rust/src/libsyntax/errors/mod.rs

// 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;
pub mod json;

#[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"
    }
}

/// Used for emitting structured error messages and other diagnostic information.
#[must_use]
pub struct DiagnosticBuilder<'a> {
    emitter: &'a RefCell<Box<Emitter>>,
    level: Level,
    message: String,
    code: Option<String>,
    span: Option<Span>,
    children: Vec<SubDiagnostic>,
}

/// For example a note attached to an error.
struct SubDiagnostic {
    level: Level,
    message: String,
    span: Option<Span>,
    render_span: Option<RenderSpan>,
}

impl<'a> DiagnosticBuilder<'a> {
    /// Emit the diagnostic.
    pub fn emit(&mut self) {
        if self.cancelled() {
            return;
        }

        self.emitter.borrow_mut().emit_struct(&self);
        self.cancel();

        // if self.is_fatal() {
        //     panic!(FatalError);
        // }
    }

    /// Cancel the diagnostic (a structured diagnostic must either be emitted or
    /// cancelled or it will panic when dropped).
    /// BEWARE: if this DiagnosticBuilder is an error, then creating it will
    /// bump the error count on the Handler and cancelling it won't undo that.
    /// If you want to decrement the error count you should use `Handler::cancel`.
    pub fn cancel(&mut self) {
        self.level = Level::Cancelled;
    }

    pub fn cancelled(&self) -> bool {
        self.level == Level::Cancelled
    }

    pub fn is_fatal(&self) -> bool {
        self.level == Level::Fatal
    }

    pub fn note(&mut self , msg: &str) -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Note, msg, None, None);
        self
    }
    pub fn span_note(&mut self ,
                     sp: Span,
                     msg: &str)
                     -> &mut DiagnosticBuilder<'a> {
        self.sub(Level::Note, msg, Some(sp), None);
        self
    }
    pub fn warn(&mut self, msg: &str) -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Warning, msg, None, None);
        self
    }
    pub fn span_warn(&mut self,
                     sp: Span,
                     msg: &str)
                     -> &mut DiagnosticBuilder<'a> {
        self.sub(Level::Warning, msg, Some(sp), None);
        self
    }
    pub fn help(&mut self , msg: &str) -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Help, msg, None, None);
        self
    }
    pub fn span_help(&mut self ,
                     sp: Span,
                     msg: &str)
                     -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Help, msg, Some(sp), None);
        self
    }
    /// Prints out a message with a suggested edit of the code.
    ///
    /// See `diagnostic::RenderSpan::Suggestion` for more information.
    pub fn span_suggestion(&mut self ,
                           sp: Span,
                           msg: &str,
                           suggestion: String)
                           -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Help, msg, Some(sp), Some(Suggestion(sp, suggestion)));
        self
    }
    pub fn span_end_note(&mut self ,
                         sp: Span,
                         msg: &str)
                         -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Note, msg, Some(sp), Some(EndSpan(sp)));
        self
    }
    pub fn fileline_warn(&mut self ,
                         sp: Span,
                         msg: &str)
                         -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Warning, msg, Some(sp), Some(FileLine(sp)));
        self
    }
    pub fn fileline_note(&mut self ,
                         sp: Span,
                         msg: &str)
                         -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Note, msg, Some(sp), Some(FileLine(sp)));
        self
    }
    pub fn fileline_help(&mut self ,
                         sp: Span,
                         msg: &str)
                         -> &mut DiagnosticBuilder<'a>  {
        self.sub(Level::Help, msg, Some(sp), Some(FileLine(sp)));
        self
    }

    pub fn span(&mut self, sp: Span) -> &mut Self {
        self.span = Some(sp);
        self
    }

    pub fn code(&mut self, s: String) -> &mut Self {
        self.code = Some(s);
        self
    }

    /// Convenience function for internal use, clients should use one of the
    /// struct_* methods on Handler.
    fn new(emitter: &'a RefCell<Box<Emitter>>,
           level: Level,
           message: &str) -> DiagnosticBuilder<'a>  {
        DiagnosticBuilder {
            emitter: emitter,
            level: level,
            message: message.to_owned(),
            code: None,
            span: None,
            children: vec![],
        }
    }

    /// Convenience function for internal use, clients should use one of the
    /// public methods above.
    fn sub(&mut self,
           level: Level,
           message: &str,
           span: Option<Span>,
           render_span: Option<RenderSpan>) {
        let sub = SubDiagnostic {
            level: level,
            message: message.to_owned(),
            span: span,
            render_span: render_span,
        };
        self.children.push(sub);
    }
}

impl<'a> fmt::Debug for DiagnosticBuilder<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.message.fmt(f)
    }
}

/// Destructor bomb - a DiagnosticBuilder must be either emitted or cancelled or
/// we emit a bug.
impl<'a> Drop for DiagnosticBuilder<'a> {
    fn drop(&mut self) {
        if !self.cancelled() {
            self.emitter.borrow_mut().emit(None, "Error constructed but not emitted", None, Bug);
            panic!();
        }
    }
}

/// 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 with_tty_emitter(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 struct_dummy<'a>(&'a self) -> DiagnosticBuilder<'a> {
        DiagnosticBuilder::new(&self.emit, Level::Cancelled, "")
    }

    pub fn struct_span_warn<'a>(&'a self,
                                sp: Span,
                                msg: &str)
                                -> DiagnosticBuilder<'a> {
        let mut result = DiagnosticBuilder::new(&self.emit, Level::Warning, msg);
        result.span(sp);
        if !self.can_emit_warnings {
            result.cancel();
        }
        result
    }
    pub fn struct_span_warn_with_code<'a>(&'a self,
                                          sp: Span,
                                          msg: &str,
                                          code: &str)
                                          -> DiagnosticBuilder<'a> {
        let mut result = DiagnosticBuilder::new(&self.emit, Level::Warning, msg);
        result.span(sp);
        result.code(code.to_owned());
        if !self.can_emit_warnings {
            result.cancel();
        }
        result
    }
    pub fn struct_warn<'a>(&'a self, msg: &str) -> DiagnosticBuilder<'a> {
        let mut result = DiagnosticBuilder::new(&self.emit, Level::Warning, msg);
        if !self.can_emit_warnings {
            result.cancel();
        }
        result
    }
    pub fn struct_span_err<'a>(&'a self,
                               sp: Span,
                               msg: &str)
                               -> DiagnosticBuilder<'a> {
        self.bump_err_count();
        let mut result = DiagnosticBuilder::new(&self.emit, Level::Error, msg);
        result.span(sp);
        result
    }
    pub fn struct_span_err_with_code<'a>(&'a self,
                                         sp: Span,
                                         msg: &str,
                                         code: &str)
                                         -> DiagnosticBuilder<'a> {
        self.bump_err_count();
        let mut result = DiagnosticBuilder::new(&self.emit, Level::Error, msg);
        result.span(sp);
        result.code(code.to_owned());
        result
    }
    pub fn struct_err<'a>(&'a self, msg: &str) -> DiagnosticBuilder<'a> {
        self.bump_err_count();
        DiagnosticBuilder::new(&self.emit, Level::Error, msg)
    }
    pub fn struct_span_fatal<'a>(&'a self,
                                 sp: Span,
                                 msg: &str)
                                 -> DiagnosticBuilder<'a> {
        self.bump_err_count();
        let mut result = DiagnosticBuilder::new(&self.emit, Level::Fatal, msg);
        result.span(sp);
        result
    }
    pub fn struct_span_fatal_with_code<'a>(&'a self,
                                           sp: Span,
                                           msg: &str,
                                           code: &str)
                                           -> DiagnosticBuilder<'a> {
        self.bump_err_count();
        let mut result = DiagnosticBuilder::new(&self.emit, Level::Fatal, msg);
        result.span(sp);
        result.code(code.to_owned());
        result
    }
    pub fn struct_fatal<'a>(&'a self, msg: &str) -> DiagnosticBuilder<'a> {
        self.bump_err_count();
        DiagnosticBuilder::new(&self.emit, Level::Fatal, msg)
    }

    pub fn cancel(&mut self, err: &mut DiagnosticBuilder) {
        if err.level == Level::Error || err.level == Level::Fatal {
            assert!(self.has_errors());
            self.err_count.set(self.err_count.get() + 1);
        }
        err.cancel();
    }

    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);
        self.bump_err_count();
        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);
        self.bump_err_count();
        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_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_note_without_error(&self, sp: Span, msg: &str) {
        self.emit.borrow_mut().emit(Some(sp), msg, None, Note);
    }
    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);
        self.bump_err_count();
        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_without_error(&self, msg: &str) {
        self.emit.borrow_mut().emit(None, msg, None, Note);
    }
    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,
    Cancelled,
}

impl fmt::Display for Level {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        use std::fmt::Display;

        self.to_str().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,
            Cancelled => unreachable!(),
        }
    }

    fn to_str(self) -> &'static str {
        match self {
            Bug => "error: internal compiler error",
            Fatal | Error => "error",
            Warning => "warning",
            Note => "note",
            Help => "help",
            Cancelled => panic!("Shouldn't call on cancelled error"),
        }
    }
}

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()),
    }
}