tried to simplify but it doesn't work :/
This commit is contained in:
Nathaniel Hamovitz
parent
5fdf93415b
commit
9b3f55ee61
@ -1,14 +1,11 @@
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use clippy_utils::consts::{miri_to_const, Constant};
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use clippy_utils::diagnostics::span_lint_and_help;
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use rustc_ast::Attribute;
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use rustc_hir::def_id::LocalDefId;
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use rustc_hir::{Item, ItemKind, VariantData};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::dep_graph::DepContext;
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use rustc_middle::ty as ty_mod;
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use rustc_middle::ty::ReprFlags;
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use rustc_middle::ty::Const;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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@ -43,37 +40,44 @@
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impl<'tcx> LateLintPass<'tcx> for TrailingZeroSizedArrayWithoutReprC {
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fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
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dbg!(item.ident);
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if is_struct_with_trailing_zero_sized_array(cx, item) && !has_repr_attr(cx, item.def_id) {
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// span_lint_and_help(
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// cx,
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// TRAILING_ZERO_SIZED_ARRAY_WITHOUT_REPR_C,
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// item.span,
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// "trailing zero-sized array in a struct which is not marked `#[repr(C)]`",
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// None,
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// "consider annotating the struct definition with `#[repr(C)]` (or another `repr` attribute)",
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// );
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eprintln!("— consider yourself linted — 🦀")
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if is_struct_with_trailing_zero_sized_array(cx, item) {
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let attrs = cx.tcx.get_attrs(item.def_id.to_def_id());
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let first_attr = attrs.first(); // Actually, I've no idea if this is guaranteed to be the first one in the source code.
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let lint_span = if let Some(first_attr) = first_attr {
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first_attr.span.until(item.span)
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} else {
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item.span
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};
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if !has_repr_attr(cx, attrs) {
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span_lint_and_help(
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cx,
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TRAILING_ZERO_SIZED_ARRAY_WITHOUT_REPR_C,
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lint_span,
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"trailing zero-sized array in a struct which is not marked `#[repr(C)]`",
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None,
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"consider annotating the struct definition with `#[repr(C)]` (or another `repr` attribute)",
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);
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}
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}
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}
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}
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fn is_struct_with_trailing_zero_sized_array(cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) -> bool {
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if_chain! {
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if let ItemKind::Struct(data, _generics) = &item.kind;
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// Check if last field is an array
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if let ItemKind::Struct(data, _) = &item.kind;
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if let VariantData::Struct(field_defs, _) = data;
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if let Some(last_field) = field_defs.last();
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if let rustc_hir::TyKind::Array(_, aconst) = last_field.ty.kind;
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let aconst_def_id = cx.tcx.hir().body_owner_def_id(aconst.body).to_def_id();
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let ty = cx.tcx.type_of(aconst_def_id);
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let constant = cx
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.tcx
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// NOTE: maybe const_eval_resolve?
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.const_eval_poly(aconst_def_id)
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.ok()
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.map(|val| rustc_middle::ty::Const::from_value(cx.tcx, val, ty));
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if let Some(Constant::Int(val)) = constant.and_then(miri_to_const);
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if val == 0;
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if let rustc_hir::TyKind::Array(_, length) = last_field.ty.kind;
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// Check if that that array zero-sized.
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let length_ldid = cx.tcx.hir().local_def_id(length.hir_id);
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let length = Const::from_anon_const(cx.tcx, length_ldid);
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if let Some(Constant::Int(length)) = miri_to_const(length);
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if length == 0;
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then {
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true
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} else {
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@ -82,54 +86,9 @@ fn is_struct_with_trailing_zero_sized_array(cx: &LateContext<'tcx>, item: &'tcx
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}
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}
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fn has_repr_attr(cx: &LateContext<'tcx>, def_id: LocalDefId) -> bool {
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let attrs_get_attrs = get_attrs_get_attrs(cx, def_id);
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let attrs_hir_map = get_attrs_hir_map(cx, def_id);
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let b11 = includes_repr_attr_using_sym(attrs_get_attrs);
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let b12 = includes_repr_attr_using_sym(attrs_hir_map);
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let b21 = includes_repr_attr_using_helper(cx, attrs_get_attrs);
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let b22 = includes_repr_attr_using_helper(cx, attrs_hir_map);
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let b3 = has_repr_attr_using_adt(cx, def_id);
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let all_same = (b11 && b12 && b21 && b22 && b3) || (!b11 && !b12 && !b21 && !b22 && !b3);
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dbg!(all_same);
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b21
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}
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fn get_attrs_get_attrs(cx: &LateContext<'tcx>, def_id: LocalDefId) -> &'tcx [Attribute] {
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cx.tcx.get_attrs(def_id.to_def_id())
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}
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fn get_attrs_hir_map(cx: &LateContext<'tcx>, def_id: LocalDefId) -> &'tcx [Attribute] {
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let hir_map = cx.tcx.hir();
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let hir_id = hir_map.local_def_id_to_hir_id(def_id);
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hir_map.attrs(hir_id)
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}
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// Don't like this because it's so dependent on the current list of `repr` flags and it would have
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// to be manually updated if that ever expanded. idk if there's any mechanism in `bitflag!` or
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// elsewhere for requiring that sort of exhaustiveness
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fn has_repr_attr_using_adt(cx: &LateContext<'tcx>, def_id: LocalDefId) -> bool {
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let ty = cx.tcx.type_of(def_id.to_def_id());
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if let ty_mod::Adt(adt, _) = ty.kind() {
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if adt.is_struct() {
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let repr = adt.repr;
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let repr_attr = ReprFlags::IS_C | ReprFlags::IS_TRANSPARENT | ReprFlags::IS_SIMD | ReprFlags::IS_LINEAR;
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repr.int.is_some() || repr.align.is_some() || repr.pack.is_some() || repr.flags.intersects(repr_attr)
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} else {
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false
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}
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} else {
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false
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}
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}
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fn includes_repr_attr_using_sym(attrs: &'tcx [Attribute]) -> bool {
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attrs.iter().any(|attr| attr.has_name(sym::repr))
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}
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fn includes_repr_attr_using_helper(cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) -> bool {
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fn has_repr_attr(cx: &LateContext<'tcx>, attrs: &[Attribute]) -> bool {
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// NOTE: there's at least four other ways to do this but I liked this one the best. (All five agreed
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// on all testcases.) Happy to use another; they're in the commit history.
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attrs
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.iter()
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.any(|attr| !rustc_attr::find_repr_attrs(cx.tcx.sess(), attr).is_empty())
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@ -8,7 +8,7 @@ struct RarelyUseful {
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last: [usize; 0],
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}
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struct OnlyFieldIsZeroSizeArray {
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struct OnlyField {
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first_and_last: [usize; 0],
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}
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@ -18,19 +18,19 @@ struct GenericArrayType<T> {
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}
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#[derive(Debug)]
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struct PlayNiceWithOtherAttributesDerive {
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struct OnlyAnotherAttributeDerive {
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field: i32,
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last: [usize; 0],
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}
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#[must_use]
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struct PlayNiceWithOtherAttributesMustUse {
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struct OnlyAnotherAttributeMustUse {
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field: i32,
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last: [usize; 0],
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}
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const ZERO: usize = 0;
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struct ZeroSizedFromExternalConst {
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struct ZeroSizedWithConst {
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field: i32,
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last: [usize; ZERO],
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}
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@ -39,7 +39,7 @@ struct ZeroSizedFromExternalConst {
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const fn compute_zero() -> usize {
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(4 + 6) - (2 * 5)
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}
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struct UsingFunction {
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struct ZeroSizedWithConstFunction {
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field: i32,
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last: [usize; compute_zero()],
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}
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@ -72,17 +72,36 @@ struct GoodReason {
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last: [usize; 0],
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}
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#[repr(C)]
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struct OnlyFieldWithReprC {
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first_and_last: [usize; 0],
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}
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struct NonZeroSizedArray {
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field: i32,
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last: [usize; 1],
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}
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const ONE: usize = 1;
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struct NonZeroSizedFromExternalConst {
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struct NonZeroSizedWithConst {
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field: i32,
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last: [usize; ONE],
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}
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#[derive(Debug)]
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#[repr(C)]
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struct OtherAttributesDerive {
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field: i32,
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last: [usize; 0],
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}
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#[must_use]
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#[repr(C)]
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struct OtherAttributesMustUse {
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field: i32,
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last: [usize; 0],
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}
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#[repr(packed)]
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struct ReprPacked {
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field: i32,
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@ -129,5 +148,6 @@ enum DontLintAnonymousStructsFromDesuraging {
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// }
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fn main() {
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let _ = PlayNiceWithOtherAttributesMustUse { field: 0, last: [] };
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let _ = OnlyAnotherAttributeMustUse { field: 0, last: [] };
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let _ = OtherAttributesMustUse { field: 0, last: [] };
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}
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