Skip to content

AssocFn with vtable_receiver #4

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
Nadrieril merged 6 commits into from
Oct 2, 2025
Merged

AssocFn with vtable_receiver #4

Changes from 1 commit
Commits
Show all changes
6 commits
Select commit Hold shift + click to select a range
822f3e2
AssocFn with vtable_receiver
ssyram Sep 19, 2025
0b51ae9
vtable_receiver -> vtable_sig
ssyram Oct 2, 2025
8616f55
use truncate_to
ssyram Oct 2, 2025
ca11fbb
use `is_vtable_safe_method`
ssyram Oct 2, 2025
0ad425c
comments as suggested
ssyram Oct 2, 2025
589dad0
panic as suggested
ssyram Oct 2, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
104 changes: 85 additions & 19 deletions frontend/exporter/src/types/new/full_def.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -325,9 +325,9 @@ pub enum FullDefKind<Body> {
associated_item: AssocItem,
inline: InlineAttr,
is_const: bool,
/// Whether this method will be included in the trait vtable. `false` if this is not a
/// trait method.
vtable_safe: bool,
/// The receiver type when this method is used in a vtable. `None` if this method is not
/// vtable safe. `Some(dyn_self)` if it is vtable safe.
vtable_receiver: Option<Ty>,
sig: PolyFnSig,
body: Option<Body>,
},
Expand Down Expand Up @@ -424,6 +424,82 @@ pub enum FullDefKind<Body> {
SyntheticCoroutineBody,
}

#[cfg(feature = "rustc")]
fn gen_vtable_receiver<'tcx>(
// The state that owns the method DefId
assoc_method_s: &StateWithOwner<'tcx>,
args: Option<ty::GenericArgsRef<'tcx>>,
) -> Option<Ty>
{
let def_id = assoc_method_s.owner_id();
let tcx = assoc_method_s.base().tcx;
let assoc_item = tcx.associated_item(def_id);
let s = &assoc_method_s.with_owner_id(assoc_item.container_id(tcx));

// The args for the container
let container_args = {
let container_def_id = assoc_item.container_id(tcx);
let container_generics = tcx.generics_of(container_def_id);
args.map(|args| {
tcx.mk_args_from_iter(args.iter().take(container_generics.count()))
})
};

let dyn_self: ty::Ty = match assoc_item.container {
ty::AssocItemContainer::Trait => {
get_trait_decl_dyn_self_ty(s, container_args)
},
ty::AssocItemContainer::Impl => {
// For impl methods, compute concrete dyn_self from the impl's trait reference
let impl_def_id = assoc_item.container_id(tcx);
let Some(impl_trait_ref) = tcx.impl_trait_ref(impl_def_id) else {
// There might be inherent impl methods, which is surely not vtable safe.
return None;
};
// Get the concrete trait reference by rebasing the impl's trait ref args onto `container_args`
let concrete_trait_ref = inst_binder(tcx, s.typing_env(), container_args, impl_trait_ref);
dyn_self_ty(tcx, s.typing_env(), concrete_trait_ref)
},
}?;

// Next, try to find the receiver "template" from the trait method declaration.
// It would be convenient for us to simply substitute `Self` with `dyn_self` in the receiver.
let origin_trait_method_id = match assoc_item.trait_item_def_id {
Some(id) => id,
// It is itself a trait method declaration
None => def_id,
};
let origin_trait_method_sig = tcx.fn_sig(origin_trait_method_id);
let base_receiver_ty = origin_trait_method_sig.skip_binder().inputs().skip_binder()[0];

use ty::TypeFoldable;

struct ReceiverReplacer<'tcx>(ty::TyCtxt<'tcx>, ty::Ty<'tcx>);

impl<'tcx> ty::TypeFolder<ty::TyCtxt<'tcx>> for ReceiverReplacer<'tcx> {
fn cx(&self) -> ty::TyCtxt<'tcx> {
self.0
}
fn fold_ty(&mut self, t: ty::Ty<'tcx>) -> ty::Ty<'tcx> {
use rustc_middle::ty::TypeSuperFoldable;
match t.kind() {
ty::Param(param) => {
if param.name == rustc_span::symbol::kw::SelfUpper {
assert!(param.index == 0);
return self.1.clone();
}
return t.super_fold_with(self);
},
_ => t.super_fold_with(self)
}
}
}

let mut replacer = ReceiverReplacer(tcx, dyn_self);

Some(base_receiver_ty.fold_with(&mut replacer).sinto(s))
}

#[cfg(feature = "rustc")]
/// Construct the `FullDefKind` for this item.
///
Expand Down Expand Up @@ -506,7 +582,7 @@ where
param_env: get_param_env(s, args),
implied_predicates: get_implied_predicates(s, args),
self_predicate: get_self_predicate(s, args),
dyn_self: get_dyn_self_ty(s, args),
dyn_self: get_trait_decl_dyn_self_ty(s, args).sinto(s),
items: tcx
.associated_items(def_id)
.in_definition_order()
Expand All @@ -525,7 +601,7 @@ where
param_env: get_param_env(s, args),
implied_predicates: get_implied_predicates(s, args),
self_predicate: get_self_predicate(s, args),
dyn_self: get_dyn_self_ty(s, args),
dyn_self: get_trait_decl_dyn_self_ty(s, args).sinto(s),
},
RDefKind::Impl { .. } => {
use std::collections::HashMap;
Expand Down Expand Up @@ -671,22 +747,12 @@ where
},
RDefKind::AssocFn { .. } => {
let item = tcx.associated_item(def_id);
let vtable_safe = match item.container {
ty::AssocItemContainer::Trait => {
rustc_trait_selection::traits::is_vtable_safe_method(
tcx,
item.container_id(tcx),
item,
)
}
_ => false,
};
FullDefKind::AssocFn {
param_env: get_param_env(s, args),
associated_item: AssocItem::sfrom_instantiated(s, &item, args),
inline: tcx.codegen_fn_attrs(def_id).inline.sinto(s),
is_const: tcx.constness(def_id) == rustc_hir::Constness::Const,
vtable_safe,
vtable_receiver: gen_vtable_receiver(s, args),
sig: get_method_sig(tcx, s.typing_env(), def_id, args).sinto(s),
body: get_body(s, args),
}
Expand Down Expand Up @@ -1016,10 +1082,10 @@ fn get_self_predicate<'tcx, S: UnderOwnerState<'tcx>>(

/// Generates a `dyn Trait<Args.., Ty = <Self as Trait>::Ty..>` type for this trait.
#[cfg(feature = "rustc")]
fn get_dyn_self_ty<'tcx, S: UnderOwnerState<'tcx>>(
fn get_trait_decl_dyn_self_ty<'tcx, S: UnderOwnerState<'tcx>>(
s: &S,
args: Option<ty::GenericArgsRef<'tcx>>,
) -> Option<Ty> {
) -> Option<ty::Ty<'tcx>> {
let tcx = s.base().tcx;
let typing_env = s.typing_env();
let def_id = s.owner_id();
Expand All @@ -1035,7 +1101,7 @@ fn get_dyn_self_ty<'tcx, S: UnderOwnerState<'tcx>>(
} else {
ty
};
ty.sinto(s)
ty
})
}

Expand Down
Loading