mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-13 23:02:43 +00:00
82 lines
3.2 KiB
Rust
82 lines
3.2 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 crate::consts::{miri_to_const, Constant};
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use crate::utils::span_lint;
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use rustc_ast::ast::{IntTy, UintTy};
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use rustc_hir::{Item, ItemKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty;
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use rustc_middle::ty::util::IntTypeExt;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use std::convert::TryFrom;
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declare_clippy_lint! {
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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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/// # #[cfg(target_pointer_width = "64")]
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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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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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declare_lint_pass!(UnportableVariant => [ENUM_CLIKE_UNPORTABLE_VARIANT]);
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnportableVariant {
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#[allow(clippy::cast_possible_truncation, clippy::cast_possible_wrap, clippy::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 ItemKind::Enum(def, _) = &item.kind {
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for var in def.variants {
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if let Some(anon_const) = &var.disr_expr {
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let def_id = cx.tcx.hir().body_owner_def_id(anon_const.body);
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let mut ty = cx.tcx.type_of(def_id.to_def_id());
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let constant = cx
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.tcx
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.const_eval_poly(def_id.to_def_id())
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.ok()
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.map(|val| rustc_middle::ty::Const::from_value(cx.tcx, val, ty));
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if let Some(Constant::Int(val)) = constant.and_then(miri_to_const) {
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if let ty::Adt(adt, _) = ty.kind {
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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.kind {
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ty::Int(IntTy::Isize) => {
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let val = ((val as i128) << 64) >> 64;
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if i32::try_from(val).is_ok() {
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continue;
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}
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},
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ty::Uint(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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