]>
Commit | Line | Data |
---|---|---|
1b1a35ee | 1 | use crate::errors::LifetimesOrBoundsMismatchOnTrait; |
ba9703b0 | 2 | use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorReported}; |
dfeec247 XL |
3 | use rustc_hir as hir; |
4 | use rustc_hir::def::{DefKind, Res}; | |
5 | use rustc_hir::intravisit; | |
6 | use rustc_hir::{GenericParamKind, ImplItemKind, TraitItemKind}; | |
74b04a01 | 7 | use rustc_infer::infer::{self, InferOk, TyCtxtInferExt}; |
29967ef6 | 8 | use rustc_infer::traits::util; |
f035d41b | 9 | use rustc_middle::ty; |
ba9703b0 | 10 | use rustc_middle::ty::error::{ExpectedFound, TypeError}; |
3dfed10e | 11 | use rustc_middle::ty::subst::{InternalSubsts, Subst}; |
ba9703b0 | 12 | use rustc_middle::ty::util::ExplicitSelf; |
3dfed10e | 13 | use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt}; |
dfeec247 | 14 | use rustc_span::Span; |
ba9703b0 XL |
15 | use rustc_trait_selection::traits::error_reporting::InferCtxtExt; |
16 | use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode, Reveal}; | |
85aaf69f | 17 | |
dfeec247 | 18 | use super::{potentially_plural_count, FnCtxt, Inherited}; |
60c5eb7d | 19 | |
85aaf69f SL |
20 | /// Checks that a method from an impl conforms to the signature of |
21 | /// the same method as declared in the trait. | |
22 | /// | |
23 | /// # Parameters | |
24 | /// | |
9fa01778 XL |
25 | /// - `impl_m`: type of the method we are checking |
26 | /// - `impl_m_span`: span to use for reporting errors | |
27 | /// - `trait_m`: the method in the trait | |
28 | /// - `impl_trait_ref`: the TraitRef corresponding to the trait implementation | |
85aaf69f | 29 | |
dfeec247 | 30 | crate fn compare_impl_method<'tcx>( |
dc9dc135 XL |
31 | tcx: TyCtxt<'tcx>, |
32 | impl_m: &ty::AssocItem, | |
33 | impl_m_span: Span, | |
34 | trait_m: &ty::AssocItem, | |
35 | impl_trait_ref: ty::TraitRef<'tcx>, | |
36 | trait_item_span: Option<Span>, | |
37 | ) { | |
dfeec247 | 38 | debug!("compare_impl_method(impl_trait_ref={:?})", impl_trait_ref); |
85aaf69f | 39 | |
ba9703b0 | 40 | let impl_m_span = tcx.sess.source_map().guess_head_span(impl_m_span); |
2c00a5a8 | 41 | |
dfeec247 XL |
42 | if let Err(ErrorReported) = compare_self_type(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) |
43 | { | |
c30ab7b3 | 44 | return; |
85aaf69f SL |
45 | } |
46 | ||
dfeec247 XL |
47 | if let Err(ErrorReported) = |
48 | compare_number_of_generics(tcx, impl_m, impl_m_span, trait_m, trait_item_span) | |
49 | { | |
c30ab7b3 SL |
50 | return; |
51 | } | |
9e0c209e | 52 | |
dfeec247 XL |
53 | if let Err(ErrorReported) = |
54 | compare_number_of_method_arguments(tcx, impl_m, impl_m_span, trait_m, trait_item_span) | |
55 | { | |
85aaf69f SL |
56 | return; |
57 | } | |
58 | ||
dfeec247 | 59 | if let Err(ErrorReported) = compare_synthetic_generics(tcx, impl_m, trait_m) { |
abe05a73 XL |
60 | return; |
61 | } | |
62 | ||
dfeec247 XL |
63 | if let Err(ErrorReported) = |
64 | compare_predicate_entailment(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) | |
65 | { | |
85aaf69f SL |
66 | return; |
67 | } | |
c30ab7b3 SL |
68 | } |
69 | ||
dc9dc135 XL |
70 | fn compare_predicate_entailment<'tcx>( |
71 | tcx: TyCtxt<'tcx>, | |
72 | impl_m: &ty::AssocItem, | |
73 | impl_m_span: Span, | |
74 | trait_m: &ty::AssocItem, | |
75 | impl_trait_ref: ty::TraitRef<'tcx>, | |
76 | ) -> Result<(), ErrorReported> { | |
476ff2be SL |
77 | let trait_to_impl_substs = impl_trait_ref.substs; |
78 | ||
7cac9316 XL |
79 | // This node-id should be used for the `body_id` field on each |
80 | // `ObligationCause` (and the `FnCtxt`). This is what | |
81 | // `regionck_item` expects. | |
3dfed10e | 82 | let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); |
7cac9316 | 83 | |
f035d41b XL |
84 | // We sometimes modify the span further down. |
85 | let mut cause = ObligationCause::new( | |
86 | impl_m_span, | |
87 | impl_m_hir_id, | |
88 | ObligationCauseCode::CompareImplMethodObligation { | |
8faf50e0 | 89 | item_name: impl_m.ident.name, |
476ff2be SL |
90 | impl_item_def_id: impl_m.def_id, |
91 | trait_item_def_id: trait_m.def_id, | |
476ff2be | 92 | }, |
f035d41b | 93 | ); |
85aaf69f SL |
94 | |
95 | // This code is best explained by example. Consider a trait: | |
96 | // | |
f035d41b XL |
97 | // trait Trait<'t, T> { |
98 | // fn method<'a, M>(t: &'t T, m: &'a M) -> Self; | |
85aaf69f SL |
99 | // } |
100 | // | |
101 | // And an impl: | |
102 | // | |
103 | // impl<'i, 'j, U> Trait<'j, &'i U> for Foo { | |
f035d41b | 104 | // fn method<'b, N>(t: &'j &'i U, m: &'b N) -> Foo; |
85aaf69f SL |
105 | // } |
106 | // | |
107 | // We wish to decide if those two method types are compatible. | |
108 | // | |
109 | // We start out with trait_to_impl_substs, that maps the trait | |
110 | // type parameters to impl type parameters. This is taken from the | |
111 | // impl trait reference: | |
112 | // | |
113 | // trait_to_impl_substs = {'t => 'j, T => &'i U, Self => Foo} | |
114 | // | |
115 | // We create a mapping `dummy_substs` that maps from the impl type | |
116 | // parameters to fresh types and regions. For type parameters, | |
117 | // this is the identity transform, but we could as well use any | |
0bf4aa26 | 118 | // placeholder types. For regions, we convert from bound to free |
85aaf69f SL |
119 | // regions (Note: but only early-bound regions, i.e., those |
120 | // declared on the impl or used in type parameter bounds). | |
121 | // | |
f035d41b | 122 | // impl_to_placeholder_substs = {'i => 'i0, U => U0, N => N0 } |
85aaf69f | 123 | // |
f035d41b | 124 | // Now we can apply placeholder_substs to the type of the impl method |
0bf4aa26 | 125 | // to yield a new function type in terms of our fresh, placeholder |
85aaf69f SL |
126 | // types: |
127 | // | |
128 | // <'b> fn(t: &'i0 U0, m: &'b) -> Foo | |
129 | // | |
130 | // We now want to extract and substitute the type of the *trait* | |
131 | // method and compare it. To do so, we must create a compound | |
132 | // substitution by combining trait_to_impl_substs and | |
f035d41b | 133 | // impl_to_placeholder_substs, and also adding a mapping for the method |
85aaf69f SL |
134 | // type parameters. We extend the mapping to also include |
135 | // the method parameters. | |
136 | // | |
f035d41b | 137 | // trait_to_placeholder_substs = { T => &'i0 U0, Self => Foo, M => N0 } |
85aaf69f SL |
138 | // |
139 | // Applying this to the trait method type yields: | |
140 | // | |
141 | // <'a> fn(t: &'i0 U0, m: &'a) -> Foo | |
142 | // | |
143 | // This type is also the same but the name of the bound region ('a | |
144 | // vs 'b). However, the normal subtyping rules on fn types handle | |
145 | // this kind of equivalency just fine. | |
146 | // | |
147 | // We now use these substitutions to ensure that all declared bounds are | |
148 | // satisfied by the implementation's method. | |
149 | // | |
150 | // We do this by creating a parameter environment which contains a | |
f035d41b XL |
151 | // substitution corresponding to impl_to_placeholder_substs. We then build |
152 | // trait_to_placeholder_substs and use it to convert the predicates contained | |
0bf4aa26 | 153 | // in the trait_m.generics to the placeholder form. |
85aaf69f SL |
154 | // |
155 | // Finally we register each of these predicates as an obligation in | |
156 | // a fresh FulfillmentCtxt, and invoke select_all_or_error. | |
157 | ||
0bf4aa26 | 158 | // Create mapping from impl to placeholder. |
f035d41b | 159 | let impl_to_placeholder_substs = InternalSubsts::identity_for_item(tcx, impl_m.def_id); |
85aaf69f | 160 | |
0bf4aa26 | 161 | // Create mapping from trait to placeholder. |
f035d41b XL |
162 | let trait_to_placeholder_substs = |
163 | impl_to_placeholder_substs.rebase_onto(tcx, impl_m.container.id(), trait_to_impl_substs); | |
164 | debug!("compare_impl_method: trait_to_placeholder_substs={:?}", trait_to_placeholder_substs); | |
85aaf69f | 165 | |
7cac9316 XL |
166 | let impl_m_generics = tcx.generics_of(impl_m.def_id); |
167 | let trait_m_generics = tcx.generics_of(trait_m.def_id); | |
168 | let impl_m_predicates = tcx.predicates_of(impl_m.def_id); | |
169 | let trait_m_predicates = tcx.predicates_of(trait_m.def_id); | |
476ff2be | 170 | |
c30ab7b3 | 171 | // Check region bounds. |
dfeec247 XL |
172 | check_region_bounds_on_impl_item( |
173 | tcx, | |
174 | impl_m_span, | |
175 | impl_m, | |
176 | trait_m, | |
177 | &trait_m_generics, | |
178 | &impl_m_generics, | |
179 | )?; | |
c30ab7b3 SL |
180 | |
181 | // Create obligations for each predicate declared by the impl | |
182 | // definition in the context of the trait's parameter | |
183 | // environment. We can't just use `impl_env.caller_bounds`, | |
184 | // however, because we want to replace all late-bound regions with | |
185 | // region variables. | |
7cac9316 XL |
186 | let impl_predicates = tcx.predicates_of(impl_m_predicates.parent.unwrap()); |
187 | let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); | |
c30ab7b3 SL |
188 | |
189 | debug!("compare_impl_method: impl_bounds={:?}", hybrid_preds); | |
190 | ||
191 | // This is the only tricky bit of the new way we check implementation methods | |
192 | // We need to build a set of predicates where only the method-level bounds | |
193 | // are from the trait and we assume all other bounds from the implementation | |
194 | // to be previously satisfied. | |
195 | // | |
196 | // We then register the obligations from the impl_m and check to see | |
197 | // if all constraints hold. | |
dfeec247 XL |
198 | hybrid_preds |
199 | .predicates | |
f035d41b | 200 | .extend(trait_m_predicates.instantiate_own(tcx, trait_to_placeholder_substs).predicates); |
c30ab7b3 | 201 | |
0bf4aa26 | 202 | // Construct trait parameter environment and then shift it into the placeholder viewpoint. |
c30ab7b3 SL |
203 | // The key step here is to update the caller_bounds's predicates to be |
204 | // the new hybrid bounds we computed. | |
9fa01778 | 205 | let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_hir_id); |
1b1a35ee XL |
206 | let param_env = |
207 | ty::ParamEnv::new(tcx.intern_predicates(&hybrid_preds.predicates), Reveal::UserFacing); | |
dfeec247 XL |
208 | let param_env = traits::normalize_param_env_or_error( |
209 | tcx, | |
210 | impl_m.def_id, | |
211 | param_env, | |
212 | normalize_cause.clone(), | |
0731742a | 213 | ); |
7cac9316 | 214 | |
041b39d2 | 215 | tcx.infer_ctxt().enter(|infcx| { |
ba9703b0 | 216 | let inh = Inherited::new(infcx, impl_m.def_id.expect_local()); |
c30ab7b3 | 217 | let infcx = &inh.infcx; |
a7813a04 | 218 | |
f035d41b | 219 | debug!("compare_impl_method: caller_bounds={:?}", param_env.caller_bounds()); |
a7813a04 XL |
220 | |
221 | let mut selcx = traits::SelectionContext::new(&infcx); | |
222 | ||
f035d41b | 223 | let impl_m_own_bounds = impl_m_predicates.instantiate_own(tcx, impl_to_placeholder_substs); |
a1dfa0c6 | 224 | let (impl_m_own_bounds, _) = infcx.replace_bound_vars_with_fresh_vars( |
83c7162d XL |
225 | impl_m_span, |
226 | infer::HigherRankedType, | |
fc512014 | 227 | ty::Binder::bind(impl_m_own_bounds.predicates), |
83c7162d | 228 | ); |
9e0c209e | 229 | for predicate in impl_m_own_bounds { |
cc61c64b | 230 | let traits::Normalized { value: predicate, obligations } = |
fc512014 | 231 | traits::normalize(&mut selcx, param_env, normalize_cause.clone(), predicate); |
a7813a04 | 232 | |
cc61c64b | 233 | inh.register_predicates(obligations); |
7cac9316 | 234 | inh.register_predicate(traits::Obligation::new(cause.clone(), param_env, predicate)); |
a7813a04 | 235 | } |
85aaf69f | 236 | |
a7813a04 XL |
237 | // We now need to check that the signature of the impl method is |
238 | // compatible with that of the trait method. We do this by | |
239 | // checking that `impl_fty <: trait_fty`. | |
240 | // | |
241 | // FIXME. Unfortunately, this doesn't quite work right now because | |
242 | // associated type normalization is not integrated into subtype | |
243 | // checks. For the comparison to be valid, we need to | |
244 | // normalize the associated types in the impl/trait methods | |
245 | // first. However, because function types bind regions, just | |
246 | // calling `normalize_associated_types_in` would have no effect on | |
247 | // any associated types appearing in the fn arguments or return | |
248 | // type. | |
249 | ||
0bf4aa26 | 250 | // Compute placeholder form of impl and trait method tys. |
3157f602 | 251 | let tcx = infcx.tcx; |
476ff2be | 252 | |
a1dfa0c6 XL |
253 | let (impl_sig, _) = infcx.replace_bound_vars_with_fresh_vars( |
254 | impl_m_span, | |
255 | infer::HigherRankedType, | |
fc512014 | 256 | tcx.fn_sig(impl_m.def_id), |
a1dfa0c6 | 257 | ); |
3157f602 | 258 | let impl_sig = |
fc512014 | 259 | inh.normalize_associated_types_in(impl_m_span, impl_m_hir_id, param_env, impl_sig); |
83c7162d | 260 | let impl_fty = tcx.mk_fn_ptr(ty::Binder::bind(impl_sig)); |
3157f602 XL |
261 | debug!("compare_impl_method: impl_fty={:?}", impl_fty); |
262 | ||
fc512014 | 263 | let trait_sig = tcx.liberate_late_bound_regions(impl_m.def_id, tcx.fn_sig(trait_m.def_id)); |
f035d41b | 264 | let trait_sig = trait_sig.subst(tcx, trait_to_placeholder_substs); |
3157f602 | 265 | let trait_sig = |
fc512014 | 266 | inh.normalize_associated_types_in(impl_m_span, impl_m_hir_id, param_env, trait_sig); |
83c7162d | 267 | let trait_fty = tcx.mk_fn_ptr(ty::Binder::bind(trait_sig)); |
3157f602 XL |
268 | |
269 | debug!("compare_impl_method: trait_fty={:?}", trait_fty); | |
270 | ||
dfeec247 XL |
271 | let sub_result = infcx.at(&cause, param_env).sup(trait_fty, impl_fty).map( |
272 | |InferOk { obligations, .. }| { | |
273 | inh.register_predicates(obligations); | |
274 | }, | |
275 | ); | |
c30ab7b3 SL |
276 | |
277 | if let Err(terr) = sub_result { | |
dfeec247 XL |
278 | debug!("sub_types failed: impl ty {:?}, trait ty {:?}", impl_fty, trait_fty); |
279 | ||
280 | let (impl_err_span, trait_err_span) = extract_spans_for_error_reporting( | |
281 | &infcx, param_env, &terr, &cause, impl_m, impl_sig, trait_m, trait_sig, | |
282 | ); | |
283 | ||
f035d41b | 284 | cause.make_mut().span = impl_err_span; |
dfeec247 XL |
285 | |
286 | let mut diag = struct_span_err!( | |
287 | tcx.sess, | |
288 | cause.span(tcx), | |
289 | E0053, | |
290 | "method `{}` has an incompatible type for trait", | |
291 | trait_m.ident | |
292 | ); | |
8faf50e0 XL |
293 | if let TypeError::Mutability = terr { |
294 | if let Some(trait_err_span) = trait_err_span { | |
dfeec247 XL |
295 | if let Ok(trait_err_str) = tcx.sess.source_map().span_to_snippet(trait_err_span) |
296 | { | |
9fa01778 | 297 | diag.span_suggestion( |
8faf50e0 | 298 | impl_err_span, |
5869c6ff | 299 | "consider changing the mutability to match the trait", |
0bf4aa26 XL |
300 | trait_err_str, |
301 | Applicability::MachineApplicable, | |
8faf50e0 XL |
302 | ); |
303 | } | |
304 | } | |
305 | } | |
c30ab7b3 | 306 | |
dfeec247 XL |
307 | infcx.note_type_err( |
308 | &mut diag, | |
309 | &cause, | |
310 | trait_err_span.map(|sp| (sp, "type in trait".to_owned())), | |
311 | Some(infer::ValuePairs::Types(ExpectedFound { | |
312 | expected: trait_fty, | |
313 | found: impl_fty, | |
314 | })), | |
315 | &terr, | |
316 | ); | |
5bcae85e | 317 | diag.emit(); |
c30ab7b3 | 318 | return Err(ErrorReported); |
a7813a04 | 319 | } |
85aaf69f | 320 | |
a7813a04 XL |
321 | // Check that all obligations are satisfied by the implementation's |
322 | // version. | |
cc61c64b | 323 | if let Err(ref errors) = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx) { |
0531ce1d | 324 | infcx.report_fulfillment_errors(errors, None, false); |
c30ab7b3 | 325 | return Err(ErrorReported); |
85aaf69f | 326 | } |
85aaf69f | 327 | |
a7813a04 | 328 | // Finally, resolve all regions. This catches wily misuses of |
c30ab7b3 | 329 | // lifetime parameters. |
9fa01778 | 330 | let fcx = FnCtxt::new(&inh, param_env, impl_m_hir_id); |
29967ef6 | 331 | fcx.regionck_item(impl_m_hir_id, impl_m_span, trait_sig.inputs_and_output); |
85aaf69f | 332 | |
c30ab7b3 SL |
333 | Ok(()) |
334 | }) | |
335 | } | |
336 | ||
dfeec247 | 337 | fn check_region_bounds_on_impl_item<'tcx>( |
dc9dc135 XL |
338 | tcx: TyCtxt<'tcx>, |
339 | span: Span, | |
340 | impl_m: &ty::AssocItem, | |
341 | trait_m: &ty::AssocItem, | |
342 | trait_generics: &ty::Generics, | |
343 | impl_generics: &ty::Generics, | |
dc9dc135 | 344 | ) -> Result<(), ErrorReported> { |
94b46f34 XL |
345 | let trait_params = trait_generics.own_counts().lifetimes; |
346 | let impl_params = impl_generics.own_counts().lifetimes; | |
c30ab7b3 | 347 | |
dfeec247 XL |
348 | debug!( |
349 | "check_region_bounds_on_impl_item: \ | |
c30ab7b3 | 350 | trait_generics={:?} \ |
dfeec247 XL |
351 | impl_generics={:?}", |
352 | trait_generics, impl_generics | |
353 | ); | |
c30ab7b3 SL |
354 | |
355 | // Must have same number of early-bound lifetime parameters. | |
356 | // Unfortunately, if the user screws up the bounds, then this | |
357 | // will change classification between early and late. E.g., | |
358 | // if in trait we have `<'a,'b:'a>`, and in impl we just have | |
359 | // `<'a,'b>`, then we have 2 early-bound lifetime parameters | |
360 | // in trait but 0 in the impl. But if we report "expected 2 | |
361 | // but found 0" it's confusing, because it looks like there | |
362 | // are zero. Since I don't quite know how to phrase things at | |
363 | // the moment, give a kind of vague error message. | |
94b46f34 | 364 | if trait_params != impl_params { |
dfeec247 | 365 | let item_kind = assoc_item_kind_str(impl_m); |
ba9703b0 | 366 | let def_span = tcx.sess.source_map().guess_head_span(span); |
5869c6ff XL |
367 | let span = tcx.hir().get_generics(impl_m.def_id).map_or(def_span, |g| g.span); |
368 | let generics_span = tcx.hir().span_if_local(trait_m.def_id).map(|sp| { | |
1b1a35ee | 369 | let def_sp = tcx.sess.source_map().guess_head_span(sp); |
5869c6ff XL |
370 | tcx.hir().get_generics(trait_m.def_id).map_or(def_sp, |g| g.span) |
371 | }); | |
372 | ||
1b1a35ee | 373 | tcx.sess.emit_err(LifetimesOrBoundsMismatchOnTrait { |
8faf50e0 | 374 | span, |
dfeec247 | 375 | item_kind, |
1b1a35ee XL |
376 | ident: impl_m.ident, |
377 | generics_span, | |
378 | }); | |
c30ab7b3 | 379 | return Err(ErrorReported); |
85aaf69f | 380 | } |
9e0c209e | 381 | |
0bf4aa26 | 382 | Ok(()) |
c30ab7b3 | 383 | } |
9e0c209e | 384 | |
dc9dc135 XL |
385 | fn extract_spans_for_error_reporting<'a, 'tcx>( |
386 | infcx: &infer::InferCtxt<'a, 'tcx>, | |
387 | param_env: ty::ParamEnv<'tcx>, | |
388 | terr: &TypeError<'_>, | |
389 | cause: &ObligationCause<'tcx>, | |
390 | impl_m: &ty::AssocItem, | |
391 | impl_sig: ty::FnSig<'tcx>, | |
392 | trait_m: &ty::AssocItem, | |
393 | trait_sig: ty::FnSig<'tcx>, | |
394 | ) -> (Span, Option<Span>) { | |
c30ab7b3 | 395 | let tcx = infcx.tcx; |
3dfed10e | 396 | let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); |
dfeec247 | 397 | let (impl_m_output, impl_m_iter) = match tcx.hir().expect_impl_item(impl_m_hir_id).kind { |
ba9703b0 | 398 | ImplItemKind::Fn(ref impl_m_sig, _) => { |
c30ab7b3 SL |
399 | (&impl_m_sig.decl.output, impl_m_sig.decl.inputs.iter()) |
400 | } | |
401 | _ => bug!("{:?} is not a method", impl_m), | |
402 | }; | |
403 | ||
404 | match *terr { | |
405 | TypeError::Mutability => { | |
f9f354fc | 406 | if let Some(def_id) = trait_m.def_id.as_local() { |
3dfed10e | 407 | let trait_m_hir_id = tcx.hir().local_def_id_to_hir_id(def_id); |
dfeec247 | 408 | let trait_m_iter = match tcx.hir().expect_trait_item(trait_m_hir_id).kind { |
ba9703b0 XL |
409 | TraitItemKind::Fn(ref trait_m_sig, _) => trait_m_sig.decl.inputs.iter(), |
410 | _ => bug!("{:?} is not a TraitItemKind::Fn", trait_m), | |
c30ab7b3 SL |
411 | }; |
412 | ||
dfeec247 XL |
413 | impl_m_iter |
414 | .zip(trait_m_iter) | |
415 | .find(|&(ref impl_arg, ref trait_arg)| { | |
416 | match (&impl_arg.kind, &trait_arg.kind) { | |
417 | ( | |
418 | &hir::TyKind::Rptr(_, ref impl_mt), | |
419 | &hir::TyKind::Rptr(_, ref trait_mt), | |
420 | ) | |
421 | | (&hir::TyKind::Ptr(ref impl_mt), &hir::TyKind::Ptr(ref trait_mt)) => { | |
422 | impl_mt.mutbl != trait_mt.mutbl | |
423 | } | |
424 | _ => false, | |
32a655c1 | 425 | } |
dfeec247 XL |
426 | }) |
427 | .map(|(ref impl_arg, ref trait_arg)| (impl_arg.span, Some(trait_arg.span))) | |
428 | .unwrap_or_else(|| (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id))) | |
c30ab7b3 | 429 | } else { |
48663c56 | 430 | (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)) |
c30ab7b3 SL |
431 | } |
432 | } | |
433 | TypeError::Sorts(ExpectedFound { .. }) => { | |
f9f354fc | 434 | if let Some(def_id) = trait_m.def_id.as_local() { |
3dfed10e | 435 | let trait_m_hir_id = tcx.hir().local_def_id_to_hir_id(def_id); |
c30ab7b3 | 436 | let (trait_m_output, trait_m_iter) = |
e74abb32 | 437 | match tcx.hir().expect_trait_item(trait_m_hir_id).kind { |
ba9703b0 | 438 | TraitItemKind::Fn(ref trait_m_sig, _) => { |
c30ab7b3 SL |
439 | (&trait_m_sig.decl.output, trait_m_sig.decl.inputs.iter()) |
440 | } | |
ba9703b0 | 441 | _ => bug!("{:?} is not a TraitItemKind::Fn", trait_m), |
9e0c209e SL |
442 | }; |
443 | ||
476ff2be SL |
444 | let impl_iter = impl_sig.inputs().iter(); |
445 | let trait_iter = trait_sig.inputs().iter(); | |
dfeec247 XL |
446 | impl_iter |
447 | .zip(trait_iter) | |
448 | .zip(impl_m_iter) | |
449 | .zip(trait_m_iter) | |
f9f354fc XL |
450 | .find_map(|(((&impl_arg_ty, &trait_arg_ty), impl_arg), trait_arg)| match infcx |
451 | .at(&cause, param_env) | |
452 | .sub(trait_arg_ty, impl_arg_ty) | |
453 | { | |
454 | Ok(_) => None, | |
455 | Err(_) => Some((impl_arg.span, Some(trait_arg.span))), | |
456 | }) | |
dfeec247 XL |
457 | .unwrap_or_else(|| { |
458 | if infcx | |
459 | .at(&cause, param_env) | |
460 | .sup(trait_sig.output(), impl_sig.output()) | |
461 | .is_err() | |
462 | { | |
463 | (impl_m_output.span(), Some(trait_m_output.span())) | |
464 | } else { | |
465 | (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)) | |
466 | } | |
467 | }) | |
c30ab7b3 | 468 | } else { |
48663c56 | 469 | (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)) |
c30ab7b3 SL |
470 | } |
471 | } | |
48663c56 | 472 | _ => (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)), |
c30ab7b3 SL |
473 | } |
474 | } | |
475 | ||
dc9dc135 XL |
476 | fn compare_self_type<'tcx>( |
477 | tcx: TyCtxt<'tcx>, | |
478 | impl_m: &ty::AssocItem, | |
479 | impl_m_span: Span, | |
480 | trait_m: &ty::AssocItem, | |
481 | impl_trait_ref: ty::TraitRef<'tcx>, | |
482 | ) -> Result<(), ErrorReported> { | |
c30ab7b3 SL |
483 | // Try to give more informative error messages about self typing |
484 | // mismatches. Note that any mismatch will also be detected | |
485 | // below, where we construct a canonical function type that | |
486 | // includes the self parameter as a normal parameter. It's just | |
487 | // that the error messages you get out of this code are a bit more | |
488 | // inscrutable, particularly for cases where one method has no | |
489 | // self. | |
476ff2be | 490 | |
dc9dc135 | 491 | let self_string = |method: &ty::AssocItem| { |
476ff2be SL |
492 | let untransformed_self_ty = match method.container { |
493 | ty::ImplContainer(_) => impl_trait_ref.self_ty(), | |
dfeec247 | 494 | ty::TraitContainer(_) => tcx.types.self_param, |
476ff2be | 495 | }; |
fc512014 | 496 | let self_arg_ty = tcx.fn_sig(method.def_id).input(0); |
0531ce1d | 497 | let param_env = ty::ParamEnv::reveal_all(); |
abe05a73 XL |
498 | |
499 | tcx.infer_ctxt().enter(|infcx| { | |
fc512014 | 500 | let self_arg_ty = tcx.liberate_late_bound_regions(method.def_id, self_arg_ty); |
abe05a73 XL |
501 | let can_eq_self = |ty| infcx.can_eq(param_env, untransformed_self_ty, ty).is_ok(); |
502 | match ExplicitSelf::determine(self_arg_ty, can_eq_self) { | |
0bf4aa26 | 503 | ExplicitSelf::ByValue => "self".to_owned(), |
dfeec247 XL |
504 | ExplicitSelf::ByReference(_, hir::Mutability::Not) => "&self".to_owned(), |
505 | ExplicitSelf::ByReference(_, hir::Mutability::Mut) => "&mut self".to_owned(), | |
506 | _ => format!("self: {}", self_arg_ty), | |
abe05a73 XL |
507 | } |
508 | }) | |
476ff2be SL |
509 | }; |
510 | ||
ba9703b0 | 511 | match (trait_m.fn_has_self_parameter, impl_m.fn_has_self_parameter) { |
476ff2be SL |
512 | (false, false) | (true, true) => {} |
513 | ||
514 | (false, true) => { | |
515 | let self_descr = self_string(impl_m); | |
dfeec247 XL |
516 | let mut err = struct_span_err!( |
517 | tcx.sess, | |
518 | impl_m_span, | |
519 | E0185, | |
520 | "method `{}` has a `{}` declaration in the impl, but \ | |
c30ab7b3 | 521 | not in the trait", |
dfeec247 XL |
522 | trait_m.ident, |
523 | self_descr | |
524 | ); | |
7cac9316 | 525 | err.span_label(impl_m_span, format!("`{}` used in impl", self_descr)); |
0731742a | 526 | if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
2c00a5a8 XL |
527 | err.span_label(span, format!("trait method declared without `{}`", self_descr)); |
528 | } else { | |
dfeec247 | 529 | err.note_trait_signature(trait_m.ident.to_string(), trait_m.signature(tcx)); |
c30ab7b3 SL |
530 | } |
531 | err.emit(); | |
532 | return Err(ErrorReported); | |
533 | } | |
476ff2be SL |
534 | |
535 | (true, false) => { | |
536 | let self_descr = self_string(trait_m); | |
dfeec247 XL |
537 | let mut err = struct_span_err!( |
538 | tcx.sess, | |
539 | impl_m_span, | |
540 | E0186, | |
541 | "method `{}` has a `{}` declaration in the trait, but \ | |
c30ab7b3 | 542 | not in the impl", |
dfeec247 XL |
543 | trait_m.ident, |
544 | self_descr | |
545 | ); | |
2c00a5a8 | 546 | err.span_label(impl_m_span, format!("expected `{}` in impl", self_descr)); |
0731742a | 547 | if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
7cac9316 XL |
548 | err.span_label(span, format!("`{}` used in trait", self_descr)); |
549 | } else { | |
dfeec247 | 550 | err.note_trait_signature(trait_m.ident.to_string(), trait_m.signature(tcx)); |
c30ab7b3 SL |
551 | } |
552 | err.emit(); | |
553 | return Err(ErrorReported); | |
554 | } | |
c30ab7b3 SL |
555 | } |
556 | ||
557 | Ok(()) | |
558 | } | |
559 | ||
dc9dc135 XL |
560 | fn compare_number_of_generics<'tcx>( |
561 | tcx: TyCtxt<'tcx>, | |
562 | impl_: &ty::AssocItem, | |
563 | _impl_span: Span, | |
564 | trait_: &ty::AssocItem, | |
532ac7d7 XL |
565 | trait_span: Option<Span>, |
566 | ) -> Result<(), ErrorReported> { | |
567 | let trait_own_counts = tcx.generics_of(trait_.def_id).own_counts(); | |
568 | let impl_own_counts = tcx.generics_of(impl_.def_id).own_counts(); | |
569 | ||
570 | let matchings = [ | |
571 | ("type", trait_own_counts.types, impl_own_counts.types), | |
572 | ("const", trait_own_counts.consts, impl_own_counts.consts), | |
573 | ]; | |
574 | ||
dfeec247 XL |
575 | let item_kind = assoc_item_kind_str(impl_); |
576 | ||
532ac7d7 XL |
577 | let mut err_occurred = false; |
578 | for &(kind, trait_count, impl_count) in &matchings { | |
579 | if impl_count != trait_count { | |
580 | err_occurred = true; | |
581 | ||
f9f354fc | 582 | let (trait_spans, impl_trait_spans) = if let Some(def_id) = trait_.def_id.as_local() { |
3dfed10e | 583 | let trait_hir_id = tcx.hir().local_def_id_to_hir_id(def_id); |
f9f354fc XL |
584 | let trait_item = tcx.hir().expect_trait_item(trait_hir_id); |
585 | if trait_item.generics.params.is_empty() { | |
586 | (Some(vec![trait_item.generics.span]), vec![]) | |
dc9dc135 | 587 | } else { |
f9f354fc XL |
588 | let arg_spans: Vec<Span> = |
589 | trait_item.generics.params.iter().map(|p| p.span).collect(); | |
590 | let impl_trait_spans: Vec<Span> = trait_item | |
591 | .generics | |
592 | .params | |
593 | .iter() | |
594 | .filter_map(|p| match p.kind { | |
595 | GenericParamKind::Type { | |
596 | synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), | |
597 | .. | |
598 | } => Some(p.span), | |
599 | _ => None, | |
600 | }) | |
601 | .collect(); | |
602 | (Some(arg_spans), impl_trait_spans) | |
603 | } | |
604 | } else { | |
605 | (trait_span.map(|s| vec![s]), vec![]) | |
606 | }; | |
9e0c209e | 607 | |
3dfed10e | 608 | let impl_hir_id = tcx.hir().local_def_id_to_hir_id(impl_.def_id.expect_local()); |
dc9dc135 | 609 | let impl_item = tcx.hir().expect_impl_item(impl_hir_id); |
dfeec247 XL |
610 | let impl_item_impl_trait_spans: Vec<Span> = impl_item |
611 | .generics | |
612 | .params | |
613 | .iter() | |
dc9dc135 XL |
614 | .filter_map(|p| match p.kind { |
615 | GenericParamKind::Type { | |
dfeec247 XL |
616 | synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), |
617 | .. | |
dc9dc135 XL |
618 | } => Some(p.span), |
619 | _ => None, | |
dfeec247 XL |
620 | }) |
621 | .collect(); | |
dc9dc135 XL |
622 | let spans = impl_item.generics.spans(); |
623 | let span = spans.primary_span(); | |
624 | ||
532ac7d7 | 625 | let mut err = tcx.sess.struct_span_err_with_code( |
dc9dc135 | 626 | spans, |
532ac7d7 | 627 | &format!( |
dfeec247 | 628 | "{} `{}` has {} {kind} parameter{} but its trait \ |
532ac7d7 | 629 | declaration has {} {kind} parameter{}", |
dfeec247 | 630 | item_kind, |
532ac7d7 XL |
631 | trait_.ident, |
632 | impl_count, | |
60c5eb7d | 633 | pluralize!(impl_count), |
532ac7d7 | 634 | trait_count, |
60c5eb7d | 635 | pluralize!(trait_count), |
532ac7d7 XL |
636 | kind = kind, |
637 | ), | |
638 | DiagnosticId::Error("E0049".into()), | |
639 | ); | |
c30ab7b3 | 640 | |
532ac7d7 | 641 | let mut suffix = None; |
c30ab7b3 | 642 | |
dc9dc135 XL |
643 | if let Some(spans) = trait_spans { |
644 | let mut spans = spans.iter(); | |
645 | if let Some(span) = spans.next() { | |
dfeec247 XL |
646 | err.span_label( |
647 | *span, | |
648 | format!( | |
649 | "expected {} {} parameter{}", | |
650 | trait_count, | |
651 | kind, | |
652 | pluralize!(trait_count), | |
653 | ), | |
654 | ); | |
dc9dc135 XL |
655 | } |
656 | for span in spans { | |
657 | err.span_label(*span, ""); | |
658 | } | |
532ac7d7 XL |
659 | } else { |
660 | suffix = Some(format!(", expected {}", trait_count)); | |
661 | } | |
c30ab7b3 | 662 | |
dc9dc135 | 663 | if let Some(span) = span { |
dfeec247 XL |
664 | err.span_label( |
665 | span, | |
666 | format!( | |
667 | "found {} {} parameter{}{}", | |
668 | impl_count, | |
669 | kind, | |
670 | pluralize!(impl_count), | |
ba9703b0 | 671 | suffix.unwrap_or_else(String::new), |
dfeec247 XL |
672 | ), |
673 | ); | |
dc9dc135 XL |
674 | } |
675 | ||
676 | for span in impl_trait_spans.iter().chain(impl_item_impl_trait_spans.iter()) { | |
677 | err.span_label(*span, "`impl Trait` introduces an implicit type parameter"); | |
678 | } | |
c30ab7b3 | 679 | |
532ac7d7 XL |
680 | err.emit(); |
681 | } | |
c30ab7b3 SL |
682 | } |
683 | ||
dfeec247 | 684 | if err_occurred { Err(ErrorReported) } else { Ok(()) } |
c30ab7b3 SL |
685 | } |
686 | ||
dc9dc135 XL |
687 | fn compare_number_of_method_arguments<'tcx>( |
688 | tcx: TyCtxt<'tcx>, | |
689 | impl_m: &ty::AssocItem, | |
690 | impl_m_span: Span, | |
691 | trait_m: &ty::AssocItem, | |
692 | trait_item_span: Option<Span>, | |
693 | ) -> Result<(), ErrorReported> { | |
041b39d2 XL |
694 | let impl_m_fty = tcx.fn_sig(impl_m.def_id); |
695 | let trait_m_fty = tcx.fn_sig(trait_m.def_id); | |
8bb4bdeb XL |
696 | let trait_number_args = trait_m_fty.inputs().skip_binder().len(); |
697 | let impl_number_args = impl_m_fty.inputs().skip_binder().len(); | |
476ff2be | 698 | if trait_number_args != impl_number_args { |
f9f354fc | 699 | let trait_span = if let Some(def_id) = trait_m.def_id.as_local() { |
3dfed10e | 700 | let trait_id = tcx.hir().local_def_id_to_hir_id(def_id); |
e74abb32 | 701 | match tcx.hir().expect_trait_item(trait_id).kind { |
ba9703b0 | 702 | TraitItemKind::Fn(ref trait_m_sig, _) => { |
dfeec247 | 703 | let pos = if trait_number_args > 0 { trait_number_args - 1 } else { 0 }; |
0731742a XL |
704 | if let Some(arg) = trait_m_sig.decl.inputs.get(pos) { |
705 | Some(if pos == 0 { | |
706 | arg.span | |
707 | } else { | |
dfeec247 XL |
708 | Span::new( |
709 | trait_m_sig.decl.inputs[0].span.lo(), | |
710 | arg.span.hi(), | |
711 | arg.span.ctxt(), | |
712 | ) | |
0731742a | 713 | }) |
c30ab7b3 SL |
714 | } else { |
715 | trait_item_span | |
716 | } | |
717 | } | |
718 | _ => bug!("{:?} is not a method", impl_m), | |
719 | } | |
720 | } else { | |
721 | trait_item_span | |
722 | }; | |
3dfed10e | 723 | let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); |
e74abb32 | 724 | let impl_span = match tcx.hir().expect_impl_item(impl_m_hir_id).kind { |
ba9703b0 | 725 | ImplItemKind::Fn(ref impl_m_sig, _) => { |
dfeec247 | 726 | let pos = if impl_number_args > 0 { impl_number_args - 1 } else { 0 }; |
0731742a XL |
727 | if let Some(arg) = impl_m_sig.decl.inputs.get(pos) { |
728 | if pos == 0 { | |
729 | arg.span | |
730 | } else { | |
dfeec247 XL |
731 | Span::new( |
732 | impl_m_sig.decl.inputs[0].span.lo(), | |
733 | arg.span.hi(), | |
734 | arg.span.ctxt(), | |
735 | ) | |
0731742a | 736 | } |
9e0c209e | 737 | } else { |
c30ab7b3 | 738 | impl_m_span |
9e0c209e SL |
739 | } |
740 | } | |
c30ab7b3 SL |
741 | _ => bug!("{:?} is not a method", impl_m), |
742 | }; | |
dfeec247 XL |
743 | let mut err = struct_span_err!( |
744 | tcx.sess, | |
745 | impl_span, | |
746 | E0050, | |
747 | "method `{}` has {} but the declaration in \ | |
c30ab7b3 | 748 | trait `{}` has {}", |
dfeec247 XL |
749 | trait_m.ident, |
750 | potentially_plural_count(impl_number_args, "parameter"), | |
751 | tcx.def_path_str(trait_m.def_id), | |
752 | trait_number_args | |
753 | ); | |
c30ab7b3 | 754 | if let Some(trait_span) = trait_span { |
dfeec247 XL |
755 | err.span_label( |
756 | trait_span, | |
757 | format!( | |
758 | "trait requires {}", | |
759 | potentially_plural_count(trait_number_args, "parameter") | |
760 | ), | |
761 | ); | |
7cac9316 | 762 | } else { |
dfeec247 | 763 | err.note_trait_signature(trait_m.ident.to_string(), trait_m.signature(tcx)); |
9e0c209e | 764 | } |
dfeec247 XL |
765 | err.span_label( |
766 | impl_span, | |
767 | format!( | |
768 | "expected {}, found {}", | |
769 | potentially_plural_count(trait_number_args, "parameter"), | |
770 | impl_number_args | |
771 | ), | |
772 | ); | |
c30ab7b3 SL |
773 | err.emit(); |
774 | return Err(ErrorReported); | |
9e0c209e | 775 | } |
c30ab7b3 SL |
776 | |
777 | Ok(()) | |
85aaf69f | 778 | } |
d9579d0f | 779 | |
dc9dc135 XL |
780 | fn compare_synthetic_generics<'tcx>( |
781 | tcx: TyCtxt<'tcx>, | |
782 | impl_m: &ty::AssocItem, | |
783 | trait_m: &ty::AssocItem, | |
784 | ) -> Result<(), ErrorReported> { | |
abe05a73 | 785 | // FIXME(chrisvittal) Clean up this function, list of FIXME items: |
94b46f34 | 786 | // 1. Better messages for the span labels |
abe05a73 | 787 | // 2. Explanation as to what is going on |
abe05a73 XL |
788 | // If we get here, we already have the same number of generics, so the zip will |
789 | // be okay. | |
790 | let mut error_found = false; | |
791 | let impl_m_generics = tcx.generics_of(impl_m.def_id); | |
792 | let trait_m_generics = tcx.generics_of(trait_m.def_id); | |
8faf50e0 XL |
793 | let impl_m_type_params = impl_m_generics.params.iter().filter_map(|param| match param.kind { |
794 | GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), | |
532ac7d7 | 795 | GenericParamDefKind::Lifetime | GenericParamDefKind::Const => None, |
94b46f34 | 796 | }); |
dfeec247 XL |
797 | let trait_m_type_params = trait_m_generics.params.iter().filter_map(|param| match param.kind { |
798 | GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), | |
799 | GenericParamDefKind::Lifetime | GenericParamDefKind::Const => None, | |
94b46f34 | 800 | }); |
dfeec247 XL |
801 | for ((impl_def_id, impl_synthetic), (trait_def_id, trait_synthetic)) in |
802 | impl_m_type_params.zip(trait_m_type_params) | |
0bf4aa26 | 803 | { |
94b46f34 | 804 | if impl_synthetic != trait_synthetic { |
3dfed10e | 805 | let impl_hir_id = tcx.hir().local_def_id_to_hir_id(impl_def_id.expect_local()); |
dc9dc135 | 806 | let impl_span = tcx.hir().span(impl_hir_id); |
94b46f34 | 807 | let trait_span = tcx.def_span(trait_def_id); |
dfeec247 XL |
808 | let mut err = struct_span_err!( |
809 | tcx.sess, | |
810 | impl_span, | |
811 | E0643, | |
812 | "method `{}` has incompatible signature for trait", | |
813 | trait_m.ident | |
814 | ); | |
94b46f34 XL |
815 | err.span_label(trait_span, "declaration in trait here"); |
816 | match (impl_synthetic, trait_synthetic) { | |
817 | // The case where the impl method uses `impl Trait` but the trait method uses | |
818 | // explicit generics | |
819 | (Some(hir::SyntheticTyParamKind::ImplTrait), None) => { | |
820 | err.span_label(impl_span, "expected generic parameter, found `impl Trait`"); | |
821 | (|| { | |
822 | // try taking the name from the trait impl | |
823 | // FIXME: this is obviously suboptimal since the name can already be used | |
824 | // as another generic argument | |
dfeec247 | 825 | let new_name = tcx.sess.source_map().span_to_snippet(trait_span).ok()?; |
6a06907d XL |
826 | let trait_m = trait_m.def_id.as_local()?; |
827 | let trait_m = tcx.hir().trait_item(hir::TraitItemId { def_id: trait_m }); | |
94b46f34 | 828 | |
6a06907d XL |
829 | let impl_m = impl_m.def_id.as_local()?; |
830 | let impl_m = tcx.hir().impl_item(hir::ImplItemId { def_id: impl_m }); | |
94b46f34 XL |
831 | |
832 | // in case there are no generics, take the spot between the function name | |
833 | // and the opening paren of the argument list | |
dfeec247 XL |
834 | let new_generics_span = |
835 | tcx.sess.source_map().generate_fn_name_span(impl_span)?.shrink_to_hi(); | |
94b46f34 | 836 | // in case there are generics, just replace them |
dfeec247 XL |
837 | let generics_span = |
838 | impl_m.generics.span.substitute_dummy(new_generics_span); | |
94b46f34 | 839 | // replace with the generics from the trait |
dfeec247 XL |
840 | let new_generics = |
841 | tcx.sess.source_map().span_to_snippet(trait_m.generics.span).ok()?; | |
94b46f34 | 842 | |
9fa01778 | 843 | err.multipart_suggestion( |
94b46f34 XL |
844 | "try changing the `impl Trait` argument to a generic parameter", |
845 | vec![ | |
846 | // replace `impl Trait` with `T` | |
847 | (impl_span, new_name), | |
848 | // replace impl method generics with trait method generics | |
849 | // This isn't quite right, as users might have changed the names | |
850 | // of the generics, but it works for the common case | |
851 | (generics_span, new_generics), | |
852 | ], | |
0bf4aa26 | 853 | Applicability::MaybeIncorrect, |
94b46f34 XL |
854 | ); |
855 | Some(()) | |
856 | })(); | |
dfeec247 | 857 | } |
94b46f34 XL |
858 | // The case where the trait method uses `impl Trait`, but the impl method uses |
859 | // explicit generics. | |
860 | (None, Some(hir::SyntheticTyParamKind::ImplTrait)) => { | |
861 | err.span_label(impl_span, "expected `impl Trait`, found generic parameter"); | |
862 | (|| { | |
6a06907d XL |
863 | let impl_m = impl_m.def_id.as_local()?; |
864 | let impl_m = tcx.hir().impl_item(hir::ImplItemId { def_id: impl_m }); | |
e74abb32 | 865 | let input_tys = match impl_m.kind { |
ba9703b0 | 866 | hir::ImplItemKind::Fn(ref sig, _) => sig.decl.inputs, |
94b46f34 XL |
867 | _ => unreachable!(), |
868 | }; | |
869 | struct Visitor(Option<Span>, hir::def_id::DefId); | |
dfeec247 XL |
870 | impl<'v> intravisit::Visitor<'v> for Visitor { |
871 | fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) { | |
872 | intravisit::walk_ty(self, ty); | |
873 | if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = | |
874 | ty.kind | |
0bf4aa26 | 875 | { |
48663c56 | 876 | if let Res::Def(DefKind::TyParam, def_id) = path.res { |
0bf4aa26 XL |
877 | if def_id == self.1 { |
878 | self.0 = Some(ty.span); | |
94b46f34 | 879 | } |
0bf4aa26 | 880 | } |
94b46f34 XL |
881 | } |
882 | } | |
ba9703b0 | 883 | type Map = intravisit::ErasedMap<'v>; |
dfeec247 XL |
884 | fn nested_visit_map( |
885 | &mut self, | |
ba9703b0 | 886 | ) -> intravisit::NestedVisitorMap<Self::Map> |
dfeec247 XL |
887 | { |
888 | intravisit::NestedVisitorMap::None | |
94b46f34 XL |
889 | } |
890 | } | |
891 | let mut visitor = Visitor(None, impl_def_id); | |
892 | for ty in input_tys { | |
dfeec247 | 893 | intravisit::Visitor::visit_ty(&mut visitor, ty); |
94b46f34 XL |
894 | } |
895 | let span = visitor.0?; | |
896 | ||
dfeec247 XL |
897 | let bounds = |
898 | impl_m.generics.params.iter().find_map(|param| match param.kind { | |
8faf50e0 | 899 | GenericParamKind::Lifetime { .. } => None, |
dfeec247 | 900 | GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => { |
9fa01778 | 901 | if param.hir_id == impl_hir_id { |
8faf50e0 | 902 | Some(¶m.bounds) |
94b46f34 XL |
903 | } else { |
904 | None | |
905 | } | |
8faf50e0 | 906 | } |
dfeec247 | 907 | })?; |
8faf50e0 | 908 | let bounds = bounds.first()?.span().to(bounds.last()?.span()); |
dfeec247 | 909 | let bounds = tcx.sess.source_map().span_to_snippet(bounds).ok()?; |
94b46f34 | 910 | |
9fa01778 | 911 | err.multipart_suggestion( |
94b46f34 XL |
912 | "try removing the generic parameter and using `impl Trait` instead", |
913 | vec![ | |
914 | // delete generic parameters | |
915 | (impl_m.generics.span, String::new()), | |
916 | // replace param usage with `impl Trait` | |
917 | (span, format!("impl {}", bounds)), | |
918 | ], | |
0bf4aa26 | 919 | Applicability::MaybeIncorrect, |
94b46f34 XL |
920 | ); |
921 | Some(()) | |
922 | })(); | |
dfeec247 | 923 | } |
94b46f34 XL |
924 | _ => unreachable!(), |
925 | } | |
abe05a73 XL |
926 | err.emit(); |
927 | error_found = true; | |
928 | } | |
929 | } | |
dfeec247 | 930 | if error_found { Err(ErrorReported) } else { Ok(()) } |
abe05a73 XL |
931 | } |
932 | ||
dfeec247 | 933 | crate fn compare_const_impl<'tcx>( |
dc9dc135 XL |
934 | tcx: TyCtxt<'tcx>, |
935 | impl_c: &ty::AssocItem, | |
936 | impl_c_span: Span, | |
937 | trait_c: &ty::AssocItem, | |
938 | impl_trait_ref: ty::TraitRef<'tcx>, | |
939 | ) { | |
c30ab7b3 | 940 | debug!("compare_const_impl(impl_trait_ref={:?})", impl_trait_ref); |
d9579d0f | 941 | |
041b39d2 | 942 | tcx.infer_ctxt().enter(|infcx| { |
532ac7d7 | 943 | let param_env = tcx.param_env(impl_c.def_id); |
ba9703b0 | 944 | let inh = Inherited::new(infcx, impl_c.def_id.expect_local()); |
cc61c64b | 945 | let infcx = &inh.infcx; |
a7813a04 XL |
946 | |
947 | // The below is for the most part highly similar to the procedure | |
948 | // for methods above. It is simpler in many respects, especially | |
949 | // because we shouldn't really have to deal with lifetimes or | |
950 | // predicates. In fact some of this should probably be put into | |
951 | // shared functions because of DRY violations... | |
476ff2be | 952 | let trait_to_impl_substs = impl_trait_ref.substs; |
a7813a04 XL |
953 | |
954 | // Create a parameter environment that represents the implementation's | |
955 | // method. | |
3dfed10e | 956 | let impl_c_hir_id = tcx.hir().local_def_id_to_hir_id(impl_c.def_id.expect_local()); |
a7813a04 | 957 | |
0bf4aa26 | 958 | // Compute placeholder form of impl and trait const tys. |
7cac9316 XL |
959 | let impl_ty = tcx.type_of(impl_c.def_id); |
960 | let trait_ty = tcx.type_of(trait_c.def_id).subst(tcx, trait_to_impl_substs); | |
f035d41b XL |
961 | let mut cause = ObligationCause::new( |
962 | impl_c_span, | |
963 | impl_c_hir_id, | |
964 | ObligationCauseCode::CompareImplConstObligation, | |
965 | ); | |
a7813a04 | 966 | |
cc61c64b | 967 | // There is no "body" here, so just pass dummy id. |
dfeec247 | 968 | let impl_ty = |
fc512014 | 969 | inh.normalize_associated_types_in(impl_c_span, impl_c_hir_id, param_env, impl_ty); |
c30ab7b3 | 970 | |
cc61c64b | 971 | debug!("compare_const_impl: impl_ty={:?}", impl_ty); |
c30ab7b3 | 972 | |
dfeec247 | 973 | let trait_ty = |
fc512014 | 974 | inh.normalize_associated_types_in(impl_c_span, impl_c_hir_id, param_env, trait_ty); |
c30ab7b3 | 975 | |
cc61c64b | 976 | debug!("compare_const_impl: trait_ty={:?}", trait_ty); |
a7813a04 | 977 | |
dfeec247 XL |
978 | let err = infcx |
979 | .at(&cause, param_env) | |
980 | .sup(trait_ty, impl_ty) | |
981 | .map(|ok| inh.register_infer_ok_obligations(ok)); | |
d9579d0f | 982 | |
a7813a04 | 983 | if let Err(terr) = err { |
dfeec247 XL |
984 | debug!( |
985 | "checking associated const for compatibility: impl ty {:?}, trait ty {:?}", | |
986 | impl_ty, trait_ty | |
987 | ); | |
5bcae85e SL |
988 | |
989 | // Locate the Span containing just the type of the offending impl | |
e74abb32 | 990 | match tcx.hir().expect_impl_item(impl_c_hir_id).kind { |
f035d41b | 991 | ImplItemKind::Const(ref ty, _) => cause.make_mut().span = ty.span, |
c30ab7b3 | 992 | _ => bug!("{:?} is not a impl const", impl_c), |
5bcae85e SL |
993 | } |
994 | ||
dfeec247 XL |
995 | let mut diag = struct_span_err!( |
996 | tcx.sess, | |
997 | cause.span, | |
998 | E0326, | |
999 | "implemented const `{}` has an incompatible type for \ | |
c30ab7b3 | 1000 | trait", |
dfeec247 XL |
1001 | trait_c.ident |
1002 | ); | |
5bcae85e | 1003 | |
f9f354fc | 1004 | let trait_c_hir_id = |
3dfed10e | 1005 | trait_c.def_id.as_local().map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id)); |
532ac7d7 | 1006 | let trait_c_span = trait_c_hir_id.map(|trait_c_hir_id| { |
7cac9316 | 1007 | // Add a label to the Span containing just the type of the const |
e74abb32 | 1008 | match tcx.hir().expect_trait_item(trait_c_hir_id).kind { |
7cac9316 XL |
1009 | TraitItemKind::Const(ref ty, _) => ty.span, |
1010 | _ => bug!("{:?} is not a trait const", trait_c), | |
1011 | } | |
1012 | }); | |
5bcae85e | 1013 | |
dfeec247 XL |
1014 | infcx.note_type_err( |
1015 | &mut diag, | |
1016 | &cause, | |
1017 | trait_c_span.map(|span| (span, "type in trait".to_owned())), | |
1018 | Some(infer::ValuePairs::Types(ExpectedFound { | |
1019 | expected: trait_ty, | |
1020 | found: impl_ty, | |
1021 | })), | |
1022 | &terr, | |
1023 | ); | |
5bcae85e | 1024 | diag.emit(); |
d9579d0f | 1025 | } |
cc61c64b | 1026 | |
7cac9316 XL |
1027 | // Check that all obligations are satisfied by the implementation's |
1028 | // version. | |
1029 | if let Err(ref errors) = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx) { | |
0531ce1d | 1030 | infcx.report_fulfillment_errors(errors, None, false); |
7cac9316 XL |
1031 | return; |
1032 | } | |
1033 | ||
9fa01778 XL |
1034 | let fcx = FnCtxt::new(&inh, param_env, impl_c_hir_id); |
1035 | fcx.regionck_item(impl_c_hir_id, impl_c_span, &[]); | |
a7813a04 | 1036 | }); |
d9579d0f | 1037 | } |
dfeec247 XL |
1038 | |
1039 | crate fn compare_ty_impl<'tcx>( | |
1040 | tcx: TyCtxt<'tcx>, | |
1041 | impl_ty: &ty::AssocItem, | |
1042 | impl_ty_span: Span, | |
1043 | trait_ty: &ty::AssocItem, | |
1044 | impl_trait_ref: ty::TraitRef<'tcx>, | |
1045 | trait_item_span: Option<Span>, | |
1046 | ) { | |
1047 | debug!("compare_impl_type(impl_trait_ref={:?})", impl_trait_ref); | |
1048 | ||
1049 | let _: Result<(), ErrorReported> = (|| { | |
1050 | compare_number_of_generics(tcx, impl_ty, impl_ty_span, trait_ty, trait_item_span)?; | |
1051 | ||
f035d41b XL |
1052 | compare_type_predicate_entailment(tcx, impl_ty, impl_ty_span, trait_ty, impl_trait_ref)?; |
1053 | ||
29967ef6 | 1054 | check_type_bounds(tcx, trait_ty, impl_ty, impl_ty_span, impl_trait_ref) |
dfeec247 XL |
1055 | })(); |
1056 | } | |
1057 | ||
1058 | /// The equivalent of [compare_predicate_entailment], but for associated types | |
1059 | /// instead of associated functions. | |
f035d41b | 1060 | fn compare_type_predicate_entailment<'tcx>( |
dfeec247 XL |
1061 | tcx: TyCtxt<'tcx>, |
1062 | impl_ty: &ty::AssocItem, | |
1063 | impl_ty_span: Span, | |
1064 | trait_ty: &ty::AssocItem, | |
1065 | impl_trait_ref: ty::TraitRef<'tcx>, | |
1066 | ) -> Result<(), ErrorReported> { | |
1067 | let impl_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); | |
1068 | let trait_to_impl_substs = | |
1069 | impl_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
1070 | ||
1071 | let impl_ty_generics = tcx.generics_of(impl_ty.def_id); | |
1072 | let trait_ty_generics = tcx.generics_of(trait_ty.def_id); | |
1073 | let impl_ty_predicates = tcx.predicates_of(impl_ty.def_id); | |
1074 | let trait_ty_predicates = tcx.predicates_of(trait_ty.def_id); | |
1075 | ||
1076 | check_region_bounds_on_impl_item( | |
1077 | tcx, | |
1078 | impl_ty_span, | |
1079 | impl_ty, | |
1080 | trait_ty, | |
1081 | &trait_ty_generics, | |
1082 | &impl_ty_generics, | |
1083 | )?; | |
1084 | ||
1085 | let impl_ty_own_bounds = impl_ty_predicates.instantiate_own(tcx, impl_substs); | |
1086 | ||
1087 | if impl_ty_own_bounds.is_empty() { | |
1088 | // Nothing to check. | |
1089 | return Ok(()); | |
1090 | } | |
1091 | ||
1092 | // This `HirId` should be used for the `body_id` field on each | |
1093 | // `ObligationCause` (and the `FnCtxt`). This is what | |
1094 | // `regionck_item` expects. | |
3dfed10e | 1095 | let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
f035d41b XL |
1096 | let cause = ObligationCause::new( |
1097 | impl_ty_span, | |
1098 | impl_ty_hir_id, | |
1099 | ObligationCauseCode::CompareImplTypeObligation { | |
dfeec247 XL |
1100 | item_name: impl_ty.ident.name, |
1101 | impl_item_def_id: impl_ty.def_id, | |
1102 | trait_item_def_id: trait_ty.def_id, | |
1103 | }, | |
f035d41b | 1104 | ); |
dfeec247 XL |
1105 | |
1106 | debug!("compare_type_predicate_entailment: trait_to_impl_substs={:?}", trait_to_impl_substs); | |
1107 | ||
1108 | // The predicates declared by the impl definition, the trait and the | |
1109 | // associated type in the trait are assumed. | |
1110 | let impl_predicates = tcx.predicates_of(impl_ty_predicates.parent.unwrap()); | |
1111 | let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); | |
1112 | hybrid_preds | |
1113 | .predicates | |
1114 | .extend(trait_ty_predicates.instantiate_own(tcx, trait_to_impl_substs).predicates); | |
1115 | ||
1116 | debug!("compare_type_predicate_entailment: bounds={:?}", hybrid_preds); | |
1117 | ||
1118 | let normalize_cause = traits::ObligationCause::misc(impl_ty_span, impl_ty_hir_id); | |
1b1a35ee XL |
1119 | let param_env = |
1120 | ty::ParamEnv::new(tcx.intern_predicates(&hybrid_preds.predicates), Reveal::UserFacing); | |
dfeec247 XL |
1121 | let param_env = traits::normalize_param_env_or_error( |
1122 | tcx, | |
1123 | impl_ty.def_id, | |
1124 | param_env, | |
1125 | normalize_cause.clone(), | |
1126 | ); | |
1127 | tcx.infer_ctxt().enter(|infcx| { | |
ba9703b0 | 1128 | let inh = Inherited::new(infcx, impl_ty.def_id.expect_local()); |
dfeec247 XL |
1129 | let infcx = &inh.infcx; |
1130 | ||
f035d41b | 1131 | debug!("compare_type_predicate_entailment: caller_bounds={:?}", param_env.caller_bounds()); |
dfeec247 XL |
1132 | |
1133 | let mut selcx = traits::SelectionContext::new(&infcx); | |
1134 | ||
1135 | for predicate in impl_ty_own_bounds.predicates { | |
1136 | let traits::Normalized { value: predicate, obligations } = | |
fc512014 | 1137 | traits::normalize(&mut selcx, param_env, normalize_cause.clone(), predicate); |
dfeec247 XL |
1138 | |
1139 | inh.register_predicates(obligations); | |
1140 | inh.register_predicate(traits::Obligation::new(cause.clone(), param_env, predicate)); | |
1141 | } | |
1142 | ||
1143 | // Check that all obligations are satisfied by the implementation's | |
1144 | // version. | |
1145 | if let Err(ref errors) = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx) { | |
1146 | infcx.report_fulfillment_errors(errors, None, false); | |
1147 | return Err(ErrorReported); | |
1148 | } | |
1149 | ||
1150 | // Finally, resolve all regions. This catches wily misuses of | |
1151 | // lifetime parameters. | |
1152 | let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id); | |
1153 | fcx.regionck_item(impl_ty_hir_id, impl_ty_span, &[]); | |
1154 | ||
1155 | Ok(()) | |
1156 | }) | |
1157 | } | |
1158 | ||
f035d41b XL |
1159 | /// Validate that `ProjectionCandidate`s created for this associated type will |
1160 | /// be valid. | |
1161 | /// | |
1162 | /// Usually given | |
1163 | /// | |
1164 | /// trait X { type Y: Copy } impl X for T { type Y = S; } | |
1165 | /// | |
1166 | /// We are able to normalize `<T as X>::U` to `S`, and so when we check the | |
1167 | /// impl is well-formed we have to prove `S: Copy`. | |
1168 | /// | |
1169 | /// For default associated types the normalization is not possible (the value | |
1170 | /// from the impl could be overridden). We also can't normalize generic | |
1171 | /// associated types (yet) because they contain bound parameters. | |
29967ef6 | 1172 | pub fn check_type_bounds<'tcx>( |
f035d41b XL |
1173 | tcx: TyCtxt<'tcx>, |
1174 | trait_ty: &ty::AssocItem, | |
1175 | impl_ty: &ty::AssocItem, | |
1176 | impl_ty_span: Span, | |
1177 | impl_trait_ref: ty::TraitRef<'tcx>, | |
1178 | ) -> Result<(), ErrorReported> { | |
f035d41b XL |
1179 | // Given |
1180 | // | |
1181 | // impl<A, B> Foo<u32> for (A, B) { | |
1182 | // type Bar<C> =... | |
1183 | // } | |
1184 | // | |
1185 | // - `impl_substs` would be `[A, B, C]` | |
1186 | // - `rebased_substs` would be `[(A, B), u32, C]`, combining the substs from | |
1187 | // the *trait* with the generic associated type parameters. | |
1188 | let impl_ty_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); | |
1189 | let rebased_substs = | |
1190 | impl_ty_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
1191 | let impl_ty_value = tcx.type_of(impl_ty.def_id); | |
1192 | ||
3dfed10e XL |
1193 | let param_env = tcx.param_env(impl_ty.def_id); |
1194 | ||
1195 | // When checking something like | |
f035d41b | 1196 | // |
3dfed10e XL |
1197 | // trait X { type Y: PartialEq<<Self as X>::Y> } |
1198 | // impl X for T { default type Y = S; } | |
f035d41b | 1199 | // |
3dfed10e XL |
1200 | // We will have to prove the bound S: PartialEq<<T as X>::Y>. In this case |
1201 | // we want <T as X>::Y to normalize to S. This is valid because we are | |
1202 | // checking the default value specifically here. Add this equality to the | |
1203 | // ParamEnv for normalization specifically. | |
1204 | let normalize_param_env = { | |
1205 | let mut predicates = param_env.caller_bounds().iter().collect::<Vec<_>>(); | |
29967ef6 XL |
1206 | match impl_ty_value.kind() { |
1207 | ty::Projection(proj) | |
1208 | if proj.item_def_id == trait_ty.def_id && proj.substs == rebased_substs => | |
1209 | { | |
1210 | // Don't include this predicate if the projected type is | |
1211 | // exactly the same as the projection. This can occur in | |
1212 | // (somewhat dubious) code like this: | |
1213 | // | |
1214 | // impl<T> X for T where T: X { type Y = <T as X>::Y; } | |
1215 | } | |
1216 | _ => predicates.push( | |
1217 | ty::Binder::dummy(ty::ProjectionPredicate { | |
1218 | projection_ty: ty::ProjectionTy { | |
1219 | item_def_id: trait_ty.def_id, | |
1220 | substs: rebased_substs, | |
1221 | }, | |
1222 | ty: impl_ty_value, | |
1223 | }) | |
1224 | .to_predicate(tcx), | |
1225 | ), | |
1226 | }; | |
1b1a35ee | 1227 | ty::ParamEnv::new(tcx.intern_predicates(&predicates), Reveal::UserFacing) |
f035d41b XL |
1228 | }; |
1229 | ||
1230 | tcx.infer_ctxt().enter(move |infcx| { | |
1231 | let inh = Inherited::new(infcx, impl_ty.def_id.expect_local()); | |
1232 | let infcx = &inh.infcx; | |
1233 | let mut selcx = traits::SelectionContext::new(&infcx); | |
1234 | ||
3dfed10e | 1235 | let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
f035d41b | 1236 | let normalize_cause = traits::ObligationCause::misc(impl_ty_span, impl_ty_hir_id); |
29967ef6 XL |
1237 | let mk_cause = |span| { |
1238 | ObligationCause::new( | |
1239 | impl_ty_span, | |
1240 | impl_ty_hir_id, | |
1241 | ObligationCauseCode::BindingObligation(trait_ty.def_id, span), | |
1242 | ) | |
1243 | }; | |
f035d41b | 1244 | |
29967ef6 XL |
1245 | let obligations = tcx |
1246 | .explicit_item_bounds(trait_ty.def_id) | |
1247 | .iter() | |
1248 | .map(|&(bound, span)| { | |
1249 | let concrete_ty_bound = bound.subst(tcx, rebased_substs); | |
1250 | debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound); | |
f035d41b | 1251 | |
29967ef6 XL |
1252 | traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound) |
1253 | }) | |
1254 | .collect(); | |
1255 | debug!("check_type_bounds: item_bounds={:?}", obligations); | |
f035d41b | 1256 | |
29967ef6 | 1257 | for mut obligation in util::elaborate_obligations(tcx, obligations) { |
f035d41b XL |
1258 | let traits::Normalized { value: normalized_predicate, obligations } = traits::normalize( |
1259 | &mut selcx, | |
3dfed10e | 1260 | normalize_param_env, |
f035d41b | 1261 | normalize_cause.clone(), |
fc512014 | 1262 | obligation.predicate, |
f035d41b | 1263 | ); |
f035d41b | 1264 | debug!("compare_projection_bounds: normalized predicate = {:?}", normalized_predicate); |
29967ef6 | 1265 | obligation.predicate = normalized_predicate; |
f035d41b XL |
1266 | |
1267 | inh.register_predicates(obligations); | |
29967ef6 | 1268 | inh.register_predicate(obligation); |
f035d41b XL |
1269 | } |
1270 | ||
1271 | // Check that all obligations are satisfied by the implementation's | |
1272 | // version. | |
1273 | if let Err(ref errors) = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx) { | |
1274 | infcx.report_fulfillment_errors(errors, None, false); | |
1275 | return Err(ErrorReported); | |
1276 | } | |
1277 | ||
1278 | // Finally, resolve all regions. This catches wily misuses of | |
1279 | // lifetime parameters. | |
1280 | let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id); | |
29967ef6 XL |
1281 | let implied_bounds = match impl_ty.container { |
1282 | ty::TraitContainer(_) => vec![], | |
1283 | ty::ImplContainer(def_id) => fcx.impl_implied_bounds(def_id, impl_ty_span), | |
1284 | }; | |
1285 | fcx.regionck_item(impl_ty_hir_id, impl_ty_span, &implied_bounds); | |
f035d41b XL |
1286 | |
1287 | Ok(()) | |
1288 | }) | |
1289 | } | |
1290 | ||
dfeec247 XL |
1291 | fn assoc_item_kind_str(impl_item: &ty::AssocItem) -> &'static str { |
1292 | match impl_item.kind { | |
1293 | ty::AssocKind::Const => "const", | |
ba9703b0 | 1294 | ty::AssocKind::Fn => "method", |
f035d41b | 1295 | ty::AssocKind::Type => "type", |
dfeec247 XL |
1296 | } |
1297 | } |