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Mirror metadata changes in layout sanity check

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This commit is contained in:
Michael Goulet 2022-11-13 21:49:54 +00:00
parent b25da9ce6d
commit 2011316e59
1 changed files with 45 additions and 7 deletions
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52
compiler/rustc_middle/src/ty/layout.rs
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@ -670,13 +670,24 @@ fn field_ty_or_layout<'tcx>(
}); });
} }
match tcx.struct_tail_erasing_lifetimes(pointee, cx.param_env()).kind() { let metadata = if let Some(metadata_def_id) = tcx.lang_items().metadata_type() {
ty::Slice(_) | ty::Str => TyMaybeWithLayout::Ty(tcx.types.usize), let metadata = tcx.normalize_erasing_regions(
ty::Dynamic(_, _, ty::Dyn) => { cx.param_env(),
TyMaybeWithLayout::Ty(tcx.mk_imm_ref( tcx.mk_projection(metadata_def_id, [pointee]),
);
// Map `Metadata = DynMetadata<dyn Trait>` back to a vtable, since it
// offers better information than `std::ptr::metadata::VTable`,
// and we rely on this layout information to trigger a panic in
// `std::mem::uninitialized::<&dyn Trait>()`, for example.
if let ty::Adt(def, substs) = metadata.kind()
&& Some(def.did()) == tcx.lang_items().dyn_metadata()
&& substs.type_at(0).is_trait()
{
tcx.mk_imm_ref(
tcx.lifetimes.re_static, tcx.lifetimes.re_static,
tcx.mk_array(tcx.types.usize, 3), tcx.mk_array(tcx.types.usize, 3),
)) )
/* FIXME: use actual fn pointers /* FIXME: use actual fn pointers
Warning: naively computing the number of entries in the Warning: naively computing the number of entries in the
vtable by counting the methods on the trait + methods on vtable by counting the methods on the trait + methods on
@ -690,9 +701,36 @@ fn field_ty_or_layout<'tcx>(
tcx.mk_array(Option<fn()>), tcx.mk_array(Option<fn()>),
]) ])
*/ */
} else {
metadata
} }
_ => bug!("TyAndLayout::field({:?}): not applicable", this), } 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()>),
])
*/
}
_ => bug!("TyAndLayout::field({:?}): not applicable", this),
}
};
TyMaybeWithLayout::Ty(metadata)
} }
// Arrays and slices. // Arrays and slices.