Relate binders explicitly, do a leak check too

compiler/rustc_codegen_ssa/src/base.rs

@@ -27,7 +27,8 @@ use rustc_session::config::{self, CrateType, EntryFnType, OptLevel, OutputType};
 use rustc_span::symbol::sym;
 use rustc_span::{DUMMY_SP, Symbol};
 use rustc_target::abi::FIRST_VARIANT;
-use rustc_trait_selection::infer::TyCtxtInferExt;
+use rustc_trait_selection::infer::at::ToTrace;
+use rustc_trait_selection::infer::{BoundRegionConversionTime, TyCtxtInferExt};
 use rustc_trait_selection::traits::{ObligationCause, ObligationCtxt};
 use tracing::{debug, info};
 
@@ -113,22 +114,38 @@ pub fn compare_simd_types<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 /// unsound, so let's validate here that the trait refs are subtypes.
 pub fn validate_trivial_unsize<'tcx>(
  tcx: TyCtxt<'tcx>,
- data_a: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
- data_b: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
+ source_data: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
+ target_data: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
 ) -> bool {
- match (data_a.principal(), data_b.principal()) {
- (Some(principal_a), Some(principal_b)) => {
+ match (source_data.principal(), target_data.principal()) {
+ (Some(hr_source_principal), Some(hr_target_principal)) => {
  let infcx = tcx.infer_ctxt().build();
+ let universe = infcx.universe();
  let ocx = ObligationCtxt::new(&infcx);
- let Ok(()) = ocx.sub(
- &ObligationCause::dummy(),
- ty::ParamEnv::reveal_all(),
- principal_a,
- principal_b,
- ) else {
- return false;
- };
- ocx.select_all_or_error().is_empty()
+ infcx.enter_forall(hr_target_principal, |target_principal| {
+ let source_principal = infcx.instantiate_binder_with_fresh_vars(
+ DUMMY_SP,
+ BoundRegionConversionTime::HigherRankedType,
+ hr_source_principal,
+ );
+ let Ok(()) = ocx.eq_trace(
+ &ObligationCause::dummy(),
+ ty::ParamEnv::reveal_all(),
+ ToTrace::to_trace(
+ &ObligationCause::dummy(),
+ hr_target_principal,
+ hr_source_principal,
+ ),
+ target_principal,
+ source_principal,
+ ) else {
+ return false;
+ };
+ if !ocx.select_all_or_error().is_empty() {
+ return false;
+ }
+ infcx.leak_check(universe, None).is_ok()
+ })
  }
  (None, None) => true,
  _ => false,

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -9,12 +9,13 @@ use rustc_infer::infer::canonical::{
  Canonical, CanonicalQueryResponse, CanonicalVarValues, QueryResponse,
 };
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk, RegionResolutionError};
+use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk, RegionResolutionError, TypeTrace};
 use rustc_macros::extension;
 use rustc_middle::arena::ArenaAllocatable;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, Upcast, Variance};
+use rustc_type_ir::relate::Relate;
 
 use super::{FromSolverError, FulfillmentContext, ScrubbedTraitError, TraitEngine};
 use crate::error_reporting::InferCtxtErrorExt;
@@ -133,6 +134,20 @@ where
  .map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
  }
 
+ pub fn eq_trace<T: Relate<TyCtxt<'tcx>>>(
+ &self,
+ cause: &ObligationCause<'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+ trace: TypeTrace<'tcx>,
+ expected: T,
+ actual: T,
+ ) -> Result<(), TypeError<'tcx>> {
+ self.infcx
+ .at(cause, param_env)
+ .eq_trace(DefineOpaqueTypes::Yes, trace, expected, actual)
+ .map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
+ }
+
  /// Checks whether `expected` is a subtype of `actual`: `expected <: actual`.
  pub fn sub<T: ToTrace<'tcx>>(
  &self,