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add helper methods for accessing struct tail

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This commit is contained in:
Lukas Markeffsky 2023-07-05 20:44:24 +02:00
parent e3de14e463
commit 7aa5f39d3b
9 changed files with 31 additions and 34 deletions
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2
compiler/rustc_hir_analysis/src/check/wfcheck.rs
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@ -981,7 +981,7 @@ fn check_type_defn<'tcx>(tcx: TyCtxt<'tcx>, item: &hir::Item<'tcx>, all_sized: b
// intermediate types must be sized.
let needs_drop_copy = || {
packed && {
let ty = tcx.type_of(variant.fields.raw.last().unwrap().did).subst_identity();
let ty = tcx.type_of(variant.tail().did).subst_identity();
let ty = tcx.erase_regions(ty);
if ty.has_infer() {
tcx.sess

14
compiler/rustc_hir_typeck/src/cast.rs
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@ -103,15 +103,13 @@ fn pointer_kind(
Ok(match *t.kind() {
ty::Slice(_) | ty::Str => Some(PointerKind::Length),
ty::Dynamic(ref tty, _, ty::Dyn) => Some(PointerKind::VTable(tty.principal_def_id())),
ty::Adt(def, substs) if def.is_struct() => {
match def.non_enum_variant().fields.raw.last() {
None => Some(PointerKind::Thin),
Some(f) => {
let field_ty = self.field_ty(span, f, substs);
self.pointer_kind(field_ty, span)?
}
ty::Adt(def, substs) if def.is_struct() => match def.non_enum_variant().tail_opt() {
None => Some(PointerKind::Thin),
Some(f) => {
let field_ty = self.field_ty(span, f, substs);
self.pointer_kind(field_ty, span)?
}
}
},
ty::Tuple(fields) => match fields.last() {
None => Some(PointerKind::Thin),
Some(&f) => self.pointer_kind(f, span)?,

16
compiler/rustc_middle/src/ty/mod.rs
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@ -2028,6 +2028,22 @@ pub fn single_field(&self) -> &FieldDef {
&self.fields[FieldIdx::from_u32(0)]
}
/// Returns the last field in this variant, if present.
#[inline]
pub fn tail_opt(&self) -> Option<&FieldDef> {
self.fields.raw.last()
}
/// Returns the last field in this variant.
///
/// # Panics
///
/// Panics, if the variant has no fields.
#[inline]
pub fn tail(&self) -> &FieldDef {
self.tail_opt().expect("expected unsized ADT to have a tail field")
}
}
impl PartialEq for VariantDef {

4
compiler/rustc_middle/src/ty/util.rs
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@ -230,7 +230,7 @@ pub fn struct_tail_with_normalize(
if !def.is_struct() {
break;
}
match def.non_enum_variant().fields.raw.last() {
match def.non_enum_variant().tail_opt() {
Some(field) => {
f();
ty = field.ty(self, substs);
@ -304,7 +304,7 @@ pub fn struct_lockstep_tails_with_normalize(
(&ty::Adt(a_def, a_substs), &ty::Adt(b_def, b_substs))
if a_def == b_def && a_def.is_struct() =>
{
if let Some(f) = a_def.non_enum_variant().fields.raw.last() {
if let Some(f) = a_def.non_enum_variant().tail_opt() {
a = f.ty(self, a_substs);
b = f.ty(self, b_substs);
} else {

2
compiler/rustc_trait_selection/src/solve/project_goals.rs
View File

@ -366,7 +366,7 @@ fn consider_builtin_pointee_candidate(
}
ty::Adt(def, substs) if def.is_struct() => {
match def.non_enum_variant().fields.raw.last() {
match def.non_enum_variant().tail_opt() {
None => tcx.types.unit,
Some(field_def) => {
let self_ty = field_def.ty(tcx, substs);

7
compiler/rustc_trait_selection/src/solve/trait_goals.rs
View File

@ -398,12 +398,7 @@ fn consider_builtin_unsize_candidate(
return Err(NoSolution);
}
let tail_field = a_def
.non_enum_variant()
.fields
.raw
.last()
.expect("expected unsized ADT to have a tail field");
let tail_field = a_def.non_enum_variant().tail();
let tail_field_ty = tcx.type_of(tail_field.did);
let a_tail_ty = tail_field_ty.subst(tcx, a_substs);

7
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View File

@ -1125,12 +1125,7 @@ fn confirm_builtin_unsize_candidate(
return Err(Unimplemented);
}
let tail_field = def
.non_enum_variant()
.fields
.raw
.last()
.expect("expected unsized ADT to have a tail field");
let tail_field = def.non_enum_variant().tail();
let tail_field_ty = tcx.type_of(tail_field.did);
// Extract `TailField<T>` and `TailField<U>` from `Struct<T>` and `Struct<U>`,

11
compiler/rustc_ty_utils/src/layout.rs
View File

@ -480,7 +480,7 @@ fn layout_of_uncached<'tcx>(
.any(|(i, v)| v.discr != ty::VariantDiscr::Relative(i.as_u32()));
let maybe_unsized = def.is_struct()
&& def.non_enum_variant().fields.raw.last().is_some_and(|last_field| {
&& def.non_enum_variant().tail_opt().is_some_and(|last_field| {
let param_env = tcx.param_env(def.did());
!tcx.type_of(last_field.did).subst_identity().is_sized(tcx, param_env)
});
@ -502,14 +502,7 @@ fn layout_of_uncached<'tcx>(
// If the struct tail is sized and can be unsized, check that unsizing doesn't move the fields around.
if cfg!(debug_assertions)
&& maybe_unsized
&& def
.non_enum_variant()
.fields
.raw
.last()
.unwrap()
.ty(tcx, substs)
.is_sized(tcx, cx.param_env)
&& def.non_enum_variant().tail().ty(tcx, substs).is_sized(tcx, cx.param_env)
{
let mut variants = variants;
let tail_replacement = cx.layout_of(Ty::new_slice(tcx, tcx.types.u8)).unwrap();

2
compiler/rustc_ty_utils/src/ty.rs
View File

@ -103,7 +103,7 @@ fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> &[Ty<'_>] {
let result = tcx.mk_type_list_from_iter(
def.variants()
.iter()
.filter_map(|v| v.fields.raw.last())
.filter_map(|v| v.tail_opt())
.flat_map(|f| sized_constraint_for_ty(tcx, def, tcx.type_of(f.did).subst_identity())),
);