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Rollup merge of #106834 - compiler-errors:new-solver-did-changed, r=lcnr

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new trait solver: only consider goal changed if response is not identity

I think this is the right way of implementing it..

r? `@lcnr`
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Matthias Krüger 2023-01-17 20:21:26 +01:00 • committed by GitHub
commit fc9e2c1081
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2 changed files with 17 additions and 1 deletions
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16
compiler/rustc_middle/src/infer/canonical.rs
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@ -68,6 +68,22 @@ pub struct CanonicalVarValues<'tcx> {
pub var_values: IndexVec<BoundVar, GenericArg<'tcx>>,
}
impl CanonicalVarValues<'_> {
pub fn is_identity(&self) -> bool {
self.var_values.iter_enumerated().all(|(bv, arg)| match arg.unpack() {
ty::GenericArgKind::Lifetime(r) => {
matches!(*r, ty::ReLateBound(ty::INNERMOST, br) if br.var == bv)
}
ty::GenericArgKind::Type(ty) => {
matches!(*ty.kind(), ty::Bound(ty::INNERMOST, bt) if bt.var == bv)
}
ty::GenericArgKind::Const(ct) => {
matches!(ct.kind(), ty::ConstKind::Bound(ty::INNERMOST, bc) if bc == bv)
}
})
}
}
/// When we canonicalize a value to form a query, we wind up replacing
/// various parts of it with canonical variables. This struct stores
/// those replaced bits to remember for when we process the query

2
compiler/rustc_trait_selection/src/solve/mod.rs
View file

@ -178,7 +178,7 @@ impl<'tcx> EvalCtxt<'tcx> {
let canonical_goal = infcx.canonicalize_query(goal, &mut orig_values);
let canonical_response = self.evaluate_canonical_goal(canonical_goal)?;
Ok((
true, // FIXME: check whether `var_values` are an identity substitution.
!canonical_response.value.var_values.is_identity(),
instantiate_canonical_query_response(infcx, &orig_values, canonical_response),
))
}