diff options
17 files changed, 135 insertions, 39 deletions
diff --git a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs index 2437a43bd5a..2fa752384a1 100644 --- a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs @@ -65,6 +65,7 @@ impl<'tcx> UniverseInfo<'tcx> { UniverseInfoInner::RelateTys { expected, found } => { let err = mbcx.infcx.err_ctxt().report_mismatched_types( &cause, + mbcx.param_env, expected, found, TypeError::RegionsPlaceholderMismatch, @@ -480,12 +481,11 @@ fn try_extract_error_from_region_constraints<'a, 'tcx>( .try_report_from_nll() .or_else(|| { if let SubregionOrigin::Subtype(trace) = cause { - Some( - infcx.err_ctxt().report_and_explain_type_error( - *trace, - TypeError::RegionsPlaceholderMismatch, - ), - ) + Some(infcx.err_ctxt().report_and_explain_type_error( + *trace, + infcx.tcx.param_env(generic_param_scope), + TypeError::RegionsPlaceholderMismatch, + )) } else { None } diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs index a16c1931a55..abce98265b3 100644 --- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs +++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs @@ -360,6 +360,7 @@ fn check_opaque_type_well_formed<'tcx>( .err_ctxt() .report_mismatched_types( &ObligationCause::misc(definition_span, def_id), + param_env, opaque_ty, definition_ty, err, diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs index fc5ec31cda8..7a56b3784f8 100644 --- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs +++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs @@ -282,6 +282,7 @@ fn compare_method_predicate_entailment<'tcx>( let emitted = report_trait_method_mismatch( infcx, cause, + param_env, terr, (trait_m, trait_sig), (impl_m, impl_sig), @@ -575,10 +576,10 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( hir.get_if_local(impl_m.def_id) .and_then(|node| node.fn_decl()) .map(|decl| (decl.output.span(), Cow::from("return type in trait"), false)), - Some(infer::ValuePairs::Terms(ExpectedFound { + Some(param_env.and(infer::ValuePairs::Terms(ExpectedFound { expected: trait_return_ty.into(), found: impl_return_ty.into(), - })), + }))), terr, false, ); @@ -602,6 +603,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( let emitted = report_trait_method_mismatch( infcx, cause, + param_env, terr, (trait_m, trait_sig), (impl_m, impl_sig), @@ -915,6 +917,7 @@ impl<'tcx> ty::FallibleTypeFolder<TyCtxt<'tcx>> for RemapHiddenTyRegions<'tcx> { fn report_trait_method_mismatch<'tcx>( infcx: &InferCtxt<'tcx>, mut cause: ObligationCause<'tcx>, + param_env: ty::ParamEnv<'tcx>, terr: TypeError<'tcx>, (trait_m, trait_sig): (ty::AssocItem, ty::FnSig<'tcx>), (impl_m, impl_sig): (ty::AssocItem, ty::FnSig<'tcx>), @@ -1000,10 +1003,10 @@ fn report_trait_method_mismatch<'tcx>( &mut diag, &cause, trait_err_span.map(|sp| (sp, Cow::from("type in trait"), false)), - Some(infer::ValuePairs::PolySigs(ExpectedFound { + Some(param_env.and(infer::ValuePairs::PolySigs(ExpectedFound { expected: ty::Binder::dummy(trait_sig), found: ty::Binder::dummy(impl_sig), - })), + }))), terr, false, ); @@ -1797,10 +1800,10 @@ fn compare_const_predicate_entailment<'tcx>( &mut diag, &cause, trait_c_span.map(|span| (span, Cow::from("type in trait"), false)), - Some(infer::ValuePairs::Terms(ExpectedFound { + Some(param_env.and(infer::ValuePairs::Terms(ExpectedFound { expected: trait_ty.into(), found: impl_ty.into(), - })), + }))), terr, false, ); diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs index 959b17b2d40..f2f9c69e49f 100644 --- a/compiler/rustc_hir_analysis/src/check/mod.rs +++ b/compiler/rustc_hir_analysis/src/check/mod.rs @@ -646,10 +646,10 @@ pub fn check_function_signature<'tcx>( &mut diag, &cause, None, - Some(infer::ValuePairs::PolySigs(ExpectedFound { + Some(param_env.and(infer::ValuePairs::PolySigs(ExpectedFound { expected: expected_sig, found: actual_sig, - })), + }))), err, false, ); diff --git a/compiler/rustc_hir_analysis/src/coherence/builtin.rs b/compiler/rustc_hir_analysis/src/coherence/builtin.rs index 76c75d976ee..b4f6b5a9dd2 100644 --- a/compiler/rustc_hir_analysis/src/coherence/builtin.rs +++ b/compiler/rustc_hir_analysis/src/coherence/builtin.rs @@ -364,6 +364,7 @@ pub(crate) fn coerce_unsized_info<'tcx>( .err_ctxt() .report_mismatched_types( &cause, + param_env, mk_ptr(mt_b.ty), target, ty::error::TypeError::Mutability, diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs index fa6a86c6911..06e2a5e3493 100644 --- a/compiler/rustc_hir_typeck/src/callee.rs +++ b/compiler/rustc_hir_typeck/src/callee.rs @@ -862,7 +862,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } Err(e) => { // FIXME(effects): better diagnostic - self.err_ctxt().report_mismatched_consts(&cause, effect, param, e).emit(); + self.err_ctxt() + .report_mismatched_consts(&cause, self.param_env, effect, param, e) + .emit(); } } } diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs index de80ccf790c..6fa958d9496 100644 --- a/compiler/rustc_hir_typeck/src/coercion.rs +++ b/compiler/rustc_hir_typeck/src/coercion.rs @@ -1723,6 +1723,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { }) => { err = fcx.err_ctxt().report_mismatched_types( cause, + fcx.param_env, expected, found, coercion_error, @@ -1752,6 +1753,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { }) => { err = fcx.err_ctxt().report_mismatched_types( cause, + fcx.param_env, expected, found, coercion_error, @@ -1787,6 +1789,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { _ => { err = fcx.err_ctxt().report_mismatched_types( cause, + fcx.param_env, expected, found, coercion_error, @@ -1897,7 +1900,8 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { block_or_return_id: hir::HirId, expression: Option<&'tcx hir::Expr<'tcx>>, ) -> Diag<'infcx> { - let mut err = fcx.err_ctxt().report_mismatched_types(cause, expected, found, ty_err); + let mut err = + fcx.err_ctxt().report_mismatched_types(cause, fcx.param_env, expected, found, ty_err); let due_to_block = matches!(fcx.tcx.hir_node(block_or_return_id), hir::Node::Block(..)); diff --git a/compiler/rustc_hir_typeck/src/demand.rs b/compiler/rustc_hir_typeck/src/demand.rs index 777248ff873..3399a9fe880 100644 --- a/compiler/rustc_hir_typeck/src/demand.rs +++ b/compiler/rustc_hir_typeck/src/demand.rs @@ -191,7 +191,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.at(cause, self.param_env) .sup(DefineOpaqueTypes::Yes, expected, actual) .map(|infer_ok| self.register_infer_ok_obligations(infer_ok)) - .map_err(|e| self.err_ctxt().report_mismatched_types(cause, expected, actual, e)) + .map_err(|e| { + self.err_ctxt().report_mismatched_types(cause, self.param_env, expected, actual, e) + }) } pub(crate) fn demand_eqtype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) { @@ -218,7 +220,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.at(cause, self.param_env) .eq(DefineOpaqueTypes::Yes, expected, actual) .map(|infer_ok| self.register_infer_ok_obligations(infer_ok)) - .map_err(|e| self.err_ctxt().report_mismatched_types(cause, expected, actual, e)) + .map_err(|e| { + self.err_ctxt().report_mismatched_types(cause, self.param_env, expected, actual, e) + }) } pub(crate) fn demand_coerce( @@ -271,7 +275,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let expr = expr.peel_drop_temps(); let cause = self.misc(expr.span); let expr_ty = self.resolve_vars_if_possible(checked_ty); - let mut err = self.err_ctxt().report_mismatched_types(&cause, expected, expr_ty, e); + let mut err = + self.err_ctxt().report_mismatched_types(&cause, self.param_env, expected, expr_ty, e); self.emit_coerce_suggestions(&mut err, expr, expr_ty, expected, expected_ty_expr, Some(e)); diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs index f29d6199a87..a6c249da103 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs @@ -827,6 +827,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { formal_and_expected_inputs[mismatch_idx.into()], provided_arg_tys[mismatch_idx.into()].0, ), + self.param_env, terr, ); err.span_label( @@ -912,7 +913,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let trace = mk_trace(provided_span, formal_and_expected_inputs[*expected_idx], provided_ty); if !matches!(trace.cause.as_failure_code(*e), FailureCode::Error0308) { - let mut err = self.err_ctxt().report_and_explain_type_error(trace, *e); + let mut err = + self.err_ctxt().report_and_explain_type_error(trace, self.param_env, *e); suggest_confusable(&mut err); reported = Some(err.emit()); return false; @@ -940,7 +942,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let (formal_ty, expected_ty) = formal_and_expected_inputs[*expected_idx]; let (provided_ty, provided_arg_span) = provided_arg_tys[*provided_idx]; let trace = mk_trace(provided_arg_span, (formal_ty, expected_ty), provided_ty); - let mut err = self.err_ctxt().report_and_explain_type_error(trace, *err); + let mut err = + self.err_ctxt().report_and_explain_type_error(trace, self.param_env, *err); self.emit_coerce_suggestions( &mut err, provided_args[*provided_idx], @@ -1113,7 +1116,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { &mut err, &trace.cause, None, - Some(trace.values), + Some(self.param_env.and(trace.values)), e, true, ); diff --git a/compiler/rustc_hir_typeck/src/method/confirm.rs b/compiler/rustc_hir_typeck/src/method/confirm.rs index f4685725dd3..96784fcb61b 100644 --- a/compiler/rustc_hir_typeck/src/method/confirm.rs +++ b/compiler/rustc_hir_typeck/src/method/confirm.rs @@ -538,7 +538,13 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> { // to the feature, like the self type can't reference method args. if self.tcx.features().arbitrary_self_types() { self.err_ctxt() - .report_mismatched_types(&cause, method_self_ty, self_ty, terr) + .report_mismatched_types( + &cause, + self.param_env, + method_self_ty, + self_ty, + terr, + ) .emit(); } else { // This has/will have errored in wfcheck, which we cannot depend on from here, as typeck on functions diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs index 86442844823..61e196bdebe 100644 --- a/compiler/rustc_passes/src/check_attr.rs +++ b/compiler/rustc_passes/src/check_attr.rs @@ -2300,10 +2300,10 @@ impl<'tcx> CheckAttrVisitor<'tcx> { &mut diag, &cause, None, - Some(ValuePairs::PolySigs(ExpectedFound { + Some(param_env.and(ValuePairs::PolySigs(ExpectedFound { expected: ty::Binder::dummy(expected_sig), found: ty::Binder::dummy(sig), - })), + }))), terr, false, ); diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs index df5800ab58a..b9a569d25e3 100644 --- a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs +++ b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs @@ -75,6 +75,7 @@ use crate::errors::{ObligationCauseFailureCode, TypeErrorAdditionalDiags}; use crate::infer; use crate::infer::relate::{self, RelateResult, TypeRelation}; use crate::infer::{InferCtxt, TypeTrace, ValuePairs}; +use crate::solve::deeply_normalize_for_diagnostics; use crate::traits::{ IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode, }; @@ -145,21 +146,31 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { pub fn report_mismatched_types( &self, cause: &ObligationCause<'tcx>, + param_env: ty::ParamEnv<'tcx>, expected: Ty<'tcx>, actual: Ty<'tcx>, err: TypeError<'tcx>, ) -> Diag<'a> { - self.report_and_explain_type_error(TypeTrace::types(cause, true, expected, actual), err) + self.report_and_explain_type_error( + TypeTrace::types(cause, true, expected, actual), + param_env, + err, + ) } pub fn report_mismatched_consts( &self, cause: &ObligationCause<'tcx>, + param_env: ty::ParamEnv<'tcx>, expected: ty::Const<'tcx>, actual: ty::Const<'tcx>, err: TypeError<'tcx>, ) -> Diag<'a> { - self.report_and_explain_type_error(TypeTrace::consts(cause, true, expected, actual), err) + self.report_and_explain_type_error( + TypeTrace::consts(cause, true, expected, actual), + param_env, + err, + ) } pub fn get_impl_future_output_ty(&self, ty: Ty<'tcx>) -> Option<Ty<'tcx>> { @@ -1133,7 +1144,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { diag: &mut Diag<'_>, cause: &ObligationCause<'tcx>, secondary_span: Option<(Span, Cow<'static, str>, bool)>, - mut values: Option<ValuePairs<'tcx>>, + mut values: Option<ty::ParamEnvAnd<'tcx, ValuePairs<'tcx>>>, terr: TypeError<'tcx>, prefer_label: bool, ) { @@ -1241,8 +1252,11 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { } let (expected_found, exp_found, is_simple_error, values) = match values { None => (None, Mismatch::Fixed("type"), false, None), - Some(values) => { - let values = self.resolve_vars_if_possible(values); + Some(ty::ParamEnvAnd { param_env, value: values }) => { + let mut values = self.resolve_vars_if_possible(values); + if self.next_trait_solver() { + values = deeply_normalize_for_diagnostics(self, param_env, values); + } let (is_simple_error, exp_found) = match values { ValuePairs::Terms(ExpectedFound { expected, found }) => { match (expected.unpack(), found.unpack()) { @@ -1773,6 +1787,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { pub fn report_and_explain_type_error( &self, trace: TypeTrace<'tcx>, + param_env: ty::ParamEnv<'tcx>, terr: TypeError<'tcx>, ) -> Diag<'a> { debug!("report_and_explain_type_error(trace={:?}, terr={:?})", trace, terr); @@ -1784,7 +1799,14 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { self.type_error_additional_suggestions(&trace, terr), ); let mut diag = self.dcx().create_err(failure_code); - self.note_type_err(&mut diag, &trace.cause, None, Some(trace.values), terr, false); + self.note_type_err( + &mut diag, + &trace.cause, + None, + Some(param_env.and(trace.values)), + terr, + false, + ); diag } diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/region.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/region.rs index 94610a9e0e6..833358b2e14 100644 --- a/compiler/rustc_trait_selection/src/error_reporting/infer/region.rs +++ b/compiler/rustc_trait_selection/src/error_reporting/infer/region.rs @@ -295,7 +295,11 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { let mut err = match origin { infer::Subtype(box trace) => { let terr = TypeError::RegionsDoesNotOutlive(sup, sub); - let mut err = self.report_and_explain_type_error(trace, terr); + let mut err = self.report_and_explain_type_error( + trace, + self.tcx.param_env(generic_param_scope), + terr, + ); match (*sub, *sup) { (ty::RePlaceholder(_), ty::RePlaceholder(_)) => {} (ty::RePlaceholder(_), _) => { @@ -646,7 +650,11 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { } infer::Subtype(box trace) => { let terr = TypeError::RegionsPlaceholderMismatch; - return self.report_and_explain_type_error(trace, terr); + return self.report_and_explain_type_error( + trace, + self.tcx.param_env(generic_param_scope), + terr, + ); } _ => { return self.report_concrete_failure( diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs index 9ee4963a360..6ef64c3ed80 100644 --- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs +++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs @@ -1290,7 +1290,6 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { ( Some(( data.projection_term, - false, self.resolve_vars_if_possible(normalized_term), data.term, )), @@ -1335,7 +1334,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { derive_better_type_error(lhs, rhs) { ( - Some((lhs, true, self.resolve_vars_if_possible(expected_term), rhs)), + Some((lhs, self.resolve_vars_if_possible(expected_term), rhs)), better_type_err, ) } else if let Some(rhs) = rhs.to_alias_term() @@ -1343,7 +1342,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { derive_better_type_error(rhs, lhs) { ( - Some((rhs, true, self.resolve_vars_if_possible(expected_term), lhs)), + Some((rhs, self.resolve_vars_if_possible(expected_term), lhs)), better_type_err, ) } else { @@ -1354,7 +1353,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { }; let msg = values - .and_then(|(predicate, _, normalized_term, expected_term)| { + .and_then(|(predicate, normalized_term, expected_term)| { self.maybe_detailed_projection_msg(predicate, normalized_term, expected_term) }) .unwrap_or_else(|| { @@ -1431,8 +1430,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { &mut diag, &obligation.cause, secondary_span, - values.map(|(_, _, normalized_ty, expected_ty)| { - infer::ValuePairs::Terms(ExpectedFound::new(true, expected_ty, normalized_ty)) + values.map(|(_, normalized_ty, expected_ty)| { + obligation.param_env.and(infer::ValuePairs::Terms(ExpectedFound::new( + true, + expected_ty, + normalized_ty, + ))) }), err, false, @@ -2654,6 +2657,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { }; self.report_and_explain_type_error( TypeTrace::trait_refs(&cause, true, expected_trait_ref, found_trait_ref), + obligation.param_env, terr, ) } @@ -2744,6 +2748,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { { return Ok(self.report_and_explain_type_error( TypeTrace::trait_refs(&obligation.cause, true, expected_trait_ref, found_trait_ref), + obligation.param_env, ty::error::TypeError::Mismatch, )); } diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs index ba57909fc23..ca23f776581 100644 --- a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs +++ b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs @@ -287,6 +287,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { FulfillmentErrorCode::Subtype(ref expected_found, ref err) => self .report_mismatched_types( &error.obligation.cause, + error.obligation.param_env, expected_found.expected, expected_found.found, *err, @@ -295,6 +296,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { FulfillmentErrorCode::ConstEquate(ref expected_found, ref err) => { let mut diag = self.report_mismatched_consts( &error.obligation.cause, + error.obligation.param_env, expected_found.expected, expected_found.found, *err, diff --git a/tests/ui/traits/next-solver/diagnostics/deeply-normalize-type-expectation.rs b/tests/ui/traits/next-solver/diagnostics/deeply-normalize-type-expectation.rs new file mode 100644 index 00000000000..5c53b745933 --- /dev/null +++ b/tests/ui/traits/next-solver/diagnostics/deeply-normalize-type-expectation.rs @@ -0,0 +1,17 @@ +//@ compile-flags: -Znext-solver + +// Make sure we try to mention a deeply normalized type in a type mismatch error. + +trait Mirror { + type Assoc; +} +impl<T> Mirror for T { + type Assoc = T; +} + +fn needs<T>(_: <T as Mirror>::Assoc) {} + +fn main() { + needs::<i32>(()); + //~^ ERROR mismatched types +} diff --git a/tests/ui/traits/next-solver/diagnostics/deeply-normalize-type-expectation.stderr b/tests/ui/traits/next-solver/diagnostics/deeply-normalize-type-expectation.stderr new file mode 100644 index 00000000000..88643945863 --- /dev/null +++ b/tests/ui/traits/next-solver/diagnostics/deeply-normalize-type-expectation.stderr @@ -0,0 +1,17 @@ +error[E0308]: mismatched types + --> $DIR/deeply-normalize-type-expectation.rs:15:18 + | +LL | needs::<i32>(()); + | ------------ ^^ expected `i32`, found `()` + | | + | arguments to this function are incorrect + | +note: function defined here + --> $DIR/deeply-normalize-type-expectation.rs:12:4 + | +LL | fn needs<T>(_: <T as Mirror>::Assoc) {} + | ^^^^^ ----------------------- + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0308`. |