1 use crate::{Diagnostic, DiagnosticId, DiagnosticStyledString};
2 use crate::{Applicability, Level, Handler, StashKey};
4 use std::fmt::{self, Debug};
5 use std::ops::{Deref, DerefMut};
6 use std::thread::panicking;
7 use syntax_pos::{MultiSpan, Span};
10 /// Used for emitting structured error messages and other diagnostic information.
12 /// If there is some state in a downstream crate you would like to
13 /// access in the methods of `DiagnosticBuilder` here, consider
14 /// extending `HandlerFlags`, accessed via `self.handler.flags`.
17 pub struct DiagnosticBuilder<'a>(Box<DiagnosticBuilderInner<'a>>);
19 /// This is a large type, and often used as a return value, especially within
20 /// the frequently-used `PResult` type. In theory, return value optimization
21 /// (RVO) should avoid unnecessary copying. In practice, it does not (at the
22 /// time of writing). The split between `DiagnosticBuilder` and
23 /// `DiagnosticBuilderInner` exists to avoid many `memcpy` calls.
26 struct DiagnosticBuilderInner<'a> {
28 diagnostic: Diagnostic,
29 allow_suggestions: bool,
32 /// In general, the `DiagnosticBuilder` uses deref to allow access to
33 /// the fields and methods of the embedded `diagnostic` in a
34 /// transparent way. *However,* many of the methods are intended to
35 /// be used in a chained way, and hence ought to return `self`. In
36 /// that case, we can't just naively forward to the method on the
37 /// `diagnostic`, because the return type would be a `&Diagnostic`
38 /// instead of a `&DiagnosticBuilder<'a>`. This `forward!` macro makes
39 /// it easy to declare such methods on the builder.
40 macro_rules! forward {
41 // Forward pattern for &self -> &Self
44 pub fn $n:ident(&self, $($name:ident: $ty:ty),* $(,)?) -> &Self
47 pub fn $n(&self, $($name: $ty),*) -> &Self {
48 self.diagnostic.$n($($name),*);
53 // Forward pattern for &mut self -> &mut Self
56 pub fn $n:ident(&mut self, $($name:ident: $ty:ty),* $(,)?) -> &mut Self
59 pub fn $n(&mut self, $($name: $ty),*) -> &mut Self {
60 self.0.diagnostic.$n($($name),*);
65 // Forward pattern for &mut self -> &mut Self, with S: Into<MultiSpan>
66 // type parameter. No obvious way to make this more generic.
69 pub fn $n:ident<S: Into<MultiSpan>>(
71 $($name:ident: $ty:ty),*
76 pub fn $n<S: Into<MultiSpan>>(&mut self, $($name: $ty),*) -> &mut Self {
77 self.0.diagnostic.$n($($name),*);
83 impl<'a> Deref for DiagnosticBuilder<'a> {
84 type Target = Diagnostic;
86 fn deref(&self) -> &Diagnostic {
91 impl<'a> DerefMut for DiagnosticBuilder<'a> {
92 fn deref_mut(&mut self) -> &mut Diagnostic {
93 &mut self.0.diagnostic
97 impl<'a> DiagnosticBuilder<'a> {
98 /// Emit the diagnostic.
99 pub fn emit(&mut self) {
100 self.0.handler.emit_diagnostic(&self);
104 /// Emit the diagnostic unless `delay` is true,
105 /// in which case the emission will be delayed as a bug.
107 /// See `emit` and `delay_as_bug` for details.
108 pub fn emit_unless(&mut self, delay: bool) {
116 /// Stashes diagnostic for possible later improvement in a different,
117 /// later stage of the compiler. The diagnostic can be accessed with
118 /// the provided `span` and `key` through `.steal_diagnostic` on `Handler`.
120 /// As with `buffer`, this is unless the handler has disabled such buffering.
121 pub fn stash(self, span: Span, key: StashKey) {
122 if let Some((diag, handler)) = self.into_diagnostic() {
123 handler.stash_diagnostic(span, key, diag);
127 /// Converts the builder to a `Diagnostic` for later emission,
128 /// unless handler has disabled such buffering.
129 pub fn into_diagnostic(mut self) -> Option<(Diagnostic, &'a Handler)> {
130 if self.0.handler.flags.dont_buffer_diagnostics ||
131 self.0.handler.flags.treat_err_as_bug.is_some()
137 let handler = self.0.handler;
139 // We need to use `ptr::read` because `DiagnosticBuilder` implements `Drop`.
142 diagnostic = std::ptr::read(&self.0.diagnostic);
143 std::mem::forget(self);
145 // Logging here is useful to help track down where in logs an error was
147 debug!("buffer: diagnostic={:?}", diagnostic);
149 Some((diagnostic, handler))
152 /// Buffers the diagnostic for later emission,
153 /// unless handler has disabled such buffering.
154 pub fn buffer(self, buffered_diagnostics: &mut Vec<Diagnostic>) {
155 buffered_diagnostics.extend(self.into_diagnostic().map(|(diag, _)| diag));
158 /// Convenience function for internal use, clients should use one of the
159 /// span_* methods instead.
160 pub fn sub<S: Into<MultiSpan>>(
166 let span = span.map(|s| s.into()).unwrap_or_else(|| MultiSpan::new());
167 self.0.diagnostic.sub(level, message, span, None);
171 /// Delay emission of this diagnostic as a bug.
173 /// This can be useful in contexts where an error indicates a bug but
174 /// typically this only happens when other compilation errors have already
175 /// happened. In those cases this can be used to defer emission of this
176 /// diagnostic as a bug in the compiler only if no other errors have been
179 /// In the meantime, though, callsites are required to deal with the "bug"
180 /// locally in whichever way makes the most sense.
181 pub fn delay_as_bug(&mut self) {
182 self.level = Level::Bug;
183 self.0.handler.delay_as_bug(self.0.diagnostic.clone());
187 /// Adds a span/label to be included in the resulting snippet.
188 /// This is pushed onto the `MultiSpan` that was created when the
189 /// diagnostic was first built. If you don't call this function at
190 /// all, and you just supplied a `Span` to create the diagnostic,
191 /// then the snippet will just include that `Span`, which is
192 /// called the primary span.
193 pub fn span_label<T: Into<String>>(&mut self, span: Span, label: T) -> &mut Self {
194 self.0.diagnostic.span_label(span, label);
198 forward!(pub fn note_expected_found(&mut self,
199 label: &dyn fmt::Display,
200 expected: DiagnosticStyledString,
201 found: DiagnosticStyledString,
204 forward!(pub fn note_expected_found_extra(&mut self,
205 label: &dyn fmt::Display,
206 expected: DiagnosticStyledString,
207 found: DiagnosticStyledString,
208 expected_extra: &dyn fmt::Display,
209 found_extra: &dyn fmt::Display,
212 forward!(pub fn note_unsuccessfull_coercion(&mut self,
213 expected: DiagnosticStyledString,
214 found: DiagnosticStyledString,
217 forward!(pub fn note(&mut self, msg: &str) -> &mut Self);
218 forward!(pub fn span_note<S: Into<MultiSpan>>(&mut self,
222 forward!(pub fn warn(&mut self, msg: &str) -> &mut Self);
223 forward!(pub fn span_warn<S: Into<MultiSpan>>(&mut self, sp: S, msg: &str) -> &mut Self);
224 forward!(pub fn help(&mut self, msg: &str) -> &mut Self);
225 forward!(pub fn span_help<S: Into<MultiSpan>>(&mut self,
230 pub fn multipart_suggestion(
233 suggestion: Vec<(Span, String)>,
234 applicability: Applicability,
236 if !self.0.allow_suggestions {
239 self.0.diagnostic.multipart_suggestion(
247 pub fn tool_only_multipart_suggestion(
250 suggestion: Vec<(Span, String)>,
251 applicability: Applicability,
253 if !self.0.allow_suggestions {
256 self.0.diagnostic.tool_only_multipart_suggestion(
264 pub fn span_suggestion(
269 applicability: Applicability,
271 if !self.0.allow_suggestions {
274 self.0.diagnostic.span_suggestion(
283 pub fn span_suggestions(
287 suggestions: impl Iterator<Item = String>,
288 applicability: Applicability,
290 if !self.0.allow_suggestions {
293 self.0.diagnostic.span_suggestions(
302 pub fn span_suggestion_short(
307 applicability: Applicability,
309 if !self.0.allow_suggestions {
312 self.0.diagnostic.span_suggestion_short(
321 pub fn span_suggestion_hidden(
326 applicability: Applicability,
328 if !self.0.allow_suggestions {
331 self.0.diagnostic.span_suggestion_hidden(
340 pub fn tool_only_span_suggestion(
345 applicability: Applicability,
347 if !self.0.allow_suggestions {
350 self.0.diagnostic.tool_only_span_suggestion(
359 forward!(pub fn set_span<S: Into<MultiSpan>>(&mut self, sp: S) -> &mut Self);
360 forward!(pub fn code(&mut self, s: DiagnosticId) -> &mut Self);
362 pub fn allow_suggestions(&mut self, allow: bool) -> &mut Self {
363 self.0.allow_suggestions = allow;
367 /// Convenience function for internal use, clients should use one of the
368 /// struct_* methods on Handler.
369 crate fn new(handler: &'a Handler, level: Level, message: &str) -> DiagnosticBuilder<'a> {
370 DiagnosticBuilder::new_with_code(handler, level, None, message)
373 /// Convenience function for internal use, clients should use one of the
374 /// struct_* methods on Handler.
375 crate fn new_with_code(handler: &'a Handler,
377 code: Option<DiagnosticId>,
379 -> DiagnosticBuilder<'a> {
380 let diagnostic = Diagnostic::new_with_code(level, code, message);
381 DiagnosticBuilder::new_diagnostic(handler, diagnostic)
384 /// Creates a new `DiagnosticBuilder` with an already constructed
386 crate fn new_diagnostic(handler: &'a Handler, diagnostic: Diagnostic)
387 -> DiagnosticBuilder<'a> {
388 DiagnosticBuilder(Box::new(DiagnosticBuilderInner {
391 allow_suggestions: true,
396 impl<'a> Debug for DiagnosticBuilder<'a> {
397 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
398 self.0.diagnostic.fmt(f)
402 /// Destructor bomb - a `DiagnosticBuilder` must be either emitted or canceled
403 /// or we emit a bug.
404 impl<'a> Drop for DiagnosticBuilder<'a> {
406 if !panicking() && !self.cancelled() {
407 let mut db = DiagnosticBuilder::new(
410 "the following error was constructed but not emitted",