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