change is_subtype to relate_types
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cd7f471931
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6f0c5ee2d4
15 changed files with 128 additions and 86 deletions
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@ -13,7 +13,7 @@ use rustc_middle::ty::layout::{
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self, FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOf, LayoutOfHelpers,
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TyAndLayout,
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};
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use rustc_middle::ty::{self, GenericArgsRef, ParamEnv, Ty, TyCtxt, TypeFoldable};
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use rustc_middle::ty::{self, GenericArgsRef, ParamEnv, Ty, TyCtxt, TypeFoldable, Variance};
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use rustc_mir_dataflow::storage::always_storage_live_locals;
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use rustc_session::Limit;
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use rustc_span::Span;
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@ -384,7 +384,7 @@ pub(super) fn mir_assign_valid_types<'tcx>(
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// all normal lifetimes are erased, higher-ranked types with their
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// late-bound lifetimes are still around and can lead to type
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// differences.
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if util::is_subtype(tcx, param_env, src.ty, dest.ty) {
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if util::relate_types(tcx, param_env, Variance::Covariant, src.ty, dest.ty) {
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// Make sure the layout is equal, too -- just to be safe. Miri really
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// needs layout equality. For performance reason we skip this check when
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// the types are equal. Equal types *can* have different layouts when
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@ -7,7 +7,7 @@ use rustc_infer::traits::Reveal;
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use rustc_middle::mir::interpret::Scalar;
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use rustc_middle::mir::visit::{NonUseContext, PlaceContext, Visitor};
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use rustc_middle::mir::*;
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use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
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use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt, Variance};
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use rustc_mir_dataflow::impls::MaybeStorageLive;
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use rustc_mir_dataflow::storage::always_storage_live_locals;
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use rustc_mir_dataflow::{Analysis, ResultsCursor};
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@ -16,7 +16,7 @@ use rustc_target::spec::abi::Abi;
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use crate::util::is_within_packed;
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use crate::util::is_subtype;
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use crate::util::relate_types;
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#[derive(Copy, Clone, Debug, PartialEq, Eq)]
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enum EdgeKind {
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@ -604,7 +604,15 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
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return true;
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}
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return crate::util::is_subtype(self.tcx, self.param_env, src, dest);
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// After borrowck subtyping should be fully explicit via
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// `Subtype` projections.
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let variance = if self.mir_phase >= MirPhase::Runtime(RuntimePhase::Initial) {
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Variance::Invariant
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} else {
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Variance::Covariant
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};
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crate::util::relate_types(self.tcx, self.param_env, variance, src, dest)
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}
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}
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@ -756,9 +764,10 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
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}
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}
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ProjectionElem::Subtype(ty) => {
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if !is_subtype(
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if !relate_types(
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self.tcx,
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self.param_env,
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Variance::Covariant,
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ty,
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place_ref.ty(&self.body.local_decls, self.tcx).ty,
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) {
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@ -5,7 +5,7 @@
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use rustc_infer::infer::TyCtxtInferExt;
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use rustc_middle::traits::{DefiningAnchor, ObligationCause};
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use rustc_middle::ty::{ParamEnv, Ty, TyCtxt};
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use rustc_middle::ty::{ParamEnv, Ty, TyCtxt, Variance};
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use rustc_trait_selection::traits::ObligationCtxt;
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/// Returns whether the two types are equal up to subtyping.
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@ -24,16 +24,22 @@ pub fn is_equal_up_to_subtyping<'tcx>(
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}
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// Check for subtyping in either direction.
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is_subtype(tcx, param_env, src, dest) || is_subtype(tcx, param_env, dest, src)
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relate_types(tcx, param_env, Variance::Covariant, src, dest)
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|| relate_types(tcx, param_env, Variance::Covariant, dest, src)
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}
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/// Returns whether `src` is a subtype of `dest`, i.e. `src <: dest`.
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///
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/// For almost all of the use cases variance should be `Covariant`,
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/// in `MirPhase` >= `MirPhase::Runtime(RuntimePhase::Initial` variance should
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/// be `Invariant`.
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///
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/// This mostly ignores opaque types as it can be used in constraining contexts
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/// while still computing the final underlying type.
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pub fn is_subtype<'tcx>(
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pub fn relate_types<'tcx>(
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tcx: TyCtxt<'tcx>,
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param_env: ParamEnv<'tcx>,
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variance: Variance,
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src: Ty<'tcx>,
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dest: Ty<'tcx>,
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) -> bool {
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@ -48,7 +54,7 @@ pub fn is_subtype<'tcx>(
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let cause = ObligationCause::dummy();
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let src = ocx.normalize(&cause, param_env, src);
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let dest = ocx.normalize(&cause, param_env, dest);
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match ocx.sub(&cause, param_env, src, dest) {
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match ocx.relate(&cause, param_env, variance, src, dest) {
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Ok(()) => {}
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Err(_) => return false,
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};
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@ -7,7 +7,7 @@ mod type_name;
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pub use self::alignment::{is_disaligned, is_within_packed};
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pub use self::check_validity_requirement::check_validity_requirement;
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pub use self::compare_types::{is_equal_up_to_subtyping, is_subtype};
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pub use self::compare_types::{is_equal_up_to_subtyping, relate_types};
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pub use self::type_name::type_name;
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/// Classify whether an operator is "left-homogeneous", i.e., the LHS has the
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