bjoernager/rust
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reject pointee without ?Sized

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This commit is contained in:
Ding Xiang Fei 2024-07-31 22:50:45 +08:00
parent 99322d84c4
commit 14a0963f96
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GPG key ID: 3CD748647EEF6359
3 changed files with 69 additions and 37 deletions
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50
compiler/rustc_builtin_macros/src/deriving/smart_ptr.rs
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@ -1,5 +1,3 @@
use std::mem::swap;
use ast::ptr::P;
use ast::HasAttrs;
use rustc_ast::mut_visit::MutVisitor;
@ -154,13 +152,28 @@ pub fn expand_deriving_smart_ptr(
{
let pointee = &mut impl_generics.params[pointee_param_idx];
self_bounds = pointee.bounds.clone();
if !contains_maybe_sized_bound(&self_bounds)
&& !contains_maybe_sized_bound_on_pointee(
&generics.where_clause.predicates,
pointee_ty_ident.name,
)
{
cx.dcx()
.struct_span_err(
pointee_ty_ident.span,
format!(
"`derive(SmartPointer)` requires {} to be marked `?Sized`",
pointee_ty_ident.name
),
)
.emit();
return;
}
let arg = GenericArg::Type(s_ty.clone());
let unsize = cx.path_all(span, true, path!(span, core::marker::Unsize), vec![arg]);
pointee.bounds.push(cx.trait_bound(unsize, false));
let mut attrs = thin_vec![];
swap(&mut pointee.attrs, &mut attrs);
// Drop `#[pointee]` attribute since it should not be recognized outside `derive(SmartPointer)`
pointee.attrs = attrs.into_iter().filter(|attr| !attr.has_name(sym::pointee)).collect();
pointee.attrs.retain(|attr| !attr.has_name(sym::pointee));
}
// # Rewrite generic parameter bounds
@ -169,14 +182,14 @@ pub fn expand_deriving_smart_ptr(
// ```
// struct<
// U: Trait<T>,
// #[pointee] T: Trait<T>,
// #[pointee] T: Trait<T> + ?Sized,
// V: Trait<T>> ...
// ```
// ... generates this `impl` generic parameters
// ```
// impl<
// U: Trait<T> + Trait<__S>,
// T: Trait<T> + Unsize<__S>, // (**)
// T: Trait<T> + ?Sized + Unsize<__S>, // (**)
// __S: Trait<__S> + ?Sized, // (*)
// V: Trait<T> + Trait<__S>> ...
// ```
@ -218,23 +231,6 @@ pub fn expand_deriving_smart_ptr(
//
// We now insert `__S` with the missing bounds marked with (*) above.
// We should also write the bounds from `#[pointee]` to `__S` as required by `Unsize<__S>`.
let sized = cx.path_global(span, path!(span, core::marker::Sized));
// For some reason, we are not allowed to write `?Sized` bound twice like `__S: ?Sized + ?Sized`.
if !contains_maybe_sized_bound(&self_bounds)
&& !contains_maybe_sized_bound_on_pointee(
&generics.where_clause.predicates,
pointee_ty_ident.name,
)
{
self_bounds.push(GenericBound::Trait(
cx.poly_trait_ref(span, sized),
TraitBoundModifiers {
polarity: ast::BoundPolarity::Maybe(span),
constness: ast::BoundConstness::Never,
asyncness: ast::BoundAsyncness::Normal,
},
));
}
{
let mut substitution =
TypeSubstitution { from_name: pointee_ty_ident.name, to_ty: &s_ty, rewritten: false };
@ -252,7 +248,7 @@ pub fn expand_deriving_smart_ptr(
// where
// U: Trait<V> + Trait<T>,
// Companion<T>: Trait<T>,
// T: Trait<T>,
// T: Trait<T> + ?Sized,
// { .. }
// ```
// ... will have a impl prelude like so
@ -263,8 +259,8 @@ pub fn expand_deriving_smart_ptr(
// U: Trait<__S>,
// Companion<T>: Trait<T>,
// Companion<__S>: Trait<__S>,
// T: Trait<T>,
// __S: Trait<__S>,
// T: Trait<T> + ?Sized,
// __S: Trait<__S> + ?Sized,
// ```
//
// We should also write a few new `where` bounds from `#[pointee] T` to `__S`