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