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https://github.com/rust-lang/rust
synced 2024-10-14 12:33:57 +00:00
repr(transparent): it's fine if the one non-1-ZST field is a ZST
This commit is contained in:
Ralf Jung
parent
0b84f18b24
commit
9dd682803f
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@ -270,13 +270,13 @@ hir_analysis_transparent_enum_variant = transparent enum needs exactly one varia
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.many_label = too many variants in `{$path}`
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.multi_label = variant here
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hir_analysis_transparent_non_zero_sized = transparent {$desc} needs at most one non-zero-sized field, but has {$field_count}
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.label = needs at most one non-zero-sized field, but has {$field_count}
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.labels = this field is non-zero-sized
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hir_analysis_transparent_non_zero_sized = transparent {$desc} needs at most one field with non-trivial size or alignment, but has {$field_count}
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.label = needs at most one field with non-trivial size or alignment, but has {$field_count}
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.labels = this field has non-zero size or requires alignment
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hir_analysis_transparent_non_zero_sized_enum = the variant of a transparent {$desc} needs at most one non-zero-sized field, but has {$field_count}
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.label = needs at most one non-zero-sized field, but has {$field_count}
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.labels = this field is non-zero-sized
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hir_analysis_transparent_non_zero_sized_enum = the variant of a transparent {$desc} needs at most one field with non-trivial size or alignment, but has {$field_count}
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.label = needs at most one field with non-trivial size or alignment, but has {$field_count}
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.labels = this field has non-zero size or requires alignment
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hir_analysis_typeof_reserved_keyword_used =
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`typeof` is a reserved keyword but unimplemented
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@ -1130,19 +1130,19 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, adt: ty::AdtDef<'tcx>)
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return;
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}
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// For each field, figure out if it's known to be a ZST and align(1), with "known"
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// respecting #[non_exhaustive] attributes.
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// For each field, figure out if it's known to have "trivial" layout (i.e., is a 1-ZST), with
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// "known" respecting #[non_exhaustive] attributes.
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let field_infos = adt.all_fields().map(|field| {
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let ty = field.ty(tcx, GenericArgs::identity_for_item(tcx, field.did));
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let param_env = tcx.param_env(field.did);
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let layout = tcx.layout_of(param_env.and(ty));
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// We are currently checking the type this field came from, so it must be local
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let span = tcx.hir().span_if_local(field.did).unwrap();
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let zst = layout.is_ok_and(|layout| layout.is_zst());
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let align = layout.ok().map(|layout| layout.align.abi.bytes());
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if !zst {
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return (span, zst, align, None);
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let trivial = layout.is_ok_and(|layout| layout.is_1zst());
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if !trivial {
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return (span, trivial, None);
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}
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// Even some 1-ZST fields are not allowed though, if they have `non_exhaustive`.
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fn check_non_exhaustive<'tcx>(
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tcx: TyCtxt<'tcx>,
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@ -1176,41 +1176,25 @@ fn check_non_exhaustive<'tcx>(
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}
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}
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(span, zst, align, check_non_exhaustive(tcx, ty).break_value())
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(span, trivial, check_non_exhaustive(tcx, ty).break_value())
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});
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let non_zst_fields = field_infos
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let non_trivial_fields = field_infos
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.clone()
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.filter_map(|(span, zst, _align, _non_exhaustive)| if !zst { Some(span) } else { None });
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let non_zst_count = non_zst_fields.clone().count();
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if non_zst_count >= 2 {
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bad_non_zero_sized_fields(tcx, adt, non_zst_count, non_zst_fields, tcx.def_span(adt.did()));
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.filter_map(|(span, trivial, _non_exhaustive)| if !trivial { Some(span) } else { None });
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let non_trivial_count = non_trivial_fields.clone().count();
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if non_trivial_count >= 2 {
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bad_non_zero_sized_fields(
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tcx,
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adt,
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non_trivial_count,
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non_trivial_fields,
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tcx.def_span(adt.did()),
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);
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return;
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}
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let incompatible_zst_fields =
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field_infos.clone().filter(|(_, _, _, opt)| opt.is_some()).count();
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let incompat = incompatible_zst_fields + non_zst_count >= 2 && non_zst_count < 2;
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for (span, zst, align, non_exhaustive) in field_infos {
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if zst && align != Some(1) {
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let mut err = struct_span_err!(
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tcx.sess,
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span,
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E0691,
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"zero-sized field in transparent {} has alignment larger than 1",
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adt.descr(),
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);
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if let Some(align_bytes) = align {
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err.span_label(
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span,
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format!("has alignment of {align_bytes}, which is larger than 1"),
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);
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} else {
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err.span_label(span, "may have alignment larger than 1");
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}
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err.emit();
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}
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if incompat && let Some((descr, def_id, args, non_exhaustive)) = non_exhaustive {
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for (span, _trivial, non_exhaustive) in field_infos {
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if let Some((descr, def_id, args, non_exhaustive)) = non_exhaustive {
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tcx.struct_span_lint_hir(
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REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
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tcx.hir().local_def_id_to_hir_id(adt.did().expect_local()),
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@ -23,23 +23,26 @@
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struct ContainsZstAndNonZst((), [i32; 2]);
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#[repr(transparent)]
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struct MultipleNonZst(u8, u8); //~ ERROR needs at most one non-zero-sized field
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struct MultipleNonZst(u8, u8); //~ ERROR needs at most one field with non-trivial size or alignment
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trait Mirror { type It: ?Sized; }
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impl<T: ?Sized> Mirror for T { type It = Self; }
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#[repr(transparent)]
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pub struct StructWithProjection(f32, <f32 as Mirror>::It);
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//~^ ERROR needs at most one non-zero-sized field
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//~^ ERROR needs at most one field with non-trivial size or alignment
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#[repr(transparent)]
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struct NontrivialAlignZst(u32, [u16; 0]); //~ ERROR alignment larger than 1
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struct NontrivialAlignZst(u32, [u16; 0]); //~ ERROR needs at most one field with non-trivial size or alignment
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#[repr(align(32))]
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struct ZstAlign32<T>(PhantomData<T>);
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#[repr(transparent)]
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struct GenericAlign<T>(ZstAlign32<T>, u32); //~ ERROR alignment larger than 1
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struct GenericAlign<T>(ZstAlign32<T>, u32); //~ ERROR needs at most one field with non-trivial size or alignment
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#[repr(transparent)]
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struct WrapsZstWithAlignment([i32; 0]);
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#[repr(transparent)] //~ ERROR unsupported representation for zero-variant enum
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enum Void {} //~ ERROR transparent enum needs exactly one variant, but has 0
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@ -58,7 +61,7 @@ enum UnitFieldEnum {
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enum TooManyFieldsEnum {
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Foo(u32, String),
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}
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//~^^^ ERROR transparent enum needs at most one non-zero-sized field, but has 2
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//~^^^ ERROR transparent enum needs at most one field with non-trivial size or alignment, but has 2
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#[repr(transparent)]
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enum MultipleVariants { //~ ERROR transparent enum needs exactly one variant, but has 2
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@ -67,13 +70,13 @@ enum MultipleVariants { //~ ERROR transparent enum needs exactly one variant, bu
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}
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#[repr(transparent)]
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enum NontrivialAlignZstEnum {
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Foo(u32, [u16; 0]), //~ ERROR alignment larger than 1
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enum NontrivialAlignZstEnum { //~ ERROR needs at most one field with non-trivial size or alignment
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Foo(u32, [u16; 0]),
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}
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#[repr(transparent)]
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enum GenericAlignEnum<T> {
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Foo { bar: ZstAlign32<T>, baz: u32 } //~ ERROR alignment larger than 1
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enum GenericAlignEnum<T> { //~ ERROR needs at most one field with non-trivial size or alignment
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Foo { bar: ZstAlign32<T>, baz: u32 }
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}
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#[repr(transparent)]
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@ -82,7 +85,7 @@ union UnitUnion {
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}
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#[repr(transparent)]
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union TooManyFields { //~ ERROR transparent union needs at most one non-zero-sized field, but has 2
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union TooManyFields { //~ ERROR transparent union needs at most one field with non-trivial size or alignment, but has 2
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u: u32,
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s: i32
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}
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@ -1,35 +1,41 @@
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error[E0690]: transparent struct needs at most one non-zero-sized field, but has 2
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error[E0690]: transparent struct needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:26:1
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LL | struct MultipleNonZst(u8, u8);
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| ^^^^^^^^^^^^^^^^^^^^^ -- -- this field is non-zero-sized
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| ^^^^^^^^^^^^^^^^^^^^^ -- -- this field has non-zero size or requires alignment
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| | |
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| | this field is non-zero-sized
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| needs at most one non-zero-sized field, but has 2
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| | this field has non-zero size or requires alignment
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| needs at most one field with non-trivial size or alignment, but has 2
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error[E0690]: transparent struct needs at most one non-zero-sized field, but has 2
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error[E0690]: transparent struct needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:32:1
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LL | pub struct StructWithProjection(f32, <f32 as Mirror>::It);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ --- ------------------- this field is non-zero-sized
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ --- ------------------- this field has non-zero size or requires alignment
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| | |
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| | this field is non-zero-sized
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| needs at most one non-zero-sized field, but has 2
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| | this field has non-zero size or requires alignment
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| needs at most one field with non-trivial size or alignment, but has 2
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error[E0691]: zero-sized field in transparent struct has alignment larger than 1
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--> $DIR/repr-transparent.rs:36:32
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error[E0690]: transparent struct needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:36:1
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LL | struct NontrivialAlignZst(u32, [u16; 0]);
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| ^^^^^^^^ has alignment of 2, which is larger than 1
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| ^^^^^^^^^^^^^^^^^^^^^^^^^ --- -------- this field has non-zero size or requires alignment
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| | |
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| | this field has non-zero size or requires alignment
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| needs at most one field with non-trivial size or alignment, but has 2
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error[E0691]: zero-sized field in transparent struct has alignment larger than 1
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--> $DIR/repr-transparent.rs:42:24
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error[E0690]: transparent struct needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:42:1
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LL | struct GenericAlign<T>(ZstAlign32<T>, u32);
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| ^^^^^^^^^^^^^ has alignment of 32, which is larger than 1
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| ^^^^^^^^^^^^^^^^^^^^^^ ------------- --- this field has non-zero size or requires alignment
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| | |
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| | this field has non-zero size or requires alignment
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| needs at most one field with non-trivial size or alignment, but has 2
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error[E0084]: unsupported representation for zero-variant enum
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--> $DIR/repr-transparent.rs:44:1
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--> $DIR/repr-transparent.rs:47:1
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LL | #[repr(transparent)]
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| ^^^^^^^^^^^^^^^^^^^^
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@ -37,23 +43,23 @@ LL | enum Void {}
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| --------- zero-variant enum
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error[E0731]: transparent enum needs exactly one variant, but has 0
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--> $DIR/repr-transparent.rs:45:1
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--> $DIR/repr-transparent.rs:48:1
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LL | enum Void {}
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| ^^^^^^^^^ needs exactly one variant, but has 0
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error[E0690]: the variant of a transparent enum needs at most one non-zero-sized field, but has 2
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--> $DIR/repr-transparent.rs:58:1
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error[E0690]: the variant of a transparent enum needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:61:1
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LL | enum TooManyFieldsEnum {
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| ^^^^^^^^^^^^^^^^^^^^^^ needs at most one non-zero-sized field, but has 2
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| ^^^^^^^^^^^^^^^^^^^^^^ needs at most one field with non-trivial size or alignment, but has 2
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LL | Foo(u32, String),
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| --- ------ this field is non-zero-sized
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| --- ------ this field has non-zero size or requires alignment
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| |
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| this field is non-zero-sized
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| this field has non-zero size or requires alignment
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error[E0731]: transparent enum needs exactly one variant, but has 2
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--> $DIR/repr-transparent.rs:64:1
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--> $DIR/repr-transparent.rs:67:1
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LL | enum MultipleVariants {
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| ^^^^^^^^^^^^^^^^^^^^^ needs exactly one variant, but has 2
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@ -62,29 +68,37 @@ LL | Foo(String),
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LL | Bar,
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| --- too many variants in `MultipleVariants`
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error[E0691]: zero-sized field in transparent enum has alignment larger than 1
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--> $DIR/repr-transparent.rs:71:14
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error[E0690]: the variant of a transparent enum needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:73:1
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LL | enum NontrivialAlignZstEnum {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ needs at most one field with non-trivial size or alignment, but has 2
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LL | Foo(u32, [u16; 0]),
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| ^^^^^^^^ has alignment of 2, which is larger than 1
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| --- -------- this field has non-zero size or requires alignment
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| |
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| this field has non-zero size or requires alignment
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error[E0691]: zero-sized field in transparent enum has alignment larger than 1
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--> $DIR/repr-transparent.rs:76:11
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error[E0690]: the variant of a transparent enum needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:78:1
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LL | enum GenericAlignEnum<T> {
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| ^^^^^^^^^^^^^^^^^^^^^^^^ needs at most one field with non-trivial size or alignment, but has 2
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LL | Foo { bar: ZstAlign32<T>, baz: u32 }
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| ^^^^^^^^^^^^^^^^^^ has alignment of 32, which is larger than 1
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| ------------------ -------- this field has non-zero size or requires alignment
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| |
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| this field has non-zero size or requires alignment
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error[E0690]: transparent union needs at most one non-zero-sized field, but has 2
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--> $DIR/repr-transparent.rs:85:1
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error[E0690]: transparent union needs at most one field with non-trivial size or alignment, but has 2
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--> $DIR/repr-transparent.rs:88:1
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LL | union TooManyFields {
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| ^^^^^^^^^^^^^^^^^^^ needs at most one non-zero-sized field, but has 2
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| ^^^^^^^^^^^^^^^^^^^ needs at most one field with non-trivial size or alignment, but has 2
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LL | u: u32,
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| ------ this field is non-zero-sized
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| ------ this field has non-zero size or requires alignment
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LL | s: i32
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| ------ this field is non-zero-sized
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| ------ this field has non-zero size or requires alignment
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error: aborting due to 11 previous errors
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Some errors have detailed explanations: E0084, E0690, E0691, E0731.
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Some errors have detailed explanations: E0084, E0690, E0731.
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For more information about an error, try `rustc --explain E0084`.
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