92 lines
3.3 KiB
Rust
92 lines
3.3 KiB
Rust
//! lint on C-like enums that are `repr(isize/usize)` and have values that
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//! don't fit into an `i32`
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use rustc::lint::*;
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use rustc::hir::*;
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use rustc::ty;
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use rustc::ty::subst::Substs;
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use syntax::ast::{IntTy, UintTy};
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use utils::span_lint;
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use consts::{Constant, miri_to_const};
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use rustc::ty::util::IntTypeExt;
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use rustc::mir::interpret::GlobalId;
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/// **What it does:** Checks for C-like enumerations that are
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/// `repr(isize/usize)` and have values that don't fit into an `i32`.
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///
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/// **Why is this bad?** This will truncate the variant value on 32 bit
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/// architectures, but works fine on 64 bit.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// #[repr(usize)]
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/// enum NonPortable {
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/// X = 0x1_0000_0000,
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/// Y = 0
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/// }
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/// ```
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declare_clippy_lint! {
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pub ENUM_CLIKE_UNPORTABLE_VARIANT,
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correctness,
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"C-like enums that are `repr(isize/usize)` and have values that don't fit into an `i32`"
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}
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pub struct UnportableVariant;
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impl LintPass for UnportableVariant {
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fn get_lints(&self) -> LintArray {
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lint_array!(ENUM_CLIKE_UNPORTABLE_VARIANT)
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnportableVariant {
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#[allow(cast_possible_truncation, cast_sign_loss)]
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fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
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if cx.tcx.data_layout.pointer_size.bits() != 64 {
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return;
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}
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if let ItemEnum(ref def, _) = item.node {
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for var in &def.variants {
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let variant = &var.node;
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if let Some(body_id) = variant.disr_expr {
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let param_env = ty::ParamEnv::empty();
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let did = cx.tcx.hir.body_owner_def_id(body_id);
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let substs = Substs::identity_for_item(cx.tcx.global_tcx(), did);
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let instance = ty::Instance::new(did, substs);
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let cid = GlobalId {
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instance,
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promoted: None
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};
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let constant = cx.tcx.const_eval(param_env.and(cid)).ok();
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if let Some(Constant::Int(val)) = constant.and_then(|c| miri_to_const(cx.tcx, c)) {
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let mut ty = cx.tcx.type_of(did);
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if let ty::TyAdt(adt, _) = ty.sty {
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if adt.is_enum() {
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ty = adt.repr.discr_type().to_ty(cx.tcx);
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}
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}
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match ty.sty {
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ty::TyInt(IntTy::Isize) => {
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let val = ((val as i128) << 64) >> 64;
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if val <= i128::from(i32::max_value()) && val >= i128::from(i32::min_value()) {
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continue;
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}
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}
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ty::TyUint(UintTy::Usize) if val > u128::from(u32::max_value()) => {},
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_ => continue,
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}
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span_lint(
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cx,
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ENUM_CLIKE_UNPORTABLE_VARIANT,
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var.span,
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"Clike enum variant discriminant is not portable to 32-bit targets",
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);
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};
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}
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}
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}
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}
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}
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