55 lines
1.8 KiB
Rust
55 lines
1.8 KiB
Rust
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use rustc_hir::Expr;
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use rustc_lint::LateContext;
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use rustc_middle::ty::{self, FloatTy, Ty};
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use crate::utils::{is_isize_or_usize, span_lint};
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use super::{utils, CAST_POSSIBLE_TRUNCATION};
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pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
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let msg = match (cast_from.is_integral(), cast_to.is_integral()) {
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(true, true) => {
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let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
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let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
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let (should_lint, suffix) = match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) {
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(true, true) | (false, false) => (to_nbits < from_nbits, ""),
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(true, false) => (
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to_nbits <= 32,
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if to_nbits == 32 {
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" on targets with 64-bit wide pointers"
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} else {
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""
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},
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),
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(false, true) => (from_nbits == 64, " on targets with 32-bit wide pointers"),
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};
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if !should_lint {
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return;
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}
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format!(
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"casting `{}` to `{}` may truncate the value{}",
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cast_from, cast_to, suffix,
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)
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},
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(false, true) => {
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format!("casting `{}` to `{}` may truncate the value", cast_from, cast_to)
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},
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(_, _) => {
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if matches!(cast_from.kind(), &ty::Float(FloatTy::F64))
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&& matches!(cast_to.kind(), &ty::Float(FloatTy::F32))
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{
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"casting `f64` to `f32` may truncate the value".to_string()
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} else {
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return;
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}
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},
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};
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span_lint(cx, CAST_POSSIBLE_TRUNCATION, expr.span, &msg);
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}
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