diff options
Diffstat (limited to 'compiler/rustc_const_eval/src/util/compare_types.rs')
-rw-r--r-- | compiler/rustc_const_eval/src/util/compare_types.rs | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/compiler/rustc_const_eval/src/util/compare_types.rs b/compiler/rustc_const_eval/src/util/compare_types.rs index 83376c8e9..265ca0c78 100644 --- a/compiler/rustc_const_eval/src/util/compare_types.rs +++ b/compiler/rustc_const_eval/src/util/compare_types.rs @@ -5,7 +5,7 @@ use rustc_infer::infer::TyCtxtInferExt; use rustc_middle::traits::{DefiningAnchor, ObligationCause}; -use rustc_middle::ty::{ParamEnv, Ty, TyCtxt}; +use rustc_middle::ty::{ParamEnv, Ty, TyCtxt, Variance}; use rustc_trait_selection::traits::ObligationCtxt; /// Returns whether the two types are equal up to subtyping. @@ -24,16 +24,22 @@ pub fn is_equal_up_to_subtyping<'tcx>( } // Check for subtyping in either direction. - is_subtype(tcx, param_env, src, dest) || is_subtype(tcx, param_env, dest, src) + relate_types(tcx, param_env, Variance::Covariant, src, dest) + || relate_types(tcx, param_env, Variance::Covariant, dest, src) } /// Returns whether `src` is a subtype of `dest`, i.e. `src <: dest`. /// +/// When validating assignments, the variance should be `Covariant`. When checking +/// during `MirPhase` >= `MirPhase::Runtime(RuntimePhase::Initial)` variance should be `Invariant` +/// because we want to check for type equality. +/// /// This mostly ignores opaque types as it can be used in constraining contexts /// while still computing the final underlying type. -pub fn is_subtype<'tcx>( +pub fn relate_types<'tcx>( tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, + variance: Variance, src: Ty<'tcx>, dest: Ty<'tcx>, ) -> bool { @@ -48,7 +54,7 @@ pub fn is_subtype<'tcx>( let cause = ObligationCause::dummy(); let src = ocx.normalize(&cause, param_env, src); let dest = ocx.normalize(&cause, param_env, dest); - match ocx.sub(&cause, param_env, src, dest) { + match ocx.relate(&cause, param_env, variance, src, dest) { Ok(()) => {} Err(_) => return false, }; |