Rollup merge of #30384 - nrc:diagnostics, r=@nikomatsakis

Should make it possible to add JSON or HTML errors. Also tidies up a lot.

2 files changed, 1018 insertions, 0 deletions

diff --git a/src/libsyntax/errors/emitter.rs b/src/libsyntax/errors/emitter.rs
new file mode 100644
index 00000000000..7fef85a833e
--- /dev/null
+++ b/src/libsyntax/errors/emitter.rs
@@ -0,0 +1,680 @@
+// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use self::Destination::*;
+
+use codemap::{self, COMMAND_LINE_SP, COMMAND_LINE_EXPN, Pos, Span};
+use diagnostics;
+
+use errors::{Level, RenderSpan};
+use errors::RenderSpan::*;
+use errors::Level::*;
+
+use std::{cmp, fmt};
+use std::io::prelude::*;
+use std::io;
+use std::rc::Rc;
+use term;
+
+
+pub trait Emitter {
+    fn emit(&mut self, span: Option<Span>, msg: &str, code: Option<&str>, lvl: Level);
+    fn custom_emit(&mut self, sp: RenderSpan, msg: &str, lvl: Level);
+}
+
+/// maximum number of lines we will print for each error; arbitrary.
+const MAX_LINES: usize = 6;
+
+#[derive(Clone, Copy)]
+pub enum ColorConfig {
+    Auto,
+    Always,
+    Never,
+}
+
+impl ColorConfig {
+    fn use_color(&self) -> bool {
+        match *self {
+            ColorConfig::Always => true,
+            ColorConfig::Never  => false,
+            ColorConfig::Auto   => stderr_isatty(),
+        }
+    }
+}
+
+// A basic emitter for when we don't have access to a codemap or registry. Used
+// for reporting very early errors, etc.
+pub struct BasicEmitter {
+    dst: Destination,
+}
+
+impl Emitter for BasicEmitter {
+    fn emit(&mut self,
+            sp: Option<Span>,
+            msg: &str,
+            code: Option<&str>,
+            lvl: Level) {
+        assert!(sp.is_none(), "BasicEmitter can't handle spans");
+        if let Err(e) = print_diagnostic(&mut self.dst, "", lvl, msg, code) {
+            panic!("failed to print diagnostics: {:?}", e);
+        }
+
+    }
+
+    fn custom_emit(&mut self, _: RenderSpan, _: &str, _: Level) {
+        panic!("BasicEmitter can't handle custom_emit");
+    }
+}
+
+impl BasicEmitter {
+    pub fn stderr(color_config: ColorConfig) -> BasicEmitter {
+        if color_config.use_color() {
+            let dst = Destination::from_stderr();
+            BasicEmitter { dst: dst }
+        } else {
+            BasicEmitter { dst: Raw(Box::new(io::stderr())) }
+        }
+    }
+}
+
+pub struct EmitterWriter {
+    dst: Destination,
+    registry: Option<diagnostics::registry::Registry>,
+    cm: Rc<codemap::CodeMap>,
+}
+
+impl Emitter for EmitterWriter {
+    fn emit(&mut self,
+            sp: Option<Span>,
+            msg: &str,
+            code: Option<&str>,
+            lvl: Level) {
+        let error = match sp {
+            Some(COMMAND_LINE_SP) => self.emit_(FileLine(COMMAND_LINE_SP), msg, code, lvl),
+            Some(sp) => self.emit_(FullSpan(sp), msg, code, lvl),
+            None => print_diagnostic(&mut self.dst, "", lvl, msg, code),
+        };
+
+        if let Err(e) = error {
+            panic!("failed to print diagnostics: {:?}", e);
+        }
+    }
+
+    fn custom_emit(&mut self,
+                   sp: RenderSpan,
+                   msg: &str,
+                   lvl: Level) {
+        match self.emit_(sp, msg, None, lvl) {
+            Ok(()) => {}
+            Err(e) => panic!("failed to print diagnostics: {:?}", e),
+        }
+    }
+}
+
+/// Do not use this for messages that end in `\n` – use `println_maybe_styled` instead. See
+/// `EmitterWriter::print_maybe_styled` for details.
+macro_rules! print_maybe_styled {
+    ($dst: expr, $style: expr, $($arg: tt)*) => {
+        $dst.print_maybe_styled(format_args!($($arg)*), $style, false)
+    }
+}
+
+macro_rules! println_maybe_styled {
+    ($dst: expr, $style: expr, $($arg: tt)*) => {
+        $dst.print_maybe_styled(format_args!($($arg)*), $style, true)
+    }
+}
+
+impl EmitterWriter {
+    pub fn stderr(color_config: ColorConfig,
+                  registry: Option<diagnostics::registry::Registry>,
+                  code_map: Rc<codemap::CodeMap>)
+                  -> EmitterWriter {
+        if color_config.use_color() {
+            let dst = Destination::from_stderr();
+            EmitterWriter { dst: dst, registry: registry, cm: code_map }
+        } else {
+            EmitterWriter { dst: Raw(Box::new(io::stderr())), registry: registry, cm: code_map }
+        }
+    }
+
+    pub fn new(dst: Box<Write + Send>,
+               registry: Option<diagnostics::registry::Registry>,
+               code_map: Rc<codemap::CodeMap>)
+               -> EmitterWriter {
+        EmitterWriter { dst: Raw(dst), registry: registry, cm: code_map }
+    }
+
+    fn emit_(&mut self,
+             rsp: RenderSpan,
+             msg: &str,
+             code: Option<&str>,
+             lvl: Level)
+             -> io::Result<()> {
+        let sp = rsp.span();
+
+        // We cannot check equality directly with COMMAND_LINE_SP
+        // since PartialEq is manually implemented to ignore the ExpnId
+        let ss = if sp.expn_id == COMMAND_LINE_EXPN {
+            "<command line option>".to_string()
+        } else if let EndSpan(_) = rsp {
+            let span_end = Span { lo: sp.hi, hi: sp.hi, expn_id: sp.expn_id};
+            self.cm.span_to_string(span_end)
+        } else {
+            self.cm.span_to_string(sp)
+        };
+
+        try!(print_diagnostic(&mut self.dst, &ss[..], lvl, msg, code));
+
+        match rsp {
+            FullSpan(_) => {
+                let lines = self.cm.span_to_lines(sp);
+                try!(self.highlight_lines(sp, lvl, lines));
+                try!(self.print_macro_backtrace(sp));
+            }
+            EndSpan(_) => {
+                let lines = self.cm.span_to_lines(sp);
+                try!(self.end_highlight_lines(sp, lvl, lines));
+                try!(self.print_macro_backtrace(sp));
+            }
+            Suggestion(_, ref suggestion) => {
+                try!(self.highlight_suggestion(sp, suggestion));
+                try!(self.print_macro_backtrace(sp));
+            }
+            FileLine(..) => {
+                // no source text in this case!
+            }
+        }
+
+        match code {
+            Some(code) =>
+                match self.registry.as_ref().and_then(|registry| registry.find_description(code)) {
+                    Some(_) => {
+                        try!(print_diagnostic(&mut self.dst, &ss[..], Help,
+                                              &format!("run `rustc --explain {}` to see a \
+                                                       detailed explanation", code), None));
+                    }
+                    None => ()
+                },
+            None => (),
+        }
+        Ok(())
+    }
+
+    fn highlight_suggestion(&mut self,
+                            sp: Span,
+                            suggestion: &str)
+                            -> io::Result<()>
+    {
+        let lines = self.cm.span_to_lines(sp).unwrap();
+        assert!(!lines.lines.is_empty());
+
+        // To build up the result, we want to take the snippet from the first
+        // line that precedes the span, prepend that with the suggestion, and
+        // then append the snippet from the last line that trails the span.
+        let fm = &lines.file;
+
+        let first_line = &lines.lines[0];
+        let prefix = fm.get_line(first_line.line_index)
+                       .map(|l| &l[..first_line.start_col.0])
+                       .unwrap_or("");
+
+        let last_line = lines.lines.last().unwrap();
+        let suffix = fm.get_line(last_line.line_index)
+                       .map(|l| &l[last_line.end_col.0..])
+                       .unwrap_or("");
+
+        let complete = format!("{}{}{}", prefix, suggestion, suffix);
+
+        // print the suggestion without any line numbers, but leave
+        // space for them. This helps with lining up with previous
+        // snippets from the actual error being reported.
+        let fm = &*lines.file;
+        let mut lines = complete.lines();
+        for (line, line_index) in lines.by_ref().take(MAX_LINES).zip(first_line.line_index..) {
+            let elided_line_num = format!("{}", line_index+1);
+            try!(write!(&mut self.dst, "{0}:{1:2$} {3}\n",
+                        fm.name, "", elided_line_num.len(), line));
+        }
+
+        // if we elided some lines, add an ellipsis
+        if lines.next().is_some() {
+            let elided_line_num = format!("{}", first_line.line_index + MAX_LINES + 1);
+            try!(write!(&mut self.dst, "{0:1$} {0:2$} ...\n",
+                        "", fm.name.len(), elided_line_num.len()));
+        }
+
+        Ok(())
+    }
+
+    fn highlight_lines(&mut self,
+                       sp: Span,
+                       lvl: Level,
+                       lines: codemap::FileLinesResult)
+                       -> io::Result<()>
+    {
+        let lines = match lines {
+            Ok(lines) => lines,
+            Err(_) => {
+                try!(write!(&mut self.dst, "(internal compiler error: unprintable span)\n"));
+                return Ok(());
+            }
+        };
+
+        let fm = &*lines.file;
+
+        let line_strings: Option<Vec<&str>> =
+            lines.lines.iter()
+                       .map(|info| fm.get_line(info.line_index))
+                       .collect();
+
+        let line_strings = match line_strings {
+            None => { return Ok(()); }
+            Some(line_strings) => line_strings
+        };
+
+        // Display only the first MAX_LINES lines.
+        let all_lines = lines.lines.len();
+        let display_lines = cmp::min(all_lines, MAX_LINES);
+        let display_line_infos = &lines.lines[..display_lines];
+        let display_line_strings = &line_strings[..display_lines];
+
+        // Calculate the widest number to format evenly and fix #11715
+        assert!(display_line_infos.len() > 0);
+        let mut max_line_num = display_line_infos[display_line_infos.len() - 1].line_index + 1;
+        let mut digits = 0;
+        while max_line_num > 0 {
+            max_line_num /= 10;
+            digits += 1;
+        }
+
+        // Print the offending lines
+        for (line_info, line) in display_line_infos.iter().zip(display_line_strings) {
+            try!(write!(&mut self.dst, "{}:{:>width$} {}\n",
+                        fm.name,
+                        line_info.line_index + 1,
+                        line,
+                        width=digits));
+        }
+
+        // If we elided something, put an ellipsis.
+        if display_lines < all_lines {
+            let last_line_index = display_line_infos.last().unwrap().line_index;
+            let s = format!("{}:{} ", fm.name, last_line_index + 1);
+            try!(write!(&mut self.dst, "{0:1$}...\n", "", s.len()));
+        }
+
+        // FIXME (#3260)
+        // If there's one line at fault we can easily point to the problem
+        if lines.lines.len() == 1 {
+            let lo = self.cm.lookup_char_pos(sp.lo);
+            let mut digits = 0;
+            let mut num = (lines.lines[0].line_index + 1) / 10;
+
+            // how many digits must be indent past?
+            while num > 0 { num /= 10; digits += 1; }
+
+            let mut s = String::new();
+            // Skip is the number of characters we need to skip because they are
+            // part of the 'filename:line ' part of the previous line.
+            let skip = fm.name.chars().count() + digits + 3;
+            for _ in 0..skip {
+                s.push(' ');
+            }
+            if let Some(orig) = fm.get_line(lines.lines[0].line_index) {
+                let mut col = skip;
+                let mut lastc = ' ';
+                let mut iter = orig.chars().enumerate();
+                for (pos, ch) in iter.by_ref() {
+                    lastc = ch;
+                    if pos >= lo.col.to_usize() { break; }
+                    // Whenever a tab occurs on the previous line, we insert one on
+                    // the error-point-squiggly-line as well (instead of a space).
+                    // That way the squiggly line will usually appear in the correct
+                    // position.
+                    match ch {
+                        '\t' => {
+                            col += 8 - col%8;
+                            s.push('\t');
+                        },
+                        _ => {
+                            col += 1;
+                            s.push(' ');
+                        },
+                    }
+                }
+
+                try!(write!(&mut self.dst, "{}", s));
+                let mut s = String::from("^");
+                let count = match lastc {
+                    // Most terminals have a tab stop every eight columns by default
+                    '\t' => 8 - col%8,
+                    _ => 1,
+                };
+                col += count;
+                s.extend(::std::iter::repeat('~').take(count));
+
+                let hi = self.cm.lookup_char_pos(sp.hi);
+                if hi.col != lo.col {
+                    for (pos, ch) in iter {
+                        if pos >= hi.col.to_usize() { break; }
+                        let count = match ch {
+                            '\t' => 8 - col%8,
+                            _ => 1,
+                        };
+                        col += count;
+                        s.extend(::std::iter::repeat('~').take(count));
+                    }
+                }
+
+                if s.len() > 1 {
+                    // One extra squiggly is replaced by a "^"
+                    s.pop();
+                }
+
+                try!(println_maybe_styled!(&mut self.dst, term::Attr::ForegroundColor(lvl.color()),
+                                           "{}", s));
+            }
+        }
+        Ok(())
+    }
+
+    /// Here are the differences between this and the normal `highlight_lines`:
+    /// `end_highlight_lines` will always put arrow on the last byte of the
+    /// span (instead of the first byte). Also, when the span is too long (more
+    /// than 6 lines), `end_highlight_lines` will print the first line, then
+    /// dot dot dot, then last line, whereas `highlight_lines` prints the first
+    /// six lines.
+    #[allow(deprecated)]
+    fn end_highlight_lines(&mut self,
+                           sp: Span,
+                           lvl: Level,
+                           lines: codemap::FileLinesResult)
+                          -> io::Result<()> {
+        let lines = match lines {
+            Ok(lines) => lines,
+            Err(_) => {
+                try!(write!(&mut self.dst, "(internal compiler error: unprintable span)\n"));
+                return Ok(());
+            }
+        };
+
+        let fm = &*lines.file;
+
+        let lines = &lines.lines[..];
+        if lines.len() > MAX_LINES {
+            if let Some(line) = fm.get_line(lines[0].line_index) {
+                try!(write!(&mut self.dst, "{}:{} {}\n", fm.name,
+                            lines[0].line_index + 1, line));
+            }
+            try!(write!(&mut self.dst, "...\n"));
+            let last_line_index = lines[lines.len() - 1].line_index;
+            if let Some(last_line) = fm.get_line(last_line_index) {
+                try!(write!(&mut self.dst, "{}:{} {}\n", fm.name,
+                            last_line_index + 1, last_line));
+            }
+        } else {
+            for line_info in lines {
+                if let Some(line) = fm.get_line(line_info.line_index) {
+                    try!(write!(&mut self.dst, "{}:{} {}\n", fm.name,
+                                line_info.line_index + 1, line));
+                }
+            }
+        }
+        let last_line_start = format!("{}:{} ", fm.name, lines[lines.len()-1].line_index + 1);
+        let hi = self.cm.lookup_char_pos(sp.hi);
+        let skip = last_line_start.chars().count();
+        let mut s = String::new();
+        for _ in 0..skip {
+            s.push(' ');
+        }
+        if let Some(orig) = fm.get_line(lines[0].line_index) {
+            let iter = orig.chars().enumerate();
+            for (pos, ch) in iter {
+                // Span seems to use half-opened interval, so subtract 1
+                if pos >= hi.col.to_usize() - 1 { break; }
+                // Whenever a tab occurs on the previous line, we insert one on
+                // the error-point-squiggly-line as well (instead of a space).
+                // That way the squiggly line will usually appear in the correct
+                // position.
+                match ch {
+                    '\t' => s.push('\t'),
+                    _ => s.push(' '),
+                }
+            }
+        }
+        s.push('^');
+        println_maybe_styled!(&mut self.dst, term::Attr::ForegroundColor(lvl.color()),
+                              "{}", s)
+    }
+
+    fn print_macro_backtrace(&mut self,
+                             sp: Span)
+                             -> io::Result<()> {
+        let mut last_span = codemap::DUMMY_SP;
+        let mut span = sp;
+
+        loop {
+            let span_name_span = self.cm.with_expn_info(span.expn_id, |expn_info| {
+                expn_info.map(|ei| {
+                    let (pre, post) = match ei.callee.format {
+                        codemap::MacroAttribute(..) => ("#[", "]"),
+                        codemap::MacroBang(..) => ("", "!"),
+                    };
+                    let macro_decl_name = format!("in this expansion of {}{}{}",
+                                                  pre,
+                                                  ei.callee.name(),
+                                                  post);
+                    let def_site_span = ei.callee.span;
+                    (ei.call_site, macro_decl_name, def_site_span)
+                })
+            });
+            let (macro_decl_name, def_site_span) = match span_name_span {
+                None => break,
+                Some((sp, macro_decl_name, def_site_span)) => {
+                    span = sp;
+                    (macro_decl_name, def_site_span)
+                }
+            };
+
+            // Don't print recursive invocations
+            if span != last_span {
+                let mut diag_string = macro_decl_name;
+                if let Some(def_site_span) = def_site_span {
+                    diag_string.push_str(&format!(" (defined in {})",
+                                                  self.cm.span_to_filename(def_site_span)));
+                }
+
+                let snippet = self.cm.span_to_string(span);
+                try!(print_diagnostic(&mut self.dst, &snippet, Note, &diag_string, None));
+            }
+            last_span = span;
+        }
+
+        Ok(())
+    }
+}
+
+fn print_diagnostic(dst: &mut Destination,
+                    topic: &str,
+                    lvl: Level,
+                    msg: &str,
+                    code: Option<&str>)
+                    -> io::Result<()> {
+    if !topic.is_empty() {
+        try!(write!(dst, "{} ", topic));
+    }
+
+    try!(print_maybe_styled!(dst, term::Attr::ForegroundColor(lvl.color()),
+                             "{}: ", lvl.to_string()));
+    try!(print_maybe_styled!(dst, term::Attr::Bold, "{}", msg));
+
+    match code {
+        Some(code) => {
+            let style = term::Attr::ForegroundColor(term::color::BRIGHT_MAGENTA);
+            try!(print_maybe_styled!(dst, style, " [{}]", code.clone()));
+        }
+        None => ()
+    }
+    try!(write!(dst, "\n"));
+    Ok(())
+}
+
+#[cfg(unix)]
+fn stderr_isatty() -> bool {
+    use libc;
+    unsafe { libc::isatty(libc::STDERR_FILENO) != 0 }
+}
+#[cfg(windows)]
+fn stderr_isatty() -> bool {
+    type DWORD = u32;
+    type BOOL = i32;
+    type HANDLE = *mut u8;
+    const STD_ERROR_HANDLE: DWORD = -12i32 as DWORD;
+    extern "system" {
+        fn GetStdHandle(which: DWORD) -> HANDLE;
+        fn GetConsoleMode(hConsoleHandle: HANDLE,
+                          lpMode: *mut DWORD) -> BOOL;
+    }
+    unsafe {
+        let handle = GetStdHandle(STD_ERROR_HANDLE);
+        let mut out = 0;
+        GetConsoleMode(handle, &mut out) != 0
+    }
+}
+
+enum Destination {
+    Terminal(Box<term::StderrTerminal>),
+    Raw(Box<Write + Send>),
+}
+
+impl Destination {
+    fn from_stderr() -> Destination {
+        match term::stderr() {
+            Some(t) => Terminal(t),
+            None    => Raw(Box::new(io::stderr())),
+        }
+    }
+
+    fn print_maybe_styled(&mut self,
+                          args: fmt::Arguments,
+                          color: term::Attr,
+                          print_newline_at_end: bool)
+                          -> io::Result<()> {
+        match *self {
+            Terminal(ref mut t) => {
+                try!(t.attr(color));
+                // If `msg` ends in a newline, we need to reset the color before
+                // the newline. We're making the assumption that we end up writing
+                // to a `LineBufferedWriter`, which means that emitting the reset
+                // after the newline ends up buffering the reset until we print
+                // another line or exit. Buffering the reset is a problem if we're
+                // sharing the terminal with any other programs (e.g. other rustc
+                // instances via `make -jN`).
+                //
+                // Note that if `msg` contains any internal newlines, this will
+                // result in the `LineBufferedWriter` flushing twice instead of
+                // once, which still leaves the opportunity for interleaved output
+                // to be miscolored. We assume this is rare enough that we don't
+                // have to worry about it.
+                try!(t.write_fmt(args));
+                try!(t.reset());
+                if print_newline_at_end {
+                    t.write_all(b"\n")
+                } else {
+                    Ok(())
+                }
+            }
+            Raw(ref mut w) => {
+                try!(w.write_fmt(args));
+                if print_newline_at_end {
+                    w.write_all(b"\n")
+                } else {
+                    Ok(())
+                }
+            }
+        }
+    }
+}
+
+impl Write for Destination {
+    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
+        match *self {
+            Terminal(ref mut t) => t.write(bytes),
+            Raw(ref mut w) => w.write(bytes),
+        }
+    }
+    fn flush(&mut self) -> io::Result<()> {
+        match *self {
+            Terminal(ref mut t) => t.flush(),
+            Raw(ref mut w) => w.flush(),
+        }
+    }
+}
+
+
+#[cfg(test)]
+mod test {
+    use errors::Level;
+    use super::EmitterWriter;
+    use codemap::{mk_sp, CodeMap};
+    use std::sync::{Arc, Mutex};
+    use std::io::{self, Write};
+    use std::str::from_utf8;
+    use std::rc::Rc;
+
+    // Diagnostic doesn't align properly in span where line number increases by one digit
+    #[test]
+    fn test_hilight_suggestion_issue_11715() {
+        struct Sink(Arc<Mutex<Vec<u8>>>);
+        impl Write for Sink {
+            fn write(&mut self, data: &[u8]) -> io::Result<usize> {
+                Write::write(&mut *self.0.lock().unwrap(), data)
+            }
+            fn flush(&mut self) -> io::Result<()> { Ok(()) }
+        }
+        let data = Arc::new(Mutex::new(Vec::new()));
+        let cm = Rc::new(CodeMap::new());
+        let mut ew = EmitterWriter::new(Box::new(Sink(data.clone())), None, cm.clone());
+        let content = "abcdefg
+        koksi
+        line3
+        line4
+        cinq
+        line6
+        line7
+        line8
+        line9
+        line10
+        e-lä-vän
+        tolv
+        dreizehn
+        ";
+        let file = cm.new_filemap_and_lines("dummy.txt", content);
+        let start = file.lines.borrow()[7];
+        let end = file.lines.borrow()[11];
+        let sp = mk_sp(start, end);
+        let lvl = Level::Error;
+        println!("span_to_lines");
+        let lines = cm.span_to_lines(sp);
+        println!("highlight_lines");
+        ew.highlight_lines(sp, lvl, lines).unwrap();
+        println!("done");
+        let vec = data.lock().unwrap().clone();
+        let vec: &[u8] = &vec;
+        let str = from_utf8(vec).unwrap();
+        println!("{}", str);
+        assert_eq!(str, "dummy.txt: 8         line8\n\
+                         dummy.txt: 9         line9\n\
+                         dummy.txt:10         line10\n\
+                         dummy.txt:11         e-lä-vän\n\
+                         dummy.txt:12         tolv\n");
+    }
+}
diff --git a/src/libsyntax/errors/mod.rs b/src/libsyntax/errors/mod.rs
new file mode 100644
index 00000000000..f2e61090ba2
--- /dev/null
+++ b/src/libsyntax/errors/mod.rs
@@ -0,0 +1,338 @@
+// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub use errors::emitter::ColorConfig;
+
+use self::Level::*;
+use self::RenderSpan::*;
+
+use codemap::{self, Span};
+use diagnostics;
+use errors::emitter::{Emitter, EmitterWriter};
+
+use std::cell::{RefCell, Cell};
+use std::{error, fmt};
+use std::io::prelude::*;
+use std::rc::Rc;
+use term;
+
+pub mod emitter;
+
+#[derive(Clone)]
+pub enum RenderSpan {
+    /// A FullSpan renders with both with an initial line for the
+    /// message, prefixed by file:linenum, followed by a summary of
+    /// the source code covered by the span.
+    FullSpan(Span),
+
+    /// Similar to a FullSpan, but the cited position is the end of
+    /// the span, instead of the start. Used, at least, for telling
+    /// compiletest/runtest to look at the last line of the span
+    /// (since `end_highlight_lines` displays an arrow to the end
+    /// of the span).
+    EndSpan(Span),
+
+    /// A suggestion renders with both with an initial line for the
+    /// message, prefixed by file:linenum, followed by a summary
+    /// of hypothetical source code, where the `String` is spliced
+    /// into the lines in place of the code covered by the span.
+    Suggestion(Span, String),
+
+    /// A FileLine renders with just a line for the message prefixed
+    /// by file:linenum.
+    FileLine(Span),
+}
+
+impl RenderSpan {
+    fn span(&self) -> Span {
+        match *self {
+            FullSpan(s) |
+            Suggestion(s, _) |
+            EndSpan(s) |
+            FileLine(s) =>
+                s
+        }
+    }
+}
+
+/// Used as a return value to signify a fatal error occurred. (It is also
+/// used as the argument to panic at the moment, but that will eventually
+/// not be true.)
+#[derive(Copy, Clone, Debug)]
+#[must_use]
+pub struct FatalError;
+
+impl fmt::Display for FatalError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        write!(f, "parser fatal error")
+    }
+}
+
+impl error::Error for FatalError {
+    fn description(&self) -> &str {
+        "The parser has encountered a fatal error"
+    }
+}
+
+/// Signifies that the compiler died with an explicit call to `.bug`
+/// or `.span_bug` rather than a failed assertion, etc.
+#[derive(Copy, Clone, Debug)]
+pub struct ExplicitBug;
+
+impl fmt::Display for ExplicitBug {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        write!(f, "parser internal bug")
+    }
+}
+
+impl error::Error for ExplicitBug {
+    fn description(&self) -> &str {
+        "The parser has encountered an internal bug"
+    }
+}
+
+/// A handler deals with errors; certain errors
+/// (fatal, bug, unimpl) may cause immediate exit,
+/// others log errors for later reporting.
+pub struct Handler {
+    err_count: Cell<usize>,
+    emit: RefCell<Box<Emitter>>,
+    pub can_emit_warnings: bool,
+    treat_err_as_bug: bool,
+    delayed_span_bug: RefCell<Option<(codemap::Span, String)>>,
+}
+
+impl Handler {
+    pub fn new(color_config: ColorConfig,
+               registry: Option<diagnostics::registry::Registry>,
+               can_emit_warnings: bool,
+               treat_err_as_bug: bool,
+               cm: Rc<codemap::CodeMap>)
+               -> Handler {
+        let emitter = Box::new(EmitterWriter::stderr(color_config, registry, cm));
+        Handler::with_emitter(can_emit_warnings, treat_err_as_bug, emitter)
+    }
+
+    pub fn with_emitter(can_emit_warnings: bool,
+                        treat_err_as_bug: bool,
+                        e: Box<Emitter>) -> Handler {
+        Handler {
+            err_count: Cell::new(0),
+            emit: RefCell::new(e),
+            can_emit_warnings: can_emit_warnings,
+            treat_err_as_bug: treat_err_as_bug,
+            delayed_span_bug: RefCell::new(None),
+        }
+    }
+
+    pub fn span_fatal(&self, sp: Span, msg: &str) -> FatalError {
+        if self.treat_err_as_bug {
+            self.span_bug(sp, msg);
+        }
+        self.emit(Some(sp), msg, Fatal);
+        return FatalError;
+    }
+    pub fn span_fatal_with_code(&self, sp: Span, msg: &str, code: &str) -> FatalError {
+        if self.treat_err_as_bug {
+            self.span_bug(sp, msg);
+        }
+        self.emit_with_code(Some(sp), msg, code, Fatal);
+        return FatalError;
+    }
+    pub fn span_err(&self, sp: Span, msg: &str) {
+        if self.treat_err_as_bug {
+            self.span_bug(sp, msg);
+        }
+        self.emit(Some(sp), msg, Error);
+        self.bump_err_count();
+    }
+    pub fn span_err_with_code(&self, sp: Span, msg: &str, code: &str) {
+        if self.treat_err_as_bug {
+            self.span_bug(sp, msg);
+        }
+        self.emit_with_code(Some(sp), msg, code, Error);
+        self.bump_err_count();
+    }
+    pub fn span_warn(&self, sp: Span, msg: &str) {
+        self.emit(Some(sp), msg, Warning);
+    }
+    pub fn span_warn_with_code(&self, sp: Span, msg: &str, code: &str) {
+        self.emit_with_code(Some(sp), msg, code, Warning);
+    }
+    pub fn span_note(&self, sp: Span, msg: &str) {
+        self.emit(Some(sp), msg, Note);
+    }
+    pub fn span_end_note(&self, sp: Span, msg: &str) {
+        self.custom_emit(EndSpan(sp), msg, Note);
+    }
+    pub fn span_help(&self, sp: Span, msg: &str) {
+        self.emit(Some(sp), msg, Help);
+    }
+    /// Prints out a message with a suggested edit of the code.
+    ///
+    /// See `diagnostic::RenderSpan::Suggestion` for more information.
+    pub fn span_suggestion(&self, sp: Span, msg: &str, suggestion: String) {
+        self.custom_emit(Suggestion(sp, suggestion), msg, Help);
+    }
+    pub fn fileline_note(&self, sp: Span, msg: &str) {
+        self.custom_emit(FileLine(sp), msg, Note);
+    }
+    pub fn fileline_help(&self, sp: Span, msg: &str) {
+        self.custom_emit(FileLine(sp), msg, Help);
+    }
+    pub fn span_bug(&self, sp: Span, msg: &str) -> ! {
+        self.emit(Some(sp), msg, Bug);
+        panic!(ExplicitBug);
+    }
+    pub fn delay_span_bug(&self, sp: Span, msg: &str) {
+        let mut delayed = self.delayed_span_bug.borrow_mut();
+        *delayed = Some((sp, msg.to_string()));
+    }
+    pub fn span_bug_no_panic(&self, sp: Span, msg: &str) {
+        self.emit(Some(sp), msg, Bug);
+        self.bump_err_count();
+    }
+    pub fn span_unimpl(&self, sp: Span, msg: &str) -> ! {
+        self.span_bug(sp, &format!("unimplemented {}", msg));
+    }
+    pub fn fatal(&self, msg: &str) -> FatalError {
+        if self.treat_err_as_bug {
+            self.bug(msg);
+        }
+        self.emit.borrow_mut().emit(None, msg, None, Fatal);
+        FatalError
+    }
+    pub fn err(&self, msg: &str) {
+        if self.treat_err_as_bug {
+            self.bug(msg);
+        }
+        self.emit.borrow_mut().emit(None, msg, None, Error);
+        self.bump_err_count();
+    }
+    pub fn warn(&self, msg: &str) {
+        self.emit.borrow_mut().emit(None, msg, None, Warning);
+    }
+    pub fn note(&self, msg: &str) {
+        self.emit.borrow_mut().emit(None, msg, None, Note);
+    }
+    pub fn help(&self, msg: &str) {
+        self.emit.borrow_mut().emit(None, msg, None, Help);
+    }
+    pub fn bug(&self, msg: &str) -> ! {
+        self.emit.borrow_mut().emit(None, msg, None, Bug);
+        panic!(ExplicitBug);
+    }
+    pub fn unimpl(&self, msg: &str) -> ! {
+        self.bug(&format!("unimplemented {}", msg));
+    }
+
+    pub fn bump_err_count(&self) {
+        self.err_count.set(self.err_count.get() + 1);
+    }
+
+    pub fn err_count(&self) -> usize {
+        self.err_count.get()
+    }
+
+    pub fn has_errors(&self) -> bool {
+        self.err_count.get() > 0
+    }
+
+    pub fn abort_if_errors(&self) {
+        let s;
+        match self.err_count.get() {
+            0 => {
+                let delayed_bug = self.delayed_span_bug.borrow();
+                match *delayed_bug {
+                    Some((span, ref errmsg)) => {
+                        self.span_bug(span, errmsg);
+                    },
+                    _ => {}
+                }
+
+                return;
+            }
+            1 => s = "aborting due to previous error".to_string(),
+            _  => {
+                s = format!("aborting due to {} previous errors",
+                            self.err_count.get());
+            }
+        }
+
+        panic!(self.fatal(&s[..]));
+    }
+
+    pub fn emit(&self,
+                sp: Option<Span>,
+                msg: &str,
+                lvl: Level) {
+        if lvl == Warning && !self.can_emit_warnings { return }
+        self.emit.borrow_mut().emit(sp, msg, None, lvl);
+    }
+
+    pub fn emit_with_code(&self,
+                          sp: Option<Span>,
+                          msg: &str,
+                          code: &str,
+                          lvl: Level) {
+        if lvl == Warning && !self.can_emit_warnings { return }
+        self.emit.borrow_mut().emit(sp, msg, Some(code), lvl);
+    }
+
+    pub fn custom_emit(&self, sp: RenderSpan, msg: &str, lvl: Level) {
+        if lvl == Warning && !self.can_emit_warnings { return }
+        self.emit.borrow_mut().custom_emit(sp, msg, lvl);
+    }
+}
+
+
+#[derive(Copy, PartialEq, Clone, Debug)]
+pub enum Level {
+    Bug,
+    Fatal,
+    Error,
+    Warning,
+    Note,
+    Help,
+}
+
+impl fmt::Display for Level {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use std::fmt::Display;
+
+        match *self {
+            Bug => "error: internal compiler error".fmt(f),
+            Fatal | Error => "error".fmt(f),
+            Warning => "warning".fmt(f),
+            Note => "note".fmt(f),
+            Help => "help".fmt(f),
+        }
+    }
+}
+
+impl Level {
+    fn color(self) -> term::color::Color {
+        match self {
+            Bug | Fatal | Error => term::color::BRIGHT_RED,
+            Warning => term::color::BRIGHT_YELLOW,
+            Note => term::color::BRIGHT_GREEN,
+            Help => term::color::BRIGHT_CYAN,
+        }
+    }
+}
+
+pub fn expect<T, M>(diag: &Handler, opt: Option<T>, msg: M) -> T where
+    M: FnOnce() -> String,
+{
+    match opt {
+        Some(t) => t,
+        None => diag.bug(&msg()),
+    }
+}