1 //! lint on C-like enums that are `repr(isize/usize)` and have values that
2 //! don't fit into an `i32`
4 use crate::consts::{miri_to_const, Constant};
5 use crate::utils::span_lint;
6 use rustc_hir::{Item, ItemKind};
7 use rustc_lint::{LateContext, LateLintPass};
8 use rustc_middle::ty::util::IntTypeExt;
9 use rustc_middle::ty::{self, IntTy, UintTy};
10 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 use std::convert::TryFrom;
13 declare_clippy_lint! {
14 /// **What it does:** Checks for C-like enumerations that are
15 /// `repr(isize/usize)` and have values that don't fit into an `i32`.
17 /// **Why is this bad?** This will truncate the variant value on 32 bit
18 /// architectures, but works fine on 64 bit.
20 /// **Known problems:** None.
24 /// # #[cfg(target_pointer_width = "64")]
26 /// enum NonPortable {
27 /// X = 0x1_0000_0000,
31 pub ENUM_CLIKE_UNPORTABLE_VARIANT,
33 "C-like enums that are `repr(isize/usize)` and have values that don't fit into an `i32`"
36 declare_lint_pass!(UnportableVariant => [ENUM_CLIKE_UNPORTABLE_VARIANT]);
38 impl<'tcx> LateLintPass<'tcx> for UnportableVariant {
39 #[allow(clippy::cast_possible_truncation, clippy::cast_possible_wrap, clippy::cast_sign_loss)]
40 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
41 if cx.tcx.data_layout.pointer_size.bits() != 64 {
44 if let ItemKind::Enum(def, _) = &item.kind {
45 for var in def.variants {
46 if let Some(anon_const) = &var.disr_expr {
47 let def_id = cx.tcx.hir().body_owner_def_id(anon_const.body);
48 let mut ty = cx.tcx.type_of(def_id.to_def_id());
51 .const_eval_poly(def_id.to_def_id())
53 .map(|val| rustc_middle::ty::Const::from_value(cx.tcx, val, ty));
54 if let Some(Constant::Int(val)) = constant.and_then(miri_to_const) {
55 if let ty::Adt(adt, _) = ty.kind() {
57 ty = adt.repr.discr_type().to_ty(cx.tcx);
61 ty::Int(IntTy::Isize) => {
62 let val = ((val as i128) << 64) >> 64;
63 if i32::try_from(val).is_ok() {
67 ty::Uint(UintTy::Usize) if val > u128::from(u32::MAX) => {},
72 ENUM_CLIKE_UNPORTABLE_VARIANT,
74 "C-like enum variant discriminant is not portable to 32-bit targets",