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Implement getting an array of attributes!

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This commit is contained in:
Nathaniel Hamovitz 2021-10-15 23:44:39 -07:00
parent 7ee8e7a9b8
commit 523b013161
1 changed files with 46 additions and 27 deletions
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73
clippy_lints/src/trailing_zero_sized_array_without_repr_c.rs
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@ -5,6 +5,7 @@
use rustc_hir::{Item, ItemKind, TyKind, VariantData};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
declare_clippy_lint! {
/// ### What it does
@ -43,9 +44,8 @@
impl<'tcx> LateLintPass<'tcx> for TrailingZeroSizedArrayWithoutReprC {
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
if is_struct_with_trailing_zero_sized_array(cx, item)
/* && !has_repr_c(cx, item) */
{
dbg!(item.ident);
if is_struct_with_trailing_zero_sized_array(cx, item) && !has_repr_c(cx, item) {
// span_lint_and_sugg(
// cx,
// todo!(),
@ -61,33 +61,52 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
}
fn is_struct_with_trailing_zero_sized_array(cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) -> bool {
dbg!(item.ident);
if_chain! {
if let ItemKind::Struct(data, _generics) = &item.kind;
if let VariantData::Struct(field_defs, _) = data;
if let Some(last_field) = field_defs.last();
if let TyKind::Array(_, aconst) = last_field.ty.kind;
let aconst_def_id = cx.tcx.hir().body_owner_def_id(aconst.body).to_def_id();
let ty = cx.tcx.type_of(aconst_def_id);
let constant = cx
.tcx
.const_eval_poly(aconst_def_id) // NOTE: maybe const_eval_resolve? seems especially cursed to be using a const expr which resolves to 0 to create a zero-sized array, tho
.ok()
.map(|val| rustc_middle::ty::Const::from_value(cx.tcx, val, ty));
if let Some(Constant::Int(val)) = constant.and_then(miri_to_const);
if val == 0;
then {
eprintln!("true");
true
} else {
// dbg!(aconst);
eprintln!("false");
false
if let ItemKind::Struct(data, _generics) = &item.kind {
if let VariantData::Struct(field_defs, _) = data {
if let Some(last_field) = field_defs.last() {
if let TyKind::Array(_, aconst) = last_field.ty.kind {
let aconst_def_id = cx.tcx.hir().body_owner_def_id(aconst.body).to_def_id();
let ty = cx.tcx.type_of(aconst_def_id);
let constant = cx
.tcx
// NOTE: maybe const_eval_resolve? seems especially cursed to be using a const expr which
// resolves to 0 to create a zero-sized array, tho
.const_eval_poly(aconst_def_id)
.ok()
.map(|val| rustc_middle::ty::Const::from_value(cx.tcx, val, ty));
if let Some(Constant::Int(val)) = constant.and_then(miri_to_const) {
if val == 0 {
eprintln!("trailing: true");
return true;
}
}
}
}
}
}
// dbg!(aconst);
eprintln!("trailing: false");
false
}
fn has_repr_c(cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) -> bool {
// todo!()
true
// let hir_id2 = if let Some(body) = cx.enclosing_body {
// body.hir_id
// } else {
// todo!();
// };
let hir_id = cx.tcx.hir().local_def_id_to_hir_id(item.def_id);
let attrs = cx.tcx.hir().attrs(hir_id);
// NOTE: Can there ever be more than one `repr` attribute?
// other `repr` syms: repr, repr128, repr_align, repr_align_enum, repr_no_niche, repr_packed,
// repr_simd, repr_transparent
if let Some(repr_attr) = attrs.iter().find(|attr| attr.has_name(sym::repr)) {
eprintln!("repr: true");
true
} else {
eprintln!("repr: false");
false
}
}