diff options
Diffstat (limited to 'compiler/rustc_infer/src/infer/canonical/query_response.rs')
| -rw-r--r-- | compiler/rustc_infer/src/infer/canonical/query_response.rs | 73 |
1 files changed, 36 insertions, 37 deletions
diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs index 09578598114..22c9c4edccc 100644 --- a/compiler/rustc_infer/src/infer/canonical/query_response.rs +++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs @@ -13,6 +13,7 @@ use std::iter; use rustc_index::{Idx, IndexVec}; use rustc_middle::arena::ArenaAllocatable; use rustc_middle::bug; +use rustc_middle::infer::canonical::CanonicalVarKind; use rustc_middle::ty::{self, BoundVar, GenericArg, GenericArgKind, Ty, TyCtxt, TypeFoldable}; use tracing::{debug, instrument}; @@ -413,26 +414,27 @@ impl<'tcx> InferCtxt<'tcx> { let mut opt_values: IndexVec<BoundVar, Option<GenericArg<'tcx>>> = IndexVec::from_elem_n(None, query_response.variables.len()); - // In terms of our example above, we are iterating over pairs like: - // [(?A, Vec<?0>), ('static, '?1), (?B, ?0)] for (original_value, result_value) in iter::zip(&original_values.var_values, result_values) { match result_value.kind() { GenericArgKind::Type(result_value) => { - // e.g., here `result_value` might be `?0` in the example above... - if let ty::Bound(debruijn, b) = *result_value.kind() { - // ...in which case we would set `canonical_vars[0]` to `Some(?U)`. - + // We disable the instantiation guess for inference variables + // and only use it for placeholders. We need to handle the + // `sub_root` of type inference variables which would make this + // more involved. They are also a lot rarer than region variables. + if let ty::Bound(debruijn, b) = *result_value.kind() + && !matches!( + query_response.variables[b.var.as_usize()], + CanonicalVarKind::Ty { .. } + ) + { // We only allow a `ty::INNERMOST` index in generic parameters. assert_eq!(debruijn, ty::INNERMOST); opt_values[b.var] = Some(*original_value); } } GenericArgKind::Lifetime(result_value) => { - // e.g., here `result_value` might be `'?1` in the example above... if let ty::ReBound(debruijn, b) = result_value.kind() { - // ... in which case we would set `canonical_vars[0]` to `Some('static)`. - // We only allow a `ty::INNERMOST` index in generic parameters. assert_eq!(debruijn, ty::INNERMOST); opt_values[b.var] = Some(*original_value); @@ -440,8 +442,6 @@ impl<'tcx> InferCtxt<'tcx> { } GenericArgKind::Const(result_value) => { if let ty::ConstKind::Bound(debruijn, b) = result_value.kind() { - // ...in which case we would set `canonical_vars[0]` to `Some(const X)`. - // We only allow a `ty::INNERMOST` index in generic parameters. assert_eq!(debruijn, ty::INNERMOST); opt_values[b.var] = Some(*original_value); @@ -453,32 +453,31 @@ impl<'tcx> InferCtxt<'tcx> { // Create result arguments: if we found a value for a // given variable in the loop above, use that. Otherwise, use // a fresh inference variable. - let result_args = CanonicalVarValues { - var_values: self.tcx.mk_args_from_iter( - query_response.variables.iter().enumerate().map(|(index, var_kind)| { - if var_kind.universe() != ty::UniverseIndex::ROOT { - // A variable from inside a binder of the query. While ideally these shouldn't - // exist at all, we have to deal with them for now. - self.instantiate_canonical_var(cause.span, var_kind, |u| { - universe_map[u.as_usize()] - }) - } else if var_kind.is_existential() { - match opt_values[BoundVar::new(index)] { - Some(k) => k, - None => self.instantiate_canonical_var(cause.span, var_kind, |u| { - universe_map[u.as_usize()] - }), - } - } else { - // For placeholders which were already part of the input, we simply map this - // universal bound variable back the placeholder of the input. - opt_values[BoundVar::new(index)].expect( - "expected placeholder to be unified with itself during response", - ) - } - }), - ), - }; + let mut var_values = Vec::with_capacity(query_response.variables.len()); + for (index, kind) in query_response.variables.iter().enumerate() { + let value = if kind.universe() != ty::UniverseIndex::ROOT { + // A variable from inside a binder of the query. While ideally these shouldn't + // exist at all, we have to deal with them for now. + self.instantiate_canonical_var(cause.span, kind, &var_values, |u| { + universe_map[u.as_usize()] + }) + } else if kind.is_existential() { + match opt_values[BoundVar::new(index)] { + Some(k) => k, + None => self.instantiate_canonical_var(cause.span, kind, &var_values, |u| { + universe_map[u.as_usize()] + }), + } + } else { + // For placeholders which were already part of the input, we simply map this + // universal bound variable back the placeholder of the input. + opt_values[BoundVar::new(index)] + .expect("expected placeholder to be unified with itself during response") + }; + var_values.push(value); + } + + let result_args = CanonicalVarValues { var_values: self.tcx.mk_args(&var_values) }; let mut obligations = PredicateObligations::new(); |