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use clippy_utils::diagnostics::span_lint_and_help;
use rustc_ast::ast::{BindingAnnotation, Pat, PatKind};
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::declare_lint_pass;
declare_clippy_lint! {
/// ### What it does
/// Checks for usages of the `ref` keyword.
/// ### Why is this bad?
/// The `ref` keyword can be confusing for people unfamiliar with it, and often
/// it is more concise to use `&` instead.
/// ### Example
/// ```no_run
/// let opt = Some(5);
/// if let Some(ref foo) = opt {}
/// ```
/// Use instead:
/// ```no_run
/// let opt = Some(5);
/// if let Some(foo) = &opt {}
/// ```
#[clippy::version = "1.71.0"]
pub REF_PATTERNS,
restriction,
"use of a ref pattern, e.g. Some(ref value)"
}
declare_lint_pass!(RefPatterns => [REF_PATTERNS]);
impl EarlyLintPass for RefPatterns {
fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat) {
if let PatKind::Ident(BindingAnnotation::REF, _, _) = pat.kind
&& !pat.span.from_expansion()
{
span_lint_and_help(
cx,
REF_PATTERNS,
pat.span,
"usage of ref pattern",
None,
"consider using `&` for clarity instead",
);
}
}
}
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