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use rustc::lint::*;
use rustc::hir::*;
use rustc::ty;
use rustc::ty::subst::Substs;
use syntax::ast::{IntTy, UintTy};
use utils::span_lint;
use consts::{Constant, miri_to_const};
use rustc::ty::util::IntTypeExt;
use rustc::mir::interpret::GlobalId;
declare_clippy_lint! {
pub ENUM_CLIKE_UNPORTABLE_VARIANT,
correctness,
"C-like enums that are `repr(isize/usize)` and have values that don't fit into an `i32`"
}
pub struct UnportableVariant;
impl LintPass for UnportableVariant {
fn get_lints(&self) -> LintArray {
lint_array!(ENUM_CLIKE_UNPORTABLE_VARIANT)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnportableVariant {
#[allow(cast_possible_truncation, 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 ItemEnum(ref def, _) = item.node {
for var in &def.variants {
let variant = &var.node;
if let Some(body_id) = variant.disr_expr {
let param_env = ty::ParamEnv::empty();
let did = cx.tcx.hir.body_owner_def_id(body_id);
let substs = Substs::identity_for_item(cx.tcx.global_tcx(), did);
let instance = ty::Instance::new(did, substs);
let cid = GlobalId {
instance,
promoted: None
};
let constant = cx.tcx.const_eval(param_env.and(cid)).ok();
if let Some(Constant::Int(val)) = constant.and_then(|c| miri_to_const(cx.tcx, c)) {
let mut ty = cx.tcx.type_of(did);
if let ty::TyAdt(adt, _) = ty.sty {
if adt.is_enum() {
ty = adt.repr.discr_type().to_ty(cx.tcx);
}
}
match ty.sty {
ty::TyInt(IntTy::Isize) => {
let val = ((val as i128) << 64) >> 64;
if val <= i128::from(i32::max_value()) && val >= i128::from(i32::min_value()) {
continue;
}
}
ty::TyUint(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",
);
};
}
}
}
}
}