src/librustc_errors/diagnostic_builder.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 Diagnostic;
  12 use Level;
  13 use Handler;
  14 use std::fmt::{self, Debug};
  15 use std::ops::{Deref, DerefMut};
  16 use std::thread::panicking;
  17 use syntax_pos::{MultiSpan, Span};
  18
  19 /// Used for emitting structured error messages and other diagnostic information.
  20 #[must_use]
  21 #[derive(Clone)]
  22 pub struct DiagnosticBuilder<'a> {
  23     handler: &'a Handler,
  24     diagnostic: Diagnostic,
  25 }
  26
  27 /// In general, the `DiagnosticBuilder` uses deref to allow access to
  28 /// the fields and methods of the embedded `diagnostic` in a
  29 /// transparent way.  *However,* many of the methods are intended to
  30 /// be used in a chained way, and hence ought to return `self`. In
  31 /// that case, we can't just naively forward to the method on the
  32 /// `diagnostic`, because the return type would be a `&Diagnostic`
  33 /// instead of a `&DiagnosticBuilder<'a>`. This `forward!` macro makes
  34 /// it easy to declare such methods on the builder.
  35 macro_rules! forward {
  36     // Forward pattern for &self -> &Self
  37     (pub fn $n:ident(&self, $($name:ident: $ty:ty),*) -> &Self) => {
  38         pub fn $n(&self, $($name: $ty),*) -> &Self {
  39             self.diagnostic.$n($($name),*);
  40             self
  41         }
  42     };
  43
  44     // Forward pattern for &mut self -> &mut Self
  45     (pub fn $n:ident(&mut self, $($name:ident: $ty:ty),*) -> &mut Self) => {
  46         pub fn $n(&mut self, $($name: $ty),*) -> &mut Self {
  47             self.diagnostic.$n($($name),*);
  48             self
  49         }
  50     };
  51
  52     // Forward pattern for &mut self -> &mut Self, with S: Into<MultiSpan>
  53     // type parameter. No obvious way to make this more generic.
  54     (pub fn $n:ident<S: Into<MultiSpan>>(&mut self, $($name:ident: $ty:ty),*) -> &mut Self) => {
  55         pub fn $n<S: Into<MultiSpan>>(&mut self, $($name: $ty),*) -> &mut Self {
  56             self.diagnostic.$n($($name),*);
  57             self
  58         }
  59     };
  60 }
  61
  62 impl<'a> Deref for DiagnosticBuilder<'a> {
  63     type Target = Diagnostic;
  64
  65     fn deref(&self) -> &Diagnostic {
  66         &self.diagnostic
  67     }
  68 }
  69
  70 impl<'a> DerefMut for DiagnosticBuilder<'a> {
  71     fn deref_mut(&mut self) -> &mut Diagnostic {
  72         &mut self.diagnostic
  73     }
  74 }
  75
  76 impl<'a> DiagnosticBuilder<'a> {
  77     /// Emit the diagnostic.
  78     pub fn emit(&mut self) {
  79         if self.cancelled() {
  80             return;
  81         }
  82
  83         match self.level {
  84             Level::Bug |
  85             Level::Fatal |
  86             Level::PhaseFatal |
  87             Level::Error => {
  88                 self.handler.bump_err_count();
  89             }
  90
  91             Level::Warning |
  92             Level::Note |
  93             Level::Help |
  94             Level::Cancelled => {
  95             }
  96         }
  97
  98         self.handler.emitter.borrow_mut().emit(&self);
  99         self.cancel();
 100         self.handler.panic_if_treat_err_as_bug();
 101
 102         // if self.is_fatal() {
 103         //     panic!(FatalError);
 104         // }
 105     }
 106
 107     /// Add a span/label to be included in the resulting snippet.
 108     /// This is pushed onto the `MultiSpan` that was created when the
 109     /// diagnostic was first built. If you don't call this function at
 110     /// all, and you just supplied a `Span` to create the diagnostic,
 111     /// then the snippet will just include that `Span`, which is
 112     /// called the primary span.
 113     forward!(pub fn span_label(&mut self, span: Span, label: &fmt::Display)
 114                                -> &mut Self);
 115
 116     forward!(pub fn note_expected_found(&mut self,
 117                                         label: &fmt::Display,
 118                                         expected: &fmt::Display,
 119                                         found: &fmt::Display)
 120                                         -> &mut Self);
 121
 122     forward!(pub fn note_expected_found_extra(&mut self,
 123                                               label: &fmt::Display,
 124                                               expected: &fmt::Display,
 125                                               found: &fmt::Display,
 126                                               expected_extra: &fmt::Display,
 127                                               found_extra: &fmt::Display)
 128                                               -> &mut Self);
 129
 130     forward!(pub fn note(&mut self, msg: &str) -> &mut Self);
 131     forward!(pub fn span_note<S: Into<MultiSpan>>(&mut self,
 132                                                   sp: S,
 133                                                   msg: &str)
 134                                                   -> &mut Self);
 135     forward!(pub fn warn(&mut self, msg: &str) -> &mut Self);
 136     forward!(pub fn span_warn<S: Into<MultiSpan>>(&mut self, sp: S, msg: &str) -> &mut Self);
 137     forward!(pub fn help(&mut self , msg: &str) -> &mut Self);
 138     forward!(pub fn span_help<S: Into<MultiSpan>>(&mut self,
 139                                                   sp: S,
 140                                                   msg: &str)
 141                                                   -> &mut Self);
 142     forward!(pub fn span_suggestion<S: Into<MultiSpan>>(&mut self,
 143                                                         sp: S,
 144                                                         msg: &str,
 145                                                         suggestion: String)
 146                                                         -> &mut Self);
 147     forward!(pub fn set_span<S: Into<MultiSpan>>(&mut self, sp: S) -> &mut Self);
 148     forward!(pub fn code(&mut self, s: String) -> &mut Self);
 149
 150     /// Convenience function for internal use, clients should use one of the
 151     /// struct_* methods on Handler.
 152     pub fn new(handler: &'a Handler, level: Level, message: &str) -> DiagnosticBuilder<'a> {
 153         DiagnosticBuilder::new_with_code(handler, level, None, message)
 154     }
 155
 156     /// Convenience function for internal use, clients should use one of the
 157     /// struct_* methods on Handler.
 158     pub fn new_with_code(handler: &'a Handler,
 159                          level: Level,
 160                          code: Option<String>,
 161                          message: &str)
 162                          -> DiagnosticBuilder<'a> {
 163         DiagnosticBuilder {
 164             handler: handler,
 165             diagnostic: Diagnostic::new_with_code(level, code, message)
 166         }
 167     }
 168
 169     pub fn into_diagnostic(mut self) -> Diagnostic {
 170         // annoyingly, the Drop impl means we can't actually move
 171         let result = self.diagnostic.clone();
 172         self.cancel();
 173         result
 174     }
 175 }
 176
 177 impl<'a> Debug for DiagnosticBuilder<'a> {
 178     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 179         self.diagnostic.fmt(f)
 180     }
 181 }
 182
 183 /// Destructor bomb - a DiagnosticBuilder must be either emitted or cancelled or
 184 /// we emit a bug.
 185 impl<'a> Drop for DiagnosticBuilder<'a> {
 186     fn drop(&mut self) {
 187         if !panicking() && !self.cancelled() {
 188             let mut db = DiagnosticBuilder::new(self.handler,
 189                                                 Level::Bug,
 190                                                 "Error constructed but not emitted");
 191             db.emit();
 192             panic!();
 193         }
 194     }
 195 }
 196