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Refactor Type::size field to TypeId::size method for type_info #156223

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Merged
rust-bors merged 2 commits into from
May 7, 2026
Merged

Refactor Type::size field to TypeId::size method for type_info #156223

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4fe8268
Refactor `Type::size` field to `TypeId::size` method for `type_info`
SpriteOvO May 6, 2026
f7649e7
Rename and move `downcast` to `project_downcast_named` for `InterpCx`
SpriteOvO May 6, 2026
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21 changes: 19 additions & 2 deletions compiler/rustc_const_eval/src/const_eval/machine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use std::borrow::{Borrow, Cow};
use std::hash::Hash;
use std::{fmt, mem};

use rustc_abi::{Align, FIRST_VARIANT, Size};
use rustc_abi::{Align, FIRST_VARIANT, FieldIdx, Size};
use rustc_ast::Mutability;
use rustc_data_structures::fx::{FxHashMap, FxIndexMap, IndexEntry};
use rustc_hir::def_id::{DefId, LocalDefId};
Expand All @@ -11,7 +11,7 @@ use rustc_middle::mir::AssertMessage;
use rustc_middle::mir::interpret::ReportedErrorInfo;
use rustc_middle::query::TyCtxtAt;
use rustc_middle::ty::layout::{HasTypingEnv, TyAndLayout, ValidityRequirement};
use rustc_middle::ty::{self, FieldInfo, Ty, TyCtxt};
use rustc_middle::ty::{self, FieldInfo, ScalarInt, Ty, TyCtxt};
use rustc_middle::{bug, mir, span_bug};
use rustc_span::{Span, Symbol, sym};
use rustc_target::callconv::FnAbi;
Expand Down Expand Up @@ -605,6 +605,23 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
ecx.write_type_info(ty, dest)?;
}

sym::size_of_type_id => {
let ty = ecx.read_type_id(&args[0])?;
let layout = ecx.layout_of(ty)?;
let variant_index = if layout.is_sized() {
let (variant, variant_place) = ecx.project_downcast_named(dest, sym::Some)?;
let size_field_place = ecx.project_field(&variant_place, FieldIdx::ZERO)?;
ecx.write_scalar(
ScalarInt::try_from_target_usize(layout.size.bytes(), ecx.tcx.tcx).unwrap(),
&size_field_place,
)?;
variant
} else {
ecx.project_downcast_named(dest, sym::None)?.0
};
ecx.write_discriminant(variant_index, dest)?;
}

sym::field_offset => {
let frt_ty = instance.args.type_at(0);
ensure_monomorphic_enough(ecx.tcx.tcx, frt_ty)?;
Expand Down
77 changes: 24 additions & 53 deletions compiler/rustc_const_eval/src/const_eval/type_info.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ mod adt;

use std::borrow::Cow;

use rustc_abi::{ExternAbi, FieldIdx, VariantIdx};
use rustc_abi::{ExternAbi, FieldIdx};
use rustc_ast::Mutability;
use rustc_hir::LangItem;
use rustc_middle::span_bug;
Expand All @@ -12,27 +12,11 @@ use rustc_span::{Symbol, sym};

use crate::const_eval::CompileTimeMachine;
use crate::interpret::{
CtfeProvenance, Immediate, InterpCx, InterpResult, MPlaceTy, MemoryKind, Projectable, Scalar,
Writeable, interp_ok,
CtfeProvenance, Immediate, InterpCx, InterpResult, MPlaceTy, MemoryKind, Scalar, Writeable,
interp_ok,
};

impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
/// Equivalent to `project_downcast`, but identifies the variant by name instead of index.
fn downcast<'a>(
&self,
place: &(impl Writeable<'tcx, CtfeProvenance> + 'a),
name: Symbol,
) -> InterpResult<'tcx, (VariantIdx, impl Writeable<'tcx, CtfeProvenance> + 'a)> {
let variants = place.layout().ty.ty_adt_def().unwrap().variants();
let variant_idx = variants
.iter_enumerated()
.find(|(_idx, var)| var.name == name)
.unwrap_or_else(|| panic!("got {name} but expected one of {variants:#?}"))
.0;

interp_ok((variant_idx, self.project_downcast(place, variant_idx)?))
}

// A general method to write an array to a static slice place.
fn allocate_fill_and_write_slice_ptr(
&mut self,
Expand Down Expand Up @@ -83,7 +67,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
let variant_index = match ty.kind() {
ty::Tuple(fields) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::Tuple)?;
self.project_downcast_named(&field_dest, sym::Tuple)?;
// project to the single tuple variant field of `type_info::Tuple` struct type
let tuple_place = self.project_field(&variant_place, FieldIdx::ZERO)?;
assert_eq!(
Expand All @@ -102,7 +86,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
}
ty::Array(ty, len) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::Array)?;
self.project_downcast_named(&field_dest, sym::Array)?;
let array_place = self.project_field(&variant_place, FieldIdx::ZERO)?;

self.write_array_type_info(array_place, *ty, *len)?;
Expand All @@ -111,7 +95,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
}
ty::Slice(ty) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::Slice)?;
self.project_downcast_named(&field_dest, sym::Slice)?;
let slice_place = self.project_field(&variant_place, FieldIdx::ZERO)?;

self.write_slice_type_info(slice_place, *ty)?;
Expand All @@ -123,16 +107,17 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
}
ty::Bool => {
let (variant, _variant_place) =
self.downcast(&field_dest, sym::Bool)?;
self.project_downcast_named(&field_dest, sym::Bool)?;
variant
}
ty::Char => {
let (variant, _variant_place) =
self.downcast(&field_dest, sym::Char)?;
self.project_downcast_named(&field_dest, sym::Char)?;
variant
}
ty::Int(int_ty) => {
let (variant, variant_place) = self.downcast(&field_dest, sym::Int)?;
let (variant, variant_place) =
self.project_downcast_named(&field_dest, sym::Int)?;
let place = self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_int_type_info(
place,
Expand All @@ -142,7 +127,8 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
variant
}
ty::Uint(uint_ty) => {
let (variant, variant_place) = self.downcast(&field_dest, sym::Int)?;
let (variant, variant_place) =
self.project_downcast_named(&field_dest, sym::Int)?;
let place = self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_int_type_info(
place,
Expand All @@ -153,18 +139,19 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
}
ty::Float(float_ty) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::Float)?;
self.project_downcast_named(&field_dest, sym::Float)?;
let place = self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_float_type_info(place, float_ty.bit_width())?;
variant
}
ty::Str => {
let (variant, _variant_place) = self.downcast(&field_dest, sym::Str)?;
let (variant, _variant_place) =
self.project_downcast_named(&field_dest, sym::Str)?;
variant
}
ty::Ref(_, ty, mutability) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::Reference)?;
self.project_downcast_named(&field_dest, sym::Reference)?;
let reference_place =
self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_reference_type_info(reference_place, *ty, *mutability)?;
Expand All @@ -173,7 +160,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
}
ty::RawPtr(ty, mutability) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::Pointer)?;
self.project_downcast_named(&field_dest, sym::Pointer)?;
let pointer_place =
self.project_field(&variant_place, FieldIdx::ZERO)?;

Expand All @@ -183,14 +170,14 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
}
ty::Dynamic(predicates, region) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::DynTrait)?;
self.project_downcast_named(&field_dest, sym::DynTrait)?;
let dyn_place = self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_dyn_trait_type_info(dyn_place, *predicates, *region)?;
variant
}
ty::FnPtr(sig, fn_header) => {
let (variant, variant_place) =
self.downcast(&field_dest, sym::FnPtr)?;
self.project_downcast_named(&field_dest, sym::FnPtr)?;
let fn_ptr_place =
self.project_field(&variant_place, FieldIdx::ZERO)?;

Expand All @@ -214,27 +201,10 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
| ty::Bound(..)
| ty::Placeholder(_)
| ty::Infer(..)
| ty::Error(_) => self.downcast(&field_dest, sym::Other)?.0,
| ty::Error(_) => self.project_downcast_named(&field_dest, sym::Other)?.0,
};
self.write_discriminant(variant_index, &field_dest)?
}
sym::size => {
let layout = self.layout_of(ty)?;
let variant_index = if layout.is_sized() {
let (variant, variant_place) = self.downcast(&field_dest, sym::Some)?;
let size_field_place =
self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_scalar(
ScalarInt::try_from_target_usize(layout.size.bytes(), self.tcx.tcx)
.unwrap(),
&size_field_place,
)?;
variant
} else {
self.downcast(&field_dest, sym::None)?.0
};
self.write_discriminant(variant_index, &field_dest)?;
}
other => span_bug!(self.tcx.span, "unknown `Type` field {other}"),
}
}
Expand Down Expand Up @@ -433,16 +403,17 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
sym::abi => match fn_sig_kind.abi() {
ExternAbi::C { .. } => {
let (rust_variant, _rust_place) =
self.downcast(&field_place, sym::ExternC)?;
self.project_downcast_named(&field_place, sym::ExternC)?;
self.write_discriminant(rust_variant, &field_place)?;
}
ExternAbi::Rust => {
let (rust_variant, _rust_place) =
self.downcast(&field_place, sym::ExternRust)?;
self.project_downcast_named(&field_place, sym::ExternRust)?;
self.write_discriminant(rust_variant, &field_place)?;
}
other_abi => {
let (variant, variant_place) = self.downcast(&field_place, sym::Named)?;
let (variant, variant_place) =
self.project_downcast_named(&field_place, sym::Named)?;
let str_place = self.allocate_str_dedup(other_abi.as_str())?;
let str_ref = self.mplace_to_imm_ptr(&str_place, None)?;
let payload = self.project_field(&variant_place, FieldIdx::ZERO)?;
Expand Down
12 changes: 6 additions & 6 deletions compiler/rustc_const_eval/src/const_eval/type_info/adt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
let (adt_ty, adt_def) = adt;
let variant_idx = match adt_def.adt_kind() {
AdtKind::Struct => {
let (variant, variant_place) = self.downcast(place, sym::Struct)?;
let (variant, variant_place) = self.project_downcast_named(place, sym::Struct)?;
let place = self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_struct_type_info(
place,
Expand All @@ -32,7 +32,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
variant
}
AdtKind::Union => {
let (variant, variant_place) = self.downcast(place, sym::Union)?;
let (variant, variant_place) = self.project_downcast_named(place, sym::Union)?;
let place = self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_union_type_info(
place,
Expand All @@ -42,7 +42,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
variant
}
AdtKind::Enum => {
let (variant, variant_place) = self.downcast(place, sym::Enum)?;
let (variant, variant_place) = self.project_downcast_named(place, sym::Enum)?;
let place = self.project_field(&variant_place, FieldIdx::ZERO)?;
self.write_enum_type_info(place, adt, generics)?;
variant
Expand Down Expand Up @@ -219,13 +219,13 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
_region: Region<'tcx>,
place: MPlaceTy<'tcx>,
) -> InterpResult<'tcx> {
let (variant_idx, _) = self.downcast(&place, sym::Lifetime)?;
let (variant_idx, _) = self.project_downcast_named(&place, sym::Lifetime)?;
self.write_discriminant(variant_idx, &place)?;
interp_ok(())
}

fn write_generic_type(&mut self, ty: Ty<'tcx>, place: MPlaceTy<'tcx>) -> InterpResult<'tcx> {
let (variant_idx, variant_place) = self.downcast(&place, sym::Type)?;
let (variant_idx, variant_place) = self.project_downcast_named(&place, sym::Type)?;
let generic_type_place = self.project_field(&variant_place, FieldIdx::ZERO)?;

for (field_idx, field_def) in generic_type_place
Expand All @@ -251,7 +251,7 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
fn write_generic_const(&mut self, c: Const<'tcx>, place: MPlaceTy<'tcx>) -> InterpResult<'tcx> {
let ConstKind::Value(c) = c.kind() else { bug!("expected a computed const, got {c:?}") };

let (variant_idx, variant_place) = self.downcast(&place, sym::Const)?;
let (variant_idx, variant_place) = self.project_downcast_named(&place, sym::Const)?;
let const_place = self.project_field(&variant_place, FieldIdx::ZERO)?;

for (field_idx, field_def) in const_place
Expand Down
17 changes: 17 additions & 0 deletions compiler/rustc_const_eval/src/interpret/projection.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ use rustc_abi::{self as abi, FieldIdx, Size, VariantIdx};
use rustc_middle::ty::Ty;
use rustc_middle::ty::layout::TyAndLayout;
use rustc_middle::{bug, mir, span_bug, ty};
use rustc_span::Symbol;
use tracing::{debug, instrument};

use super::{
Expand Down Expand Up @@ -227,6 +228,22 @@ where
base.offset(Size::ZERO, layout, self)
}

/// Equivalent to `project_downcast`, but identifies the variant by name instead of index.
pub fn project_downcast_named<P: Projectable<'tcx, M::Provenance>>(
&self,
base: &P,
name: Symbol,
) -> InterpResult<'tcx, (VariantIdx, P)> {
let variants = base.layout().ty.ty_adt_def().unwrap().variants();
let variant_idx = variants
.iter_enumerated()
.find(|(_idx, var)| var.name == name)
.unwrap_or_else(|| panic!("got {name} but expected one of {variants:#?}"))
.0;

interp_ok((variant_idx, self.project_downcast(base, variant_idx)?))
}

/// Compute the offset and field layout for accessing the given index.
pub fn project_index<P: Projectable<'tcx, M::Provenance>>(
&self,
Expand Down
24 changes: 7 additions & 17 deletions compiler/rustc_hir_analysis/src/check/intrinsic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -199,6 +199,7 @@ fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hi
| sym::sinf64
| sym::sinf128
| sym::size_of
| sym::size_of_type_id
| sym::sqrtf16
| sym::sqrtf32
| sym::sqrtf64
Expand Down Expand Up @@ -281,6 +282,7 @@ pub(crate) fn check_intrinsic_type(
let va_list_ty = tcx.type_of(did).instantiate(tcx, &[region.into()]).skip_norm_wip();
(Ty::new_ref(tcx, env_region, va_list_ty, mutbl), va_list_ty)
};
let type_id_ty = || tcx.type_of(tcx.lang_items().type_id().unwrap()).no_bound_vars().unwrap();

let safety = intrinsic_operation_unsafety(tcx, intrinsic_id);
let n_lts = 0;
Expand All @@ -294,6 +296,7 @@ pub(crate) fn check_intrinsic_type(
sym::size_of_val | sym::align_of_val => {
(1, 0, vec![Ty::new_imm_ptr(tcx, param(0))], tcx.types.usize)
}
sym::size_of_type_id => (0, 0, vec![type_id_ty()], Ty::new_option(tcx, tcx.types.usize)),
sym::offset_of => (1, 0, vec![tcx.types.u32, tcx.types.u32], tcx.types.usize),
sym::field_offset => (1, 0, vec![], tcx.types.usize),
sym::rustc_peek => (1, 0, vec![param(0)], param(0)),
Expand All @@ -313,16 +316,8 @@ pub(crate) fn check_intrinsic_type(
sym::needs_drop => (1, 0, vec![], tcx.types.bool),

sym::type_name => (1, 0, vec![], Ty::new_static_str(tcx)),
sym::type_id => (
1,
0,
vec![],
tcx.type_of(tcx.lang_items().type_id().unwrap()).no_bound_vars().unwrap(),
),
sym::type_id_eq => {
let type_id = tcx.type_of(tcx.lang_items().type_id().unwrap()).no_bound_vars().unwrap();
(0, 0, vec![type_id, type_id], tcx.types.bool)
}
sym::type_id => (1, 0, vec![], type_id_ty()),
sym::type_id_eq => (0, 0, vec![type_id_ty(), type_id_ty()], tcx.types.bool),
sym::type_id_vtable => {
let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, span);
let dyn_metadata_adt_ref = tcx.adt_def(dyn_metadata);
Expand All @@ -335,17 +330,12 @@ pub(crate) fn check_intrinsic_type(
let option_args = tcx.mk_args(&[dyn_ty.into()]);
let ret_ty = Ty::new_adt(tcx, option_adt_ref, option_args);

(
0,
0,
vec![tcx.type_of(tcx.lang_items().type_id().unwrap()).no_bound_vars().unwrap(); 2],
ret_ty,
)
(0, 0, vec![type_id_ty(); 2], ret_ty)
}
sym::type_of => (
0,
0,
vec![tcx.type_of(tcx.lang_items().type_id().unwrap()).no_bound_vars().unwrap()],
vec![type_id_ty()],
tcx.type_of(tcx.lang_items().type_struct().unwrap()).no_bound_vars().unwrap(),
),
sym::offload => (
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_span/src/symbol.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1927,6 +1927,7 @@ symbols! {
sinf128,
size,
size_of,
size_of_type_id,
size_of_val,
sized,
sized_hierarchy,
Expand Down
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