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     /// Emit the diagnostic unless `delay` is true,
 104     /// in which case the emission will be delayed as a bug.
 105     ///
 106     /// See `emit` and `delay_as_bug` for details.
 107     pub fn emit_unless(&mut self, delay: bool) {
 108         if delay {
 109             self.delay_as_bug()
 110         } else {
 111             self.emit()
 112         }
 113     }
 114
 115     /// Buffers the diagnostic for later emission, unless handler
 116     /// has disabled such buffering.
 117     pub fn buffer(mut self, buffered_diagnostics: &mut Vec<Diagnostic>) {
 118         if self.handler.flags.dont_buffer_diagnostics ||
 119             self.handler.flags.treat_err_as_bug.is_some()
 120         {
 121             self.emit();
 122             return;
 123         }
 124
 125         // We need to use `ptr::read` because `DiagnosticBuilder`
 126         // implements `Drop`.
 127         let diagnostic;
 128         unsafe {
 129             diagnostic = std::ptr::read(&self.diagnostic);
 130             std::mem::forget(self);
 131         };
 132         // Logging here is useful to help track down where in logs an error was
 133         // actually emitted.
 134         debug!("buffer: diagnostic={:?}", diagnostic);
 135         buffered_diagnostics.push(diagnostic);
 136     }
 137
 138     /// Convenience function for internal use, clients should use one of the
 139     /// span_* methods instead.
 140     pub fn sub<S: Into<MultiSpan>>(
 141         &mut self,
 142         level: Level,
 143         message: &str,
 144         span: Option<S>,
 145     ) -> &mut Self {
 146         let span = span.map(|s| s.into()).unwrap_or_else(|| MultiSpan::new());
 147         self.diagnostic.sub(level, message, span, None);
 148         self
 149     }
 150
 151     /// Delay emission of this diagnostic as a bug.
 152     ///
 153     /// This can be useful in contexts where an error indicates a bug but
 154     /// typically this only happens when other compilation errors have already
 155     /// happened. In those cases this can be used to defer emission of this
 156     /// diagnostic as a bug in the compiler only if no other errors have been
 157     /// emitted.
 158     ///
 159     /// In the meantime, though, callsites are required to deal with the "bug"
 160     /// locally in whichever way makes the most sense.
 161     pub fn delay_as_bug(&mut self) {
 162         self.level = Level::Bug;
 163         self.handler.delay_as_bug(self.diagnostic.clone());
 164         self.cancel();
 165     }
 166
 167     /// Adds a span/label to be included in the resulting snippet.
 168     /// This is pushed onto the `MultiSpan` that was created when the
 169     /// diagnostic was first built. If you don't call this function at
 170     /// all, and you just supplied a `Span` to create the diagnostic,
 171     /// then the snippet will just include that `Span`, which is
 172     /// called the primary span.
 173     pub fn span_label<T: Into<String>>(&mut self, span: Span, label: T) -> &mut Self {
 174         self.diagnostic.span_label(span, label);
 175         self
 176     }
 177
 178     forward!(pub fn note_expected_found(&mut self,
 179                                         label: &dyn fmt::Display,
 180                                         expected: DiagnosticStyledString,
 181                                         found: DiagnosticStyledString,
 182                                         ) -> &mut Self);
 183
 184     forward!(pub fn note_expected_found_extra(&mut self,
 185                                               label: &dyn fmt::Display,
 186                                               expected: DiagnosticStyledString,
 187                                               found: DiagnosticStyledString,
 188                                               expected_extra: &dyn fmt::Display,
 189                                               found_extra: &dyn fmt::Display,
 190                                               ) -> &mut Self);
 191
 192     forward!(pub fn note(&mut self, msg: &str) -> &mut Self);
 193     forward!(pub fn span_note<S: Into<MultiSpan>>(&mut self,
 194                                                   sp: S,
 195                                                   msg: &str,
 196                                                   ) -> &mut Self);
 197     forward!(pub fn warn(&mut self, msg: &str) -> &mut Self);
 198     forward!(pub fn span_warn<S: Into<MultiSpan>>(&mut self, sp: S, msg: &str) -> &mut Self);
 199     forward!(pub fn help(&mut self, msg: &str) -> &mut Self);
 200     forward!(pub fn span_help<S: Into<MultiSpan>>(&mut self,
 201                                                   sp: S,
 202                                                   msg: &str,
 203                                                   ) -> &mut Self);
 204
 205     pub fn multipart_suggestion(
 206         &mut self,
 207         msg: &str,
 208         suggestion: Vec<(Span, String)>,
 209         applicability: Applicability,
 210     ) -> &mut Self {
 211         if !self.allow_suggestions {
 212             return self
 213         }
 214         self.diagnostic.multipart_suggestion(
 215             msg,
 216             suggestion,
 217             applicability,
 218         );
 219         self
 220     }
 221
 222     pub fn tool_only_multipart_suggestion(
 223         &mut self,
 224         msg: &str,
 225         suggestion: Vec<(Span, String)>,
 226         applicability: Applicability,
 227     ) -> &mut Self {
 228         if !self.allow_suggestions {
 229             return self
 230         }
 231         self.diagnostic.tool_only_multipart_suggestion(
 232             msg,
 233             suggestion,
 234             applicability,
 235         );
 236         self
 237     }
 238
 239
 240     pub fn span_suggestion(
 241         &mut self,
 242         sp: Span,
 243         msg: &str,
 244         suggestion: String,
 245         applicability: Applicability,
 246     ) -> &mut Self {
 247         if !self.allow_suggestions {
 248             return self
 249         }
 250         self.diagnostic.span_suggestion(
 251             sp,
 252             msg,
 253             suggestion,
 254             applicability,
 255         );
 256         self
 257     }
 258
 259     pub fn span_suggestions(
 260         &mut self,
 261         sp: Span,
 262         msg: &str,
 263         suggestions: impl Iterator<Item = String>,
 264         applicability: Applicability,
 265     ) -> &mut Self {
 266         if !self.allow_suggestions {
 267             return self
 268         }
 269         self.diagnostic.span_suggestions(
 270             sp,
 271             msg,
 272             suggestions,
 273             applicability,
 274         );
 275         self
 276     }
 277
 278     pub fn span_suggestion_short(
 279         &mut self,
 280         sp: Span,
 281         msg: &str,
 282         suggestion: String,
 283         applicability: Applicability,
 284     ) -> &mut Self {
 285         if !self.allow_suggestions {
 286             return self
 287         }
 288         self.diagnostic.span_suggestion_short(
 289             sp,
 290             msg,
 291             suggestion,
 292             applicability,
 293         );
 294         self
 295     }
 296
 297     pub fn span_suggestion_hidden(
 298         &mut self,
 299         sp: Span,
 300         msg: &str,
 301         suggestion: String,
 302         applicability: Applicability,
 303     ) -> &mut Self {
 304         if !self.allow_suggestions {
 305             return self
 306         }
 307         self.diagnostic.span_suggestion_hidden(
 308             sp,
 309             msg,
 310             suggestion,
 311             applicability,
 312         );
 313         self
 314     }
 315
 316     pub fn tool_only_span_suggestion(
 317         &mut self,
 318         sp: Span,
 319         msg: &str,
 320         suggestion: String,
 321         applicability: Applicability,
 322     ) -> &mut Self {
 323         if !self.allow_suggestions {
 324             return self
 325         }
 326         self.diagnostic.tool_only_span_suggestion(
 327             sp,
 328             msg,
 329             suggestion,
 330             applicability,
 331         );
 332         self
 333     }
 334
 335     forward!(pub fn set_span<S: Into<MultiSpan>>(&mut self, sp: S) -> &mut Self);
 336     forward!(pub fn code(&mut self, s: DiagnosticId) -> &mut Self);
 337
 338     pub fn allow_suggestions(&mut self, allow: bool) -> &mut Self {
 339         self.allow_suggestions = allow;
 340         self
 341     }
 342
 343     /// Convenience function for internal use, clients should use one of the
 344     /// struct_* methods on Handler.
 345     pub fn new(handler: &'a Handler, level: Level, message: &str) -> DiagnosticBuilder<'a> {
 346         DiagnosticBuilder::new_with_code(handler, level, None, message)
 347     }
 348
 349     /// Convenience function for internal use, clients should use one of the
 350     /// struct_* methods on Handler.
 351     crate fn new_with_code(handler: &'a Handler,
 352                          level: Level,
 353                          code: Option<DiagnosticId>,
 354                          message: &str)
 355                          -> DiagnosticBuilder<'a> {
 356         let diagnostic = Diagnostic::new_with_code(level, code, message);
 357         DiagnosticBuilder::new_diagnostic(handler, diagnostic)
 358     }
 359
 360     /// Creates a new `DiagnosticBuilder` with an already constructed
 361     /// diagnostic.
 362     pub fn new_diagnostic(handler: &'a Handler, diagnostic: Diagnostic)
 363                          -> DiagnosticBuilder<'a> {
 364         DiagnosticBuilder {
 365             handler,
 366             diagnostic,
 367             allow_suggestions: true,
 368         }
 369     }
 370 }
 371
 372 impl<'a> Debug for DiagnosticBuilder<'a> {
 373     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 374         self.diagnostic.fmt(f)
 375     }
 376 }
 377
 378 /// Destructor bomb - a `DiagnosticBuilder` must be either emitted or canceled
 379 /// or we emit a bug.
 380 impl<'a> Drop for DiagnosticBuilder<'a> {
 381     fn drop(&mut self) {
 382         if !panicking() && !self.cancelled() {
 383             let mut db = DiagnosticBuilder::new(self.handler,
 384                                                 Level::Bug,
 385                                                 "Error constructed but not emitted");
 386             db.emit();
 387             panic!();
 388         }
 389     }
 390 }