new trait solver: only consider goal changed if response is not identity
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38a76f3322
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2 changed files with 17 additions and 1 deletions
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@ -68,6 +68,22 @@ pub struct CanonicalVarValues<'tcx> {
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pub var_values: IndexVec<BoundVar, GenericArg<'tcx>>,
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pub var_values: IndexVec<BoundVar, GenericArg<'tcx>>,
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}
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}
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impl CanonicalVarValues<'_> {
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pub fn is_identity(&self) -> bool {
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self.var_values.iter_enumerated().all(|(bv, arg)| match arg.unpack() {
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ty::GenericArgKind::Lifetime(r) => {
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matches!(*r, ty::ReLateBound(ty::INNERMOST, br) if br.var == bv)
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}
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ty::GenericArgKind::Type(ty) => {
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matches!(*ty.kind(), ty::Bound(ty::INNERMOST, bt) if bt.var == bv)
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}
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ty::GenericArgKind::Const(ct) => {
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matches!(ct.kind(), ty::ConstKind::Bound(ty::INNERMOST, bc) if bc == bv)
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}
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})
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}
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}
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/// When we canonicalize a value to form a query, we wind up replacing
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/// When we canonicalize a value to form a query, we wind up replacing
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/// various parts of it with canonical variables. This struct stores
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/// various parts of it with canonical variables. This struct stores
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/// those replaced bits to remember for when we process the query
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/// those replaced bits to remember for when we process the query
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@ -178,7 +178,7 @@ impl<'tcx> EvalCtxt<'tcx> {
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let canonical_goal = infcx.canonicalize_query(goal, &mut orig_values);
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let canonical_goal = infcx.canonicalize_query(goal, &mut orig_values);
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let canonical_response = self.evaluate_canonical_goal(canonical_goal)?;
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let canonical_response = self.evaluate_canonical_goal(canonical_goal)?;
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Ok((
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Ok((
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true, // FIXME: check whether `var_values` are an identity substitution.
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!canonical_response.value.var_values.is_identity(),
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instantiate_canonical_query_response(infcx, &orig_values, canonical_response),
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instantiate_canonical_query_response(infcx, &orig_values, canonical_response),
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))
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))
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}
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}
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