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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_errors::Applicability;
use rustc_hir::{Item, ItemKind, TyKind, VariantData}; use rustc_hir::{Item, ItemKind, TyKind, VariantData};
use rustc_lint::{LateContext, LateLintPass}; use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint}; use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
declare_clippy_lint! { declare_clippy_lint! {
/// ### What it does /// ### What it does
@ -43,9 +44,8 @@ declare_lint_pass!(TrailingZeroSizedArrayWithoutReprC => [TRAILING_ZERO_SIZED_AR
impl<'tcx> LateLintPass<'tcx> for TrailingZeroSizedArrayWithoutReprC { impl<'tcx> LateLintPass<'tcx> for TrailingZeroSizedArrayWithoutReprC {
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) { fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
if is_struct_with_trailing_zero_sized_array(cx, item) dbg!(item.ident);
/* && !has_repr_c(cx, item) */ if is_struct_with_trailing_zero_sized_array(cx, item) && !has_repr_c(cx, item) {
{
// span_lint_and_sugg( // span_lint_and_sugg(
// cx, // cx,
// todo!(), // todo!(),
@ -61,33 +61,52 @@ impl<'tcx> LateLintPass<'tcx> for TrailingZeroSizedArrayWithoutReprC {
} }
fn is_struct_with_trailing_zero_sized_array(cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) -> bool { fn is_struct_with_trailing_zero_sized_array(cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) -> bool {
dbg!(item.ident); if let ItemKind::Struct(data, _generics) = &item.kind {
if_chain! { if let VariantData::Struct(field_defs, _) = data {
if let ItemKind::Struct(data, _generics) = &item.kind; if let Some(last_field) = field_defs.last() {
if let VariantData::Struct(field_defs, _) = data; if let TyKind::Array(_, aconst) = last_field.ty.kind {
if let Some(last_field) = field_defs.last(); let aconst_def_id = cx.tcx.hir().body_owner_def_id(aconst.body).to_def_id();
if let TyKind::Array(_, aconst) = last_field.ty.kind; let ty = cx.tcx.type_of(aconst_def_id);
let aconst_def_id = cx.tcx.hir().body_owner_def_id(aconst.body).to_def_id(); let constant = cx
let ty = cx.tcx.type_of(aconst_def_id); .tcx
let constant = cx // NOTE: maybe const_eval_resolve? seems especially cursed to be using a const expr which
.tcx // resolves to 0 to create a zero-sized array, tho
.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 .const_eval_poly(aconst_def_id)
.ok() .ok()
.map(|val| rustc_middle::ty::Const::from_value(cx.tcx, val, ty)); .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 let Some(Constant::Int(val)) = constant.and_then(miri_to_const) {
if val == 0; if val == 0 {
then { eprintln!("trailing: true");
eprintln!("true"); return true;
true }
} else { }
// dbg!(aconst); }
eprintln!("false"); }
false
} }
} }
// dbg!(aconst);
eprintln!("trailing: false");
false
} }
fn has_repr_c(cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) -> bool { fn has_repr_c(cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) -> bool {
// todo!() // let hir_id2 = if let Some(body) = cx.enclosing_body {
true // 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
}
} }