rust/crates/hir-ty/src/layout.rs

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//! Compute the binary representation of a type
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use std::fmt;
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use base_db::salsa::Cycle;
use chalk_ir::{AdtId, FloatTy, IntTy, TyKind, UintTy};
use hir_def::{
layout::{
Abi, FieldsShape, Integer, LayoutCalculator, LayoutS, Primitive, ReprOptions, Scalar, Size,
StructKind, TargetDataLayout, WrappingRange,
},
LocalFieldId, StructId,
};
use la_arena::{Idx, RawIdx};
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use rustc_abi::AddressSpace;
use rustc_index::{IndexSlice, IndexVec};
use stdx::never;
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use triomphe::Arc;
use crate::{
consteval::try_const_usize,
db::{HirDatabase, InternedClosure},
infer::normalize,
layout::adt::struct_variant_idx,
utils::ClosureSubst,
Interner, ProjectionTy, Substitution, TraitEnvironment, Ty,
};
pub use self::{
adt::{layout_of_adt_query, layout_of_adt_recover},
target::target_data_layout_query,
};
mod adt;
mod target;
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct RustcEnumVariantIdx(pub usize);
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impl rustc_index::Idx for RustcEnumVariantIdx {
fn new(idx: usize) -> Self {
RustcEnumVariantIdx(idx)
}
fn index(self) -> usize {
self.0
}
}
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct RustcFieldIdx(pub LocalFieldId);
impl RustcFieldIdx {
pub fn new(idx: usize) -> Self {
RustcFieldIdx(Idx::from_raw(RawIdx::from(idx as u32)))
}
}
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impl rustc_index::Idx for RustcFieldIdx {
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fn new(idx: usize) -> Self {
RustcFieldIdx(Idx::from_raw(RawIdx::from(idx as u32)))
}
fn index(self) -> usize {
u32::from(self.0.into_raw()) as usize
}
}
pub type Layout = LayoutS<RustcFieldIdx, RustcEnumVariantIdx>;
pub type TagEncoding = hir_def::layout::TagEncoding<RustcEnumVariantIdx>;
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pub type Variants = hir_def::layout::Variants<RustcFieldIdx, RustcEnumVariantIdx>;
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum LayoutError {
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HasErrorConst,
HasErrorType,
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HasPlaceholder,
InvalidSimdType,
NotImplemented,
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RecursiveTypeWithoutIndirection,
SizeOverflow,
TargetLayoutNotAvailable,
Unknown,
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UserReprTooSmall,
}
impl std::error::Error for LayoutError {}
impl fmt::Display for LayoutError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
LayoutError::HasErrorConst => write!(f, "type contains an unevaluatable const"),
LayoutError::HasErrorType => write!(f, "type contains an error"),
LayoutError::HasPlaceholder => write!(f, "type contains placeholders"),
LayoutError::InvalidSimdType => write!(f, "invalid simd type definition"),
LayoutError::NotImplemented => write!(f, "not implemented"),
LayoutError::RecursiveTypeWithoutIndirection => {
write!(f, "recursive type without indirection")
}
LayoutError::SizeOverflow => write!(f, "size overflow"),
LayoutError::TargetLayoutNotAvailable => write!(f, "target layout not available"),
LayoutError::Unknown => write!(f, "unknown"),
LayoutError::UserReprTooSmall => {
write!(f, "the `#[repr]` hint is too small to hold the discriminants of the enum")
}
}
}
}
struct LayoutCx<'a> {
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target: &'a TargetDataLayout,
}
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impl<'a> LayoutCalculator for LayoutCx<'a> {
type TargetDataLayoutRef = &'a TargetDataLayout;
fn delayed_bug(&self, txt: String) {
never!("{}", txt);
}
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fn current_data_layout(&self) -> &'a TargetDataLayout {
self.target
}
}
// FIXME: move this to the `rustc_abi`.
fn layout_of_simd_ty(
db: &dyn HirDatabase,
id: StructId,
subst: &Substitution,
env: Arc<TraitEnvironment>,
dl: &TargetDataLayout,
) -> Result<Arc<Layout>, LayoutError> {
let fields = db.field_types(id.into());
// Supported SIMD vectors are homogeneous ADTs with at least one field:
//
// * #[repr(simd)] struct S(T, T, T, T);
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// * #[repr(simd)] struct S { it: T, y: T, z: T, w: T }
// * #[repr(simd)] struct S([T; 4])
//
// where T is a primitive scalar (integer/float/pointer).
let f0_ty = match fields.iter().next() {
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Some(it) => it.1.clone().substitute(Interner, subst),
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None => return Err(LayoutError::InvalidSimdType),
};
// The element type and number of elements of the SIMD vector
// are obtained from:
//
// * the element type and length of the single array field, if
// the first field is of array type, or
//
// * the homogeneous field type and the number of fields.
let (e_ty, e_len, is_array) = if let TyKind::Array(e_ty, _) = f0_ty.kind(Interner) {
// Extract the number of elements from the layout of the array field:
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let FieldsShape::Array { count, .. } = db.layout_of_ty(f0_ty.clone(), env.clone())?.fields
else {
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return Err(LayoutError::Unknown);
};
(e_ty.clone(), count, true)
} else {
// First ADT field is not an array:
(f0_ty, fields.iter().count() as u64, false)
};
// Compute the ABI of the element type:
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let e_ly = db.layout_of_ty(e_ty, env)?;
let Abi::Scalar(e_abi) = e_ly.abi else {
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return Err(LayoutError::Unknown);
};
// Compute the size and alignment of the vector:
let size = e_ly.size.checked_mul(e_len, dl).ok_or(LayoutError::SizeOverflow)?;
let align = dl.vector_align(size);
let size = size.align_to(align.abi);
// Compute the placement of the vector fields:
let fields = if is_array {
FieldsShape::Arbitrary { offsets: [Size::ZERO].into(), memory_index: [0].into() }
} else {
FieldsShape::Array { stride: e_ly.size, count: e_len }
};
Ok(Arc::new(Layout {
variants: Variants::Single { index: struct_variant_idx() },
fields,
abi: Abi::Vector { element: e_abi, count: e_len },
largest_niche: e_ly.largest_niche,
size,
align,
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max_repr_align: None,
unadjusted_abi_align: align.abi,
}))
}
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pub fn layout_of_ty_query(
db: &dyn HirDatabase,
ty: Ty,
trait_env: Arc<TraitEnvironment>,
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) -> Result<Arc<Layout>, LayoutError> {
let krate = trait_env.krate;
let Ok(target) = db.target_data_layout(krate) else {
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return Err(LayoutError::TargetLayoutNotAvailable);
};
let cx = LayoutCx { target: &target };
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let dl = cx.current_data_layout();
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let ty = normalize(db, trait_env.clone(), ty);
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let result = match ty.kind(Interner) {
TyKind::Adt(AdtId(def), subst) => {
if let hir_def::AdtId::StructId(s) = def {
let data = db.struct_data(*s);
let repr = data.repr.unwrap_or_default();
if repr.simd() {
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return layout_of_simd_ty(db, *s, subst, trait_env, &target);
}
};
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return db.layout_of_adt(*def, subst.clone(), trait_env);
}
TyKind::Scalar(s) => match s {
chalk_ir::Scalar::Bool => Layout::scalar(
dl,
Scalar::Initialized {
value: Primitive::Int(Integer::I8, false),
valid_range: WrappingRange { start: 0, end: 1 },
},
),
chalk_ir::Scalar::Char => Layout::scalar(
dl,
Scalar::Initialized {
value: Primitive::Int(Integer::I32, false),
valid_range: WrappingRange { start: 0, end: 0x10FFFF },
},
),
chalk_ir::Scalar::Int(i) => scalar(
dl,
Primitive::Int(
match i {
IntTy::Isize => dl.ptr_sized_integer(),
IntTy::I8 => Integer::I8,
IntTy::I16 => Integer::I16,
IntTy::I32 => Integer::I32,
IntTy::I64 => Integer::I64,
IntTy::I128 => Integer::I128,
},
true,
),
),
chalk_ir::Scalar::Uint(i) => scalar(
dl,
Primitive::Int(
match i {
UintTy::Usize => dl.ptr_sized_integer(),
UintTy::U8 => Integer::I8,
UintTy::U16 => Integer::I16,
UintTy::U32 => Integer::I32,
UintTy::U64 => Integer::I64,
UintTy::U128 => Integer::I128,
},
false,
),
),
chalk_ir::Scalar::Float(f) => scalar(
dl,
match f {
FloatTy::F32 => Primitive::F32,
FloatTy::F64 => Primitive::F64,
},
),
},
TyKind::Tuple(len, tys) => {
let kind = if *len == 0 { StructKind::AlwaysSized } else { StructKind::MaybeUnsized };
let fields = tys
.iter(Interner)
.map(|k| db.layout_of_ty(k.assert_ty_ref(Interner).clone(), trait_env.clone()))
.collect::<Result<Vec<_>, _>>()?;
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let fields = fields.iter().map(|it| &**it).collect::<Vec<_>>();
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let fields = fields.iter().collect::<IndexVec<_, _>>();
cx.univariant(dl, &fields, &ReprOptions::default(), kind).ok_or(LayoutError::Unknown)?
}
TyKind::Array(element, count) => {
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let count = try_const_usize(db, count).ok_or(LayoutError::HasErrorConst)? as u64;
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let element = db.layout_of_ty(element.clone(), trait_env)?;
let size = element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow)?;
let abi = if count != 0 && matches!(element.abi, Abi::Uninhabited) {
Abi::Uninhabited
} else {
Abi::Aggregate { sized: true }
};
let largest_niche = if count != 0 { element.largest_niche } else { None };
Layout {
variants: Variants::Single { index: struct_variant_idx() },
fields: FieldsShape::Array { stride: element.size, count },
abi,
largest_niche,
align: element.align,
size,
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max_repr_align: None,
unadjusted_abi_align: element.align.abi,
}
}
TyKind::Slice(element) => {
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let element = db.layout_of_ty(element.clone(), trait_env)?;
Layout {
variants: Variants::Single { index: struct_variant_idx() },
fields: FieldsShape::Array { stride: element.size, count: 0 },
abi: Abi::Aggregate { sized: false },
largest_niche: None,
align: element.align,
size: Size::ZERO,
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max_repr_align: None,
unadjusted_abi_align: element.align.abi,
}
}
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TyKind::Str => Layout {
variants: Variants::Single { index: struct_variant_idx() },
fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 },
abi: Abi::Aggregate { sized: false },
largest_niche: None,
align: dl.i8_align,
size: Size::ZERO,
max_repr_align: None,
unadjusted_abi_align: dl.i8_align.abi,
},
// Potentially-wide pointers.
TyKind::Ref(_, _, pointee) | TyKind::Raw(_, pointee) => {
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let mut data_ptr = scalar_unit(dl, Primitive::Pointer(AddressSpace::DATA));
if matches!(ty.kind(Interner), TyKind::Ref(..)) {
data_ptr.valid_range_mut().start = 1;
}
// let pointee = tcx.normalize_erasing_regions(param_env, pointee);
// if pointee.is_sized(tcx.at(DUMMY_SP), param_env) {
Rename many interner functions. (This is a large commit. The changes to `compiler/rustc_middle/src/ty/context.rs` are the most important ones.) The current naming scheme is a mess, with a mix of `_intern_`, `intern_` and `mk_` prefixes, with little consistency. In particular, in many cases it's easy to use an iterator interner when a (preferable) slice interner is available. The guiding principles of the new naming system: - No `_intern_` prefixes. - The `intern_` prefix is for internal operations. - The `mk_` prefix is for external operations. - For cases where there is a slice interner and an iterator interner, the former is `mk_foo` and the latter is `mk_foo_from_iter`. Also, `slice_interners!` and `direct_interners!` can now be `pub` or non-`pub`, which helps enforce the internal/external operations division. It's not perfect, but I think it's a clear improvement. The following lists show everything that was renamed. slice_interners - const_list - mk_const_list -> mk_const_list_from_iter - intern_const_list -> mk_const_list - substs - mk_substs -> mk_substs_from_iter - intern_substs -> mk_substs - check_substs -> check_and_mk_substs (this is a weird one) - canonical_var_infos - intern_canonical_var_infos -> mk_canonical_var_infos - poly_existential_predicates - mk_poly_existential_predicates -> mk_poly_existential_predicates_from_iter - intern_poly_existential_predicates -> mk_poly_existential_predicates - _intern_poly_existential_predicates -> intern_poly_existential_predicates - predicates - mk_predicates -> mk_predicates_from_iter - intern_predicates -> mk_predicates - _intern_predicates -> intern_predicates - projs - intern_projs -> mk_projs - place_elems - mk_place_elems -> mk_place_elems_from_iter - intern_place_elems -> mk_place_elems - bound_variable_kinds - mk_bound_variable_kinds -> mk_bound_variable_kinds_from_iter - intern_bound_variable_kinds -> mk_bound_variable_kinds direct_interners - region - intern_region (unchanged) - const - mk_const_internal -> intern_const - const_allocation - intern_const_alloc -> mk_const_alloc - layout - intern_layout -> mk_layout - adt_def - intern_adt_def -> mk_adt_def_from_data (unusual case, hard to avoid) - alloc_adt_def(!) -> mk_adt_def - external_constraints - intern_external_constraints -> mk_external_constraints Other - type_list - mk_type_list -> mk_type_list_from_iter - intern_type_list -> mk_type_list - tup - mk_tup -> mk_tup_from_iter - intern_tup -> mk_tup
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// return Ok(tcx.mk_layout(LayoutS::scalar(cx, data_ptr)));
// }
let mut unsized_part = struct_tail_erasing_lifetimes(db, pointee.clone());
if let TyKind::AssociatedType(id, subst) = unsized_part.kind(Interner) {
unsized_part = TyKind::Alias(chalk_ir::AliasTy::Projection(ProjectionTy {
associated_ty_id: *id,
substitution: subst.clone(),
}))
.intern(Interner);
}
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unsized_part = normalize(db, trait_env, unsized_part);
let metadata = match unsized_part.kind(Interner) {
TyKind::Slice(_) | TyKind::Str => {
scalar_unit(dl, Primitive::Int(dl.ptr_sized_integer(), false))
}
TyKind::Dyn(..) => {
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let mut vtable = scalar_unit(dl, Primitive::Pointer(AddressSpace::DATA));
vtable.valid_range_mut().start = 1;
vtable
}
_ => {
// pointee is sized
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return Ok(Arc::new(Layout::scalar(dl, data_ptr)));
}
};
// Effectively a (ptr, meta) tuple.
cx.scalar_pair(data_ptr, metadata)
}
TyKind::FnDef(_, _) => layout_of_unit(&cx, dl)?,
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TyKind::Never => cx.layout_of_never_type(),
TyKind::Dyn(_) | TyKind::Foreign(_) => {
let mut unit = layout_of_unit(&cx, dl)?;
match unit.abi {
Abi::Aggregate { ref mut sized } => *sized = false,
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_ => return Err(LayoutError::Unknown),
}
unit
}
TyKind::Function(_) => {
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let mut ptr = scalar_unit(dl, Primitive::Pointer(dl.instruction_address_space));
ptr.valid_range_mut().start = 1;
Layout::scalar(dl, ptr)
}
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TyKind::OpaqueType(opaque_ty_id, _) => {
let impl_trait_id = db.lookup_intern_impl_trait_id((*opaque_ty_id).into());
match impl_trait_id {
crate::ImplTraitId::ReturnTypeImplTrait(func, idx) => {
let infer = db.infer(func.into());
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return db.layout_of_ty(infer.type_of_rpit[idx].clone(), trait_env);
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}
crate::ImplTraitId::AsyncBlockTypeImplTrait(_, _) => {
return Err(LayoutError::NotImplemented)
}
}
}
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TyKind::Closure(c, subst) => {
let InternedClosure(def, _) = db.lookup_intern_closure((*c).into());
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let infer = db.infer(def);
let (captures, _) = infer.closure_info(c);
let fields = captures
.iter()
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.map(|it| {
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db.layout_of_ty(
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it.ty.clone().substitute(Interner, ClosureSubst(subst).parent_subst()),
trait_env.clone(),
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)
})
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.collect::<Result<Vec<_>, _>>()?;
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let fields = fields.iter().map(|it| &**it).collect::<Vec<_>>();
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let fields = fields.iter().collect::<IndexVec<_, _>>();
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cx.univariant(dl, &fields, &ReprOptions::default(), StructKind::AlwaysSized)
.ok_or(LayoutError::Unknown)?
}
TyKind::Coroutine(_, _) | TyKind::CoroutineWitness(_, _) => {
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return Err(LayoutError::NotImplemented)
}
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TyKind::Error => return Err(LayoutError::HasErrorType),
TyKind::AssociatedType(id, subst) => {
// Try again with `TyKind::Alias` to normalize the associated type.
let ty = TyKind::Alias(chalk_ir::AliasTy::Projection(ProjectionTy {
associated_ty_id: *id,
substitution: subst.clone(),
}))
.intern(Interner);
return db.layout_of_ty(ty, trait_env);
}
TyKind::Alias(_)
| TyKind::Placeholder(_)
| TyKind::BoundVar(_)
| TyKind::InferenceVar(_, _) => return Err(LayoutError::HasPlaceholder),
};
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Ok(Arc::new(result))
}
pub fn layout_of_ty_recover(
_: &dyn HirDatabase,
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_: &Cycle,
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_: &Ty,
_: &Arc<TraitEnvironment>,
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) -> Result<Arc<Layout>, LayoutError> {
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Err(LayoutError::RecursiveTypeWithoutIndirection)
}
fn layout_of_unit(cx: &LayoutCx<'_>, dl: &TargetDataLayout) -> Result<Layout, LayoutError> {
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cx.univariant::<RustcFieldIdx, RustcEnumVariantIdx, &&Layout>(
dl,
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IndexSlice::empty(),
&ReprOptions::default(),
StructKind::AlwaysSized,
)
.ok_or(LayoutError::Unknown)
}
fn struct_tail_erasing_lifetimes(db: &dyn HirDatabase, pointee: Ty) -> Ty {
match pointee.kind(Interner) {
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TyKind::Adt(AdtId(hir_def::AdtId::StructId(i)), subst) => {
let data = db.struct_data(*i);
let mut it = data.variant_data.fields().iter().rev();
match it.next() {
Some((f, _)) => {
let last_field_ty = field_ty(db, (*i).into(), f, subst);
struct_tail_erasing_lifetimes(db, last_field_ty)
}
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None => pointee,
}
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}
_ => pointee,
}
}
fn field_ty(
db: &dyn HirDatabase,
def: hir_def::VariantId,
fd: LocalFieldId,
subst: &Substitution,
) -> Ty {
db.field_types(def)[fd].clone().substitute(Interner, subst)
}
fn scalar_unit(dl: &TargetDataLayout, value: Primitive) -> Scalar {
Scalar::Initialized { value, valid_range: WrappingRange::full(value.size(dl)) }
}
fn scalar(dl: &TargetDataLayout, value: Primitive) -> Layout {
Layout::scalar(dl, scalar_unit(dl, value))
}
#[cfg(test)]
mod tests;