply_style(&mut self, lvl: Level, style: Style) -> io::Result<()> {
1514         let mut spec = ColorSpec::new();
1515         match style {
1516             Style::LineAndColumn => {}
1517             Style::LineNumber => {
1518                 spec.set_bold(true);
1519                 spec.set_intense(true);
1520                 if cfg!(windows) {
1521                     spec.set_fg(Some(Color::Cyan));
1522                 } else {
1523                     spec.set_fg(Some(Color::Blue));
1524                 }
1525             }
1526             Style::Quotation => {}
1527             Style::OldSchoolNoteText | Style::MainHeaderMsg => {
1528                 spec.set_bold(true);
1529                 if cfg!(windows) {
1530                     spec.set_intense(true)
1531                         .set_fg(Some(Color::White));
1532                 }
1533             }
1534             Style::UnderlinePrimary | Style::LabelPrimary => {
1535                 spec = lvl.color();
1536                 spec.set_bold(true);
1537             }
1538             Style::UnderlineSecondary |
1539             Style::LabelSecondary => {
1540                 spec.set_bold(true)
1541                     .set_intense(true);
1542                 if cfg!(windows) {
1543                     spec.set_fg(Some(Color::Cyan));
1544                 } else {
1545                     spec.set_fg(Some(Color::Blue));
1546                 }
1547             }
1548             Style::HeaderMsg |
1549             Style::NoStyle => {}
1550             Style::Level(lvl) => {
1551                 spec = lvl.color();
1552                 spec.set_bold(true);
1553             }
1554             Style::Highlight => {
1555                 spec.set_bold(true);
1556             }
1557         }
1558         self.set_color(&spec)
1559     }
1560
1561     fn set_color(&mut self, color: &ColorSpec) -> io::Result<()> {
1562         match *self {
1563             WritableDst::Terminal(ref mut t) => t.set_color(color),
1564             WritableDst::Buffered(_, ref mut t) => t.set_color(color),
1565             WritableDst::Raw(_) => Ok(())
1566         }
1567     }
1568
1569     fn reset(&mut self) -> io::Result<()> {
1570         match *self {
1571             WritableDst::Terminal(ref mut t) => t.reset(),
1572             WritableDst::Buffered(_, ref mut t) => t.reset(),
1573             WritableDst::Raw(_) => Ok(()),
1574         }
1575     }
1576 }
1577
1578 impl<'a> Write for WritableDst<'a> {
1579     fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
1580         match *self {
1581             WritableDst::Terminal(ref mut t) => t.write(bytes),
1582             WritableDst::Buffered(_, ref mut buf) => buf.write(bytes),
1583             WritableDst::Raw(ref mut w) => w.write(bytes),
1584         }
1585     }
1586
1587     fn flush(&mut self) -> io::Result<()> {
1588         match *self {
1589             WritableDst::Terminal(ref mut t) => t.flush(),
1590             WritableDst::Buffered(_, ref mut buf) => buf.flush(),
1591             WritableDst::Raw(ref mut w) => w.flush(),
1592         }
1593     }
1594 }
1595
1596 impl<'a> Drop for WritableDst<'a> {
1597     fn drop(&mut self) {
1598         match *self {
1599             WritableDst::Buffered(ref mut dst, ref mut buf) => {
1600                 drop(dst.print(buf));
1601             }
1602             _ => {}
1603         }
1604     }
1605 }