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Commit | Line | Data |
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3dfed10e | 1 | use crate::astconv::AstConv; |
3dfed10e XL |
2 | use rustc_data_structures::fx::FxHashMap; |
3 | use rustc_errors::{pluralize, struct_span_err, Applicability}; | |
4 | use rustc_hir as hir; | |
5 | use rustc_hir::def_id::DefId; | |
6 | use rustc_middle::ty; | |
7 | use rustc_session::parse::feature_err; | |
fc512014 | 8 | use rustc_span::lev_distance::find_best_match_for_name; |
3dfed10e XL |
9 | use rustc_span::symbol::{sym, Ident}; |
10 | use rustc_span::{Span, DUMMY_SP}; | |
11 | ||
12 | use std::collections::BTreeSet; | |
cdc7bbd5 | 13 | use std::iter; |
3dfed10e XL |
14 | |
15 | impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { | |
16 | /// On missing type parameters, emit an E0393 error and provide a structured suggestion using | |
17 | /// the type parameter's name as a placeholder. | |
18 | pub(crate) fn complain_about_missing_type_params( | |
19 | &self, | |
20 | missing_type_params: Vec<String>, | |
21 | def_id: DefId, | |
22 | span: Span, | |
23 | empty_generic_args: bool, | |
24 | ) { | |
25 | if missing_type_params.is_empty() { | |
26 | return; | |
27 | } | |
28 | let display = | |
29 | missing_type_params.iter().map(|n| format!("`{}`", n)).collect::<Vec<_>>().join(", "); | |
30 | let mut err = struct_span_err!( | |
31 | self.tcx().sess, | |
32 | span, | |
33 | E0393, | |
34 | "the type parameter{} {} must be explicitly specified", | |
35 | pluralize!(missing_type_params.len()), | |
36 | display, | |
37 | ); | |
38 | err.span_label( | |
39 | self.tcx().def_span(def_id), | |
40 | &format!( | |
41 | "type parameter{} {} must be specified for this", | |
42 | pluralize!(missing_type_params.len()), | |
43 | display, | |
44 | ), | |
45 | ); | |
46 | let mut suggested = false; | |
47 | if let (Ok(snippet), true) = ( | |
48 | self.tcx().sess.source_map().span_to_snippet(span), | |
49 | // Don't suggest setting the type params if there are some already: the order is | |
50 | // tricky to get right and the user will already know what the syntax is. | |
51 | empty_generic_args, | |
52 | ) { | |
53 | if snippet.ends_with('>') { | |
54 | // The user wrote `Trait<'a, T>` or similar. To provide an accurate suggestion | |
55 | // we would have to preserve the right order. For now, as clearly the user is | |
56 | // aware of the syntax, we do nothing. | |
57 | } else { | |
58 | // The user wrote `Iterator`, so we don't have a type we can suggest, but at | |
59 | // least we can clue them to the correct syntax `Iterator<Type>`. | |
60 | err.span_suggestion( | |
61 | span, | |
62 | &format!( | |
63 | "set the type parameter{plural} to the desired type{plural}", | |
64 | plural = pluralize!(missing_type_params.len()), | |
65 | ), | |
66 | format!("{}<{}>", snippet, missing_type_params.join(", ")), | |
67 | Applicability::HasPlaceholders, | |
68 | ); | |
69 | suggested = true; | |
70 | } | |
71 | } | |
72 | if !suggested { | |
73 | err.span_label( | |
74 | span, | |
75 | format!( | |
76 | "missing reference{} to {}", | |
77 | pluralize!(missing_type_params.len()), | |
78 | display, | |
79 | ), | |
80 | ); | |
81 | } | |
82 | err.note( | |
83 | "because of the default `Self` reference, type parameters must be \ | |
84 | specified on object types", | |
85 | ); | |
86 | err.emit(); | |
87 | } | |
88 | ||
89 | /// When the code is using the `Fn` traits directly, instead of the `Fn(A) -> B` syntax, emit | |
90 | /// an error and attempt to build a reasonable structured suggestion. | |
91 | pub(crate) fn complain_about_internal_fn_trait( | |
92 | &self, | |
93 | span: Span, | |
94 | trait_def_id: DefId, | |
a2a8927a | 95 | trait_segment: &'_ hir::PathSegment<'_>, |
5099ac24 | 96 | is_impl: bool, |
3dfed10e | 97 | ) { |
5099ac24 FG |
98 | if self.tcx().features().unboxed_closures { |
99 | return; | |
100 | } | |
101 | ||
3dfed10e | 102 | let trait_def = self.tcx().trait_def(trait_def_id); |
5099ac24 FG |
103 | if !trait_def.paren_sugar { |
104 | if trait_segment.args().parenthesized { | |
105 | // For now, require that parenthetical notation be used only with `Fn()` etc. | |
106 | let mut err = feature_err( | |
107 | &self.tcx().sess.parse_sess, | |
108 | sym::unboxed_closures, | |
109 | span, | |
110 | "parenthetical notation is only stable when used with `Fn`-family traits", | |
111 | ); | |
112 | err.emit(); | |
113 | } | |
3dfed10e | 114 | |
5099ac24 FG |
115 | return; |
116 | } | |
117 | ||
118 | let sess = self.tcx().sess; | |
119 | ||
120 | if !trait_segment.args().parenthesized { | |
3dfed10e | 121 | // For now, require that parenthetical notation be used only with `Fn()` etc. |
5099ac24 FG |
122 | let mut err = feature_err( |
123 | &sess.parse_sess, | |
124 | sym::unboxed_closures, | |
125 | span, | |
126 | "the precise format of `Fn`-family traits' type parameters is subject to change", | |
127 | ); | |
128 | // Do not suggest the other syntax if we are in trait impl: | |
129 | // the desugaring would contain an associated type constrait. | |
130 | if !is_impl { | |
131 | let args = trait_segment | |
132 | .args | |
133 | .as_ref() | |
134 | .and_then(|args| args.args.get(0)) | |
135 | .and_then(|arg| match arg { | |
136 | hir::GenericArg::Type(ty) => match ty.kind { | |
137 | hir::TyKind::Tup(t) => t | |
138 | .iter() | |
139 | .map(|e| sess.source_map().span_to_snippet(e.span)) | |
140 | .collect::<Result<Vec<_>, _>>() | |
141 | .map(|a| a.join(", ")), | |
142 | _ => sess.source_map().span_to_snippet(ty.span), | |
143 | } | |
144 | .map(|s| format!("({})", s)) | |
145 | .ok(), | |
146 | _ => None, | |
147 | }) | |
148 | .unwrap_or_else(|| "()".to_string()); | |
149 | let ret = trait_segment | |
150 | .args() | |
151 | .bindings | |
152 | .iter() | |
153 | .find_map(|b| match (b.ident.name == sym::Output, &b.kind) { | |
154 | (true, hir::TypeBindingKind::Equality { term }) => { | |
155 | let span = match term { | |
156 | hir::Term::Ty(ty) => ty.span, | |
157 | hir::Term::Const(c) => self.tcx().hir().span(c.hir_id), | |
158 | }; | |
159 | sess.source_map().span_to_snippet(span).ok() | |
160 | } | |
161 | _ => None, | |
162 | }) | |
163 | .unwrap_or_else(|| "()".to_string()); | |
164 | err.span_suggestion( | |
165 | span, | |
166 | "use parenthetical notation instead", | |
167 | format!("{}{} -> {}", trait_segment.ident, args, ret), | |
168 | Applicability::MaybeIncorrect, | |
169 | ); | |
3dfed10e XL |
170 | } |
171 | err.emit(); | |
172 | } | |
5099ac24 FG |
173 | |
174 | if is_impl { | |
175 | let trait_name = self.tcx().def_path_str(trait_def_id); | |
176 | struct_span_err!( | |
177 | self.tcx().sess, | |
178 | span, | |
179 | E0183, | |
180 | "manual implementations of `{}` are experimental", | |
181 | trait_name, | |
182 | ) | |
183 | .span_label( | |
184 | span, | |
185 | format!("manual implementations of `{}` are experimental", trait_name), | |
186 | ) | |
187 | .help("add `#![feature(unboxed_closures)]` to the crate attributes to enable") | |
188 | .emit(); | |
189 | } | |
3dfed10e XL |
190 | } |
191 | ||
192 | pub(crate) fn complain_about_assoc_type_not_found<I>( | |
193 | &self, | |
194 | all_candidates: impl Fn() -> I, | |
195 | ty_param_name: &str, | |
196 | assoc_name: Ident, | |
197 | span: Span, | |
198 | ) where | |
199 | I: Iterator<Item = ty::PolyTraitRef<'tcx>>, | |
200 | { | |
201 | // The fallback span is needed because `assoc_name` might be an `Fn()`'s `Output` without a | |
202 | // valid span, so we point at the whole path segment instead. | |
203 | let span = if assoc_name.span != DUMMY_SP { assoc_name.span } else { span }; | |
204 | let mut err = struct_span_err!( | |
205 | self.tcx().sess, | |
206 | span, | |
207 | E0220, | |
208 | "associated type `{}` not found for `{}`", | |
209 | assoc_name, | |
210 | ty_param_name | |
211 | ); | |
212 | ||
213 | let all_candidate_names: Vec<_> = all_candidates() | |
5099ac24 | 214 | .flat_map(|r| self.tcx().associated_items(r.def_id()).in_definition_order()) |
3dfed10e | 215 | .filter_map( |
5099ac24 | 216 | |item| if item.kind == ty::AssocKind::Type { Some(item.name) } else { None }, |
3dfed10e XL |
217 | ) |
218 | .collect(); | |
219 | ||
220 | if let (Some(suggested_name), true) = ( | |
fc512014 | 221 | find_best_match_for_name(&all_candidate_names, assoc_name.name, None), |
3dfed10e XL |
222 | assoc_name.span != DUMMY_SP, |
223 | ) { | |
224 | err.span_suggestion( | |
225 | assoc_name.span, | |
226 | "there is an associated type with a similar name", | |
227 | suggested_name.to_string(), | |
228 | Applicability::MaybeIncorrect, | |
229 | ); | |
230 | } else { | |
231 | err.span_label(span, format!("associated type `{}` not found", assoc_name)); | |
232 | } | |
233 | ||
234 | err.emit(); | |
235 | } | |
236 | ||
237 | /// When there are any missing associated types, emit an E0191 error and attempt to supply a | |
238 | /// reasonable suggestion on how to write it. For the case of multiple associated types in the | |
c295e0f8 | 239 | /// same trait bound have the same name (as they come from different supertraits), we instead |
3dfed10e XL |
240 | /// emit a generic note suggesting using a `where` clause to constraint instead. |
241 | pub(crate) fn complain_about_missing_associated_types( | |
242 | &self, | |
243 | associated_types: FxHashMap<Span, BTreeSet<DefId>>, | |
244 | potential_assoc_types: Vec<Span>, | |
245 | trait_bounds: &[hir::PolyTraitRef<'_>], | |
246 | ) { | |
247 | if associated_types.values().all(|v| v.is_empty()) { | |
248 | return; | |
249 | } | |
250 | let tcx = self.tcx(); | |
251 | // FIXME: Marked `mut` so that we can replace the spans further below with a more | |
252 | // appropriate one, but this should be handled earlier in the span assignment. | |
253 | let mut associated_types: FxHashMap<Span, Vec<_>> = associated_types | |
254 | .into_iter() | |
255 | .map(|(span, def_ids)| { | |
256 | (span, def_ids.into_iter().map(|did| tcx.associated_item(did)).collect()) | |
257 | }) | |
258 | .collect(); | |
259 | let mut names = vec![]; | |
260 | ||
261 | // Account for things like `dyn Foo + 'a`, like in tests `issue-22434.rs` and | |
262 | // `issue-22560.rs`. | |
263 | let mut trait_bound_spans: Vec<Span> = vec![]; | |
264 | for (span, items) in &associated_types { | |
265 | if !items.is_empty() { | |
266 | trait_bound_spans.push(*span); | |
267 | } | |
268 | for assoc_item in items { | |
269 | let trait_def_id = assoc_item.container.id(); | |
270 | names.push(format!( | |
271 | "`{}` (from trait `{}`)", | |
5099ac24 | 272 | assoc_item.name, |
3dfed10e XL |
273 | tcx.def_path_str(trait_def_id), |
274 | )); | |
275 | } | |
276 | } | |
277 | if let ([], [bound]) = (&potential_assoc_types[..], &trait_bounds) { | |
6a06907d | 278 | match bound.trait_ref.path.segments { |
3dfed10e XL |
279 | // FIXME: `trait_ref.path.span` can point to a full path with multiple |
280 | // segments, even though `trait_ref.path.segments` is of length `1`. Work | |
281 | // around that bug here, even though it should be fixed elsewhere. | |
282 | // This would otherwise cause an invalid suggestion. For an example, look at | |
283 | // `src/test/ui/issues/issue-28344.rs` where instead of the following: | |
284 | // | |
285 | // error[E0191]: the value of the associated type `Output` | |
286 | // (from trait `std::ops::BitXor`) must be specified | |
287 | // --> $DIR/issue-28344.rs:4:17 | |
288 | // | | |
289 | // LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8); | |
290 | // | ^^^^^^ help: specify the associated type: | |
291 | // | `BitXor<Output = Type>` | |
292 | // | |
293 | // we would output: | |
294 | // | |
295 | // error[E0191]: the value of the associated type `Output` | |
296 | // (from trait `std::ops::BitXor`) must be specified | |
297 | // --> $DIR/issue-28344.rs:4:17 | |
298 | // | | |
299 | // LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8); | |
300 | // | ^^^^^^^^^^^^^ help: specify the associated type: | |
301 | // | `BitXor::bitor<Output = Type>` | |
302 | [segment] if segment.args.is_none() => { | |
303 | trait_bound_spans = vec![segment.ident.span]; | |
304 | associated_types = associated_types | |
305 | .into_iter() | |
306 | .map(|(_, items)| (segment.ident.span, items)) | |
307 | .collect(); | |
308 | } | |
309 | _ => {} | |
310 | } | |
311 | } | |
312 | names.sort(); | |
313 | trait_bound_spans.sort(); | |
314 | let mut err = struct_span_err!( | |
315 | tcx.sess, | |
316 | trait_bound_spans, | |
317 | E0191, | |
318 | "the value of the associated type{} {} must be specified", | |
319 | pluralize!(names.len()), | |
320 | names.join(", "), | |
321 | ); | |
322 | let mut suggestions = vec![]; | |
323 | let mut types_count = 0; | |
324 | let mut where_constraints = vec![]; | |
325 | for (span, assoc_items) in &associated_types { | |
326 | let mut names: FxHashMap<_, usize> = FxHashMap::default(); | |
327 | for item in assoc_items { | |
328 | types_count += 1; | |
5099ac24 | 329 | *names.entry(item.name).or_insert(0) += 1; |
3dfed10e XL |
330 | } |
331 | let mut dupes = false; | |
332 | for item in assoc_items { | |
5099ac24 | 333 | let prefix = if names[&item.name] > 1 { |
3dfed10e XL |
334 | let trait_def_id = item.container.id(); |
335 | dupes = true; | |
336 | format!("{}::", tcx.def_path_str(trait_def_id)) | |
337 | } else { | |
338 | String::new() | |
339 | }; | |
340 | if let Some(sp) = tcx.hir().span_if_local(item.def_id) { | |
5099ac24 | 341 | err.span_label(sp, format!("`{}{}` defined here", prefix, item.name)); |
3dfed10e XL |
342 | } |
343 | } | |
344 | if potential_assoc_types.len() == assoc_items.len() { | |
345 | // Only suggest when the amount of missing associated types equals the number of | |
346 | // extra type arguments present, as that gives us a relatively high confidence | |
347 | // that the user forgot to give the associtated type's name. The canonical | |
348 | // example would be trying to use `Iterator<isize>` instead of | |
349 | // `Iterator<Item = isize>`. | |
cdc7bbd5 | 350 | for (potential, item) in iter::zip(&potential_assoc_types, assoc_items) { |
3dfed10e | 351 | if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(*potential) { |
5099ac24 | 352 | suggestions.push((*potential, format!("{} = {}", item.name, snippet))); |
3dfed10e XL |
353 | } |
354 | } | |
355 | } else if let (Ok(snippet), false) = | |
356 | (tcx.sess.source_map().span_to_snippet(*span), dupes) | |
357 | { | |
358 | let types: Vec<_> = | |
5099ac24 | 359 | assoc_items.iter().map(|item| format!("{} = Type", item.name)).collect(); |
3dfed10e XL |
360 | let code = if snippet.ends_with('>') { |
361 | // The user wrote `Trait<'a>` or similar and we don't have a type we can | |
362 | // suggest, but at least we can clue them to the correct syntax | |
363 | // `Trait<'a, Item = Type>` while accounting for the `<'a>` in the | |
364 | // suggestion. | |
365 | format!("{}, {}>", &snippet[..snippet.len() - 1], types.join(", ")) | |
366 | } else { | |
367 | // The user wrote `Iterator`, so we don't have a type we can suggest, but at | |
368 | // least we can clue them to the correct syntax `Iterator<Item = Type>`. | |
369 | format!("{}<{}>", snippet, types.join(", ")) | |
370 | }; | |
371 | suggestions.push((*span, code)); | |
372 | } else if dupes { | |
373 | where_constraints.push(*span); | |
374 | } | |
375 | } | |
376 | let where_msg = "consider introducing a new type parameter, adding `where` constraints \ | |
377 | using the fully-qualified path to the associated types"; | |
378 | if !where_constraints.is_empty() && suggestions.is_empty() { | |
379 | // If there are duplicates associated type names and a single trait bound do not | |
c295e0f8 | 380 | // use structured suggestion, it means that there are multiple supertraits with |
3dfed10e XL |
381 | // the same associated type name. |
382 | err.help(where_msg); | |
383 | } | |
384 | if suggestions.len() != 1 { | |
385 | // We don't need this label if there's an inline suggestion, show otherwise. | |
386 | for (span, assoc_items) in &associated_types { | |
387 | let mut names: FxHashMap<_, usize> = FxHashMap::default(); | |
388 | for item in assoc_items { | |
389 | types_count += 1; | |
5099ac24 | 390 | *names.entry(item.name).or_insert(0) += 1; |
3dfed10e XL |
391 | } |
392 | let mut label = vec![]; | |
393 | for item in assoc_items { | |
5099ac24 | 394 | let postfix = if names[&item.name] > 1 { |
3dfed10e XL |
395 | let trait_def_id = item.container.id(); |
396 | format!(" (from trait `{}`)", tcx.def_path_str(trait_def_id)) | |
397 | } else { | |
398 | String::new() | |
399 | }; | |
5099ac24 | 400 | label.push(format!("`{}`{}", item.name, postfix)); |
3dfed10e XL |
401 | } |
402 | if !label.is_empty() { | |
403 | err.span_label( | |
404 | *span, | |
405 | format!( | |
406 | "associated type{} {} must be specified", | |
407 | pluralize!(label.len()), | |
408 | label.join(", "), | |
409 | ), | |
410 | ); | |
411 | } | |
412 | } | |
413 | } | |
414 | if !suggestions.is_empty() { | |
415 | err.multipart_suggestion( | |
416 | &format!("specify the associated type{}", pluralize!(types_count)), | |
417 | suggestions, | |
418 | Applicability::HasPlaceholders, | |
419 | ); | |
420 | if !where_constraints.is_empty() { | |
421 | err.span_help(where_constraints, where_msg); | |
422 | } | |
423 | } | |
424 | err.emit(); | |
425 | } | |
426 | } |