bjoernager/rust
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Move nested quantification check to ast_validation

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This commit is contained in:
Jack Huey 2021-04-21 03:12:04 -04:00
parent 9891582897
commit 4568e7d62e
2 changed files with 52 additions and 75 deletions
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47
compiler/rustc_ast_passes/src/ast_validation.rs
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@ -81,6 +81,13 @@ struct AstValidator<'a> {
is_assoc_ty_bound_banned: bool,
lint_buffer: &'a mut LintBuffer,
/// This is slightly complicated. Our representation for poly-trait-refs contains a single
/// binder and thus we only allow a single level of quantification. However,
/// the syntax of Rust permits quantification in two places in where clauses,
/// e.g., `T: for <'a> Foo<'a>` and `for <'a, 'b> &'b T: Foo<'a>`. If both are
/// defined, then error.
trait_ref_hack: bool,
}
impl<'a> AstValidator<'a> {
@ -1213,8 +1220,25 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
deny_equality_constraints(self, predicate, generics);
}
}
walk_list!(self, visit_generic_param, &generics.params);
for predicate in &generics.where_clause.predicates {
match predicate {
WherePredicate::BoundPredicate(bound_pred) => {
// A type binding, eg `for<'c> Foo: Send+Clone+'c`
self.check_late_bound_lifetime_defs(&bound_pred.bound_generic_params);
visit::walk_generics(self, generics)
self.visit_ty(&bound_pred.bounded_ty);
self.trait_ref_hack = !bound_pred.bound_generic_params.is_empty();
walk_list!(self, visit_param_bound, &bound_pred.bounds);
walk_list!(self, visit_generic_param, &bound_pred.bound_generic_params);
self.trait_ref_hack = false;
}
_ => {
self.visit_where_predicate(predicate);
}
}
}
}
fn visit_generic_param(&mut self, param: &'a GenericParam) {
@ -1263,17 +1287,21 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
visit::walk_pat(self, pat)
}
fn visit_where_predicate(&mut self, p: &'a WherePredicate) {
if let &WherePredicate::BoundPredicate(ref bound_predicate) = p {
// A type binding, eg `for<'c> Foo: Send+Clone+'c`
self.check_late_bound_lifetime_defs(&bound_predicate.bound_generic_params);
}
visit::walk_where_predicate(self, p);
}
fn visit_poly_trait_ref(&mut self, t: &'a PolyTraitRef, m: &'a TraitBoundModifier) {
self.check_late_bound_lifetime_defs(&t.bound_generic_params);
if self.trait_ref_hack && !t.bound_generic_params.is_empty() {
struct_span_err!(
self.err_handler(),
t.span,
E0316,
"nested quantification of lifetimes"
)
.emit();
}
let trait_ref_hack = self.trait_ref_hack;
self.trait_ref_hack = false;
visit::walk_poly_trait_ref(self, t, m);
self.trait_ref_hack = trait_ref_hack;
}
fn visit_variant_data(&mut self, s: &'a VariantData) {
@ -1492,6 +1520,7 @@ pub fn check_crate(session: &Session, krate: &Crate, lints: &mut LintBuffer) ->
is_impl_trait_banned: false,
is_assoc_ty_bound_banned: false,
lint_buffer: lints,
trait_ref_hack: false,
};
visit::walk_crate(&mut validator, krate);