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Add BoundKind in visit_param_bounds to check questions in bounds #96246

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Apr 25, 2022
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Add BoundKind in visit_param_bounds to check questions in bounds #96246

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4375b36
Add `BoundCtxt` in `visit_param_bounds` to check questions in bounds
SparrowLii Apr 20, 2022
38bd4fb
rename to `BoundKind` and add comments
SparrowLii Apr 21, 2022
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46 changes: 34 additions & 12 deletions compiler/rustc_ast/src/visit.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,25 @@ pub enum FnCtxt {
Assoc(AssocCtxt),
}

#[derive(Copy, Clone, Debug)]
pub enum BoundKind {
/// Trait bounds in generics bounds and type/trait alias.
/// E.g., `<T: Bound>`, `type A: Bound`, or `where T: Bound`.
Bound,

/// Trait bounds in `impl` type.
/// E.g., `type Foo = impl Bound1 + Bound2 + Bound3`.
Impl,

/// Trait bounds in trait object type.
/// E.g., `dyn Bound1 + Bound2 + Bound3`.
TraitObject,

/// Super traits of a trait.
/// E.g., `trait A: B`
SuperTraits,
}

#[derive(Copy, Clone, Debug)]
pub enum FnKind<'a> {
/// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
Expand Down Expand Up @@ -139,7 +158,7 @@ pub trait Visitor<'ast>: Sized {
fn visit_trait_ref(&mut self, t: &'ast TraitRef) {
walk_trait_ref(self, t)
}
fn visit_param_bound(&mut self, bounds: &'ast GenericBound) {
fn visit_param_bound(&mut self, bounds: &'ast GenericBound, _ctxt: BoundKind) {
walk_param_bound(self, bounds)
}
fn visit_poly_trait_ref(&mut self, t: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
Expand Down Expand Up @@ -311,7 +330,7 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
ItemKind::GlobalAsm(ref asm) => walk_inline_asm(visitor, asm),
ItemKind::TyAlias(box TyAlias { ref generics, ref bounds, ref ty, .. }) => {
visitor.visit_generics(generics);
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
walk_list!(visitor, visit_ty, ty);
}
ItemKind::Enum(ref enum_definition, ref generics) => {
Expand Down Expand Up @@ -346,12 +365,12 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
ref items,
}) => {
visitor.visit_generics(generics);
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::SuperTraits);
walk_list!(visitor, visit_assoc_item, items, AssocCtxt::Trait);
}
ItemKind::TraitAlias(ref generics, ref bounds) => {
visitor.visit_generics(generics);
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
}
ItemKind::MacCall(ref mac) => visitor.visit_mac_call(mac),
ItemKind::MacroDef(ref ts) => visitor.visit_mac_def(ts, item.id),
Expand Down Expand Up @@ -416,8 +435,11 @@ pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) {
visitor.visit_ty(ty);
visitor.visit_anon_const(length)
}
TyKind::TraitObject(ref bounds, ..) | TyKind::ImplTrait(_, ref bounds) => {
walk_list!(visitor, visit_param_bound, bounds);
TyKind::TraitObject(ref bounds, ..) => {
walk_list!(visitor, visit_param_bound, bounds, BoundKind::TraitObject);
}
TyKind::ImplTrait(_, ref bounds) => {
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Impl);
}
TyKind::Typeof(ref expression) => visitor.visit_anon_const(expression),
TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => {}
Expand Down Expand Up @@ -503,7 +525,7 @@ pub fn walk_assoc_constraint<'a, V: Visitor<'a>>(visitor: &mut V, constraint: &'
Term::Const(c) => visitor.visit_anon_const(c),
},
AssocConstraintKind::Bound { ref bounds } => {
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
}
}
}
Expand Down Expand Up @@ -566,7 +588,7 @@ pub fn walk_foreign_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a ForeignI
}
ForeignItemKind::TyAlias(box TyAlias { generics, bounds, ty, .. }) => {
visitor.visit_generics(generics);
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
walk_list!(visitor, visit_ty, ty);
}
ForeignItemKind::MacCall(mac) => {
Expand All @@ -585,7 +607,7 @@ pub fn walk_param_bound<'a, V: Visitor<'a>>(visitor: &mut V, bound: &'a GenericB
pub fn walk_generic_param<'a, V: Visitor<'a>>(visitor: &mut V, param: &'a GenericParam) {
visitor.visit_ident(param.ident);
walk_list!(visitor, visit_attribute, param.attrs.iter());
walk_list!(visitor, visit_param_bound, &param.bounds);
walk_list!(visitor, visit_param_bound, &param.bounds, BoundKind::Bound);
match param.kind {
GenericParamKind::Lifetime => (),
GenericParamKind::Type { ref default } => walk_list!(visitor, visit_ty, default),
Expand All @@ -612,14 +634,14 @@ pub fn walk_where_predicate<'a, V: Visitor<'a>>(visitor: &mut V, predicate: &'a
..
}) => {
visitor.visit_ty(bounded_ty);
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
walk_list!(visitor, visit_generic_param, bound_generic_params);
}
WherePredicate::RegionPredicate(WhereRegionPredicate {
ref lifetime, ref bounds, ..
}) => {
visitor.visit_lifetime(lifetime);
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
}
WherePredicate::EqPredicate(WhereEqPredicate { ref lhs_ty, ref rhs_ty, .. }) => {
visitor.visit_ty(lhs_ty);
Expand Down Expand Up @@ -672,7 +694,7 @@ pub fn walk_assoc_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem,
}
AssocItemKind::TyAlias(box TyAlias { generics, bounds, ty, .. }) => {
visitor.visit_generics(generics);
walk_list!(visitor, visit_param_bound, bounds);
walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
walk_list!(visitor, visit_ty, ty);
}
AssocItemKind::MacCall(mac) => {
Expand Down
71 changes: 35 additions & 36 deletions compiler/rustc_ast_passes/src/ast_validation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@

use itertools::{Either, Itertools};
use rustc_ast::ptr::P;
use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
use rustc_ast::walk_list;
use rustc_ast::*;
use rustc_ast_pretty::pprust::{self, State};
Expand Down Expand Up @@ -345,23 +345,6 @@ impl<'a> AstValidator<'a> {
}
}

// FIXME(ecstaticmorse): Instead, use `bound_context` to check this in `visit_param_bound`.
fn no_questions_in_bounds(&self, bounds: &GenericBounds, where_: &str, is_trait: bool) {
for bound in bounds {
if let GenericBound::Trait(ref poly, TraitBoundModifier::Maybe) = *bound {
let mut err = self.err_handler().struct_span_err(
poly.span,
&format!("`?Trait` is not permitted in {}", where_),
);
if is_trait {
let path_str = pprust::path_to_string(&poly.trait_ref.path);
err.note(&format!("traits are `?{}` by default", path_str));
}
err.emit();
}
}
}

fn check_late_bound_lifetime_defs(&self, params: &[GenericParam]) {
// Check only lifetime parameters are present and that the lifetime
// parameters that are present have no bounds.
Expand Down Expand Up @@ -873,7 +856,6 @@ impl<'a> AstValidator<'a> {
any_lifetime_bounds = true;
}
}
self.no_questions_in_bounds(bounds, "trait object types", false);
}
TyKind::ImplTrait(_, ref bounds) => {
if self.is_impl_trait_banned {
Expand Down Expand Up @@ -1242,14 +1224,15 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
self.deny_where_clause(&generics.where_clause, item.ident.span);
self.deny_items(items, item.ident.span);
}
self.no_questions_in_bounds(bounds, "supertraits", true);

// Equivalent of `visit::walk_item` for `ItemKind::Trait` that inserts a bound
// context for the supertraits.
self.visit_vis(&item.vis);
self.visit_ident(item.ident);
self.visit_generics(generics);
self.with_banned_tilde_const(|this| walk_list!(this, visit_param_bound, bounds));
self.with_banned_tilde_const(|this| {
walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits)
});
walk_list!(self, visit_assoc_item, items, AssocCtxt::Trait);
walk_list!(self, visit_attribute, &item.attrs);
return;
Expand Down Expand Up @@ -1476,23 +1459,39 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
visit::walk_generic_param(self, param);
}

fn visit_param_bound(&mut self, bound: &'a GenericBound) {
match bound {
GenericBound::Trait(_, TraitBoundModifier::MaybeConst) => {
if !self.is_tilde_const_allowed {
fn visit_param_bound(&mut self, bound: &'a GenericBound, ctxt: BoundKind) {
if let GenericBound::Trait(ref poly, modify) = *bound {
match (ctxt, modify) {
(BoundKind::SuperTraits, TraitBoundModifier::Maybe) => {
let mut err = self.err_handler().struct_span_err(
poly.span,
&format!("`?Trait` is not permitted in supertraits"),
);
let path_str = pprust::path_to_string(&poly.trait_ref.path);
err.note(&format!("traits are `?{}` by default", path_str));
err.emit();
}
(BoundKind::TraitObject, TraitBoundModifier::Maybe) => {
let mut err = self.err_handler().struct_span_err(
poly.span,
&format!("`?Trait` is not permitted in trait object types"),
);
err.emit();
}
(_, TraitBoundModifier::MaybeConst) => {
if !self.is_tilde_const_allowed {
self.err_handler()
.struct_span_err(bound.span(), "`~const` is not allowed here")
.note("only allowed on bounds on traits' associated types and functions, const fns, const impls and its associated functions")
.emit();
}
}
(_, TraitBoundModifier::MaybeConstMaybe) => {
self.err_handler()
.struct_span_err(bound.span(), "`~const` is not allowed here")
.note("only allowed on bounds on traits' associated types and functions, const fns, const impls and its associated functions")
.emit();
.span_err(bound.span(), "`~const` and `?` are mutually exclusive");
}
_ => {}
}

GenericBound::Trait(_, TraitBoundModifier::MaybeConstMaybe) => {
self.err_handler()
.span_err(bound.span(), "`~const` and `?` are mutually exclusive");
}

_ => {}
}

visit::walk_param_bound(self, bound)
Expand Down Expand Up @@ -1662,7 +1661,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
walk_list!(self, visit_attribute, &item.attrs);
self.with_tilde_const_allowed(|this| {
this.visit_generics(generics);
walk_list!(this, visit_param_bound, bounds);
walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
});
walk_list!(self, visit_ty, ty);
}
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_ast_passes/src/node_count.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,7 @@ impl<'ast> Visitor<'ast> for NodeCounter {
self.count += 1;
walk_trait_ref(self, t)
}
fn visit_param_bound(&mut self, bounds: &GenericBound) {
fn visit_param_bound(&mut self, bounds: &GenericBound, _ctxt: BoundKind) {
self.count += 1;
walk_param_bound(self, bounds)
}
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_passes/src/hir_stats.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
// completely accurate (some things might be counted twice, others missed).

use rustc_ast::visit as ast_visit;
use rustc_ast::visit::BoundKind;
use rustc_ast::{self as ast, AttrId, NodeId};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_hir as hir;
Expand Down Expand Up @@ -302,7 +303,7 @@ impl<'v> ast_visit::Visitor<'v> for StatCollector<'v> {
ast_visit::walk_assoc_item(self, item, ctxt);
}

fn visit_param_bound(&mut self, bounds: &'v ast::GenericBound) {
fn visit_param_bound(&mut self, bounds: &'v ast::GenericBound, _ctxt: BoundKind) {
self.record("GenericBound", Id::None, bounds);
ast_visit::walk_param_bound(self, bounds)
}
Expand Down
12 changes: 6 additions & 6 deletions compiler/rustc_resolve/src/late.rs
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Expand Up @@ -12,7 +12,7 @@ use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
use crate::{ResolutionError, Resolver, Segment, UseError};

use rustc_ast::ptr::P;
use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
use rustc_ast::*;
use rustc_ast_lowering::ResolverAstLowering;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
Expand Down Expand Up @@ -835,7 +835,7 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
this.visit_generic_param_vec(&bound_generic_params, false);
this.visit_ty(bounded_ty);
for bound in bounds {
this.visit_param_bound(bound)
this.visit_param_bound(bound, BoundKind::Bound)
}
},
);
Expand Down Expand Up @@ -1026,12 +1026,12 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
match param.kind {
GenericParamKind::Lifetime => {
for bound in &param.bounds {
this.visit_param_bound(bound);
this.visit_param_bound(bound, BoundKind::Bound);
}
}
GenericParamKind::Type { ref default } => {
for bound in &param.bounds {
this.visit_param_bound(bound);
this.visit_param_bound(bound, BoundKind::Bound);
}

if let Some(ref ty) = default {
Expand Down Expand Up @@ -1496,7 +1496,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
|this| {
this.visit_generics(generics);
walk_list!(this, visit_param_bound, bounds);
walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);

let walk_assoc_item =
|this: &mut Self,
Expand Down Expand Up @@ -1580,7 +1580,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
|this| {
this.visit_generics(generics);
walk_list!(this, visit_param_bound, bounds);
walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
},
);
},
Expand Down