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//! lint on C-like enums that are `repr(isize/usize)` and have values that
//! don't fit into an `i32`
use clippy_utils::consts::{miri_to_const, Constant};
use clippy_utils::diagnostics::span_lint;
use rustc_hir::{Item, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::util::IntTypeExt;
use rustc_middle::ty::{self, IntTy, UintTy};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// ### What it does
/// Checks for C-like enumerations that are
/// `repr(isize/usize)` and have values that don't fit into an `i32`.
///
/// ### Why is this bad?
/// This will truncate the variant value on 32 bit
/// architectures, but works fine on 64 bit.
///
/// ### Example
/// ```rust
/// # #[cfg(target_pointer_width = "64")]
/// #[repr(usize)]
/// enum NonPortable {
/// X = 0x1_0000_0000,
/// Y = 0,
/// }
/// ```
#[clippy::version = "pre 1.29.0"]
pub ENUM_CLIKE_UNPORTABLE_VARIANT,
correctness,
"C-like enums that are `repr(isize/usize)` and have values that don't fit into an `i32`"
}
declare_lint_pass!(UnportableVariant => [ENUM_CLIKE_UNPORTABLE_VARIANT]);
impl<'tcx> LateLintPass<'tcx> for UnportableVariant {
#[expect(clippy::cast_possible_wrap)]
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
if cx.tcx.data_layout.pointer_size.bits() != 64 {
return;
}
if let ItemKind::Enum(def, _) = &item.kind {
for var in def.variants {
if let Some(anon_const) = &var.disr_expr {
let def_id = cx.tcx.hir().body_owner_def_id(anon_const.body);
let mut ty = cx.tcx.type_of(def_id.to_def_id());
let constant = cx
.tcx
.const_eval_poly(def_id.to_def_id())
.ok()
.map(|val| rustc_middle::mir::ConstantKind::from_value(val, ty));
if let Some(Constant::Int(val)) = constant.and_then(|c| miri_to_const(cx.tcx, c)) {
if let ty::Adt(adt, _) = ty.kind() {
if adt.is_enum() {
ty = adt.repr().discr_type().to_ty(cx.tcx);
}
}
match ty.kind() {
ty::Int(IntTy::Isize) => {
let val = ((val as i128) << 64) >> 64;
if i32::try_from(val).is_ok() {
continue;
}
},
ty::Uint(UintTy::Usize) if val > u128::from(u32::MAX) => {},
_ => continue,
}
span_lint(
cx,
ENUM_CLIKE_UNPORTABLE_VARIANT,
var.span,
"C-like enum variant discriminant is not portable to 32-bit targets",
);
};
}
}
}
}
}
|
