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review comment: Deduplicate dyn ty_and_layout_field code

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This commit is contained in:
Michael Goulet 2023-01-04 01:02:52 +00:00
parent 2011316e59
commit a5d39cf290
1 changed files with 19 additions and 36 deletions
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55
compiler/rustc_middle/src/ty/layout.rs
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@ -670,6 +670,23 @@ fn field_ty_or_layout<'tcx>(
});
}
let mk_dyn_vtable = || {
tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.usize, 3))
/* FIXME: use actual fn pointers
Warning: naively computing the number of entries in the
vtable by counting the methods on the trait + methods on
all parent traits does not work, because some methods can
be not object safe and thus excluded from the vtable.
Increase this counter if you tried to implement this but
failed to do it without duplicating a lot of code from
other places in the compiler: 2
tcx.mk_tup(&[
tcx.mk_array(tcx.types.usize, 3),
tcx.mk_array(Option<fn()>),
])
*/
};
let metadata = if let Some(metadata_def_id) = tcx.lang_items().metadata_type() {
let metadata = tcx.normalize_erasing_regions(
cx.param_env(),
@ -684,48 +701,14 @@ fn field_ty_or_layout<'tcx>(
&& Some(def.did()) == tcx.lang_items().dyn_metadata()
&& substs.type_at(0).is_trait()
{
tcx.mk_imm_ref(
tcx.lifetimes.re_static,
tcx.mk_array(tcx.types.usize, 3),
)
/* FIXME: use actual fn pointers
Warning: naively computing the number of entries in the
vtable by counting the methods on the trait + methods on
all parent traits does not work, because some methods can
be not object safe and thus excluded from the vtable.
Increase this counter if you tried to implement this but
failed to do it without duplicating a lot of code from
other places in the compiler: 2
tcx.mk_tup(&[
tcx.mk_array(tcx.types.usize, 3),
tcx.mk_array(Option<fn()>),
])
*/
mk_dyn_vtable()
} else {
metadata
}
} else {
match tcx.struct_tail_erasing_lifetimes(pointee, cx.param_env()).kind() {
ty::Slice(_) | ty::Str => tcx.types.usize,
ty::Dynamic(_, _, ty::Dyn) => {
tcx.mk_imm_ref(
tcx.lifetimes.re_static,
tcx.mk_array(tcx.types.usize, 3),
)
/* FIXME: use actual fn pointers
Warning: naively computing the number of entries in the
vtable by counting the methods on the trait + methods on
all parent traits does not work, because some methods can
be not object safe and thus excluded from the vtable.
Increase this counter if you tried to implement this but
failed to do it without duplicating a lot of code from
other places in the compiler: 2
tcx.mk_tup(&[
tcx.mk_array(tcx.types.usize, 3),
tcx.mk_array(Option<fn()>),
])
*/
}
ty::Dynamic(_, _, ty::Dyn) => mk_dyn_vtable(),
_ => bug!("TyAndLayout::field({:?}): not applicable", this),
}
};