src/libsyntax/diagnostic.rs

   1 // Copyright 2012 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 pub use self::Level::*;
  12 pub use self::RenderSpan::*;
  13 pub use self::ColorConfig::*;
  14 use self::Destination::*;
  15
  16 use codemap::{self, COMMAND_LINE_SP, COMMAND_LINE_EXPN, Pos, Span};
  17 use diagnostics;
  18
  19 use std::cell::{RefCell, Cell};
  20 use std::{cmp, error, fmt};
  21 use std::io::prelude::*;
  22 use std::io;
  23 use term::{self, WriterWrapper};
  24 use libc;
  25
  26 /// maximum number of lines we will print for each error; arbitrary.
  27 const MAX_LINES: usize = 6;
  28
  29 #[derive(Clone)]
  30 pub enum RenderSpan {
  31     /// A FullSpan renders with both with an initial line for the
  32     /// message, prefixed by file:linenum, followed by a summary of
  33     /// the source code covered by the span.
  34     FullSpan(Span),
  35
  36     /// Similar to a FullSpan, but the cited position is the end of
  37     /// the span, instead of the start. Used, at least, for telling
  38     /// compiletest/runtest to look at the last line of the span
  39     /// (since `end_highlight_lines` displays an arrow to the end
  40     /// of the span).
  41     EndSpan(Span),
  42
  43     /// A suggestion renders with both with an initial line for the
  44     /// message, prefixed by file:linenum, followed by a summary
  45     /// of hypothetical source code, where the `String` is spliced
  46     /// into the lines in place of the code covered by the span.
  47     Suggestion(Span, String),
  48
  49     /// A FileLine renders with just a line for the message prefixed
  50     /// by file:linenum.
  51     FileLine(Span),
  52 }
  53
  54 impl RenderSpan {
  55     fn span(&self) -> Span {
  56         match *self {
  57             FullSpan(s) |
  58             Suggestion(s, _) |
  59             EndSpan(s) |
  60             FileLine(s) =>
  61                 s
  62         }
  63     }
  64 }
  65
  66 #[derive(Clone, Copy)]
  67 pub enum ColorConfig {
  68     Auto,
  69     Always,
  70     Never
  71 }
  72
  73 pub trait Emitter {
  74     fn emit(&mut self, cmsp: Option<(&codemap::CodeMap, Span)>,
  75             msg: &str, code: Option<&str>, lvl: Level);
  76     fn custom_emit(&mut self, cm: &codemap::CodeMap,
  77                    sp: RenderSpan, msg: &str, lvl: Level);
  78 }
  79
  80 /// Used as a return value to signify a fatal error occurred. (It is also
  81 /// used as the argument to panic at the moment, but that will eventually
  82 /// not be true.)
  83 #[derive(Copy, Clone, Debug)]
  84 #[must_use]
  85 pub struct FatalError;
  86
  87 impl fmt::Display for FatalError {
  88     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
  89         write!(f, "parser fatal error")
  90     }
  91 }
  92
  93 impl error::Error for FatalError {
  94     fn description(&self) -> &str {
  95         "The parser has encountered a fatal error"
  96     }
  97 }
  98
  99 /// Signifies that the compiler died with an explicit call to `.bug`
 100 /// or `.span_bug` rather than a failed assertion, etc.
 101 #[derive(Copy, Clone, Debug)]
 102 pub struct ExplicitBug;
 103
 104 impl fmt::Display for ExplicitBug {
 105     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 106         write!(f, "parser internal bug")
 107     }
 108 }
 109
 110 impl error::Error for ExplicitBug {
 111     fn description(&self) -> &str {
 112         "The parser has encountered an internal bug"
 113     }
 114 }
 115
 116 /// A span-handler is like a handler but also
 117 /// accepts span information for source-location
 118 /// reporting.
 119 pub struct SpanHandler {
 120     pub handler: Handler,
 121     pub cm: codemap::CodeMap,
 122 }
 123
 124 impl SpanHandler {
 125     pub fn new(handler: Handler, cm: codemap::CodeMap) -> SpanHandler {
 126         SpanHandler {
 127             handler: handler,
 128             cm: cm,
 129         }
 130     }
 131     pub fn span_fatal(&self, sp: Span, msg: &str) -> FatalError {
 132         self.handler.emit(Some((&self.cm, sp)), msg, Fatal);
 133         return FatalError;
 134     }
 135     pub fn span_fatal_with_code(&self, sp: Span, msg: &str, code: &str) -> FatalError {
 136         self.handler.emit_with_code(Some((&self.cm, sp)), msg, code, Fatal);
 137         return FatalError;
 138     }
 139     pub fn span_err(&self, sp: Span, msg: &str) {
 140         self.handler.emit(Some((&self.cm, sp)), msg, Error);
 141         self.handler.bump_err_count();
 142     }
 143     pub fn span_err_with_code(&self, sp: Span, msg: &str, code: &str) {
 144         self.handler.emit_with_code(Some((&self.cm, sp)), msg, code, Error);
 145         self.handler.bump_err_count();
 146     }
 147     pub fn span_warn(&self, sp: Span, msg: &str) {
 148         self.handler.emit(Some((&self.cm, sp)), msg, Warning);
 149     }
 150     pub fn span_warn_with_code(&self, sp: Span, msg: &str, code: &str) {
 151         self.handler.emit_with_code(Some((&self.cm, sp)), msg, code, Warning);
 152     }
 153     pub fn span_note(&self, sp: Span, msg: &str) {
 154         self.handler.emit(Some((&self.cm, sp)), msg, Note);
 155     }
 156     pub fn span_end_note(&self, sp: Span, msg: &str) {
 157         self.handler.custom_emit(&self.cm, EndSpan(sp), msg, Note);
 158     }
 159     pub fn span_help(&self, sp: Span, msg: &str) {
 160         self.handler.emit(Some((&self.cm, sp)), msg, Help);
 161     }
 162     /// Prints out a message with a suggested edit of the code.
 163     ///
 164     /// See `diagnostic::RenderSpan::Suggestion` for more information.
 165     pub fn span_suggestion(&self, sp: Span, msg: &str, suggestion: String) {
 166         self.handler.custom_emit(&self.cm, Suggestion(sp, suggestion), msg, Help);
 167     }
 168     pub fn fileline_note(&self, sp: Span, msg: &str) {
 169         self.handler.custom_emit(&self.cm, FileLine(sp), msg, Note);
 170     }
 171     pub fn fileline_help(&self, sp: Span, msg: &str) {
 172         self.handler.custom_emit(&self.cm, FileLine(sp), msg, Help);
 173     }
 174     pub fn span_bug(&self, sp: Span, msg: &str) -> ! {
 175         self.handler.emit(Some((&self.cm, sp)), msg, Bug);
 176         panic!(ExplicitBug);
 177     }
 178     pub fn span_unimpl(&self, sp: Span, msg: &str) -> ! {
 179         self.span_bug(sp, &format!("unimplemented {}", msg));
 180     }
 181     pub fn handler<'a>(&'a self) -> &'a Handler {
 182         &self.handler
 183     }
 184 }
 185
 186 /// A handler deals with errors; certain errors
 187 /// (fatal, bug, unimpl) may cause immediate exit,
 188 /// others log errors for later reporting.
 189 pub struct Handler {
 190     err_count: Cell<usize>,
 191     emit: RefCell<Box<Emitter + Send>>,
 192     pub can_emit_warnings: bool
 193 }
 194
 195 impl Handler {
 196     pub fn new(color_config: ColorConfig,
 197                registry: Option<diagnostics::registry::Registry>,
 198                can_emit_warnings: bool) -> Handler {
 199         let emitter = Box::new(EmitterWriter::stderr(color_config, registry));
 200         Handler::with_emitter(can_emit_warnings, emitter)
 201     }
 202     pub fn with_emitter(can_emit_warnings: bool, e: Box<Emitter + Send>) -> Handler {
 203         Handler {
 204             err_count: Cell::new(0),
 205             emit: RefCell::new(e),
 206             can_emit_warnings: can_emit_warnings
 207         }
 208     }
 209     pub fn fatal(&self, msg: &str) -> ! {
 210         self.emit.borrow_mut().emit(None, msg, None, Fatal);
 211
 212         // Suppress the fatal error message from the panic below as we've
 213         // already terminated in our own "legitimate" fashion.
 214         io::set_panic(Box::new(io::sink()));
 215         panic!(FatalError);
 216     }
 217     pub fn err(&self, msg: &str) {
 218         self.emit.borrow_mut().emit(None, msg, None, Error);
 219         self.bump_err_count();
 220     }
 221     pub fn bump_err_count(&self) {
 222         self.err_count.set(self.err_count.get() + 1);
 223     }
 224     pub fn err_count(&self) -> usize {
 225         self.err_count.get()
 226     }
 227     pub fn has_errors(&self) -> bool {
 228         self.err_count.get() > 0
 229     }
 230     pub fn abort_if_errors(&self) {
 231         let s;
 232         match self.err_count.get() {
 233           0 => return,
 234           1 => s = "aborting due to previous error".to_string(),
 235           _   => {
 236             s = format!("aborting due to {} previous errors",
 237                         self.err_count.get());
 238           }
 239         }
 240         self.fatal(&s[..]);
 241     }
 242     pub fn warn(&self, msg: &str) {
 243         self.emit.borrow_mut().emit(None, msg, None, Warning);
 244     }
 245     pub fn note(&self, msg: &str) {
 246         self.emit.borrow_mut().emit(None, msg, None, Note);
 247     }
 248     pub fn help(&self, msg: &str) {
 249         self.emit.borrow_mut().emit(None, msg, None, Help);
 250     }
 251     pub fn bug(&self, msg: &str) -> ! {
 252         self.emit.borrow_mut().emit(None, msg, None, Bug);
 253         panic!(ExplicitBug);
 254     }
 255     pub fn unimpl(&self, msg: &str) -> ! {
 256         self.bug(&format!("unimplemented {}", msg));
 257     }
 258     pub fn emit(&self,
 259                 cmsp: Option<(&codemap::CodeMap, Span)>,
 260                 msg: &str,
 261                 lvl: Level) {
 262         if lvl == Warning && !self.can_emit_warnings { return }
 263         self.emit.borrow_mut().emit(cmsp, msg, None, lvl);
 264     }
 265     pub fn emit_with_code(&self,
 266                           cmsp: Option<(&codemap::CodeMap, Span)>,
 267                           msg: &str,
 268                           code: &str,
 269                           lvl: Level) {
 270         if lvl == Warning && !self.can_emit_warnings { return }
 271         self.emit.borrow_mut().emit(cmsp, msg, Some(code), lvl);
 272     }
 273     pub fn custom_emit(&self, cm: &codemap::CodeMap,
 274                        sp: RenderSpan, msg: &str, lvl: Level) {
 275         if lvl == Warning && !self.can_emit_warnings { return }
 276         self.emit.borrow_mut().custom_emit(cm, sp, msg, lvl);
 277     }
 278 }
 279
 280 #[derive(Copy, PartialEq, Clone, Debug)]
 281 pub enum Level {
 282     Bug,
 283     Fatal,
 284     Error,
 285     Warning,
 286     Note,
 287     Help,
 288 }
 289
 290 impl fmt::Display for Level {
 291     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 292         use std::fmt::Display;
 293
 294         match *self {
 295             Bug => "error: internal compiler error".fmt(f),
 296             Fatal | Error => "error".fmt(f),
 297             Warning => "warning".fmt(f),
 298             Note => "note".fmt(f),
 299             Help => "help".fmt(f),
 300         }
 301     }
 302 }
 303
 304 impl Level {
 305     fn color(self) -> term::color::Color {
 306         match self {
 307             Bug | Fatal | Error => term::color::BRIGHT_RED,
 308             Warning => term::color::BRIGHT_YELLOW,
 309             Note => term::color::BRIGHT_GREEN,
 310             Help => term::color::BRIGHT_CYAN,
 311         }
 312     }
 313 }
 314
 315 pub struct EmitterWriter {
 316     dst: Destination,
 317     registry: Option<diagnostics::registry::Registry>
 318 }
 319
 320 enum Destination {
 321     Terminal(Box<term::Terminal<WriterWrapper> + Send>),
 322     Raw(Box<Write + Send>),
 323 }
 324
 325 /// Do not use this for messages that end in `\n` – use `println_maybe_styled` instead. See
 326 /// `EmitterWriter::print_maybe_styled` for details.
 327 macro_rules! print_maybe_styled {
 328     ($writer: expr, $style: expr, $($arg: tt)*) => {
 329         $writer.print_maybe_styled(format_args!($($arg)*), $style, false)
 330     }
 331 }
 332
 333 macro_rules! println_maybe_styled {
 334     ($writer: expr, $style: expr, $($arg: tt)*) => {
 335         $writer.print_maybe_styled(format_args!($($arg)*), $style, true)
 336     }
 337 }
 338
 339 impl EmitterWriter {
 340     pub fn stderr(color_config: ColorConfig,
 341                   registry: Option<diagnostics::registry::Registry>) -> EmitterWriter {
 342         let stderr = io::stderr();
 343
 344         let use_color = match color_config {
 345             Always => true,
 346             Never  => false,
 347             Auto   => stderr_isatty(),
 348         };
 349
 350         if use_color {
 351             let dst = match term::stderr() {
 352                 Some(t) => Terminal(t),
 353                 None    => Raw(Box::new(stderr)),
 354             };
 355             EmitterWriter { dst: dst, registry: registry }
 356         } else {
 357             EmitterWriter { dst: Raw(Box::new(stderr)), registry: registry }
 358         }
 359     }
 360
 361     pub fn new(dst: Box<Write + Send>,
 362                registry: Option<diagnostics::registry::Registry>) -> EmitterWriter {
 363         EmitterWriter { dst: Raw(dst), registry: registry }
 364     }
 365
 366     fn print_maybe_styled(&mut self,
 367                           args: fmt::Arguments,
 368                           color: term::attr::Attr,
 369                           print_newline_at_end: bool) -> io::Result<()> {
 370         match self.dst {
 371             Terminal(ref mut t) => {
 372                 try!(t.attr(color));
 373                 // If `msg` ends in a newline, we need to reset the color before
 374                 // the newline. We're making the assumption that we end up writing
 375                 // to a `LineBufferedWriter`, which means that emitting the reset
 376                 // after the newline ends up buffering the reset until we print
 377                 // another line or exit. Buffering the reset is a problem if we're
 378                 // sharing the terminal with any other programs (e.g. other rustc
 379                 // instances via `make -jN`).
 380                 //
 381                 // Note that if `msg` contains any internal newlines, this will
 382                 // result in the `LineBufferedWriter` flushing twice instead of
 383                 // once, which still leaves the opportunity for interleaved output
 384                 // to be miscolored. We assume this is rare enough that we don't
 385                 // have to worry about it.
 386                 try!(t.write_fmt(args));
 387                 try!(t.reset());
 388                 if print_newline_at_end {
 389                     t.write_all(b"\n")
 390                 } else {
 391                     Ok(())
 392                 }
 393             }
 394             Raw(ref mut w) => {
 395                 try!(w.write_fmt(args));
 396                 if print_newline_at_end {
 397                     w.write_all(b"\n")
 398                 } else {
 399                     Ok(())
 400                 }
 401             }
 402         }
 403     }
 404
 405     fn print_diagnostic(&mut self, topic: &str, lvl: Level,
 406                         msg: &str, code: Option<&str>) -> io::Result<()> {
 407         if !topic.is_empty() {
 408             try!(write!(&mut self.dst, "{} ", topic));
 409         }
 410
 411         try!(print_maybe_styled!(self, term::attr::ForegroundColor(lvl.color()),
 412                                  "{}: ", lvl.to_string()));
 413         try!(print_maybe_styled!(self, term::attr::Bold, "{}", msg));
 414
 415         match code {
 416             Some(code) => {
 417                 let style = term::attr::ForegroundColor(term::color::BRIGHT_MAGENTA);
 418                 try!(print_maybe_styled!(self, style, " [{}]", code.clone()));
 419             }
 420             None => ()
 421         }
 422         try!(write!(&mut self.dst, "\n"));
 423         Ok(())
 424     }
 425
 426     fn emit_(&mut self, cm: &codemap::CodeMap, rsp: RenderSpan,
 427              msg: &str, code: Option<&str>, lvl: Level) -> io::Result<()> {
 428         let sp = rsp.span();
 429
 430         // We cannot check equality directly with COMMAND_LINE_SP
 431         // since PartialEq is manually implemented to ignore the ExpnId
 432         let ss = if sp.expn_id == COMMAND_LINE_EXPN {
 433             "<command line option>".to_string()
 434         } else if let EndSpan(_) = rsp {
 435             let span_end = Span { lo: sp.hi, hi: sp.hi, expn_id: sp.expn_id};
 436             cm.span_to_string(span_end)
 437         } else {
 438             cm.span_to_string(sp)
 439         };
 440
 441         try!(self.print_diagnostic(&ss[..], lvl, msg, code));
 442
 443         match rsp {
 444             FullSpan(_) => {
 445                 try!(self.highlight_lines(cm, sp, lvl, cm.span_to_lines(sp)));
 446                 try!(self.print_macro_backtrace(cm, sp));
 447             }
 448             EndSpan(_) => {
 449                 try!(self.end_highlight_lines(cm, sp, lvl, cm.span_to_lines(sp)));
 450                 try!(self.print_macro_backtrace(cm, sp));
 451             }
 452             Suggestion(_, ref suggestion) => {
 453                 try!(self.highlight_suggestion(cm, sp, suggestion));
 454                 try!(self.print_macro_backtrace(cm, sp));
 455             }
 456             FileLine(..) => {
 457                 // no source text in this case!
 458             }
 459         }
 460
 461         match code {
 462             Some(code) =>
 463                 match self.registry.as_ref().and_then(|registry| registry.find_description(code)) {
 464                     Some(_) => {
 465                         try!(self.print_diagnostic(&ss[..], Help,
 466                                                    &format!("run `rustc --explain {}` to see a \
 467                                                              detailed explanation", code), None));
 468                     }
 469                     None => ()
 470                 },
 471             None => (),
 472         }
 473         Ok(())
 474     }
 475
 476     fn highlight_suggestion(&mut self,
 477                             cm: &codemap::CodeMap,
 478                             sp: Span,
 479                             suggestion: &str)
 480                             -> io::Result<()>
 481     {
 482         let lines = cm.span_to_lines(sp).unwrap();
 483         assert!(!lines.lines.is_empty());
 484
 485         // To build up the result, we want to take the snippet from the first
 486         // line that precedes the span, prepend that with the suggestion, and
 487         // then append the snippet from the last line that trails the span.
 488         let fm = &lines.file;
 489
 490         let first_line = &lines.lines[0];
 491         let prefix = fm.get_line(first_line.line_index)
 492                        .map(|l| &l[..first_line.start_col.0])
 493                        .unwrap_or("");
 494
 495         let last_line = lines.lines.last().unwrap();
 496         let suffix = fm.get_line(last_line.line_index)
 497                        .map(|l| &l[last_line.end_col.0..])
 498                        .unwrap_or("");
 499
 500         let complete = format!("{}{}{}", prefix, suggestion, suffix);
 501
 502         // print the suggestion without any line numbers, but leave
 503         // space for them. This helps with lining up with previous
 504         // snippets from the actual error being reported.
 505         let fm = &*lines.file;
 506         let mut lines = complete.lines();
 507         for (line, line_index) in lines.by_ref().take(MAX_LINES).zip(first_line.line_index..) {
 508             let elided_line_num = format!("{}", line_index+1);
 509             try!(write!(&mut self.dst, "{0}:{1:2$} {3}\n",
 510                         fm.name, "", elided_line_num.len(), line));
 511         }
 512
 513         // if we elided some lines, add an ellipsis
 514         if lines.next().is_some() {
 515             let elided_line_num = format!("{}", first_line.line_index + MAX_LINES + 1);
 516             try!(write!(&mut self.dst, "{0:1$} {0:2$} ...\n",
 517                         "", fm.name.len(), elided_line_num.len()));
 518         }
 519
 520         Ok(())
 521     }
 522
 523     fn highlight_lines(&mut self,
 524                        cm: &codemap::CodeMap,
 525                        sp: Span,
 526                        lvl: Level,
 527                        lines: codemap::FileLinesResult)
 528                        -> io::Result<()>
 529     {
 530         let lines = match lines {
 531             Ok(lines) => lines,
 532             Err(_) => {
 533                 try!(write!(&mut self.dst, "(internal compiler error: unprintable span)\n"));
 534                 return Ok(());
 535             }
 536         };
 537
 538         let fm = &*lines.file;
 539
 540         let line_strings: Option<Vec<&str>> =
 541             lines.lines.iter()
 542                        .map(|info| fm.get_line(info.line_index))
 543                        .collect();
 544
 545         let line_strings = match line_strings {
 546             None => { return Ok(()); }
 547             Some(line_strings) => line_strings
 548         };
 549
 550         // Display only the first MAX_LINES lines.
 551         let all_lines = lines.lines.len();
 552         let display_lines = cmp::min(all_lines, MAX_LINES);
 553         let display_line_infos = &lines.lines[..display_lines];
 554         let display_line_strings = &line_strings[..display_lines];
 555
 556         // Calculate the widest number to format evenly and fix #11715
 557         assert!(display_line_infos.len() > 0);
 558         let mut max_line_num = display_line_infos[display_line_infos.len() - 1].line_index + 1;
 559         let mut digits = 0;
 560         while max_line_num > 0 {
 561             max_line_num /= 10;
 562             digits += 1;
 563         }
 564
 565         // Print the offending lines
 566         for (line_info, line) in display_line_infos.iter().zip(display_line_strings) {
 567             try!(write!(&mut self.dst, "{}:{:>width$} {}\n",
 568                         fm.name,
 569                         line_info.line_index + 1,
 570                         line,
 571                         width=digits));
 572         }
 573
 574         // If we elided something, put an ellipsis.
 575         if display_lines < all_lines {
 576             let last_line_index = display_line_infos.last().unwrap().line_index;
 577             let s = format!("{}:{} ", fm.name, last_line_index + 1);
 578             try!(write!(&mut self.dst, "{0:1$}...\n", "", s.len()));
 579         }
 580
 581         // FIXME (#3260)
 582         // If there's one line at fault we can easily point to the problem
 583         if lines.lines.len() == 1 {
 584             let lo = cm.lookup_char_pos(sp.lo);
 585             let mut digits = 0;
 586             let mut num = (lines.lines[0].line_index + 1) / 10;
 587
 588             // how many digits must be indent past?
 589             while num > 0 { num /= 10; digits += 1; }
 590
 591             let mut s = String::new();
 592             // Skip is the number of characters we need to skip because they are
 593             // part of the 'filename:line ' part of the previous line.
 594             let skip = fm.name.chars().count() + digits + 3;
 595             for _ in 0..skip {
 596                 s.push(' ');
 597             }
 598             if let Some(orig) = fm.get_line(lines.lines[0].line_index) {
 599                 let mut col = skip;
 600                 let mut lastc = ' ';
 601                 let mut iter = orig.chars().enumerate();
 602                 for (pos, ch) in iter.by_ref() {
 603                     lastc = ch;
 604                     if pos >= lo.col.to_usize() { break; }
 605                     // Whenever a tab occurs on the previous line, we insert one on
 606                     // the error-point-squiggly-line as well (instead of a space).
 607                     // That way the squiggly line will usually appear in the correct
 608                     // position.
 609                     match ch {
 610                         '\t' => {
 611                             col += 8 - col%8;
 612                             s.push('\t');
 613                         },
 614                         _ => {
 615                             col += 1;
 616                             s.push(' ');
 617                         },
 618                     }
 619                 }
 620
 621                 try!(write!(&mut self.dst, "{}", s));
 622                 let mut s = String::from("^");
 623                 let count = match lastc {
 624                     // Most terminals have a tab stop every eight columns by default
 625                     '\t' => 8 - col%8,
 626                     _ => 1,
 627                 };
 628                 col += count;
 629                 s.extend(::std::iter::repeat('~').take(count));
 630
 631                 let hi = cm.lookup_char_pos(sp.hi);
 632                 if hi.col != lo.col {
 633                     for (pos, ch) in iter {
 634                         if pos >= hi.col.to_usize() { break; }
 635                         let count = match ch {
 636                             '\t' => 8 - col%8,
 637                             _ => 1,
 638                         };
 639                         col += count;
 640                         s.extend(::std::iter::repeat('~').take(count));
 641                     }
 642                 }
 643
 644                 if s.len() > 1 {
 645                     // One extra squiggly is replaced by a "^"
 646                     s.pop();
 647                 }
 648
 649                 try!(println_maybe_styled!(self, term::attr::ForegroundColor(lvl.color()),
 650                                            "{}", s));
 651             }
 652         }
 653         Ok(())
 654     }
 655
 656     /// Here are the differences between this and the normal `highlight_lines`:
 657     /// `end_highlight_lines` will always put arrow on the last byte of the
 658     /// span (instead of the first byte). Also, when the span is too long (more
 659     /// than 6 lines), `end_highlight_lines` will print the first line, then
 660     /// dot dot dot, then last line, whereas `highlight_lines` prints the first
 661     /// six lines.
 662     #[allow(deprecated)]
 663     fn end_highlight_lines(&mut self,
 664                            cm: &codemap::CodeMap,
 665                            sp: Span,
 666                            lvl: Level,
 667                            lines: codemap::FileLinesResult)
 668                           -> io::Result<()> {
 669         let lines = match lines {
 670             Ok(lines) => lines,
 671             Err(_) => {
 672                 try!(write!(&mut self.dst, "(internal compiler error: unprintable span)\n"));
 673                 return Ok(());
 674             }
 675         };
 676
 677         let fm = &*lines.file;
 678
 679         let lines = &lines.lines[..];
 680         if lines.len() > MAX_LINES {
 681             if let Some(line) = fm.get_line(lines[0].line_index) {
 682                 try!(write!(&mut self.dst, "{}:{} {}\n", fm.name,
 683                             lines[0].line_index + 1, line));
 684             }
 685             try!(write!(&mut self.dst, "...\n"));
 686             let last_line_index = lines[lines.len() - 1].line_index;
 687             if let Some(last_line) = fm.get_line(last_line_index) {
 688                 try!(write!(&mut self.dst, "{}:{} {}\n", fm.name,
 689                             last_line_index + 1, last_line));
 690             }
 691         } else {
 692             for line_info in lines {
 693                 if let Some(line) = fm.get_line(line_info.line_index) {
 694                     try!(write!(&mut self.dst, "{}:{} {}\n", fm.name,
 695                                 line_info.line_index + 1, line));
 696                 }
 697             }
 698         }
 699         let last_line_start = format!("{}:{} ", fm.name, lines[lines.len()-1].line_index + 1);
 700         let hi = cm.lookup_char_pos(sp.hi);
 701         let skip = last_line_start.chars().count();
 702         let mut s = String::new();
 703         for _ in 0..skip {
 704             s.push(' ');
 705         }
 706         if let Some(orig) = fm.get_line(lines[0].line_index) {
 707             let iter = orig.chars().enumerate();
 708             for (pos, ch) in iter {
 709                 // Span seems to use half-opened interval, so subtract 1
 710                 if pos >= hi.col.to_usize() - 1 { break; }
 711                 // Whenever a tab occurs on the previous line, we insert one on
 712                 // the error-point-squiggly-line as well (instead of a space).
 713                 // That way the squiggly line will usually appear in the correct
 714                 // position.
 715                 match ch {
 716                     '\t' => s.push('\t'),
 717                     _ => s.push(' '),
 718                 }
 719             }
 720         }
 721         s.push('^');
 722         println_maybe_styled!(self, term::attr::ForegroundColor(lvl.color()),
 723                               "{}", s)
 724     }
 725
 726     fn print_macro_backtrace(&mut self,
 727                              cm: &codemap::CodeMap,
 728                              sp: Span)
 729                              -> io::Result<()> {
 730         let cs = try!(cm.with_expn_info(sp.expn_id, |expn_info| -> io::Result<_> {
 731             match expn_info {
 732                 Some(ei) => {
 733                     let ss = ei.callee.span.map_or(String::new(),
 734                                                    |span| cm.span_to_string(span));
 735                     let (pre, post) = match ei.callee.format {
 736                         codemap::MacroAttribute => ("#[", "]"),
 737                         codemap::MacroBang => ("", "!"),
 738                         codemap::CompilerExpansion => ("", ""),
 739                     };
 740                     try!(self.print_diagnostic(&ss, Note,
 741                                                &format!("in expansion of {}{}{}",
 742                                                         pre,
 743                                                         ei.callee.name,
 744                                                         post),
 745                                                None));
 746                     let ss = cm.span_to_string(ei.call_site);
 747                     try!(self.print_diagnostic(&ss, Note, "expansion site", None));
 748                     Ok(Some(ei.call_site))
 749                 }
 750                 None => Ok(None)
 751         }
 752         }));
 753         cs.map_or(Ok(()), |call_site| self.print_macro_backtrace(cm, call_site))
 754     }
 755 }
 756
 757 #[cfg(unix)]
 758 fn stderr_isatty() -> bool {
 759     unsafe { libc::isatty(libc::STDERR_FILENO) != 0 }
 760 }
 761 #[cfg(windows)]
 762 fn stderr_isatty() -> bool {
 763     const STD_ERROR_HANDLE: libc::DWORD = -12i32 as libc::DWORD;
 764     extern "system" {
 765         fn GetStdHandle(which: libc::DWORD) -> libc::HANDLE;
 766         fn GetConsoleMode(hConsoleHandle: libc::HANDLE,
 767                           lpMode: libc::LPDWORD) -> libc::BOOL;
 768     }
 769     unsafe {
 770         let handle = GetStdHandle(STD_ERROR_HANDLE);
 771         let mut out = 0;
 772         GetConsoleMode(handle, &mut out) != 0
 773     }
 774 }
 775
 776 impl Write for Destination {
 777     fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
 778         match *self {
 779             Terminal(ref mut t) => t.write(bytes),
 780             Raw(ref mut w) => w.write(bytes),
 781         }
 782     }
 783     fn flush(&mut self) -> io::Result<()> {
 784         match *self {
 785             Terminal(ref mut t) => t.flush(),
 786             Raw(ref mut w) => w.flush(),
 787         }
 788     }
 789 }
 790
 791 impl Emitter for EmitterWriter {
 792     fn emit(&mut self,
 793             cmsp: Option<(&codemap::CodeMap, Span)>,
 794             msg: &str, code: Option<&str>, lvl: Level) {
 795         let error = match cmsp {
 796             Some((cm, COMMAND_LINE_SP)) => self.emit_(cm,
 797                                                 FileLine(COMMAND_LINE_SP),
 798                                                 msg, code, lvl),
 799             Some((cm, sp)) => self.emit_(cm, FullSpan(sp), msg, code, lvl),
 800             None => self.print_diagnostic("", lvl, msg, code),
 801         };
 802
 803         match error {
 804             Ok(()) => {}
 805             Err(e) => panic!("failed to print diagnostics: {:?}", e),
 806         }
 807     }
 808
 809     fn custom_emit(&mut self, cm: &codemap::CodeMap,
 810                    sp: RenderSpan, msg: &str, lvl: Level) {
 811         match self.emit_(cm, sp, msg, None, lvl) {
 812             Ok(()) => {}
 813             Err(e) => panic!("failed to print diagnostics: {:?}", e),
 814         }
 815     }
 816 }
 817
 818 pub fn expect<T, M>(diag: &SpanHandler, opt: Option<T>, msg: M) -> T where
 819     M: FnOnce() -> String,
 820 {
 821     match opt {
 822         Some(t) => t,
 823         None => diag.handler().bug(&msg()),
 824     }
 825 }
 826
 827 #[cfg(test)]
 828 mod test {
 829     use super::{EmitterWriter, Level};
 830     use codemap::{mk_sp, CodeMap, BytePos};
 831     use std::sync::{Arc, Mutex};
 832     use std::io::{self, Write};
 833     use std::str::from_utf8;
 834
 835     // Diagnostic doesn't align properly in span where line number increases by one digit
 836     #[test]
 837     fn test_hilight_suggestion_issue_11715() {
 838         struct Sink(Arc<Mutex<Vec<u8>>>);
 839         impl Write for Sink {
 840             fn write(&mut self, data: &[u8]) -> io::Result<usize> {
 841                 Write::write(&mut *self.0.lock().unwrap(), data)
 842             }
 843             fn flush(&mut self) -> io::Result<()> { Ok(()) }
 844         }
 845         let data = Arc::new(Mutex::new(Vec::new()));
 846         let mut ew = EmitterWriter::new(Box::new(Sink(data.clone())), None);
 847         let cm = CodeMap::new();
 848         let content = "abcdefg
 849         koksi
 850         line3
 851         line4
 852         cinq
 853         line6
 854         line7
 855         line8
 856         line9
 857         line10
 858         e-lä-vän
 859         tolv
 860         dreizehn
 861         ";
 862         let file = cm.new_filemap_and_lines("dummy.txt", content);
 863         let start = file.lines.borrow()[7];
 864         let end = file.lines.borrow()[11];
 865         let sp = mk_sp(start, end);
 866         let lvl = Level::Error;
 867         println!("span_to_lines");
 868         let lines = cm.span_to_lines(sp);
 869         println!("highlight_lines");
 870         ew.highlight_lines(&cm, sp, lvl, lines).unwrap();
 871         println!("done");
 872         let vec = data.lock().unwrap().clone();
 873         let vec: &[u8] = &vec;
 874         let str = from_utf8(vec).unwrap();
 875         println!("{}", str);
 876         assert_eq!(str, "dummy.txt: 8         line8\n\
 877                          dummy.txt: 9         line9\n\
 878                          dummy.txt:10         line10\n\
 879                          dummy.txt:11         e-lä-vän\n\
 880                          dummy.txt:12         tolv\n");
 881     }
 882 }