bjoernager/rust
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Specialize ZeroSized constants

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ZeroSized constants can be represented as `mir::Const::Val` even if
their layout is not yet known. In those cases, CrateItem::body() was
crashing when trying to convert a `ConstValue::ZeroSized` into its
stable counterpart `ConstantKind::Allocated`.

Instead, we now map `ConstValue::ZeroSized` into a new variant:
`ConstantKind::ZeroSized`.
This commit is contained in:
Celina G. Val 2023-10-26 20:10:54 -07:00
parent ab5c841a1f
commit 613e6181a6
3 changed files with 18 additions and 6 deletions
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19
compiler/rustc_smir/src/rustc_smir/mod.rs
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@ -1284,11 +1284,15 @@ impl<'tcx> Stable<'tcx> for ty::Const<'tcx> {
let kind = match self.kind() {
ty::Value(val) => {
let const_val = tables.tcx.valtree_to_const_val((self.ty(), val));
stable_mir::ty::ConstantKind::Allocated(alloc::new_allocation(
self.ty(),
const_val,
tables,
))
if matches!(const_val, mir::ConstValue::ZeroSized) {
ConstantKind::ZeroSized
} else {
stable_mir::ty::ConstantKind::Allocated(alloc::new_allocation(
self.ty(),
const_val,
tables,
))
}
}
ty::ParamCt(param) => stable_mir::ty::ConstantKind::Param(param.stable(tables)),
ty::ErrorCt(_) => unreachable!(),
@ -1402,6 +1406,11 @@ impl<'tcx> Stable<'tcx> for rustc_middle::mir::Const<'tcx> {
let id = tables.intern_const(*self);
Const::new(kind, ty, id)
}
mir::Const::Val(val, ty) if matches!(val, mir::ConstValue::ZeroSized) => {
let ty = ty.stable(tables);
let id = tables.intern_const(*self);
Const::new(ConstantKind::ZeroSized, ty, id)
}
mir::Const::Val(val, ty) => {
let kind = ConstantKind::Allocated(alloc::new_allocation(ty, val, tables));
let ty = ty.stable(tables);