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create NullableUnion in some cases

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Folkert 2021-01-15 01:02:34 +01:00
parent b47ccb20fd
commit 51cad15399
3 changed files with 41 additions and 2 deletions
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26
compiler/mono/src/layout.rs
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@ -1019,7 +1019,21 @@ fn layout_from_flat_type<'a>(
let mut tags_vec: std::vec::Vec<_> = tags.into_iter().collect();
tags_vec.sort();
for (_name, variables) in tags_vec {
let mut nullable = None;
for (index, (_name, variables)) in tags_vec.iter().enumerate() {
if variables.is_empty() {
nullable = Some((index as i64, TAG_SIZE));
break;
}
}
for (index, (_name, variables)) in tags_vec.into_iter().enumerate() {
if matches!(nullable, Some((i, _)) if i == index as i64) {
// don't add the
continue;
}
let mut tag_layout = Vec::with_capacity_in(variables.len() + 1, arena);
// store the discriminant
@ -1047,7 +1061,15 @@ fn layout_from_flat_type<'a>(
tag_layouts.push(tag_layout.into_bump_slice());
}
Ok(Layout::RecursiveUnion(tag_layouts.into_bump_slice()))
if let Some((tag_id, tag_id_layout)) = nullable {
Ok(Layout::NullableUnion {
nullable_id: tag_id,
nullable_layout: tag_id_layout,
foo: tag_layouts.into_bump_slice(),
})
} else {
Ok(Layout::RecursiveUnion(tag_layouts.into_bump_slice()))
}
}
EmptyTagUnion => {
panic!("TODO make Layout for empty Tag Union");