mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-30 15:03:36 +00:00
80 lines
2.7 KiB
Rust
80 lines
2.7 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::middle::const_val::ConstVal;
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use rustc_const_math::*;
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use rustc::hir::*;
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use rustc::ty;
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use rustc::traits::Reveal;
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use rustc::ty::subst::Substs;
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use utils::span_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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/// #[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_lint! {
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pub ENUM_CLIKE_UNPORTABLE_VARIANT,
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Warn,
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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 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 expr = &cx.tcx.hir.body(body_id).value;
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let did = cx.tcx.hir.body_owner_def_id(body_id);
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let param_env = ty::ParamEnv::empty(Reveal::UserFacing);
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let substs = Substs::identity_for_item(cx.tcx.global_tcx(), did);
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let bad = match cx.tcx
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.at(expr.span)
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.const_eval(param_env.and((did, substs)))
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{
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Ok(&ty::Const {
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val: ConstVal::Integral(Usize(Us64(i))),
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..
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}) => u64::from(i as u32) != i,
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Ok(&ty::Const {
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val: ConstVal::Integral(Isize(Is64(i))),
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..
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}) => i64::from(i as i32) != i,
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_ => false,
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};
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if bad {
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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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