78 lines
2.6 KiB
Rust
78 lines
2.6 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::is_from_proc_macro;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_session::declare_lint_pass;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for usage of `as` conversions.
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///
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/// Note that this lint is specialized in linting *every single* use of `as`
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/// regardless of whether good alternatives exist or not. If you want more
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/// precise lints for `as`, please consider using these separate lints:
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///
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/// - `clippy::cast_lossless`
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/// - `clippy::cast_possible_truncation`
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/// - `clippy::cast_possible_wrap`
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/// - `clippy::cast_precision_loss`
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/// - `clippy::cast_sign_loss`
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/// - `clippy::char_lit_as_u8`
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/// - `clippy::fn_to_numeric_cast`
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/// - `clippy::fn_to_numeric_cast_with_truncation`
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/// - `clippy::ptr_as_ptr`
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/// - `clippy::unnecessary_cast`
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/// - `invalid_reference_casting`
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///
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/// There is a good explanation the reason why this lint should work in this
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/// way and how it is useful [in this
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/// issue](https://github.com/rust-lang/rust-clippy/issues/5122).
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///
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/// ### Why restrict this?
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/// `as` conversions will perform many kinds of
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/// conversions, including silently lossy conversions and dangerous coercions.
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/// There are cases when it makes sense to use `as`, so the lint is
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/// Allow by default.
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///
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/// ### Example
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/// ```rust,ignore
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/// let a: u32;
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/// ...
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/// f(a as u16);
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/// ```
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///
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/// Use instead:
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/// ```rust,ignore
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/// f(a.try_into()?);
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///
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/// // or
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///
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/// f(a.try_into().expect("Unexpected u16 overflow in f"));
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/// ```
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#[clippy::version = "1.41.0"]
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pub AS_CONVERSIONS,
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restriction,
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"using a potentially dangerous silent `as` conversion"
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}
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declare_lint_pass!(AsConversions => [AS_CONVERSIONS]);
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impl<'tcx> LateLintPass<'tcx> for AsConversions {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
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if let ExprKind::Cast(_, _) = expr.kind
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&& !expr.span.in_external_macro(cx.sess().source_map())
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&& !is_from_proc_macro(cx, expr)
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{
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#[expect(clippy::collapsible_span_lint_calls, reason = "rust-clippy#7797")]
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span_lint_and_then(
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cx,
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AS_CONVERSIONS,
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expr.span,
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"using a potentially dangerous silent `as` conversion",
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|diag| {
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diag.help("consider using a safe wrapper for this conversion");
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},
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);
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}
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}
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}
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