src/librustc_errors/diagnostic_builder.rs

   1 use crate::Diagnostic;
   2 use crate::DiagnosticId;
   3 use crate::DiagnosticStyledString;
   4 use crate::Applicability;
   5
   6 use crate::Level;
   7 use crate::Handler;
   8 use std::fmt::{self, Debug};
   9 use std::ops::{Deref, DerefMut};
  10 use std::thread::panicking;
  11 use syntax_pos::{MultiSpan, Span};
  12 use log::debug;
  13
  14 /// Used for emitting structured error messages and other diagnostic information.
  15 ///
  16 /// If there is some state in a downstream crate you would like to
  17 /// access in the methods of `DiagnosticBuilder` here, consider
  18 /// extending `HandlerFlags`, accessed via `self.handler.flags`.
  19 #[must_use]
  20 #[derive(Clone)]
  21 pub struct DiagnosticBuilder<'a> {
  22     pub handler: &'a Handler,
  23     diagnostic: Diagnostic,
  24     allow_suggestions: bool,
  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     (
  38         $(#[$attrs:meta])*
  39         pub fn $n:ident(&self, $($name:ident: $ty:ty),* $(,)*) -> &Self
  40     ) => {
  41         $(#[$attrs])*
  42         pub fn $n(&self, $($name: $ty),*) -> &Self {
  43             self.diagnostic.$n($($name),*);
  44             self
  45         }
  46     };
  47
  48     // Forward pattern for &mut self -> &mut Self
  49     (
  50         $(#[$attrs:meta])*
  51         pub fn $n:ident(&mut self, $($name:ident: $ty:ty),* $(,)*) -> &mut Self
  52     ) => {
  53         $(#[$attrs])*
  54         pub fn $n(&mut self, $($name: $ty),*) -> &mut Self {
  55             self.diagnostic.$n($($name),*);
  56             self
  57         }
  58     };
  59
  60     // Forward pattern for &mut self -> &mut Self, with S: Into<MultiSpan>
  61     // type parameter. No obvious way to make this more generic.
  62     (
  63         $(#[$attrs:meta])*
  64         pub fn $n:ident<S: Into<MultiSpan>>(
  65             &mut self,
  66             $($name:ident: $ty:ty),*
  67             $(,)*
  68         ) -> &mut Self
  69     ) => {
  70         $(#[$attrs])*
  71         pub fn $n<S: Into<MultiSpan>>(&mut self, $($name: $ty),*) -> &mut Self {
  72             self.diagnostic.$n($($name),*);
  73             self
  74         }
  75     };
  76 }
  77
  78 impl<'a> Deref for DiagnosticBuilder<'a> {
  79     type Target = Diagnostic;
  80
  81     fn deref(&self) -> &Diagnostic {
  82         &self.diagnostic
  83     }
  84 }
  85
  86 impl<'a> DerefMut for DiagnosticBuilder<'a> {
  87     fn deref_mut(&mut self) -> &mut Diagnostic {
  88         &mut self.diagnostic
  89     }
  90 }
  91
  92 impl<'a> DiagnosticBuilder<'a> {
  93     /// Emit the diagnostic.
  94     pub fn emit(&mut self) {
  95         if self.cancelled() {
  96             return;
  97         }
  98
  99         self.handler.emit_db(&self);
 100         self.cancel();
 101     }
 102
 103     /// Buffers the diagnostic for later emission, unless handler
 104     /// has disabled such buffering.
 105     pub fn buffer(mut self, buffered_diagnostics: &mut Vec<Diagnostic>) {
 106         if self.handler.flags.dont_buffer_diagnostics || self.handler.flags.treat_err_as_bug {
 107             self.emit();
 108             return;
 109         }
 110
 111         // We need to use `ptr::read` because `DiagnosticBuilder`
 112         // implements `Drop`.
 113         let diagnostic;
 114         unsafe {
 115             diagnostic = std::ptr::read(&self.diagnostic);
 116             std::mem::forget(self);
 117         };
 118         // Logging here is useful to help track down where in logs an error was
 119         // actually emitted.
 120         debug!("buffer: diagnostic={:?}", diagnostic);
 121         buffered_diagnostics.push(diagnostic);
 122     }
 123
 124     /// Convenience function for internal use, clients should use one of the
 125     /// span_* methods instead.
 126     pub fn sub<S: Into<MultiSpan>>(
 127         &mut self,
 128         level: Level,
 129         message: &str,
 130         span: Option<S>,
 131     ) -> &mut Self {
 132         let span = span.map(|s| s.into()).unwrap_or_else(|| MultiSpan::new());
 133         self.diagnostic.sub(level, message, span, None);
 134         self
 135     }
 136
 137     /// Delay emission of this diagnostic as a bug.
 138     ///
 139     /// This can be useful in contexts where an error indicates a bug but
 140     /// typically this only happens when other compilation errors have already
 141     /// happened. In those cases this can be used to defer emission of this
 142     /// diagnostic as a bug in the compiler only if no other errors have been
 143     /// emitted.
 144     ///
 145     /// In the meantime, though, callsites are required to deal with the "bug"
 146     /// locally in whichever way makes the most sense.
 147     pub fn delay_as_bug(&mut self) {
 148         self.level = Level::Bug;
 149         self.handler.delay_as_bug(self.diagnostic.clone());
 150         self.cancel();
 151     }
 152
 153     /// Adds a span/label to be included in the resulting snippet.
 154     /// This is pushed onto the `MultiSpan` that was created when the
 155     /// diagnostic was first built. If you don't call this function at
 156     /// all, and you just supplied a `Span` to create the diagnostic,
 157     /// then the snippet will just include that `Span`, which is
 158     /// called the primary span.
 159     pub fn span_label<T: Into<String>>(&mut self, span: Span, label: T) -> &mut Self {
 160         self.diagnostic.span_label(span, label);
 161         self
 162     }
 163
 164     forward!(pub fn note_expected_found(&mut self,
 165                                         label: &dyn fmt::Display,
 166                                         expected: DiagnosticStyledString,
 167                                         found: DiagnosticStyledString,
 168                                         ) -> &mut Self);
 169
 170     forward!(pub fn note_expected_found_extra(&mut self,
 171                                               label: &dyn fmt::Display,
 172                                               expected: DiagnosticStyledString,
 173                                               found: DiagnosticStyledString,
 174                                               expected_extra: &dyn fmt::Display,
 175                                               found_extra: &dyn fmt::Display,
 176                                               ) -> &mut Self);
 177
 178     forward!(pub fn note(&mut self, msg: &str) -> &mut Self);
 179     forward!(pub fn span_note<S: Into<MultiSpan>>(&mut self,
 180                                                   sp: S,
 181                                                   msg: &str,
 182                                                   ) -> &mut Self);
 183     forward!(pub fn warn(&mut self, msg: &str) -> &mut Self);
 184     forward!(pub fn span_warn<S: Into<MultiSpan>>(&mut self, sp: S, msg: &str) -> &mut Self);
 185     forward!(pub fn help(&mut self , msg: &str) -> &mut Self);
 186     forward!(pub fn span_help<S: Into<MultiSpan>>(&mut self,
 187                                                   sp: S,
 188                                                   msg: &str,
 189                                                   ) -> &mut Self);
 190
 191     pub fn multipart_suggestion(
 192         &mut self,
 193         msg: &str,
 194         suggestion: Vec<(Span, String)>,
 195         applicability: Applicability,
 196     ) -> &mut Self {
 197         if !self.allow_suggestions {
 198             return self
 199         }
 200         self.diagnostic.multipart_suggestion(
 201             msg,
 202             suggestion,
 203             applicability,
 204         );
 205         self
 206     }
 207
 208     pub fn span_suggestion(
 209         &mut self,
 210         sp: Span,
 211         msg: &str,
 212         suggestion: String,
 213         applicability: Applicability,
 214     ) -> &mut Self {
 215         if !self.allow_suggestions {
 216             return self
 217         }
 218         self.diagnostic.span_suggestion(
 219             sp,
 220             msg,
 221             suggestion,
 222             applicability,
 223         );
 224         self
 225     }
 226
 227     pub fn span_suggestions(
 228         &mut self,
 229         sp: Span,
 230         msg: &str,
 231         suggestions: impl Iterator<Item = String>,
 232         applicability: Applicability,
 233     ) -> &mut Self {
 234         if !self.allow_suggestions {
 235             return self
 236         }
 237         self.diagnostic.span_suggestions(
 238             sp,
 239             msg,
 240             suggestions,
 241             applicability,
 242         );
 243         self
 244     }
 245
 246     pub fn span_suggestion_short(
 247         &mut self,
 248         sp: Span,
 249         msg: &str,
 250         suggestion: String,
 251         applicability: Applicability,
 252     ) -> &mut Self {
 253         if !self.allow_suggestions {
 254             return self
 255         }
 256         self.diagnostic.span_suggestion_short(
 257             sp,
 258             msg,
 259             suggestion,
 260             applicability,
 261         );
 262         self
 263     }
 264     forward!(pub fn set_span<S: Into<MultiSpan>>(&mut self, sp: S) -> &mut Self);
 265     forward!(pub fn code(&mut self, s: DiagnosticId) -> &mut Self);
 266
 267     pub fn allow_suggestions(&mut self, allow: bool) -> &mut Self {
 268         self.allow_suggestions = allow;
 269         self
 270     }
 271
 272     /// Convenience function for internal use, clients should use one of the
 273     /// struct_* methods on Handler.
 274     pub fn new(handler: &'a Handler, level: Level, message: &str) -> DiagnosticBuilder<'a> {
 275         DiagnosticBuilder::new_with_code(handler, level, None, message)
 276     }
 277
 278     /// Convenience function for internal use, clients should use one of the
 279     /// struct_* methods on Handler.
 280     pub fn new_with_code(handler: &'a Handler,
 281                          level: Level,
 282                          code: Option<DiagnosticId>,
 283                          message: &str)
 284                          -> DiagnosticBuilder<'a> {
 285         let diagnostic = Diagnostic::new_with_code(level, code, message);
 286         DiagnosticBuilder::new_diagnostic(handler, diagnostic)
 287     }
 288
 289     /// Creates a new `DiagnosticBuilder` with an already constructed
 290     /// diagnostic.
 291     pub fn new_diagnostic(handler: &'a Handler, diagnostic: Diagnostic)
 292                          -> DiagnosticBuilder<'a> {
 293         DiagnosticBuilder {
 294             handler,
 295             diagnostic,
 296             allow_suggestions: true,
 297         }
 298     }
 299 }
 300
 301 impl<'a> Debug for DiagnosticBuilder<'a> {
 302     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 303         self.diagnostic.fmt(f)
 304     }
 305 }
 306
 307 /// Destructor bomb - a `DiagnosticBuilder` must be either emitted or canceled
 308 /// or we emit a bug.
 309 impl<'a> Drop for DiagnosticBuilder<'a> {
 310     fn drop(&mut self) {
 311         if !panicking() && !self.cancelled() {
 312             let mut db = DiagnosticBuilder::new(self.handler,
 313                                                 Level::Bug,
 314                                                 "Error constructed but not emitted");
 315             db.emit();
 316             panic!();
 317         }
 318     }
 319 }