]>
Commit | Line | Data |
---|---|---|
85aaf69f SL |
1 | // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
bd371182 | 11 | use middle::free_region::FreeRegionMap; |
54a0048b SL |
12 | use rustc::infer::{self, InferOk, TypeOrigin}; |
13 | use rustc::ty::{self, TyCtxt}; | |
14 | use rustc::traits::{self, ProjectionMode}; | |
15 | use rustc::ty::subst::{self, Subst, Substs, VecPerParamSpace}; | |
85aaf69f SL |
16 | |
17 | use syntax::ast; | |
c34b1796 | 18 | use syntax::codemap::Span; |
85aaf69f SL |
19 | |
20 | use super::assoc; | |
21 | ||
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 | /// | |
27 | /// - impl_m: type of the method we are checking | |
28 | /// - impl_m_span: span to use for reporting errors | |
29 | /// - impl_m_body_id: id of the method body | |
30 | /// - trait_m: the method in the trait | |
31 | /// - impl_trait_ref: the TraitRef corresponding to the trait implementation | |
32 | ||
54a0048b | 33 | pub fn compare_impl_method<'tcx>(tcx: &TyCtxt<'tcx>, |
85aaf69f SL |
34 | impl_m: &ty::Method<'tcx>, |
35 | impl_m_span: Span, | |
36 | impl_m_body_id: ast::NodeId, | |
37 | trait_m: &ty::Method<'tcx>, | |
38 | impl_trait_ref: &ty::TraitRef<'tcx>) { | |
62682a34 SL |
39 | debug!("compare_impl_method(impl_trait_ref={:?})", |
40 | impl_trait_ref); | |
85aaf69f | 41 | |
62682a34 SL |
42 | debug!("compare_impl_method: impl_trait_ref (liberated) = {:?}", |
43 | impl_trait_ref); | |
85aaf69f | 44 | |
54a0048b | 45 | let mut infcx = infer::new_infer_ctxt(tcx, &tcx.tables, None, ProjectionMode::AnyFinal); |
7453a54e | 46 | let mut fulfillment_cx = traits::FulfillmentContext::new(); |
85aaf69f SL |
47 | |
48 | let trait_to_impl_substs = &impl_trait_ref.substs; | |
49 | ||
50 | // Try to give more informative error messages about self typing | |
51 | // mismatches. Note that any mismatch will also be detected | |
52 | // below, where we construct a canonical function type that | |
53 | // includes the self parameter as a normal parameter. It's just | |
54 | // that the error messages you get out of this code are a bit more | |
55 | // inscrutable, particularly for cases where one method has no | |
56 | // self. | |
57 | match (&trait_m.explicit_self, &impl_m.explicit_self) { | |
9cc50fc6 SL |
58 | (&ty::ExplicitSelfCategory::Static, |
59 | &ty::ExplicitSelfCategory::Static) => {} | |
60 | (&ty::ExplicitSelfCategory::Static, _) => { | |
85aaf69f SL |
61 | span_err!(tcx.sess, impl_m_span, E0185, |
62 | "method `{}` has a `{}` declaration in the impl, \ | |
63 | but not in the trait", | |
62682a34 SL |
64 | trait_m.name, |
65 | impl_m.explicit_self); | |
85aaf69f SL |
66 | return; |
67 | } | |
9cc50fc6 | 68 | (_, &ty::ExplicitSelfCategory::Static) => { |
85aaf69f SL |
69 | span_err!(tcx.sess, impl_m_span, E0186, |
70 | "method `{}` has a `{}` declaration in the trait, \ | |
71 | but not in the impl", | |
62682a34 SL |
72 | trait_m.name, |
73 | trait_m.explicit_self); | |
85aaf69f SL |
74 | return; |
75 | } | |
76 | _ => { | |
77 | // Let the type checker catch other errors below | |
78 | } | |
79 | } | |
80 | ||
81 | let num_impl_m_type_params = impl_m.generics.types.len(subst::FnSpace); | |
82 | let num_trait_m_type_params = trait_m.generics.types.len(subst::FnSpace); | |
83 | if num_impl_m_type_params != num_trait_m_type_params { | |
84 | span_err!(tcx.sess, impl_m_span, E0049, | |
85 | "method `{}` has {} type parameter{} \ | |
86 | but its trait declaration has {} type parameter{}", | |
c1a9b12d | 87 | trait_m.name, |
85aaf69f SL |
88 | num_impl_m_type_params, |
89 | if num_impl_m_type_params == 1 {""} else {"s"}, | |
90 | num_trait_m_type_params, | |
91 | if num_trait_m_type_params == 1 {""} else {"s"}); | |
92 | return; | |
93 | } | |
94 | ||
95 | if impl_m.fty.sig.0.inputs.len() != trait_m.fty.sig.0.inputs.len() { | |
96 | span_err!(tcx.sess, impl_m_span, E0050, | |
97 | "method `{}` has {} parameter{} \ | |
98 | but the declaration in trait `{}` has {}", | |
c1a9b12d | 99 | trait_m.name, |
85aaf69f SL |
100 | impl_m.fty.sig.0.inputs.len(), |
101 | if impl_m.fty.sig.0.inputs.len() == 1 {""} else {"s"}, | |
c1a9b12d | 102 | tcx.item_path_str(trait_m.def_id), |
85aaf69f SL |
103 | trait_m.fty.sig.0.inputs.len()); |
104 | return; | |
105 | } | |
106 | ||
107 | // This code is best explained by example. Consider a trait: | |
108 | // | |
109 | // trait Trait<'t,T> { | |
110 | // fn method<'a,M>(t: &'t T, m: &'a M) -> Self; | |
111 | // } | |
112 | // | |
113 | // And an impl: | |
114 | // | |
115 | // impl<'i, 'j, U> Trait<'j, &'i U> for Foo { | |
116 | // fn method<'b,N>(t: &'j &'i U, m: &'b N) -> Foo; | |
117 | // } | |
118 | // | |
119 | // We wish to decide if those two method types are compatible. | |
120 | // | |
121 | // We start out with trait_to_impl_substs, that maps the trait | |
122 | // type parameters to impl type parameters. This is taken from the | |
123 | // impl trait reference: | |
124 | // | |
125 | // trait_to_impl_substs = {'t => 'j, T => &'i U, Self => Foo} | |
126 | // | |
127 | // We create a mapping `dummy_substs` that maps from the impl type | |
128 | // parameters to fresh types and regions. For type parameters, | |
129 | // this is the identity transform, but we could as well use any | |
130 | // skolemized types. For regions, we convert from bound to free | |
131 | // regions (Note: but only early-bound regions, i.e., those | |
132 | // declared on the impl or used in type parameter bounds). | |
133 | // | |
134 | // impl_to_skol_substs = {'i => 'i0, U => U0, N => N0 } | |
135 | // | |
136 | // Now we can apply skol_substs to the type of the impl method | |
137 | // to yield a new function type in terms of our fresh, skolemized | |
138 | // types: | |
139 | // | |
140 | // <'b> fn(t: &'i0 U0, m: &'b) -> Foo | |
141 | // | |
142 | // We now want to extract and substitute the type of the *trait* | |
143 | // method and compare it. To do so, we must create a compound | |
144 | // substitution by combining trait_to_impl_substs and | |
145 | // impl_to_skol_substs, and also adding a mapping for the method | |
146 | // type parameters. We extend the mapping to also include | |
147 | // the method parameters. | |
148 | // | |
149 | // trait_to_skol_substs = { T => &'i0 U0, Self => Foo, M => N0 } | |
150 | // | |
151 | // Applying this to the trait method type yields: | |
152 | // | |
153 | // <'a> fn(t: &'i0 U0, m: &'a) -> Foo | |
154 | // | |
155 | // This type is also the same but the name of the bound region ('a | |
156 | // vs 'b). However, the normal subtyping rules on fn types handle | |
157 | // this kind of equivalency just fine. | |
158 | // | |
159 | // We now use these substitutions to ensure that all declared bounds are | |
160 | // satisfied by the implementation's method. | |
161 | // | |
162 | // We do this by creating a parameter environment which contains a | |
163 | // substitution corresponding to impl_to_skol_substs. We then build | |
164 | // trait_to_skol_substs and use it to convert the predicates contained | |
165 | // in the trait_m.generics to the skolemized form. | |
166 | // | |
167 | // Finally we register each of these predicates as an obligation in | |
168 | // a fresh FulfillmentCtxt, and invoke select_all_or_error. | |
169 | ||
170 | // Create a parameter environment that represents the implementation's | |
171 | // method. | |
b039eaaf SL |
172 | let impl_m_node_id = tcx.map.as_local_node_id(impl_m.def_id).unwrap(); |
173 | let impl_param_env = ty::ParameterEnvironment::for_item(tcx, impl_m_node_id); | |
85aaf69f SL |
174 | |
175 | // Create mapping from impl to skolemized. | |
176 | let impl_to_skol_substs = &impl_param_env.free_substs; | |
177 | ||
178 | // Create mapping from trait to skolemized. | |
179 | let trait_to_skol_substs = | |
180 | trait_to_impl_substs | |
181 | .subst(tcx, impl_to_skol_substs) | |
182 | .with_method(impl_to_skol_substs.types.get_slice(subst::FnSpace).to_vec(), | |
54a0048b | 183 | impl_to_skol_substs.regions.get_slice(subst::FnSpace).to_vec()); |
62682a34 SL |
184 | debug!("compare_impl_method: trait_to_skol_substs={:?}", |
185 | trait_to_skol_substs); | |
85aaf69f SL |
186 | |
187 | // Check region bounds. FIXME(@jroesch) refactor this away when removing | |
188 | // ParamBounds. | |
189 | if !check_region_bounds_on_impl_method(tcx, | |
190 | impl_m_span, | |
191 | impl_m, | |
192 | &trait_m.generics, | |
193 | &impl_m.generics, | |
194 | &trait_to_skol_substs, | |
195 | impl_to_skol_substs) { | |
196 | return; | |
197 | } | |
198 | ||
199 | // Create obligations for each predicate declared by the impl | |
200 | // definition in the context of the trait's parameter | |
201 | // environment. We can't just use `impl_env.caller_bounds`, | |
202 | // however, because we want to replace all late-bound regions with | |
203 | // region variables. | |
204 | let impl_bounds = | |
205 | impl_m.predicates.instantiate(tcx, impl_to_skol_substs); | |
206 | ||
207 | let (impl_bounds, _) = | |
208 | infcx.replace_late_bound_regions_with_fresh_var( | |
209 | impl_m_span, | |
210 | infer::HigherRankedType, | |
211 | &ty::Binder(impl_bounds)); | |
62682a34 SL |
212 | debug!("compare_impl_method: impl_bounds={:?}", |
213 | impl_bounds); | |
85aaf69f SL |
214 | |
215 | // Normalize the associated types in the trait_bounds. | |
216 | let trait_bounds = trait_m.predicates.instantiate(tcx, &trait_to_skol_substs); | |
217 | ||
218 | // Obtain the predicate split predicate sets for each. | |
219 | let trait_pred = trait_bounds.predicates.split(); | |
220 | let impl_pred = impl_bounds.predicates.split(); | |
221 | ||
222 | // This is the only tricky bit of the new way we check implementation methods | |
223 | // We need to build a set of predicates where only the FnSpace bounds | |
224 | // are from the trait and we assume all other bounds from the implementation | |
225 | // to be previously satisfied. | |
226 | // | |
227 | // We then register the obligations from the impl_m and check to see | |
228 | // if all constraints hold. | |
229 | let hybrid_preds = VecPerParamSpace::new( | |
230 | impl_pred.types, | |
231 | impl_pred.selfs, | |
232 | trait_pred.fns | |
233 | ); | |
234 | ||
235 | // Construct trait parameter environment and then shift it into the skolemized viewpoint. | |
236 | // The key step here is to update the caller_bounds's predicates to be | |
237 | // the new hybrid bounds we computed. | |
238 | let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_body_id); | |
239 | let trait_param_env = impl_param_env.with_caller_bounds(hybrid_preds.into_vec()); | |
240 | let trait_param_env = traits::normalize_param_env_or_error(trait_param_env, | |
241 | normalize_cause.clone()); | |
c1a9b12d SL |
242 | // FIXME(@jroesch) this seems ugly, but is a temporary change |
243 | infcx.parameter_environment = trait_param_env; | |
85aaf69f | 244 | |
62682a34 | 245 | debug!("compare_impl_method: trait_bounds={:?}", |
c1a9b12d | 246 | infcx.parameter_environment.caller_bounds); |
85aaf69f | 247 | |
c1a9b12d | 248 | let mut selcx = traits::SelectionContext::new(&infcx); |
85aaf69f SL |
249 | |
250 | for predicate in impl_pred.fns { | |
251 | let traits::Normalized { value: predicate, .. } = | |
252 | traits::normalize(&mut selcx, normalize_cause.clone(), &predicate); | |
253 | ||
254 | let cause = traits::ObligationCause { | |
255 | span: impl_m_span, | |
256 | body_id: impl_m_body_id, | |
257 | code: traits::ObligationCauseCode::CompareImplMethodObligation | |
258 | }; | |
259 | ||
260 | fulfillment_cx.register_predicate_obligation( | |
261 | &infcx, | |
262 | traits::Obligation::new(cause, predicate)); | |
263 | } | |
264 | ||
265 | // We now need to check that the signature of the impl method is | |
266 | // compatible with that of the trait method. We do this by | |
267 | // checking that `impl_fty <: trait_fty`. | |
268 | // | |
269 | // FIXME. Unfortunately, this doesn't quite work right now because | |
270 | // associated type normalization is not integrated into subtype | |
271 | // checks. For the comparison to be valid, we need to | |
272 | // normalize the associated types in the impl/trait methods | |
273 | // first. However, because function types bind regions, just | |
274 | // calling `normalize_associated_types_in` would have no effect on | |
275 | // any associated types appearing in the fn arguments or return | |
276 | // type. | |
277 | ||
278 | // Compute skolemized form of impl and trait method tys. | |
54a0048b | 279 | let impl_fty = tcx.mk_fn_ptr(impl_m.fty.clone()); |
85aaf69f | 280 | let impl_fty = impl_fty.subst(tcx, impl_to_skol_substs); |
54a0048b | 281 | let trait_fty = tcx.mk_fn_ptr(trait_m.fty.clone()); |
85aaf69f SL |
282 | let trait_fty = trait_fty.subst(tcx, &trait_to_skol_substs); |
283 | ||
c34b1796 | 284 | let err = infcx.commit_if_ok(|snapshot| { |
92a42be0 | 285 | let origin = TypeOrigin::MethodCompatCheck(impl_m_span); |
85aaf69f SL |
286 | |
287 | let (impl_sig, _) = | |
288 | infcx.replace_late_bound_regions_with_fresh_var(impl_m_span, | |
289 | infer::HigherRankedType, | |
290 | &impl_m.fty.sig); | |
291 | let impl_sig = | |
292 | impl_sig.subst(tcx, impl_to_skol_substs); | |
293 | let impl_sig = | |
294 | assoc::normalize_associated_types_in(&infcx, | |
85aaf69f SL |
295 | &mut fulfillment_cx, |
296 | impl_m_span, | |
297 | impl_m_body_id, | |
298 | &impl_sig); | |
54a0048b | 299 | let impl_fty = tcx.mk_fn_ptr(ty::BareFnTy { |
c1a9b12d SL |
300 | unsafety: impl_m.fty.unsafety, |
301 | abi: impl_m.fty.abi, | |
302 | sig: ty::Binder(impl_sig) | |
54a0048b | 303 | }); |
62682a34 SL |
304 | debug!("compare_impl_method: impl_fty={:?}", |
305 | impl_fty); | |
85aaf69f SL |
306 | |
307 | let (trait_sig, skol_map) = | |
308 | infcx.skolemize_late_bound_regions(&trait_m.fty.sig, snapshot); | |
309 | let trait_sig = | |
310 | trait_sig.subst(tcx, &trait_to_skol_substs); | |
311 | let trait_sig = | |
312 | assoc::normalize_associated_types_in(&infcx, | |
85aaf69f SL |
313 | &mut fulfillment_cx, |
314 | impl_m_span, | |
315 | impl_m_body_id, | |
316 | &trait_sig); | |
54a0048b | 317 | let trait_fty = tcx.mk_fn_ptr(ty::BareFnTy { |
c1a9b12d SL |
318 | unsafety: trait_m.fty.unsafety, |
319 | abi: trait_m.fty.abi, | |
320 | sig: ty::Binder(trait_sig) | |
54a0048b | 321 | }); |
85aaf69f | 322 | |
62682a34 SL |
323 | debug!("compare_impl_method: trait_fty={:?}", |
324 | trait_fty); | |
85aaf69f | 325 | |
54a0048b | 326 | infer::mk_subty(&infcx, false, origin, impl_fty, trait_fty)?; |
85aaf69f SL |
327 | |
328 | infcx.leak_check(&skol_map, snapshot) | |
329 | }); | |
330 | ||
331 | match err { | |
332 | Ok(()) => { } | |
333 | Err(terr) => { | |
62682a34 SL |
334 | debug!("checking trait method for compatibility: impl ty {:?}, trait ty {:?}", |
335 | impl_fty, | |
336 | trait_fty); | |
85aaf69f SL |
337 | span_err!(tcx.sess, impl_m_span, E0053, |
338 | "method `{}` has an incompatible type for trait: {}", | |
c1a9b12d | 339 | trait_m.name, |
62682a34 | 340 | terr); |
85aaf69f SL |
341 | return; |
342 | } | |
343 | } | |
344 | ||
345 | // Check that all obligations are satisfied by the implementation's | |
346 | // version. | |
c1a9b12d | 347 | match fulfillment_cx.select_all_or_error(&infcx) { |
85aaf69f SL |
348 | Err(ref errors) => { traits::report_fulfillment_errors(&infcx, errors) } |
349 | Ok(_) => {} | |
350 | } | |
351 | ||
bd371182 AL |
352 | // Finally, resolve all regions. This catches wily misuses of |
353 | // lifetime parameters. We have to build up a plausible lifetime | |
354 | // environment based on what we find in the trait. We could also | |
355 | // include the obligations derived from the method argument types, | |
356 | // but I don't think it's necessary -- after all, those are still | |
357 | // in effect when type-checking the body, and all the | |
358 | // where-clauses in the header etc should be implied by the trait | |
359 | // anyway, so it shouldn't be needed there either. Anyway, we can | |
360 | // always add more relations later (it's backwards compat). | |
361 | let mut free_regions = FreeRegionMap::new(); | |
c1a9b12d SL |
362 | free_regions.relate_free_regions_from_predicates(tcx, |
363 | &infcx.parameter_environment.caller_bounds); | |
bd371182 AL |
364 | |
365 | infcx.resolve_regions_and_report_errors(&free_regions, impl_m_body_id); | |
85aaf69f | 366 | |
54a0048b | 367 | fn check_region_bounds_on_impl_method<'tcx>(tcx: &TyCtxt<'tcx>, |
85aaf69f SL |
368 | span: Span, |
369 | impl_m: &ty::Method<'tcx>, | |
370 | trait_generics: &ty::Generics<'tcx>, | |
371 | impl_generics: &ty::Generics<'tcx>, | |
372 | trait_to_skol_substs: &Substs<'tcx>, | |
373 | impl_to_skol_substs: &Substs<'tcx>) | |
374 | -> bool | |
375 | { | |
376 | ||
377 | let trait_params = trait_generics.regions.get_slice(subst::FnSpace); | |
378 | let impl_params = impl_generics.regions.get_slice(subst::FnSpace); | |
379 | ||
380 | debug!("check_region_bounds_on_impl_method: \ | |
62682a34 SL |
381 | trait_generics={:?} \ |
382 | impl_generics={:?} \ | |
383 | trait_to_skol_substs={:?} \ | |
384 | impl_to_skol_substs={:?}", | |
385 | trait_generics, | |
386 | impl_generics, | |
387 | trait_to_skol_substs, | |
388 | impl_to_skol_substs); | |
85aaf69f SL |
389 | |
390 | // Must have same number of early-bound lifetime parameters. | |
391 | // Unfortunately, if the user screws up the bounds, then this | |
392 | // will change classification between early and late. E.g., | |
393 | // if in trait we have `<'a,'b:'a>`, and in impl we just have | |
394 | // `<'a,'b>`, then we have 2 early-bound lifetime parameters | |
395 | // in trait but 0 in the impl. But if we report "expected 2 | |
396 | // but found 0" it's confusing, because it looks like there | |
397 | // are zero. Since I don't quite know how to phrase things at | |
398 | // the moment, give a kind of vague error message. | |
399 | if trait_params.len() != impl_params.len() { | |
400 | span_err!(tcx.sess, span, E0195, | |
401 | "lifetime parameters or bounds on method `{}` do \ | |
402 | not match the trait declaration", | |
c1a9b12d | 403 | impl_m.name); |
85aaf69f SL |
404 | return false; |
405 | } | |
406 | ||
407 | return true; | |
408 | } | |
409 | } | |
d9579d0f | 410 | |
54a0048b | 411 | pub fn compare_const_impl<'tcx>(tcx: &TyCtxt<'tcx>, |
d9579d0f AL |
412 | impl_c: &ty::AssociatedConst<'tcx>, |
413 | impl_c_span: Span, | |
414 | trait_c: &ty::AssociatedConst<'tcx>, | |
415 | impl_trait_ref: &ty::TraitRef<'tcx>) { | |
62682a34 SL |
416 | debug!("compare_const_impl(impl_trait_ref={:?})", |
417 | impl_trait_ref); | |
d9579d0f | 418 | |
54a0048b | 419 | let infcx = infer::new_infer_ctxt(tcx, &tcx.tables, None, ProjectionMode::AnyFinal); |
7453a54e | 420 | let mut fulfillment_cx = traits::FulfillmentContext::new(); |
d9579d0f AL |
421 | |
422 | // The below is for the most part highly similar to the procedure | |
423 | // for methods above. It is simpler in many respects, especially | |
424 | // because we shouldn't really have to deal with lifetimes or | |
425 | // predicates. In fact some of this should probably be put into | |
426 | // shared functions because of DRY violations... | |
427 | let trait_to_impl_substs = &impl_trait_ref.substs; | |
428 | ||
429 | // Create a parameter environment that represents the implementation's | |
430 | // method. | |
b039eaaf SL |
431 | let impl_c_node_id = tcx.map.as_local_node_id(impl_c.def_id).unwrap(); |
432 | let impl_param_env = ty::ParameterEnvironment::for_item(tcx, impl_c_node_id); | |
d9579d0f AL |
433 | |
434 | // Create mapping from impl to skolemized. | |
435 | let impl_to_skol_substs = &impl_param_env.free_substs; | |
436 | ||
437 | // Create mapping from trait to skolemized. | |
438 | let trait_to_skol_substs = | |
439 | trait_to_impl_substs | |
440 | .subst(tcx, impl_to_skol_substs) | |
441 | .with_method(impl_to_skol_substs.types.get_slice(subst::FnSpace).to_vec(), | |
54a0048b | 442 | impl_to_skol_substs.regions.get_slice(subst::FnSpace).to_vec()); |
62682a34 SL |
443 | debug!("compare_const_impl: trait_to_skol_substs={:?}", |
444 | trait_to_skol_substs); | |
d9579d0f AL |
445 | |
446 | // Compute skolemized form of impl and trait const tys. | |
447 | let impl_ty = impl_c.ty.subst(tcx, impl_to_skol_substs); | |
448 | let trait_ty = trait_c.ty.subst(tcx, &trait_to_skol_substs); | |
449 | ||
450 | let err = infcx.commit_if_ok(|_| { | |
92a42be0 | 451 | let origin = TypeOrigin::Misc(impl_c_span); |
d9579d0f AL |
452 | |
453 | // There is no "body" here, so just pass dummy id. | |
454 | let impl_ty = | |
455 | assoc::normalize_associated_types_in(&infcx, | |
d9579d0f AL |
456 | &mut fulfillment_cx, |
457 | impl_c_span, | |
458 | 0, | |
459 | &impl_ty); | |
c1a9b12d | 460 | |
62682a34 SL |
461 | debug!("compare_const_impl: impl_ty={:?}", |
462 | impl_ty); | |
d9579d0f AL |
463 | |
464 | let trait_ty = | |
465 | assoc::normalize_associated_types_in(&infcx, | |
d9579d0f AL |
466 | &mut fulfillment_cx, |
467 | impl_c_span, | |
468 | 0, | |
469 | &trait_ty); | |
c1a9b12d | 470 | |
62682a34 SL |
471 | debug!("compare_const_impl: trait_ty={:?}", |
472 | trait_ty); | |
d9579d0f AL |
473 | |
474 | infer::mk_subty(&infcx, false, origin, impl_ty, trait_ty) | |
475 | }); | |
476 | ||
477 | match err { | |
54a0048b SL |
478 | Ok(InferOk { obligations, .. }) => { |
479 | // FIXME(#32730) propagate obligations | |
480 | assert!(obligations.is_empty()) | |
481 | } | |
d9579d0f | 482 | Err(terr) => { |
62682a34 SL |
483 | debug!("checking associated const for compatibility: impl ty {:?}, trait ty {:?}", |
484 | impl_ty, | |
485 | trait_ty); | |
d9579d0f AL |
486 | span_err!(tcx.sess, impl_c_span, E0326, |
487 | "implemented const `{}` has an incompatible type for \ | |
488 | trait: {}", | |
c1a9b12d | 489 | trait_c.name, |
62682a34 | 490 | terr); |
d9579d0f AL |
491 | return; |
492 | } | |
493 | } | |
494 | } |