]>
Commit | Line | Data |
---|---|---|
1b1a35ee | 1 | use crate::errors::LifetimesOrBoundsMismatchOnTrait; |
c295e0f8 | 2 | use rustc_data_structures::stable_set::FxHashSet; |
ba9703b0 | 3 | use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorReported}; |
dfeec247 XL |
4 | use rustc_hir as hir; |
5 | use rustc_hir::def::{DefKind, Res}; | |
6 | use rustc_hir::intravisit; | |
7 | use rustc_hir::{GenericParamKind, ImplItemKind, TraitItemKind}; | |
74b04a01 | 8 | use rustc_infer::infer::{self, InferOk, TyCtxtInferExt}; |
29967ef6 | 9 | use rustc_infer::traits::util; |
f035d41b | 10 | use rustc_middle::ty; |
ba9703b0 | 11 | use rustc_middle::ty::error::{ExpectedFound, TypeError}; |
3dfed10e | 12 | use rustc_middle::ty::subst::{InternalSubsts, Subst}; |
ba9703b0 | 13 | use rustc_middle::ty::util::ExplicitSelf; |
3dfed10e | 14 | use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt}; |
dfeec247 | 15 | use rustc_span::Span; |
ba9703b0 XL |
16 | use rustc_trait_selection::traits::error_reporting::InferCtxtExt; |
17 | use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode, Reveal}; | |
cdc7bbd5 | 18 | use std::iter; |
85aaf69f | 19 | |
dfeec247 | 20 | use super::{potentially_plural_count, FnCtxt, Inherited}; |
60c5eb7d | 21 | |
85aaf69f SL |
22 | /// Checks that a method from an impl conforms to the signature of |
23 | /// the same method as declared in the trait. | |
24 | /// | |
25 | /// # Parameters | |
26 | /// | |
9fa01778 XL |
27 | /// - `impl_m`: type of the method we are checking |
28 | /// - `impl_m_span`: span to use for reporting errors | |
29 | /// - `trait_m`: the method in the trait | |
30 | /// - `impl_trait_ref`: the TraitRef corresponding to the trait implementation | |
85aaf69f | 31 | |
dfeec247 | 32 | crate fn compare_impl_method<'tcx>( |
dc9dc135 XL |
33 | tcx: TyCtxt<'tcx>, |
34 | impl_m: &ty::AssocItem, | |
35 | impl_m_span: Span, | |
36 | trait_m: &ty::AssocItem, | |
37 | impl_trait_ref: ty::TraitRef<'tcx>, | |
38 | trait_item_span: Option<Span>, | |
39 | ) { | |
dfeec247 | 40 | debug!("compare_impl_method(impl_trait_ref={:?})", impl_trait_ref); |
85aaf69f | 41 | |
ba9703b0 | 42 | let impl_m_span = tcx.sess.source_map().guess_head_span(impl_m_span); |
2c00a5a8 | 43 | |
dfeec247 XL |
44 | if let Err(ErrorReported) = compare_self_type(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) |
45 | { | |
c30ab7b3 | 46 | return; |
85aaf69f SL |
47 | } |
48 | ||
dfeec247 XL |
49 | if let Err(ErrorReported) = |
50 | compare_number_of_generics(tcx, impl_m, impl_m_span, trait_m, trait_item_span) | |
51 | { | |
c30ab7b3 SL |
52 | return; |
53 | } | |
9e0c209e | 54 | |
dfeec247 XL |
55 | if let Err(ErrorReported) = |
56 | compare_number_of_method_arguments(tcx, impl_m, impl_m_span, trait_m, trait_item_span) | |
57 | { | |
85aaf69f SL |
58 | return; |
59 | } | |
60 | ||
dfeec247 | 61 | if let Err(ErrorReported) = compare_synthetic_generics(tcx, impl_m, trait_m) { |
abe05a73 XL |
62 | return; |
63 | } | |
64 | ||
dfeec247 XL |
65 | if let Err(ErrorReported) = |
66 | compare_predicate_entailment(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) | |
67 | { | |
85aaf69f SL |
68 | return; |
69 | } | |
136023e0 XL |
70 | |
71 | if let Err(ErrorReported) = compare_const_param_types(tcx, impl_m, trait_m, trait_item_span) { | |
72 | return; | |
73 | } | |
c30ab7b3 SL |
74 | } |
75 | ||
dc9dc135 XL |
76 | fn compare_predicate_entailment<'tcx>( |
77 | tcx: TyCtxt<'tcx>, | |
78 | impl_m: &ty::AssocItem, | |
79 | impl_m_span: Span, | |
80 | trait_m: &ty::AssocItem, | |
81 | impl_trait_ref: ty::TraitRef<'tcx>, | |
82 | ) -> Result<(), ErrorReported> { | |
476ff2be SL |
83 | let trait_to_impl_substs = impl_trait_ref.substs; |
84 | ||
7cac9316 XL |
85 | // This node-id should be used for the `body_id` field on each |
86 | // `ObligationCause` (and the `FnCtxt`). This is what | |
87 | // `regionck_item` expects. | |
3dfed10e | 88 | let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); |
7cac9316 | 89 | |
f035d41b XL |
90 | // We sometimes modify the span further down. |
91 | let mut cause = ObligationCause::new( | |
92 | impl_m_span, | |
93 | impl_m_hir_id, | |
94 | ObligationCauseCode::CompareImplMethodObligation { | |
476ff2be SL |
95 | impl_item_def_id: impl_m.def_id, |
96 | trait_item_def_id: trait_m.def_id, | |
476ff2be | 97 | }, |
f035d41b | 98 | ); |
85aaf69f SL |
99 | |
100 | // This code is best explained by example. Consider a trait: | |
101 | // | |
f035d41b XL |
102 | // trait Trait<'t, T> { |
103 | // fn method<'a, M>(t: &'t T, m: &'a M) -> Self; | |
85aaf69f SL |
104 | // } |
105 | // | |
106 | // And an impl: | |
107 | // | |
108 | // impl<'i, 'j, U> Trait<'j, &'i U> for Foo { | |
f035d41b | 109 | // fn method<'b, N>(t: &'j &'i U, m: &'b N) -> Foo; |
85aaf69f SL |
110 | // } |
111 | // | |
112 | // We wish to decide if those two method types are compatible. | |
113 | // | |
114 | // We start out with trait_to_impl_substs, that maps the trait | |
115 | // type parameters to impl type parameters. This is taken from the | |
116 | // impl trait reference: | |
117 | // | |
118 | // trait_to_impl_substs = {'t => 'j, T => &'i U, Self => Foo} | |
119 | // | |
120 | // We create a mapping `dummy_substs` that maps from the impl type | |
121 | // parameters to fresh types and regions. For type parameters, | |
122 | // this is the identity transform, but we could as well use any | |
0bf4aa26 | 123 | // placeholder types. For regions, we convert from bound to free |
85aaf69f SL |
124 | // regions (Note: but only early-bound regions, i.e., those |
125 | // declared on the impl or used in type parameter bounds). | |
126 | // | |
f035d41b | 127 | // impl_to_placeholder_substs = {'i => 'i0, U => U0, N => N0 } |
85aaf69f | 128 | // |
f035d41b | 129 | // Now we can apply placeholder_substs to the type of the impl method |
0bf4aa26 | 130 | // to yield a new function type in terms of our fresh, placeholder |
85aaf69f SL |
131 | // types: |
132 | // | |
133 | // <'b> fn(t: &'i0 U0, m: &'b) -> Foo | |
134 | // | |
135 | // We now want to extract and substitute the type of the *trait* | |
136 | // method and compare it. To do so, we must create a compound | |
137 | // substitution by combining trait_to_impl_substs and | |
f035d41b | 138 | // impl_to_placeholder_substs, and also adding a mapping for the method |
85aaf69f SL |
139 | // type parameters. We extend the mapping to also include |
140 | // the method parameters. | |
141 | // | |
f035d41b | 142 | // trait_to_placeholder_substs = { T => &'i0 U0, Self => Foo, M => N0 } |
85aaf69f SL |
143 | // |
144 | // Applying this to the trait method type yields: | |
145 | // | |
146 | // <'a> fn(t: &'i0 U0, m: &'a) -> Foo | |
147 | // | |
148 | // This type is also the same but the name of the bound region ('a | |
149 | // vs 'b). However, the normal subtyping rules on fn types handle | |
150 | // this kind of equivalency just fine. | |
151 | // | |
152 | // We now use these substitutions to ensure that all declared bounds are | |
153 | // satisfied by the implementation's method. | |
154 | // | |
155 | // We do this by creating a parameter environment which contains a | |
f035d41b XL |
156 | // substitution corresponding to impl_to_placeholder_substs. We then build |
157 | // trait_to_placeholder_substs and use it to convert the predicates contained | |
0bf4aa26 | 158 | // in the trait_m.generics to the placeholder form. |
85aaf69f SL |
159 | // |
160 | // Finally we register each of these predicates as an obligation in | |
161 | // a fresh FulfillmentCtxt, and invoke select_all_or_error. | |
162 | ||
0bf4aa26 | 163 | // Create mapping from impl to placeholder. |
f035d41b | 164 | let impl_to_placeholder_substs = InternalSubsts::identity_for_item(tcx, impl_m.def_id); |
85aaf69f | 165 | |
0bf4aa26 | 166 | // Create mapping from trait to placeholder. |
f035d41b XL |
167 | let trait_to_placeholder_substs = |
168 | impl_to_placeholder_substs.rebase_onto(tcx, impl_m.container.id(), trait_to_impl_substs); | |
169 | debug!("compare_impl_method: trait_to_placeholder_substs={:?}", trait_to_placeholder_substs); | |
85aaf69f | 170 | |
7cac9316 XL |
171 | let impl_m_generics = tcx.generics_of(impl_m.def_id); |
172 | let trait_m_generics = tcx.generics_of(trait_m.def_id); | |
173 | let impl_m_predicates = tcx.predicates_of(impl_m.def_id); | |
174 | let trait_m_predicates = tcx.predicates_of(trait_m.def_id); | |
476ff2be | 175 | |
c30ab7b3 | 176 | // Check region bounds. |
dfeec247 XL |
177 | check_region_bounds_on_impl_item( |
178 | tcx, | |
179 | impl_m_span, | |
180 | impl_m, | |
181 | trait_m, | |
182 | &trait_m_generics, | |
183 | &impl_m_generics, | |
184 | )?; | |
c30ab7b3 SL |
185 | |
186 | // Create obligations for each predicate declared by the impl | |
187 | // definition in the context of the trait's parameter | |
188 | // environment. We can't just use `impl_env.caller_bounds`, | |
189 | // however, because we want to replace all late-bound regions with | |
190 | // region variables. | |
7cac9316 XL |
191 | let impl_predicates = tcx.predicates_of(impl_m_predicates.parent.unwrap()); |
192 | let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); | |
c30ab7b3 SL |
193 | |
194 | debug!("compare_impl_method: impl_bounds={:?}", hybrid_preds); | |
195 | ||
196 | // This is the only tricky bit of the new way we check implementation methods | |
197 | // We need to build a set of predicates where only the method-level bounds | |
198 | // are from the trait and we assume all other bounds from the implementation | |
199 | // to be previously satisfied. | |
200 | // | |
201 | // We then register the obligations from the impl_m and check to see | |
202 | // if all constraints hold. | |
dfeec247 XL |
203 | hybrid_preds |
204 | .predicates | |
f035d41b | 205 | .extend(trait_m_predicates.instantiate_own(tcx, trait_to_placeholder_substs).predicates); |
c30ab7b3 | 206 | |
0bf4aa26 | 207 | // Construct trait parameter environment and then shift it into the placeholder viewpoint. |
c30ab7b3 SL |
208 | // The key step here is to update the caller_bounds's predicates to be |
209 | // the new hybrid bounds we computed. | |
9fa01778 | 210 | let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_hir_id); |
a2a8927a XL |
211 | let param_env = ty::ParamEnv::new( |
212 | tcx.intern_predicates(&hybrid_preds.predicates), | |
213 | Reveal::UserFacing, | |
214 | hir::Constness::NotConst, | |
215 | ); | |
3c0e092e XL |
216 | let param_env = |
217 | traits::normalize_param_env_or_error(tcx, impl_m.def_id, param_env, normalize_cause); | |
7cac9316 | 218 | |
041b39d2 | 219 | tcx.infer_ctxt().enter(|infcx| { |
ba9703b0 | 220 | let inh = Inherited::new(infcx, impl_m.def_id.expect_local()); |
c30ab7b3 | 221 | let infcx = &inh.infcx; |
a7813a04 | 222 | |
f035d41b | 223 | debug!("compare_impl_method: caller_bounds={:?}", param_env.caller_bounds()); |
a7813a04 XL |
224 | |
225 | let mut selcx = traits::SelectionContext::new(&infcx); | |
226 | ||
f035d41b | 227 | let impl_m_own_bounds = impl_m_predicates.instantiate_own(tcx, impl_to_placeholder_substs); |
3c0e092e XL |
228 | for (predicate, span) in iter::zip(impl_m_own_bounds.predicates, impl_m_own_bounds.spans) { |
229 | let normalize_cause = traits::ObligationCause::misc(span, impl_m_hir_id); | |
cc61c64b | 230 | let traits::Normalized { value: predicate, obligations } = |
3c0e092e | 231 | traits::normalize(&mut selcx, param_env, normalize_cause, predicate); |
a7813a04 | 232 | |
cc61c64b | 233 | inh.register_predicates(obligations); |
3c0e092e | 234 | let mut cause = cause.clone(); |
a2a8927a | 235 | cause.span = span; |
3c0e092e | 236 | inh.register_predicate(traits::Obligation::new(cause, param_env, predicate)); |
a7813a04 | 237 | } |
85aaf69f | 238 | |
a7813a04 XL |
239 | // We now need to check that the signature of the impl method is |
240 | // compatible with that of the trait method. We do this by | |
241 | // checking that `impl_fty <: trait_fty`. | |
242 | // | |
243 | // FIXME. Unfortunately, this doesn't quite work right now because | |
244 | // associated type normalization is not integrated into subtype | |
245 | // checks. For the comparison to be valid, we need to | |
246 | // normalize the associated types in the impl/trait methods | |
247 | // first. However, because function types bind regions, just | |
248 | // calling `normalize_associated_types_in` would have no effect on | |
249 | // any associated types appearing in the fn arguments or return | |
250 | // type. | |
251 | ||
0bf4aa26 | 252 | // Compute placeholder form of impl and trait method tys. |
3157f602 | 253 | let tcx = infcx.tcx; |
476ff2be | 254 | |
c295e0f8 | 255 | let mut wf_tys = FxHashSet::default(); |
94222f64 | 256 | |
a1dfa0c6 XL |
257 | let (impl_sig, _) = infcx.replace_bound_vars_with_fresh_vars( |
258 | impl_m_span, | |
259 | infer::HigherRankedType, | |
fc512014 | 260 | tcx.fn_sig(impl_m.def_id), |
a1dfa0c6 | 261 | ); |
3157f602 | 262 | let impl_sig = |
fc512014 | 263 | inh.normalize_associated_types_in(impl_m_span, impl_m_hir_id, param_env, impl_sig); |
136023e0 | 264 | let impl_fty = tcx.mk_fn_ptr(ty::Binder::dummy(impl_sig)); |
3157f602 XL |
265 | debug!("compare_impl_method: impl_fty={:?}", impl_fty); |
266 | ||
94222f64 | 267 | // First liberate late bound regions and subst placeholders |
fc512014 | 268 | let trait_sig = tcx.liberate_late_bound_regions(impl_m.def_id, tcx.fn_sig(trait_m.def_id)); |
f035d41b | 269 | let trait_sig = trait_sig.subst(tcx, trait_to_placeholder_substs); |
3157f602 | 270 | let trait_sig = |
fc512014 | 271 | inh.normalize_associated_types_in(impl_m_span, impl_m_hir_id, param_env, trait_sig); |
c295e0f8 | 272 | // Add the resulting inputs and output as well-formed. |
94222f64 | 273 | wf_tys.extend(trait_sig.inputs_and_output.iter()); |
136023e0 | 274 | let trait_fty = tcx.mk_fn_ptr(ty::Binder::dummy(trait_sig)); |
3157f602 XL |
275 | |
276 | debug!("compare_impl_method: trait_fty={:?}", trait_fty); | |
277 | ||
dfeec247 XL |
278 | let sub_result = infcx.at(&cause, param_env).sup(trait_fty, impl_fty).map( |
279 | |InferOk { obligations, .. }| { | |
3c0e092e XL |
280 | // FIXME: We'd want to keep more accurate spans than "the method signature" when |
281 | // processing the comparison between the trait and impl fn, but we sadly lose them | |
282 | // and point at the whole signature when a trait bound or specific input or output | |
283 | // type would be more appropriate. In other places we have a `Vec<Span>` | |
284 | // corresponding to their `Vec<Predicate>`, but we don't have that here. | |
285 | // Fixing this would improve the output of test `issue-83765.rs`. | |
dfeec247 XL |
286 | inh.register_predicates(obligations); |
287 | }, | |
288 | ); | |
c30ab7b3 SL |
289 | |
290 | if let Err(terr) = sub_result { | |
dfeec247 XL |
291 | debug!("sub_types failed: impl ty {:?}, trait ty {:?}", impl_fty, trait_fty); |
292 | ||
cdc7bbd5 XL |
293 | let (impl_err_span, trait_err_span) = |
294 | extract_spans_for_error_reporting(&infcx, &terr, &cause, impl_m, trait_m); | |
dfeec247 | 295 | |
a2a8927a | 296 | cause.span = impl_err_span; |
dfeec247 XL |
297 | |
298 | let mut diag = struct_span_err!( | |
299 | tcx.sess, | |
300 | cause.span(tcx), | |
301 | E0053, | |
302 | "method `{}` has an incompatible type for trait", | |
5099ac24 | 303 | trait_m.name |
dfeec247 | 304 | ); |
cdc7bbd5 XL |
305 | match &terr { |
306 | TypeError::ArgumentMutability(0) | TypeError::ArgumentSorts(_, 0) | |
307 | if trait_m.fn_has_self_parameter => | |
308 | { | |
309 | let ty = trait_sig.inputs()[0]; | |
310 | let sugg = match ExplicitSelf::determine(ty, |_| ty == impl_trait_ref.self_ty()) | |
dfeec247 | 311 | { |
cdc7bbd5 XL |
312 | ExplicitSelf::ByValue => "self".to_owned(), |
313 | ExplicitSelf::ByReference(_, hir::Mutability::Not) => "&self".to_owned(), | |
314 | ExplicitSelf::ByReference(_, hir::Mutability::Mut) => { | |
315 | "&mut self".to_owned() | |
316 | } | |
317 | _ => format!("self: {}", ty), | |
318 | }; | |
319 | ||
320 | // When the `impl` receiver is an arbitrary self type, like `self: Box<Self>`, the | |
321 | // span points only at the type `Box<Self`>, but we want to cover the whole | |
322 | // argument pattern and type. | |
a2a8927a | 323 | let span = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
cdc7bbd5 XL |
324 | ImplItemKind::Fn(ref sig, body) => tcx |
325 | .hir() | |
326 | .body_param_names(body) | |
327 | .zip(sig.decl.inputs.iter()) | |
328 | .map(|(param, ty)| param.span.to(ty.span)) | |
329 | .next() | |
330 | .unwrap_or(impl_err_span), | |
331 | _ => bug!("{:?} is not a method", impl_m), | |
332 | }; | |
333 | ||
334 | diag.span_suggestion( | |
335 | span, | |
336 | "change the self-receiver type to match the trait", | |
337 | sugg, | |
338 | Applicability::MachineApplicable, | |
339 | ); | |
340 | } | |
341 | TypeError::ArgumentMutability(i) | TypeError::ArgumentSorts(_, i) => { | |
342 | if trait_sig.inputs().len() == *i { | |
343 | // Suggestion to change output type. We do not suggest in `async` functions | |
344 | // to avoid complex logic or incorrect output. | |
a2a8927a | 345 | match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
cdc7bbd5 XL |
346 | ImplItemKind::Fn(ref sig, _) |
347 | if sig.header.asyncness == hir::IsAsync::NotAsync => | |
348 | { | |
349 | let msg = "change the output type to match the trait"; | |
350 | let ap = Applicability::MachineApplicable; | |
351 | match sig.decl.output { | |
352 | hir::FnRetTy::DefaultReturn(sp) => { | |
353 | let sugg = format!("-> {} ", trait_sig.output()); | |
354 | diag.span_suggestion_verbose(sp, msg, sugg, ap); | |
355 | } | |
356 | hir::FnRetTy::Return(hir_ty) => { | |
357 | let sugg = trait_sig.output().to_string(); | |
358 | diag.span_suggestion(hir_ty.span, msg, sugg, ap); | |
359 | } | |
360 | }; | |
361 | } | |
362 | _ => {} | |
363 | }; | |
364 | } else if let Some(trait_ty) = trait_sig.inputs().get(*i) { | |
9fa01778 | 365 | diag.span_suggestion( |
8faf50e0 | 366 | impl_err_span, |
cdc7bbd5 XL |
367 | "change the parameter type to match the trait", |
368 | trait_ty.to_string(), | |
0bf4aa26 | 369 | Applicability::MachineApplicable, |
8faf50e0 XL |
370 | ); |
371 | } | |
372 | } | |
cdc7bbd5 | 373 | _ => {} |
8faf50e0 | 374 | } |
c30ab7b3 | 375 | |
dfeec247 XL |
376 | infcx.note_type_err( |
377 | &mut diag, | |
378 | &cause, | |
379 | trait_err_span.map(|sp| (sp, "type in trait".to_owned())), | |
5099ac24 FG |
380 | Some(infer::ValuePairs::Terms(ExpectedFound { |
381 | expected: trait_fty.into(), | |
382 | found: impl_fty.into(), | |
dfeec247 XL |
383 | })), |
384 | &terr, | |
a2a8927a | 385 | false, |
dfeec247 | 386 | ); |
5bcae85e | 387 | diag.emit(); |
c30ab7b3 | 388 | return Err(ErrorReported); |
a7813a04 | 389 | } |
85aaf69f | 390 | |
a7813a04 XL |
391 | // Check that all obligations are satisfied by the implementation's |
392 | // version. | |
3c0e092e XL |
393 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
394 | if !errors.is_empty() { | |
395 | infcx.report_fulfillment_errors(&errors, None, false); | |
c30ab7b3 | 396 | return Err(ErrorReported); |
85aaf69f | 397 | } |
85aaf69f | 398 | |
a7813a04 | 399 | // Finally, resolve all regions. This catches wily misuses of |
c30ab7b3 | 400 | // lifetime parameters. |
9fa01778 | 401 | let fcx = FnCtxt::new(&inh, param_env, impl_m_hir_id); |
c295e0f8 | 402 | fcx.regionck_item(impl_m_hir_id, impl_m_span, wf_tys); |
85aaf69f | 403 | |
c30ab7b3 SL |
404 | Ok(()) |
405 | }) | |
406 | } | |
407 | ||
dfeec247 | 408 | fn check_region_bounds_on_impl_item<'tcx>( |
dc9dc135 XL |
409 | tcx: TyCtxt<'tcx>, |
410 | span: Span, | |
411 | impl_m: &ty::AssocItem, | |
412 | trait_m: &ty::AssocItem, | |
413 | trait_generics: &ty::Generics, | |
414 | impl_generics: &ty::Generics, | |
dc9dc135 | 415 | ) -> Result<(), ErrorReported> { |
94b46f34 XL |
416 | let trait_params = trait_generics.own_counts().lifetimes; |
417 | let impl_params = impl_generics.own_counts().lifetimes; | |
c30ab7b3 | 418 | |
dfeec247 XL |
419 | debug!( |
420 | "check_region_bounds_on_impl_item: \ | |
c30ab7b3 | 421 | trait_generics={:?} \ |
dfeec247 XL |
422 | impl_generics={:?}", |
423 | trait_generics, impl_generics | |
424 | ); | |
c30ab7b3 SL |
425 | |
426 | // Must have same number of early-bound lifetime parameters. | |
427 | // Unfortunately, if the user screws up the bounds, then this | |
428 | // will change classification between early and late. E.g., | |
429 | // if in trait we have `<'a,'b:'a>`, and in impl we just have | |
430 | // `<'a,'b>`, then we have 2 early-bound lifetime parameters | |
431 | // in trait but 0 in the impl. But if we report "expected 2 | |
432 | // but found 0" it's confusing, because it looks like there | |
433 | // are zero. Since I don't quite know how to phrase things at | |
434 | // the moment, give a kind of vague error message. | |
94b46f34 | 435 | if trait_params != impl_params { |
dfeec247 | 436 | let item_kind = assoc_item_kind_str(impl_m); |
ba9703b0 | 437 | let def_span = tcx.sess.source_map().guess_head_span(span); |
5099ac24 FG |
438 | let span = impl_m |
439 | .def_id | |
440 | .as_local() | |
441 | .and_then(|did| tcx.hir().get_generics(did)) | |
442 | .map_or(def_span, |g| g.span); | |
5869c6ff | 443 | let generics_span = tcx.hir().span_if_local(trait_m.def_id).map(|sp| { |
1b1a35ee | 444 | let def_sp = tcx.sess.source_map().guess_head_span(sp); |
5099ac24 FG |
445 | trait_m |
446 | .def_id | |
447 | .as_local() | |
448 | .and_then(|did| tcx.hir().get_generics(did)) | |
449 | .map_or(def_sp, |g| g.span) | |
5869c6ff XL |
450 | }); |
451 | ||
1b1a35ee | 452 | tcx.sess.emit_err(LifetimesOrBoundsMismatchOnTrait { |
8faf50e0 | 453 | span, |
dfeec247 | 454 | item_kind, |
5099ac24 | 455 | ident: impl_m.ident(tcx), |
1b1a35ee XL |
456 | generics_span, |
457 | }); | |
c30ab7b3 | 458 | return Err(ErrorReported); |
85aaf69f | 459 | } |
9e0c209e | 460 | |
0bf4aa26 | 461 | Ok(()) |
c30ab7b3 | 462 | } |
9e0c209e | 463 | |
3c0e092e | 464 | #[instrument(level = "debug", skip(infcx))] |
dc9dc135 XL |
465 | fn extract_spans_for_error_reporting<'a, 'tcx>( |
466 | infcx: &infer::InferCtxt<'a, 'tcx>, | |
dc9dc135 XL |
467 | terr: &TypeError<'_>, |
468 | cause: &ObligationCause<'tcx>, | |
469 | impl_m: &ty::AssocItem, | |
dc9dc135 | 470 | trait_m: &ty::AssocItem, |
dc9dc135 | 471 | ) -> (Span, Option<Span>) { |
c30ab7b3 | 472 | let tcx = infcx.tcx; |
a2a8927a | 473 | let mut impl_args = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
cdc7bbd5 XL |
474 | ImplItemKind::Fn(ref sig, _) => { |
475 | sig.decl.inputs.iter().map(|t| t.span).chain(iter::once(sig.decl.output.span())) | |
c30ab7b3 SL |
476 | } |
477 | _ => bug!("{:?} is not a method", impl_m), | |
478 | }; | |
a2a8927a XL |
479 | let trait_args = |
480 | trait_m.def_id.as_local().map(|def_id| match tcx.hir().expect_trait_item(def_id).kind { | |
cdc7bbd5 XL |
481 | TraitItemKind::Fn(ref sig, _) => { |
482 | sig.decl.inputs.iter().map(|t| t.span).chain(iter::once(sig.decl.output.span())) | |
c30ab7b3 | 483 | } |
cdc7bbd5 | 484 | _ => bug!("{:?} is not a TraitItemKind::Fn", trait_m), |
a2a8927a | 485 | }); |
9e0c209e | 486 | |
cdc7bbd5 XL |
487 | match *terr { |
488 | TypeError::ArgumentMutability(i) => { | |
489 | (impl_args.nth(i).unwrap(), trait_args.and_then(|mut args| args.nth(i))) | |
490 | } | |
491 | TypeError::ArgumentSorts(ExpectedFound { .. }, i) => { | |
492 | (impl_args.nth(i).unwrap(), trait_args.and_then(|mut args| args.nth(i))) | |
c30ab7b3 | 493 | } |
48663c56 | 494 | _ => (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)), |
c30ab7b3 SL |
495 | } |
496 | } | |
497 | ||
dc9dc135 XL |
498 | fn compare_self_type<'tcx>( |
499 | tcx: TyCtxt<'tcx>, | |
500 | impl_m: &ty::AssocItem, | |
501 | impl_m_span: Span, | |
502 | trait_m: &ty::AssocItem, | |
503 | impl_trait_ref: ty::TraitRef<'tcx>, | |
504 | ) -> Result<(), ErrorReported> { | |
c30ab7b3 SL |
505 | // Try to give more informative error messages about self typing |
506 | // mismatches. Note that any mismatch will also be detected | |
507 | // below, where we construct a canonical function type that | |
508 | // includes the self parameter as a normal parameter. It's just | |
509 | // that the error messages you get out of this code are a bit more | |
510 | // inscrutable, particularly for cases where one method has no | |
511 | // self. | |
476ff2be | 512 | |
dc9dc135 | 513 | let self_string = |method: &ty::AssocItem| { |
476ff2be SL |
514 | let untransformed_self_ty = match method.container { |
515 | ty::ImplContainer(_) => impl_trait_ref.self_ty(), | |
dfeec247 | 516 | ty::TraitContainer(_) => tcx.types.self_param, |
476ff2be | 517 | }; |
fc512014 | 518 | let self_arg_ty = tcx.fn_sig(method.def_id).input(0); |
0531ce1d | 519 | let param_env = ty::ParamEnv::reveal_all(); |
abe05a73 XL |
520 | |
521 | tcx.infer_ctxt().enter(|infcx| { | |
fc512014 | 522 | let self_arg_ty = tcx.liberate_late_bound_regions(method.def_id, self_arg_ty); |
abe05a73 XL |
523 | let can_eq_self = |ty| infcx.can_eq(param_env, untransformed_self_ty, ty).is_ok(); |
524 | match ExplicitSelf::determine(self_arg_ty, can_eq_self) { | |
0bf4aa26 | 525 | ExplicitSelf::ByValue => "self".to_owned(), |
dfeec247 XL |
526 | ExplicitSelf::ByReference(_, hir::Mutability::Not) => "&self".to_owned(), |
527 | ExplicitSelf::ByReference(_, hir::Mutability::Mut) => "&mut self".to_owned(), | |
528 | _ => format!("self: {}", self_arg_ty), | |
abe05a73 XL |
529 | } |
530 | }) | |
476ff2be SL |
531 | }; |
532 | ||
ba9703b0 | 533 | match (trait_m.fn_has_self_parameter, impl_m.fn_has_self_parameter) { |
476ff2be SL |
534 | (false, false) | (true, true) => {} |
535 | ||
536 | (false, true) => { | |
537 | let self_descr = self_string(impl_m); | |
dfeec247 XL |
538 | let mut err = struct_span_err!( |
539 | tcx.sess, | |
540 | impl_m_span, | |
541 | E0185, | |
cdc7bbd5 | 542 | "method `{}` has a `{}` declaration in the impl, but not in the trait", |
5099ac24 | 543 | trait_m.name, |
dfeec247 XL |
544 | self_descr |
545 | ); | |
7cac9316 | 546 | err.span_label(impl_m_span, format!("`{}` used in impl", self_descr)); |
0731742a | 547 | if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
2c00a5a8 XL |
548 | err.span_label(span, format!("trait method declared without `{}`", self_descr)); |
549 | } else { | |
5099ac24 | 550 | err.note_trait_signature(trait_m.name.to_string(), trait_m.signature(tcx)); |
c30ab7b3 SL |
551 | } |
552 | err.emit(); | |
553 | return Err(ErrorReported); | |
554 | } | |
476ff2be SL |
555 | |
556 | (true, false) => { | |
557 | let self_descr = self_string(trait_m); | |
dfeec247 XL |
558 | let mut err = struct_span_err!( |
559 | tcx.sess, | |
560 | impl_m_span, | |
561 | E0186, | |
cdc7bbd5 | 562 | "method `{}` has a `{}` declaration in the trait, but not in the impl", |
5099ac24 | 563 | trait_m.name, |
dfeec247 XL |
564 | self_descr |
565 | ); | |
2c00a5a8 | 566 | err.span_label(impl_m_span, format!("expected `{}` in impl", self_descr)); |
0731742a | 567 | if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
7cac9316 XL |
568 | err.span_label(span, format!("`{}` used in trait", self_descr)); |
569 | } else { | |
5099ac24 | 570 | err.note_trait_signature(trait_m.name.to_string(), trait_m.signature(tcx)); |
c30ab7b3 SL |
571 | } |
572 | err.emit(); | |
573 | return Err(ErrorReported); | |
574 | } | |
c30ab7b3 SL |
575 | } |
576 | ||
577 | Ok(()) | |
578 | } | |
579 | ||
dc9dc135 XL |
580 | fn compare_number_of_generics<'tcx>( |
581 | tcx: TyCtxt<'tcx>, | |
582 | impl_: &ty::AssocItem, | |
583 | _impl_span: Span, | |
584 | trait_: &ty::AssocItem, | |
532ac7d7 XL |
585 | trait_span: Option<Span>, |
586 | ) -> Result<(), ErrorReported> { | |
587 | let trait_own_counts = tcx.generics_of(trait_.def_id).own_counts(); | |
588 | let impl_own_counts = tcx.generics_of(impl_.def_id).own_counts(); | |
589 | ||
590 | let matchings = [ | |
591 | ("type", trait_own_counts.types, impl_own_counts.types), | |
592 | ("const", trait_own_counts.consts, impl_own_counts.consts), | |
593 | ]; | |
594 | ||
dfeec247 XL |
595 | let item_kind = assoc_item_kind_str(impl_); |
596 | ||
532ac7d7 | 597 | let mut err_occurred = false; |
136023e0 | 598 | for (kind, trait_count, impl_count) in matchings { |
532ac7d7 XL |
599 | if impl_count != trait_count { |
600 | err_occurred = true; | |
601 | ||
f9f354fc | 602 | let (trait_spans, impl_trait_spans) = if let Some(def_id) = trait_.def_id.as_local() { |
a2a8927a | 603 | let trait_item = tcx.hir().expect_trait_item(def_id); |
f9f354fc XL |
604 | if trait_item.generics.params.is_empty() { |
605 | (Some(vec![trait_item.generics.span]), vec![]) | |
dc9dc135 | 606 | } else { |
f9f354fc XL |
607 | let arg_spans: Vec<Span> = |
608 | trait_item.generics.params.iter().map(|p| p.span).collect(); | |
609 | let impl_trait_spans: Vec<Span> = trait_item | |
610 | .generics | |
611 | .params | |
612 | .iter() | |
613 | .filter_map(|p| match p.kind { | |
3c0e092e | 614 | GenericParamKind::Type { synthetic: true, .. } => Some(p.span), |
f9f354fc XL |
615 | _ => None, |
616 | }) | |
617 | .collect(); | |
618 | (Some(arg_spans), impl_trait_spans) | |
619 | } | |
620 | } else { | |
621 | (trait_span.map(|s| vec![s]), vec![]) | |
622 | }; | |
9e0c209e | 623 | |
a2a8927a | 624 | let impl_item = tcx.hir().expect_impl_item(impl_.def_id.expect_local()); |
dfeec247 XL |
625 | let impl_item_impl_trait_spans: Vec<Span> = impl_item |
626 | .generics | |
627 | .params | |
628 | .iter() | |
dc9dc135 | 629 | .filter_map(|p| match p.kind { |
3c0e092e | 630 | GenericParamKind::Type { synthetic: true, .. } => Some(p.span), |
dc9dc135 | 631 | _ => None, |
dfeec247 XL |
632 | }) |
633 | .collect(); | |
dc9dc135 XL |
634 | let spans = impl_item.generics.spans(); |
635 | let span = spans.primary_span(); | |
636 | ||
532ac7d7 | 637 | let mut err = tcx.sess.struct_span_err_with_code( |
dc9dc135 | 638 | spans, |
532ac7d7 | 639 | &format!( |
dfeec247 | 640 | "{} `{}` has {} {kind} parameter{} but its trait \ |
532ac7d7 | 641 | declaration has {} {kind} parameter{}", |
dfeec247 | 642 | item_kind, |
5099ac24 | 643 | trait_.name, |
532ac7d7 | 644 | impl_count, |
60c5eb7d | 645 | pluralize!(impl_count), |
532ac7d7 | 646 | trait_count, |
60c5eb7d | 647 | pluralize!(trait_count), |
532ac7d7 XL |
648 | kind = kind, |
649 | ), | |
650 | DiagnosticId::Error("E0049".into()), | |
651 | ); | |
c30ab7b3 | 652 | |
532ac7d7 | 653 | let mut suffix = None; |
c30ab7b3 | 654 | |
dc9dc135 XL |
655 | if let Some(spans) = trait_spans { |
656 | let mut spans = spans.iter(); | |
657 | if let Some(span) = spans.next() { | |
dfeec247 XL |
658 | err.span_label( |
659 | *span, | |
660 | format!( | |
661 | "expected {} {} parameter{}", | |
662 | trait_count, | |
663 | kind, | |
664 | pluralize!(trait_count), | |
665 | ), | |
666 | ); | |
dc9dc135 XL |
667 | } |
668 | for span in spans { | |
669 | err.span_label(*span, ""); | |
670 | } | |
532ac7d7 XL |
671 | } else { |
672 | suffix = Some(format!(", expected {}", trait_count)); | |
673 | } | |
c30ab7b3 | 674 | |
dc9dc135 | 675 | if let Some(span) = span { |
dfeec247 XL |
676 | err.span_label( |
677 | span, | |
678 | format!( | |
679 | "found {} {} parameter{}{}", | |
680 | impl_count, | |
681 | kind, | |
682 | pluralize!(impl_count), | |
ba9703b0 | 683 | suffix.unwrap_or_else(String::new), |
dfeec247 XL |
684 | ), |
685 | ); | |
dc9dc135 XL |
686 | } |
687 | ||
688 | for span in impl_trait_spans.iter().chain(impl_item_impl_trait_spans.iter()) { | |
689 | err.span_label(*span, "`impl Trait` introduces an implicit type parameter"); | |
690 | } | |
c30ab7b3 | 691 | |
532ac7d7 XL |
692 | err.emit(); |
693 | } | |
c30ab7b3 SL |
694 | } |
695 | ||
dfeec247 | 696 | if err_occurred { Err(ErrorReported) } else { Ok(()) } |
c30ab7b3 SL |
697 | } |
698 | ||
dc9dc135 XL |
699 | fn compare_number_of_method_arguments<'tcx>( |
700 | tcx: TyCtxt<'tcx>, | |
701 | impl_m: &ty::AssocItem, | |
702 | impl_m_span: Span, | |
703 | trait_m: &ty::AssocItem, | |
704 | trait_item_span: Option<Span>, | |
705 | ) -> Result<(), ErrorReported> { | |
041b39d2 XL |
706 | let impl_m_fty = tcx.fn_sig(impl_m.def_id); |
707 | let trait_m_fty = tcx.fn_sig(trait_m.def_id); | |
8bb4bdeb XL |
708 | let trait_number_args = trait_m_fty.inputs().skip_binder().len(); |
709 | let impl_number_args = impl_m_fty.inputs().skip_binder().len(); | |
476ff2be | 710 | if trait_number_args != impl_number_args { |
f9f354fc | 711 | let trait_span = if let Some(def_id) = trait_m.def_id.as_local() { |
a2a8927a | 712 | match tcx.hir().expect_trait_item(def_id).kind { |
ba9703b0 | 713 | TraitItemKind::Fn(ref trait_m_sig, _) => { |
dfeec247 | 714 | let pos = if trait_number_args > 0 { trait_number_args - 1 } else { 0 }; |
0731742a XL |
715 | if let Some(arg) = trait_m_sig.decl.inputs.get(pos) { |
716 | Some(if pos == 0 { | |
717 | arg.span | |
718 | } else { | |
94222f64 | 719 | arg.span.with_lo(trait_m_sig.decl.inputs[0].span.lo()) |
0731742a | 720 | }) |
c30ab7b3 SL |
721 | } else { |
722 | trait_item_span | |
723 | } | |
724 | } | |
725 | _ => bug!("{:?} is not a method", impl_m), | |
726 | } | |
727 | } else { | |
728 | trait_item_span | |
729 | }; | |
a2a8927a | 730 | let impl_span = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
ba9703b0 | 731 | ImplItemKind::Fn(ref impl_m_sig, _) => { |
dfeec247 | 732 | let pos = if impl_number_args > 0 { impl_number_args - 1 } else { 0 }; |
0731742a XL |
733 | if let Some(arg) = impl_m_sig.decl.inputs.get(pos) { |
734 | if pos == 0 { | |
735 | arg.span | |
736 | } else { | |
94222f64 | 737 | arg.span.with_lo(impl_m_sig.decl.inputs[0].span.lo()) |
0731742a | 738 | } |
9e0c209e | 739 | } else { |
c30ab7b3 | 740 | impl_m_span |
9e0c209e SL |
741 | } |
742 | } | |
c30ab7b3 SL |
743 | _ => bug!("{:?} is not a method", impl_m), |
744 | }; | |
dfeec247 XL |
745 | let mut err = struct_span_err!( |
746 | tcx.sess, | |
747 | impl_span, | |
748 | E0050, | |
a2a8927a | 749 | "method `{}` has {} but the declaration in trait `{}` has {}", |
5099ac24 | 750 | trait_m.name, |
dfeec247 XL |
751 | potentially_plural_count(impl_number_args, "parameter"), |
752 | tcx.def_path_str(trait_m.def_id), | |
753 | trait_number_args | |
754 | ); | |
c30ab7b3 | 755 | if let Some(trait_span) = trait_span { |
dfeec247 XL |
756 | err.span_label( |
757 | trait_span, | |
758 | format!( | |
759 | "trait requires {}", | |
760 | potentially_plural_count(trait_number_args, "parameter") | |
761 | ), | |
762 | ); | |
7cac9316 | 763 | } else { |
5099ac24 | 764 | err.note_trait_signature(trait_m.name.to_string(), trait_m.signature(tcx)); |
9e0c209e | 765 | } |
dfeec247 XL |
766 | err.span_label( |
767 | impl_span, | |
768 | format!( | |
769 | "expected {}, found {}", | |
770 | potentially_plural_count(trait_number_args, "parameter"), | |
771 | impl_number_args | |
772 | ), | |
773 | ); | |
c30ab7b3 SL |
774 | err.emit(); |
775 | return Err(ErrorReported); | |
9e0c209e | 776 | } |
c30ab7b3 SL |
777 | |
778 | Ok(()) | |
85aaf69f | 779 | } |
d9579d0f | 780 | |
dc9dc135 XL |
781 | fn compare_synthetic_generics<'tcx>( |
782 | tcx: TyCtxt<'tcx>, | |
783 | impl_m: &ty::AssocItem, | |
784 | trait_m: &ty::AssocItem, | |
785 | ) -> Result<(), ErrorReported> { | |
abe05a73 | 786 | // FIXME(chrisvittal) Clean up this function, list of FIXME items: |
94b46f34 | 787 | // 1. Better messages for the span labels |
abe05a73 | 788 | // 2. Explanation as to what is going on |
abe05a73 XL |
789 | // If we get here, we already have the same number of generics, so the zip will |
790 | // be okay. | |
791 | let mut error_found = false; | |
792 | let impl_m_generics = tcx.generics_of(impl_m.def_id); | |
793 | let trait_m_generics = tcx.generics_of(trait_m.def_id); | |
8faf50e0 XL |
794 | let impl_m_type_params = impl_m_generics.params.iter().filter_map(|param| match param.kind { |
795 | GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), | |
cdc7bbd5 | 796 | GenericParamDefKind::Lifetime | GenericParamDefKind::Const { .. } => None, |
94b46f34 | 797 | }); |
dfeec247 XL |
798 | let trait_m_type_params = trait_m_generics.params.iter().filter_map(|param| match param.kind { |
799 | GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), | |
cdc7bbd5 | 800 | GenericParamDefKind::Lifetime | GenericParamDefKind::Const { .. } => None, |
94b46f34 | 801 | }); |
dfeec247 | 802 | for ((impl_def_id, impl_synthetic), (trait_def_id, trait_synthetic)) in |
cdc7bbd5 | 803 | iter::zip(impl_m_type_params, trait_m_type_params) |
0bf4aa26 | 804 | { |
94b46f34 | 805 | if impl_synthetic != trait_synthetic { |
3dfed10e | 806 | let impl_hir_id = tcx.hir().local_def_id_to_hir_id(impl_def_id.expect_local()); |
dc9dc135 | 807 | let impl_span = tcx.hir().span(impl_hir_id); |
94b46f34 | 808 | let trait_span = tcx.def_span(trait_def_id); |
dfeec247 XL |
809 | let mut err = struct_span_err!( |
810 | tcx.sess, | |
811 | impl_span, | |
812 | E0643, | |
813 | "method `{}` has incompatible signature for trait", | |
5099ac24 | 814 | trait_m.name |
dfeec247 | 815 | ); |
94b46f34 XL |
816 | err.span_label(trait_span, "declaration in trait here"); |
817 | match (impl_synthetic, trait_synthetic) { | |
818 | // The case where the impl method uses `impl Trait` but the trait method uses | |
819 | // explicit generics | |
3c0e092e | 820 | (true, false) => { |
94b46f34 XL |
821 | err.span_label(impl_span, "expected generic parameter, found `impl Trait`"); |
822 | (|| { | |
823 | // try taking the name from the trait impl | |
824 | // FIXME: this is obviously suboptimal since the name can already be used | |
825 | // as another generic argument | |
dfeec247 | 826 | let new_name = tcx.sess.source_map().span_to_snippet(trait_span).ok()?; |
6a06907d XL |
827 | let trait_m = trait_m.def_id.as_local()?; |
828 | let trait_m = tcx.hir().trait_item(hir::TraitItemId { def_id: trait_m }); | |
94b46f34 | 829 | |
6a06907d XL |
830 | let impl_m = impl_m.def_id.as_local()?; |
831 | let impl_m = tcx.hir().impl_item(hir::ImplItemId { def_id: impl_m }); | |
94b46f34 XL |
832 | |
833 | // in case there are no generics, take the spot between the function name | |
834 | // and the opening paren of the argument list | |
dfeec247 XL |
835 | let new_generics_span = |
836 | tcx.sess.source_map().generate_fn_name_span(impl_span)?.shrink_to_hi(); | |
94b46f34 | 837 | // in case there are generics, just replace them |
dfeec247 XL |
838 | let generics_span = |
839 | impl_m.generics.span.substitute_dummy(new_generics_span); | |
94b46f34 | 840 | // replace with the generics from the trait |
dfeec247 XL |
841 | let new_generics = |
842 | tcx.sess.source_map().span_to_snippet(trait_m.generics.span).ok()?; | |
94b46f34 | 843 | |
9fa01778 | 844 | err.multipart_suggestion( |
94b46f34 XL |
845 | "try changing the `impl Trait` argument to a generic parameter", |
846 | vec![ | |
847 | // replace `impl Trait` with `T` | |
848 | (impl_span, new_name), | |
849 | // replace impl method generics with trait method generics | |
850 | // This isn't quite right, as users might have changed the names | |
851 | // of the generics, but it works for the common case | |
852 | (generics_span, new_generics), | |
853 | ], | |
0bf4aa26 | 854 | Applicability::MaybeIncorrect, |
94b46f34 XL |
855 | ); |
856 | Some(()) | |
857 | })(); | |
dfeec247 | 858 | } |
94b46f34 XL |
859 | // The case where the trait method uses `impl Trait`, but the impl method uses |
860 | // explicit generics. | |
3c0e092e | 861 | (false, true) => { |
94b46f34 XL |
862 | err.span_label(impl_span, "expected `impl Trait`, found generic parameter"); |
863 | (|| { | |
6a06907d XL |
864 | let impl_m = impl_m.def_id.as_local()?; |
865 | let impl_m = tcx.hir().impl_item(hir::ImplItemId { def_id: impl_m }); | |
e74abb32 | 866 | let input_tys = match impl_m.kind { |
ba9703b0 | 867 | hir::ImplItemKind::Fn(ref sig, _) => sig.decl.inputs, |
94b46f34 XL |
868 | _ => unreachable!(), |
869 | }; | |
870 | struct Visitor(Option<Span>, hir::def_id::DefId); | |
dfeec247 XL |
871 | impl<'v> intravisit::Visitor<'v> for Visitor { |
872 | fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) { | |
873 | intravisit::walk_ty(self, ty); | |
874 | if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = | |
875 | ty.kind | |
0bf4aa26 | 876 | { |
48663c56 | 877 | if let Res::Def(DefKind::TyParam, def_id) = path.res { |
0bf4aa26 XL |
878 | if def_id == self.1 { |
879 | self.0 = Some(ty.span); | |
94b46f34 | 880 | } |
0bf4aa26 | 881 | } |
94b46f34 XL |
882 | } |
883 | } | |
94b46f34 XL |
884 | } |
885 | let mut visitor = Visitor(None, impl_def_id); | |
886 | for ty in input_tys { | |
dfeec247 | 887 | intravisit::Visitor::visit_ty(&mut visitor, ty); |
94b46f34 XL |
888 | } |
889 | let span = visitor.0?; | |
890 | ||
dfeec247 XL |
891 | let bounds = |
892 | impl_m.generics.params.iter().find_map(|param| match param.kind { | |
8faf50e0 | 893 | GenericParamKind::Lifetime { .. } => None, |
dfeec247 | 894 | GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => { |
9fa01778 | 895 | if param.hir_id == impl_hir_id { |
8faf50e0 | 896 | Some(¶m.bounds) |
94b46f34 XL |
897 | } else { |
898 | None | |
899 | } | |
8faf50e0 | 900 | } |
dfeec247 | 901 | })?; |
8faf50e0 | 902 | let bounds = bounds.first()?.span().to(bounds.last()?.span()); |
dfeec247 | 903 | let bounds = tcx.sess.source_map().span_to_snippet(bounds).ok()?; |
94b46f34 | 904 | |
9fa01778 | 905 | err.multipart_suggestion( |
94b46f34 XL |
906 | "try removing the generic parameter and using `impl Trait` instead", |
907 | vec![ | |
908 | // delete generic parameters | |
909 | (impl_m.generics.span, String::new()), | |
910 | // replace param usage with `impl Trait` | |
911 | (span, format!("impl {}", bounds)), | |
912 | ], | |
0bf4aa26 | 913 | Applicability::MaybeIncorrect, |
94b46f34 XL |
914 | ); |
915 | Some(()) | |
916 | })(); | |
dfeec247 | 917 | } |
94b46f34 XL |
918 | _ => unreachable!(), |
919 | } | |
abe05a73 XL |
920 | err.emit(); |
921 | error_found = true; | |
922 | } | |
923 | } | |
dfeec247 | 924 | if error_found { Err(ErrorReported) } else { Ok(()) } |
abe05a73 XL |
925 | } |
926 | ||
136023e0 XL |
927 | fn compare_const_param_types<'tcx>( |
928 | tcx: TyCtxt<'tcx>, | |
929 | impl_m: &ty::AssocItem, | |
930 | trait_m: &ty::AssocItem, | |
931 | trait_item_span: Option<Span>, | |
932 | ) -> Result<(), ErrorReported> { | |
933 | let const_params_of = |def_id| { | |
934 | tcx.generics_of(def_id).params.iter().filter_map(|param| match param.kind { | |
935 | GenericParamDefKind::Const { .. } => Some(param.def_id), | |
936 | _ => None, | |
937 | }) | |
938 | }; | |
939 | let const_params_impl = const_params_of(impl_m.def_id); | |
940 | let const_params_trait = const_params_of(trait_m.def_id); | |
941 | ||
942 | for (const_param_impl, const_param_trait) in iter::zip(const_params_impl, const_params_trait) { | |
943 | let impl_ty = tcx.type_of(const_param_impl); | |
944 | let trait_ty = tcx.type_of(const_param_trait); | |
945 | if impl_ty != trait_ty { | |
946 | let (impl_span, impl_ident) = match tcx.hir().get_if_local(const_param_impl) { | |
947 | Some(hir::Node::GenericParam(hir::GenericParam { span, name, .. })) => ( | |
948 | span, | |
949 | match name { | |
950 | hir::ParamName::Plain(ident) => Some(ident), | |
951 | _ => None, | |
952 | }, | |
953 | ), | |
954 | other => bug!( | |
955 | "expected GenericParam, found {:?}", | |
956 | other.map_or_else(|| "nothing".to_string(), |n| format!("{:?}", n)) | |
957 | ), | |
958 | }; | |
959 | let trait_span = match tcx.hir().get_if_local(const_param_trait) { | |
960 | Some(hir::Node::GenericParam(hir::GenericParam { span, .. })) => Some(span), | |
961 | _ => None, | |
962 | }; | |
963 | let mut err = struct_span_err!( | |
964 | tcx.sess, | |
965 | *impl_span, | |
966 | E0053, | |
967 | "method `{}` has an incompatible const parameter type for trait", | |
5099ac24 | 968 | trait_m.name |
136023e0 XL |
969 | ); |
970 | err.span_note( | |
971 | trait_span.map_or_else(|| trait_item_span.unwrap_or(*impl_span), |span| *span), | |
972 | &format!( | |
973 | "the const parameter{} has type `{}`, but the declaration \ | |
974 | in trait `{}` has type `{}`", | |
975 | &impl_ident.map_or_else(|| "".to_string(), |ident| format!(" `{}`", ident)), | |
976 | impl_ty, | |
977 | tcx.def_path_str(trait_m.def_id), | |
978 | trait_ty | |
979 | ), | |
980 | ); | |
981 | err.emit(); | |
982 | return Err(ErrorReported); | |
983 | } | |
984 | } | |
985 | ||
986 | Ok(()) | |
987 | } | |
988 | ||
dfeec247 | 989 | crate fn compare_const_impl<'tcx>( |
dc9dc135 XL |
990 | tcx: TyCtxt<'tcx>, |
991 | impl_c: &ty::AssocItem, | |
992 | impl_c_span: Span, | |
993 | trait_c: &ty::AssocItem, | |
994 | impl_trait_ref: ty::TraitRef<'tcx>, | |
995 | ) { | |
c30ab7b3 | 996 | debug!("compare_const_impl(impl_trait_ref={:?})", impl_trait_ref); |
d9579d0f | 997 | |
041b39d2 | 998 | tcx.infer_ctxt().enter(|infcx| { |
532ac7d7 | 999 | let param_env = tcx.param_env(impl_c.def_id); |
ba9703b0 | 1000 | let inh = Inherited::new(infcx, impl_c.def_id.expect_local()); |
cc61c64b | 1001 | let infcx = &inh.infcx; |
a7813a04 XL |
1002 | |
1003 | // The below is for the most part highly similar to the procedure | |
1004 | // for methods above. It is simpler in many respects, especially | |
1005 | // because we shouldn't really have to deal with lifetimes or | |
1006 | // predicates. In fact some of this should probably be put into | |
1007 | // shared functions because of DRY violations... | |
476ff2be | 1008 | let trait_to_impl_substs = impl_trait_ref.substs; |
a7813a04 XL |
1009 | |
1010 | // Create a parameter environment that represents the implementation's | |
1011 | // method. | |
3dfed10e | 1012 | let impl_c_hir_id = tcx.hir().local_def_id_to_hir_id(impl_c.def_id.expect_local()); |
a7813a04 | 1013 | |
0bf4aa26 | 1014 | // Compute placeholder form of impl and trait const tys. |
7cac9316 XL |
1015 | let impl_ty = tcx.type_of(impl_c.def_id); |
1016 | let trait_ty = tcx.type_of(trait_c.def_id).subst(tcx, trait_to_impl_substs); | |
f035d41b XL |
1017 | let mut cause = ObligationCause::new( |
1018 | impl_c_span, | |
1019 | impl_c_hir_id, | |
1020 | ObligationCauseCode::CompareImplConstObligation, | |
1021 | ); | |
a7813a04 | 1022 | |
cc61c64b | 1023 | // There is no "body" here, so just pass dummy id. |
dfeec247 | 1024 | let impl_ty = |
fc512014 | 1025 | inh.normalize_associated_types_in(impl_c_span, impl_c_hir_id, param_env, impl_ty); |
c30ab7b3 | 1026 | |
cc61c64b | 1027 | debug!("compare_const_impl: impl_ty={:?}", impl_ty); |
c30ab7b3 | 1028 | |
dfeec247 | 1029 | let trait_ty = |
fc512014 | 1030 | inh.normalize_associated_types_in(impl_c_span, impl_c_hir_id, param_env, trait_ty); |
c30ab7b3 | 1031 | |
cc61c64b | 1032 | debug!("compare_const_impl: trait_ty={:?}", trait_ty); |
a7813a04 | 1033 | |
dfeec247 XL |
1034 | let err = infcx |
1035 | .at(&cause, param_env) | |
1036 | .sup(trait_ty, impl_ty) | |
1037 | .map(|ok| inh.register_infer_ok_obligations(ok)); | |
d9579d0f | 1038 | |
a7813a04 | 1039 | if let Err(terr) = err { |
dfeec247 XL |
1040 | debug!( |
1041 | "checking associated const for compatibility: impl ty {:?}, trait ty {:?}", | |
1042 | impl_ty, trait_ty | |
1043 | ); | |
5bcae85e SL |
1044 | |
1045 | // Locate the Span containing just the type of the offending impl | |
a2a8927a XL |
1046 | match tcx.hir().expect_impl_item(impl_c.def_id.expect_local()).kind { |
1047 | ImplItemKind::Const(ref ty, _) => cause.span = ty.span, | |
c30ab7b3 | 1048 | _ => bug!("{:?} is not a impl const", impl_c), |
5bcae85e SL |
1049 | } |
1050 | ||
dfeec247 XL |
1051 | let mut diag = struct_span_err!( |
1052 | tcx.sess, | |
1053 | cause.span, | |
1054 | E0326, | |
cdc7bbd5 | 1055 | "implemented const `{}` has an incompatible type for trait", |
5099ac24 | 1056 | trait_c.name |
dfeec247 | 1057 | ); |
5bcae85e | 1058 | |
a2a8927a | 1059 | let trait_c_span = trait_c.def_id.as_local().map(|trait_c_def_id| { |
7cac9316 | 1060 | // Add a label to the Span containing just the type of the const |
a2a8927a | 1061 | match tcx.hir().expect_trait_item(trait_c_def_id).kind { |
7cac9316 XL |
1062 | TraitItemKind::Const(ref ty, _) => ty.span, |
1063 | _ => bug!("{:?} is not a trait const", trait_c), | |
1064 | } | |
1065 | }); | |
5bcae85e | 1066 | |
dfeec247 XL |
1067 | infcx.note_type_err( |
1068 | &mut diag, | |
1069 | &cause, | |
1070 | trait_c_span.map(|span| (span, "type in trait".to_owned())), | |
5099ac24 FG |
1071 | Some(infer::ValuePairs::Terms(ExpectedFound { |
1072 | expected: trait_ty.into(), | |
1073 | found: impl_ty.into(), | |
dfeec247 XL |
1074 | })), |
1075 | &terr, | |
a2a8927a | 1076 | false, |
dfeec247 | 1077 | ); |
5bcae85e | 1078 | diag.emit(); |
d9579d0f | 1079 | } |
cc61c64b | 1080 | |
7cac9316 XL |
1081 | // Check that all obligations are satisfied by the implementation's |
1082 | // version. | |
3c0e092e XL |
1083 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
1084 | if !errors.is_empty() { | |
1085 | infcx.report_fulfillment_errors(&errors, None, false); | |
7cac9316 XL |
1086 | return; |
1087 | } | |
1088 | ||
9fa01778 | 1089 | let fcx = FnCtxt::new(&inh, param_env, impl_c_hir_id); |
c295e0f8 | 1090 | fcx.regionck_item(impl_c_hir_id, impl_c_span, FxHashSet::default()); |
a7813a04 | 1091 | }); |
d9579d0f | 1092 | } |
dfeec247 XL |
1093 | |
1094 | crate fn compare_ty_impl<'tcx>( | |
1095 | tcx: TyCtxt<'tcx>, | |
1096 | impl_ty: &ty::AssocItem, | |
1097 | impl_ty_span: Span, | |
1098 | trait_ty: &ty::AssocItem, | |
1099 | impl_trait_ref: ty::TraitRef<'tcx>, | |
1100 | trait_item_span: Option<Span>, | |
1101 | ) { | |
1102 | debug!("compare_impl_type(impl_trait_ref={:?})", impl_trait_ref); | |
1103 | ||
1104 | let _: Result<(), ErrorReported> = (|| { | |
1105 | compare_number_of_generics(tcx, impl_ty, impl_ty_span, trait_ty, trait_item_span)?; | |
1106 | ||
a2a8927a XL |
1107 | let sp = tcx.def_span(impl_ty.def_id); |
1108 | compare_type_predicate_entailment(tcx, impl_ty, sp, trait_ty, impl_trait_ref)?; | |
f035d41b | 1109 | |
29967ef6 | 1110 | check_type_bounds(tcx, trait_ty, impl_ty, impl_ty_span, impl_trait_ref) |
dfeec247 XL |
1111 | })(); |
1112 | } | |
1113 | ||
1114 | /// The equivalent of [compare_predicate_entailment], but for associated types | |
1115 | /// instead of associated functions. | |
f035d41b | 1116 | fn compare_type_predicate_entailment<'tcx>( |
dfeec247 XL |
1117 | tcx: TyCtxt<'tcx>, |
1118 | impl_ty: &ty::AssocItem, | |
1119 | impl_ty_span: Span, | |
1120 | trait_ty: &ty::AssocItem, | |
1121 | impl_trait_ref: ty::TraitRef<'tcx>, | |
1122 | ) -> Result<(), ErrorReported> { | |
1123 | let impl_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); | |
1124 | let trait_to_impl_substs = | |
1125 | impl_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
1126 | ||
1127 | let impl_ty_generics = tcx.generics_of(impl_ty.def_id); | |
1128 | let trait_ty_generics = tcx.generics_of(trait_ty.def_id); | |
1129 | let impl_ty_predicates = tcx.predicates_of(impl_ty.def_id); | |
1130 | let trait_ty_predicates = tcx.predicates_of(trait_ty.def_id); | |
1131 | ||
1132 | check_region_bounds_on_impl_item( | |
1133 | tcx, | |
1134 | impl_ty_span, | |
1135 | impl_ty, | |
1136 | trait_ty, | |
1137 | &trait_ty_generics, | |
1138 | &impl_ty_generics, | |
1139 | )?; | |
1140 | ||
1141 | let impl_ty_own_bounds = impl_ty_predicates.instantiate_own(tcx, impl_substs); | |
1142 | ||
1143 | if impl_ty_own_bounds.is_empty() { | |
1144 | // Nothing to check. | |
1145 | return Ok(()); | |
1146 | } | |
1147 | ||
1148 | // This `HirId` should be used for the `body_id` field on each | |
1149 | // `ObligationCause` (and the `FnCtxt`). This is what | |
1150 | // `regionck_item` expects. | |
3dfed10e | 1151 | let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
f035d41b XL |
1152 | let cause = ObligationCause::new( |
1153 | impl_ty_span, | |
1154 | impl_ty_hir_id, | |
1155 | ObligationCauseCode::CompareImplTypeObligation { | |
dfeec247 XL |
1156 | impl_item_def_id: impl_ty.def_id, |
1157 | trait_item_def_id: trait_ty.def_id, | |
1158 | }, | |
f035d41b | 1159 | ); |
dfeec247 XL |
1160 | |
1161 | debug!("compare_type_predicate_entailment: trait_to_impl_substs={:?}", trait_to_impl_substs); | |
1162 | ||
1163 | // The predicates declared by the impl definition, the trait and the | |
1164 | // associated type in the trait are assumed. | |
1165 | let impl_predicates = tcx.predicates_of(impl_ty_predicates.parent.unwrap()); | |
1166 | let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); | |
1167 | hybrid_preds | |
1168 | .predicates | |
1169 | .extend(trait_ty_predicates.instantiate_own(tcx, trait_to_impl_substs).predicates); | |
1170 | ||
1171 | debug!("compare_type_predicate_entailment: bounds={:?}", hybrid_preds); | |
1172 | ||
1173 | let normalize_cause = traits::ObligationCause::misc(impl_ty_span, impl_ty_hir_id); | |
a2a8927a XL |
1174 | let param_env = ty::ParamEnv::new( |
1175 | tcx.intern_predicates(&hybrid_preds.predicates), | |
1176 | Reveal::UserFacing, | |
1177 | hir::Constness::NotConst, | |
1178 | ); | |
dfeec247 XL |
1179 | let param_env = traits::normalize_param_env_or_error( |
1180 | tcx, | |
1181 | impl_ty.def_id, | |
1182 | param_env, | |
1183 | normalize_cause.clone(), | |
1184 | ); | |
1185 | tcx.infer_ctxt().enter(|infcx| { | |
ba9703b0 | 1186 | let inh = Inherited::new(infcx, impl_ty.def_id.expect_local()); |
dfeec247 XL |
1187 | let infcx = &inh.infcx; |
1188 | ||
f035d41b | 1189 | debug!("compare_type_predicate_entailment: caller_bounds={:?}", param_env.caller_bounds()); |
dfeec247 XL |
1190 | |
1191 | let mut selcx = traits::SelectionContext::new(&infcx); | |
1192 | ||
1193 | for predicate in impl_ty_own_bounds.predicates { | |
1194 | let traits::Normalized { value: predicate, obligations } = | |
fc512014 | 1195 | traits::normalize(&mut selcx, param_env, normalize_cause.clone(), predicate); |
dfeec247 XL |
1196 | |
1197 | inh.register_predicates(obligations); | |
1198 | inh.register_predicate(traits::Obligation::new(cause.clone(), param_env, predicate)); | |
1199 | } | |
1200 | ||
1201 | // Check that all obligations are satisfied by the implementation's | |
1202 | // version. | |
3c0e092e XL |
1203 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
1204 | if !errors.is_empty() { | |
1205 | infcx.report_fulfillment_errors(&errors, None, false); | |
dfeec247 XL |
1206 | return Err(ErrorReported); |
1207 | } | |
1208 | ||
1209 | // Finally, resolve all regions. This catches wily misuses of | |
1210 | // lifetime parameters. | |
1211 | let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id); | |
c295e0f8 | 1212 | fcx.regionck_item(impl_ty_hir_id, impl_ty_span, FxHashSet::default()); |
dfeec247 XL |
1213 | |
1214 | Ok(()) | |
1215 | }) | |
1216 | } | |
1217 | ||
f035d41b XL |
1218 | /// Validate that `ProjectionCandidate`s created for this associated type will |
1219 | /// be valid. | |
1220 | /// | |
1221 | /// Usually given | |
1222 | /// | |
1223 | /// trait X { type Y: Copy } impl X for T { type Y = S; } | |
1224 | /// | |
1225 | /// We are able to normalize `<T as X>::U` to `S`, and so when we check the | |
1226 | /// impl is well-formed we have to prove `S: Copy`. | |
1227 | /// | |
1228 | /// For default associated types the normalization is not possible (the value | |
1229 | /// from the impl could be overridden). We also can't normalize generic | |
1230 | /// associated types (yet) because they contain bound parameters. | |
94222f64 | 1231 | #[tracing::instrument(level = "debug", skip(tcx))] |
29967ef6 | 1232 | pub fn check_type_bounds<'tcx>( |
f035d41b XL |
1233 | tcx: TyCtxt<'tcx>, |
1234 | trait_ty: &ty::AssocItem, | |
1235 | impl_ty: &ty::AssocItem, | |
1236 | impl_ty_span: Span, | |
1237 | impl_trait_ref: ty::TraitRef<'tcx>, | |
1238 | ) -> Result<(), ErrorReported> { | |
f035d41b XL |
1239 | // Given |
1240 | // | |
1241 | // impl<A, B> Foo<u32> for (A, B) { | |
1242 | // type Bar<C> =... | |
1243 | // } | |
1244 | // | |
94222f64 XL |
1245 | // - `impl_trait_ref` would be `<(A, B) as Foo<u32>> |
1246 | // - `impl_ty_substs` would be `[A, B, ^0.0]` (`^0.0` here is the bound var with db 0 and index 0) | |
1247 | // - `rebased_substs` would be `[(A, B), u32, ^0.0]`, combining the substs from | |
1248 | // the *trait* with the generic associated type parameters (as bound vars). | |
1249 | // | |
1250 | // A note regarding the use of bound vars here: | |
1251 | // Imagine as an example | |
1252 | // ``` | |
1253 | // trait Family { | |
1254 | // type Member<C: Eq>; | |
1255 | // } | |
1256 | // | |
1257 | // impl Family for VecFamily { | |
1258 | // type Member<C: Eq> = i32; | |
1259 | // } | |
1260 | // ``` | |
1261 | // Here, we would generate | |
1262 | // ```notrust | |
1263 | // forall<C> { Normalize(<VecFamily as Family>::Member<C> => i32) } | |
1264 | // ``` | |
1265 | // when we really would like to generate | |
1266 | // ```notrust | |
1267 | // forall<C> { Normalize(<VecFamily as Family>::Member<C> => i32) :- Implemented(C: Eq) } | |
1268 | // ``` | |
1269 | // But, this is probably fine, because although the first clause can be used with types C that | |
1270 | // do not implement Eq, for it to cause some kind of problem, there would have to be a | |
1271 | // VecFamily::Member<X> for some type X where !(X: Eq), that appears in the value of type | |
1272 | // Member<C: Eq> = .... That type would fail a well-formedness check that we ought to be doing | |
1273 | // elsewhere, which would check that any <T as Family>::Member<X> meets the bounds declared in | |
1274 | // the trait (notably, that X: Eq and T: Family). | |
1275 | let defs: &ty::Generics = tcx.generics_of(impl_ty.def_id); | |
1276 | let mut substs = smallvec::SmallVec::with_capacity(defs.count()); | |
1277 | if let Some(def_id) = defs.parent { | |
1278 | let parent_defs = tcx.generics_of(def_id); | |
1279 | InternalSubsts::fill_item(&mut substs, tcx, parent_defs, &mut |param, _| { | |
1280 | tcx.mk_param_from_def(param) | |
1281 | }); | |
1282 | } | |
1283 | let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> = | |
1284 | smallvec::SmallVec::with_capacity(defs.count()); | |
1285 | InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param.kind { | |
1286 | GenericParamDefKind::Type { .. } => { | |
1287 | let kind = ty::BoundTyKind::Param(param.name); | |
1288 | let bound_var = ty::BoundVariableKind::Ty(kind); | |
1289 | bound_vars.push(bound_var); | |
1290 | tcx.mk_ty(ty::Bound( | |
1291 | ty::INNERMOST, | |
1292 | ty::BoundTy { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, | |
1293 | )) | |
1294 | .into() | |
1295 | } | |
1296 | GenericParamDefKind::Lifetime => { | |
1297 | let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name); | |
1298 | let bound_var = ty::BoundVariableKind::Region(kind); | |
1299 | bound_vars.push(bound_var); | |
1300 | tcx.mk_region(ty::ReLateBound( | |
1301 | ty::INNERMOST, | |
1302 | ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, | |
1303 | )) | |
1304 | .into() | |
1305 | } | |
1306 | GenericParamDefKind::Const { .. } => { | |
1307 | let bound_var = ty::BoundVariableKind::Const; | |
1308 | bound_vars.push(bound_var); | |
5099ac24 | 1309 | tcx.mk_const(ty::ConstS { |
94222f64 XL |
1310 | ty: tcx.type_of(param.def_id), |
1311 | val: ty::ConstKind::Bound( | |
1312 | ty::INNERMOST, | |
1313 | ty::BoundVar::from_usize(bound_vars.len() - 1), | |
1314 | ), | |
1315 | }) | |
1316 | .into() | |
1317 | } | |
1318 | }); | |
1319 | let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter()); | |
1320 | let impl_ty_substs = tcx.intern_substs(&substs); | |
1321 | ||
f035d41b XL |
1322 | let rebased_substs = |
1323 | impl_ty_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
1324 | let impl_ty_value = tcx.type_of(impl_ty.def_id); | |
1325 | ||
3dfed10e XL |
1326 | let param_env = tcx.param_env(impl_ty.def_id); |
1327 | ||
1328 | // When checking something like | |
f035d41b | 1329 | // |
3dfed10e XL |
1330 | // trait X { type Y: PartialEq<<Self as X>::Y> } |
1331 | // impl X for T { default type Y = S; } | |
f035d41b | 1332 | // |
3dfed10e XL |
1333 | // We will have to prove the bound S: PartialEq<<T as X>::Y>. In this case |
1334 | // we want <T as X>::Y to normalize to S. This is valid because we are | |
1335 | // checking the default value specifically here. Add this equality to the | |
1336 | // ParamEnv for normalization specifically. | |
1337 | let normalize_param_env = { | |
1338 | let mut predicates = param_env.caller_bounds().iter().collect::<Vec<_>>(); | |
29967ef6 XL |
1339 | match impl_ty_value.kind() { |
1340 | ty::Projection(proj) | |
1341 | if proj.item_def_id == trait_ty.def_id && proj.substs == rebased_substs => | |
1342 | { | |
1343 | // Don't include this predicate if the projected type is | |
1344 | // exactly the same as the projection. This can occur in | |
1345 | // (somewhat dubious) code like this: | |
1346 | // | |
1347 | // impl<T> X for T where T: X { type Y = <T as X>::Y; } | |
1348 | } | |
1349 | _ => predicates.push( | |
94222f64 XL |
1350 | ty::Binder::bind_with_vars( |
1351 | ty::ProjectionPredicate { | |
1352 | projection_ty: ty::ProjectionTy { | |
1353 | item_def_id: trait_ty.def_id, | |
1354 | substs: rebased_substs, | |
1355 | }, | |
5099ac24 | 1356 | term: impl_ty_value.into(), |
29967ef6 | 1357 | }, |
94222f64 XL |
1358 | bound_vars, |
1359 | ) | |
29967ef6 XL |
1360 | .to_predicate(tcx), |
1361 | ), | |
1362 | }; | |
a2a8927a XL |
1363 | ty::ParamEnv::new( |
1364 | tcx.intern_predicates(&predicates), | |
1365 | Reveal::UserFacing, | |
1366 | param_env.constness(), | |
1367 | ) | |
f035d41b | 1368 | }; |
94222f64 XL |
1369 | debug!(?normalize_param_env); |
1370 | ||
1371 | let impl_ty_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); | |
1372 | let rebased_substs = | |
1373 | impl_ty_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
f035d41b XL |
1374 | |
1375 | tcx.infer_ctxt().enter(move |infcx| { | |
a2a8927a | 1376 | let inh = Inherited::new(infcx, impl_ty.def_id.expect_local()); |
f035d41b XL |
1377 | let infcx = &inh.infcx; |
1378 | let mut selcx = traits::SelectionContext::new(&infcx); | |
1379 | ||
3dfed10e | 1380 | let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
5099ac24 FG |
1381 | let normalize_cause = ObligationCause::new( |
1382 | impl_ty_span, | |
1383 | impl_ty_hir_id, | |
1384 | ObligationCauseCode::CheckAssociatedTypeBounds { | |
1385 | impl_item_def_id: impl_ty.def_id, | |
1386 | trait_item_def_id: trait_ty.def_id, | |
1387 | }, | |
1388 | ); | |
3c0e092e XL |
1389 | let mk_cause = |span: Span| { |
1390 | let code = if span.is_dummy() { | |
1391 | traits::MiscObligation | |
1392 | } else { | |
1393 | traits::BindingObligation(trait_ty.def_id, span) | |
1394 | }; | |
1395 | ObligationCause::new(impl_ty_span, impl_ty_hir_id, code) | |
29967ef6 | 1396 | }; |
f035d41b | 1397 | |
29967ef6 XL |
1398 | let obligations = tcx |
1399 | .explicit_item_bounds(trait_ty.def_id) | |
1400 | .iter() | |
1401 | .map(|&(bound, span)| { | |
94222f64 | 1402 | debug!(?bound); |
29967ef6 XL |
1403 | let concrete_ty_bound = bound.subst(tcx, rebased_substs); |
1404 | debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound); | |
f035d41b | 1405 | |
29967ef6 XL |
1406 | traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound) |
1407 | }) | |
1408 | .collect(); | |
1409 | debug!("check_type_bounds: item_bounds={:?}", obligations); | |
f035d41b | 1410 | |
29967ef6 | 1411 | for mut obligation in util::elaborate_obligations(tcx, obligations) { |
f035d41b XL |
1412 | let traits::Normalized { value: normalized_predicate, obligations } = traits::normalize( |
1413 | &mut selcx, | |
3dfed10e | 1414 | normalize_param_env, |
f035d41b | 1415 | normalize_cause.clone(), |
fc512014 | 1416 | obligation.predicate, |
f035d41b | 1417 | ); |
f035d41b | 1418 | debug!("compare_projection_bounds: normalized predicate = {:?}", normalized_predicate); |
29967ef6 | 1419 | obligation.predicate = normalized_predicate; |
f035d41b XL |
1420 | |
1421 | inh.register_predicates(obligations); | |
29967ef6 | 1422 | inh.register_predicate(obligation); |
f035d41b XL |
1423 | } |
1424 | ||
1425 | // Check that all obligations are satisfied by the implementation's | |
1426 | // version. | |
a2a8927a | 1427 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
3c0e092e XL |
1428 | if !errors.is_empty() { |
1429 | infcx.report_fulfillment_errors(&errors, None, false); | |
f035d41b XL |
1430 | return Err(ErrorReported); |
1431 | } | |
1432 | ||
1433 | // Finally, resolve all regions. This catches wily misuses of | |
1434 | // lifetime parameters. | |
1435 | let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id); | |
29967ef6 | 1436 | let implied_bounds = match impl_ty.container { |
c295e0f8 | 1437 | ty::TraitContainer(_) => FxHashSet::default(), |
29967ef6 XL |
1438 | ty::ImplContainer(def_id) => fcx.impl_implied_bounds(def_id, impl_ty_span), |
1439 | }; | |
c295e0f8 | 1440 | fcx.regionck_item(impl_ty_hir_id, impl_ty_span, implied_bounds); |
f035d41b XL |
1441 | |
1442 | Ok(()) | |
1443 | }) | |
1444 | } | |
1445 | ||
dfeec247 XL |
1446 | fn assoc_item_kind_str(impl_item: &ty::AssocItem) -> &'static str { |
1447 | match impl_item.kind { | |
1448 | ty::AssocKind::Const => "const", | |
ba9703b0 | 1449 | ty::AssocKind::Fn => "method", |
f035d41b | 1450 | ty::AssocKind::Type => "type", |
dfeec247 XL |
1451 | } |
1452 | } |