Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/utils.rs')
| -rw-r--r-- | crates/hir-ty/src/utils.rs | 50 |
1 files changed, 46 insertions, 4 deletions
diff --git a/crates/hir-ty/src/utils.rs b/crates/hir-ty/src/utils.rs index f60b4607f2..8f36188b78 100644 --- a/crates/hir-ty/src/utils.rs +++ b/crates/hir-ty/src/utils.rs @@ -20,8 +20,8 @@ use hir_def::{ lang_item::LangItem, resolver::{HasResolver, TypeNs}, type_ref::{TraitBoundModifier, TypeRef}, - ConstParamId, FunctionId, GenericDefId, ItemContainerId, Lookup, TraitId, TypeAliasId, - TypeOrConstParamId, TypeParamId, + ConstParamId, EnumId, EnumVariantId, FunctionId, GenericDefId, ItemContainerId, + LocalEnumVariantId, Lookup, TraitId, TypeAliasId, TypeOrConstParamId, TypeParamId, }; use hir_expand::name::Name; use intern::Interned; @@ -30,8 +30,12 @@ use smallvec::{smallvec, SmallVec}; use stdx::never; use crate::{ - consteval::unknown_const, db::HirDatabase, ChalkTraitId, Const, ConstScalar, GenericArg, - Interner, Substitution, TraitRef, TraitRefExt, Ty, TyExt, WhereClause, + consteval::unknown_const, + db::HirDatabase, + layout::{Layout, TagEncoding}, + mir::pad16, + ChalkTraitId, Const, ConstScalar, GenericArg, Interner, Substitution, TraitRef, TraitRefExt, + Ty, TyExt, WhereClause, }; pub(crate) fn fn_traits( @@ -440,3 +444,41 @@ impl FallibleTypeFolder<Interner> for UnevaluatedConstEvaluatorFolder<'_> { Ok(constant) } } + +pub(crate) fn detect_variant_from_bytes<'a>( + layout: &'a Layout, + db: &dyn HirDatabase, + krate: CrateId, + b: &[u8], + e: EnumId, +) -> Option<(LocalEnumVariantId, &'a Layout)> { + let (var_id, var_layout) = match &layout.variants { + hir_def::layout::Variants::Single { index } => (index.0, &*layout), + hir_def::layout::Variants::Multiple { tag, tag_encoding, variants, .. } => { + let target_data_layout = db.target_data_layout(krate)?; + let size = tag.size(&*target_data_layout).bytes_usize(); + let offset = layout.fields.offset(0).bytes_usize(); // The only field on enum variants is the tag field + let tag = i128::from_le_bytes(pad16(&b[offset..offset + size], false)); + match tag_encoding { + TagEncoding::Direct => { + let x = variants.iter_enumerated().find(|x| { + db.const_eval_discriminant(EnumVariantId { parent: e, local_id: x.0 .0 }) + == Ok(tag) + })?; + (x.0 .0, x.1) + } + TagEncoding::Niche { untagged_variant, niche_start, .. } => { + let candidate_tag = tag.wrapping_sub(*niche_start as i128) as usize; + let variant = variants + .iter_enumerated() + .map(|(x, _)| x) + .filter(|x| x != untagged_variant) + .nth(candidate_tag) + .unwrap_or(*untagged_variant); + (variant.0, &variants[variant]) + } + } + } + }; + Some((var_id, var_layout)) +} |