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1 | | -use super::FnCtxt; |
| 1 | +use rustc_hir::def::DefKind; |
| 2 | +use rustc_infer::traits::ObligationCause; |
| 3 | +use rustc_middle::ty::{ |
| 4 | + self, DefiningScopeKind, EarlyBinder, OpaqueHiddenType, OpaqueTypeKey, TypeVisitableExt, |
| 5 | + TypingMode, |
| 6 | +}; |
| 7 | +use rustc_trait_selection::error_reporting::infer::need_type_info::TypeAnnotationNeeded; |
| 8 | +use rustc_trait_selection::opaque_types::{ |
| 9 | + NonDefiningUseReason, opaque_type_has_defining_use_args, report_item_does_not_constrain_error, |
| 10 | +}; |
| 11 | +use rustc_trait_selection::solve; |
| 12 | +use tracing::{debug, instrument}; |
| 13 | + |
| 14 | +use crate::FnCtxt; |
| 15 | + |
2 | 16 | impl<'tcx> FnCtxt<'_, 'tcx> { |
| 17 | + /// This takes all the opaque type uses during HIR typeck. It first computes |
| 18 | + /// the concrete hidden type by iterating over all defining uses. |
| 19 | + /// |
| 20 | + /// A use during HIR typeck is defining if all non-lifetime arguments are |
| 21 | + /// unique generic parameters and the hidden type does not reference any |
| 22 | + /// inference variables. |
| 23 | + /// |
| 24 | + /// It then uses these defining uses to guide inference for all other uses. |
| 25 | + #[instrument(level = "debug", skip(self))] |
| 26 | + pub(super) fn handle_opaque_type_uses_next(&mut self) { |
| 27 | + // We clone the opaques instead of stealing them here as they are still used for |
| 28 | + // normalization in the next generation trait solver. |
| 29 | + let mut opaque_types: Vec<_> = self.infcx.clone_opaque_types(); |
| 30 | + let num_entries = self.inner.borrow_mut().opaque_types().num_entries(); |
| 31 | + let prev = self.checked_opaque_types_storage_entries.replace(Some(num_entries)); |
| 32 | + debug_assert_eq!(prev, None); |
| 33 | + for entry in &mut opaque_types { |
| 34 | + *entry = self.resolve_vars_if_possible(*entry); |
| 35 | + } |
| 36 | + debug!(?opaque_types); |
| 37 | + |
| 38 | + self.compute_concrete_opaque_types(&opaque_types); |
| 39 | + self.apply_computed_concrete_opaque_types(&opaque_types); |
| 40 | + } |
| 41 | +} |
| 42 | + |
| 43 | +enum UsageKind<'tcx> { |
| 44 | + None, |
| 45 | + NonDefiningUse(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>), |
| 46 | + UnconstrainedHiddenType(OpaqueHiddenType<'tcx>), |
| 47 | + HasDefiningUse, |
| 48 | +} |
| 49 | + |
| 50 | +impl<'tcx> UsageKind<'tcx> { |
| 51 | + fn merge(&mut self, other: UsageKind<'tcx>) { |
| 52 | + match (&*self, &other) { |
| 53 | + (UsageKind::HasDefiningUse, _) | (_, UsageKind::None) => unreachable!(), |
| 54 | + (UsageKind::None, _) => *self = other, |
| 55 | + // When mergining non-defining uses, prefer earlier ones. This means |
| 56 | + // the error happens as early as possible. |
| 57 | + ( |
| 58 | + UsageKind::NonDefiningUse(..) | UsageKind::UnconstrainedHiddenType(..), |
| 59 | + UsageKind::NonDefiningUse(..), |
| 60 | + ) => {} |
| 61 | + // When merging unconstrained hidden types, we prefer later ones. This is |
| 62 | + // used as in most cases, the defining use is the final return statement |
| 63 | + // of our function, and other uses with defining arguments are likely not |
| 64 | + // intended to be defining. |
| 65 | + ( |
| 66 | + UsageKind::NonDefiningUse(..) | UsageKind::UnconstrainedHiddenType(..), |
| 67 | + UsageKind::UnconstrainedHiddenType(..) | UsageKind::HasDefiningUse, |
| 68 | + ) => *self = other, |
| 69 | + } |
| 70 | + } |
| 71 | +} |
| 72 | + |
| 73 | +impl<'tcx> FnCtxt<'_, 'tcx> { |
| 74 | + fn compute_concrete_opaque_types( |
| 75 | + &mut self, |
| 76 | + opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)], |
| 77 | + ) { |
| 78 | + let tcx = self.tcx; |
| 79 | + let TypingMode::Analysis { defining_opaque_types_and_generators } = self.typing_mode() |
| 80 | + else { |
| 81 | + unreachable!(); |
| 82 | + }; |
| 83 | + |
| 84 | + for def_id in defining_opaque_types_and_generators { |
| 85 | + match tcx.def_kind(def_id) { |
| 86 | + DefKind::OpaqueTy => {} |
| 87 | + DefKind::Closure => continue, |
| 88 | + _ => unreachable!("not opaque or generator: {def_id:?}"), |
| 89 | + } |
| 90 | + |
| 91 | + let mut usage_kind = UsageKind::None; |
| 92 | + for &(opaque_type_key, hidden_type) in opaque_types { |
| 93 | + if opaque_type_key.def_id != def_id { |
| 94 | + continue; |
| 95 | + } |
| 96 | + |
| 97 | + usage_kind.merge(self.consider_opaque_type_use(opaque_type_key, hidden_type)); |
| 98 | + if let UsageKind::HasDefiningUse = usage_kind { |
| 99 | + break; |
| 100 | + } |
| 101 | + } |
| 102 | + |
| 103 | + let guar = match usage_kind { |
| 104 | + UsageKind::None => { |
| 105 | + if let Some(guar) = self.tainted_by_errors() { |
| 106 | + guar |
| 107 | + } else { |
| 108 | + report_item_does_not_constrain_error(self.tcx, self.body_id, def_id, None) |
| 109 | + } |
| 110 | + } |
| 111 | + UsageKind::NonDefiningUse(opaque_type_key, hidden_type) => { |
| 112 | + report_item_does_not_constrain_error( |
| 113 | + self.tcx, |
| 114 | + self.body_id, |
| 115 | + def_id, |
| 116 | + Some((opaque_type_key, hidden_type.span)), |
| 117 | + ) |
| 118 | + } |
| 119 | + UsageKind::UnconstrainedHiddenType(hidden_type) => { |
| 120 | + let infer_var = hidden_type |
| 121 | + .ty |
| 122 | + .walk() |
| 123 | + .filter_map(ty::GenericArg::as_term) |
| 124 | + .find(|term| term.is_infer()) |
| 125 | + .unwrap_or_else(|| hidden_type.ty.into()); |
| 126 | + self.err_ctxt() |
| 127 | + .emit_inference_failure_err( |
| 128 | + self.body_id, |
| 129 | + hidden_type.span, |
| 130 | + infer_var, |
| 131 | + TypeAnnotationNeeded::E0282, |
| 132 | + false, |
| 133 | + ) |
| 134 | + .emit() |
| 135 | + } |
| 136 | + UsageKind::HasDefiningUse => continue, |
| 137 | + }; |
| 138 | + |
| 139 | + self.typeck_results |
| 140 | + .borrow_mut() |
| 141 | + .concrete_opaque_types |
| 142 | + .insert(def_id, OpaqueHiddenType::new_error(tcx, guar)); |
| 143 | + self.set_tainted_by_errors(guar); |
| 144 | + } |
| 145 | + } |
| 146 | + |
| 147 | + fn consider_opaque_type_use( |
| 148 | + &mut self, |
| 149 | + opaque_type_key: OpaqueTypeKey<'tcx>, |
| 150 | + hidden_type: OpaqueHiddenType<'tcx>, |
| 151 | + ) -> UsageKind<'tcx> { |
| 152 | + if let Err(err) = opaque_type_has_defining_use_args( |
| 153 | + &self, |
| 154 | + opaque_type_key, |
| 155 | + hidden_type.span, |
| 156 | + DefiningScopeKind::HirTypeck, |
| 157 | + ) { |
| 158 | + match err { |
| 159 | + NonDefiningUseReason::Tainted(guar) => { |
| 160 | + self.typeck_results.borrow_mut().concrete_opaque_types.insert( |
| 161 | + opaque_type_key.def_id, |
| 162 | + OpaqueHiddenType::new_error(self.tcx, guar), |
| 163 | + ); |
| 164 | + return UsageKind::HasDefiningUse; |
| 165 | + } |
| 166 | + _ => return UsageKind::NonDefiningUse(opaque_type_key, hidden_type), |
| 167 | + }; |
| 168 | + } |
| 169 | + |
| 170 | + // We ignore uses of the opaque if they have any inference variables |
| 171 | + // as this can frequently happen with recursive calls. |
| 172 | + // |
| 173 | + // See `tests/ui/traits/next-solver/opaques/universal-args-non-defining.rs`. |
| 174 | + if hidden_type.ty.has_non_region_infer() { |
| 175 | + return UsageKind::UnconstrainedHiddenType(hidden_type); |
| 176 | + } |
| 177 | + |
| 178 | + let cause = ObligationCause::misc(hidden_type.span, self.body_id); |
| 179 | + let at = self.at(&cause, self.param_env); |
| 180 | + let hidden_type = match solve::deeply_normalize(at, hidden_type) { |
| 181 | + Ok(hidden_type) => hidden_type, |
| 182 | + Err(errors) => { |
| 183 | + let guar = self.err_ctxt().report_fulfillment_errors(errors); |
| 184 | + OpaqueHiddenType::new_error(self.tcx, guar) |
| 185 | + } |
| 186 | + }; |
| 187 | + let hidden_type = hidden_type.remap_generic_params_to_declaration_params( |
| 188 | + opaque_type_key, |
| 189 | + self.tcx, |
| 190 | + DefiningScopeKind::HirTypeck, |
| 191 | + ); |
| 192 | + |
| 193 | + let prev = self |
| 194 | + .typeck_results |
| 195 | + .borrow_mut() |
| 196 | + .concrete_opaque_types |
| 197 | + .insert(opaque_type_key.def_id, hidden_type); |
| 198 | + assert!(prev.is_none()); |
| 199 | + UsageKind::HasDefiningUse |
| 200 | + } |
| 201 | + |
| 202 | + fn apply_computed_concrete_opaque_types( |
| 203 | + &mut self, |
| 204 | + opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)], |
| 205 | + ) { |
| 206 | + let tcx = self.tcx; |
| 207 | + for &(key, hidden_type) in opaque_types { |
| 208 | + let expected = |
| 209 | + *self.typeck_results.borrow_mut().concrete_opaque_types.get(&key.def_id).unwrap(); |
| 210 | + |
| 211 | + let expected = EarlyBinder::bind(expected.ty).instantiate(tcx, key.args); |
| 212 | + self.demand_eqtype(hidden_type.span, expected, hidden_type.ty); |
| 213 | + } |
| 214 | + } |
| 215 | + |
3 | 216 | /// We may in theory add further uses of an opaque after cloning the opaque |
4 | 217 | /// types storage during writeback when computing the defining uses. |
5 | 218 | /// |
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