diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/engine.rs | 18 | ||||
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs | 43 |
2 files changed, 44 insertions, 17 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/engine.rs b/compiler/rustc_trait_selection/src/traits/engine.rs index 64d01ddb09a..c028e89e4ea 100644 --- a/compiler/rustc_trait_selection/src/traits/engine.rs +++ b/compiler/rustc_trait_selection/src/traits/engine.rs @@ -112,6 +112,24 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> { self.register_infer_ok_obligations(infer_ok) } + /// Makes `expected <: actual`. + pub fn eq_exp<T>( + &self, + cause: &ObligationCause<'tcx>, + param_env: ty::ParamEnv<'tcx>, + a_is_expected: bool, + a: T, + b: T, + ) -> Result<(), TypeError<'tcx>> + where + T: ToTrace<'tcx>, + { + self.infcx + .at(cause, param_env) + .eq_exp(a_is_expected, a, b) + .map(|infer_ok| self.register_infer_ok_obligations(infer_ok)) + } + pub fn eq<T: ToTrace<'tcx>>( &self, cause: &ObligationCause<'tcx>, diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs index 049b24b3997..203f6724cb2 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs @@ -1576,9 +1576,11 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> { return; } + let mut values = None; + self.probe(|_| { + let ocx = ObligationCtxt::new_in_snapshot(self); let mut err = error.err; - let mut values = None; // try to find the mismatched types to report the error with. // @@ -1588,21 +1590,16 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> { if let ty::PredicateKind::Clause(ty::Clause::Projection(data)) = bound_predicate.skip_binder() { - let mut selcx = SelectionContext::new(self); let data = self.replace_bound_vars_with_fresh_vars( obligation.cause.span, infer::LateBoundRegionConversionTime::HigherRankedType, bound_predicate.rebind(data), ); - let mut obligations = vec![]; - // FIXME(normalization): Change this to use `At::normalize` - let normalized_ty = super::normalize_projection_type( - &mut selcx, + let normalized_ty = ocx.normalize( + &obligation.cause, obligation.param_env, - data.projection_ty, - obligation.cause.clone(), - 0, - &mut obligations, + self.tcx + .mk_projection(data.projection_ty.item_def_id, data.projection_ty.substs), ); debug!(?obligation.cause, ?obligation.param_env); @@ -1618,19 +1615,31 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> { | ObligationCauseCode::ObjectCastObligation(..) | ObligationCauseCode::OpaqueType ); - if let Err(new_err) = self.at(&obligation.cause, obligation.param_env).eq_exp( + let expected_ty = data.term.ty().unwrap(); + + // constrain inference variables a bit more to nested obligations from normalize so + // we can have more helpful errors. + ocx.select_where_possible(); + + if let Err(new_err) = ocx.eq_exp( + &obligation.cause, + obligation.param_env, is_normalized_ty_expected, normalized_ty, - data.term, + expected_ty, ) { - values = Some((data, is_normalized_ty_expected, normalized_ty, data.term)); + values = Some((data, is_normalized_ty_expected, normalized_ty, expected_ty)); err = new_err; } } let msg = values .and_then(|(predicate, _, normalized_ty, expected_ty)| { - self.maybe_detailed_projection_msg(predicate, normalized_ty, expected_ty) + self.maybe_detailed_projection_msg( + predicate, + normalized_ty.into(), + expected_ty.into(), + ) }) .unwrap_or_else(|| format!("type mismatch resolving `{}`", predicate)); let mut diag = struct_span_err!(self.tcx.sess, obligation.cause.span, E0271, "{msg}"); @@ -1672,11 +1681,11 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> { &mut diag, &obligation.cause, secondary_span, - values.map(|(_, is_normalized_ty_expected, normalized_ty, term)| { + values.map(|(_, is_normalized_ty_expected, normalized_ty, expected_ty)| { infer::ValuePairs::Terms(ExpectedFound::new( is_normalized_ty_expected, - normalized_ty, - term, + normalized_ty.into(), + expected_ty.into(), )) }), err, |