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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 crate::consts::{miri_to_const, Constant};
use crate::utils::span_lint;
use rustc::ty;
use rustc::ty::util::IntTypeExt;
use rustc_hir::*;
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use std::convert::TryFrom;
use syntax::ast::{IntTy, UintTy};
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # #[cfg(target_pointer_width = "64")]
/// #[repr(usize)]
/// enum NonPortable {
/// X = 0x1_0000_0000,
/// Y = 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<'a, 'tcx> LateLintPass<'a, 'tcx> for UnportableVariant {
#[allow(clippy::cast_possible_truncation, clippy::cast_possible_wrap, clippy::cast_sign_loss)]
fn check_item(&mut self, cx: &LateContext<'a, '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 constant = cx.tcx.const_eval_poly(def_id).ok();
if let Some(Constant::Int(val)) = constant.and_then(miri_to_const) {
let mut ty = cx.tcx.type_of(def_id);
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_value()) => {},
_ => continue,
}
span_lint(
cx,
ENUM_CLIKE_UNPORTABLE_VARIANT,
var.span,
"Clike enum variant discriminant is not portable to 32-bit targets",
);
};
}
}
}
}
}
|
