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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::is_type_lang_item;
use rustc_errors::Applicability;
use rustc_hir::{Expr, LangItem};
use rustc_lint::LateContext;
use crate::methods::method_call;
use super::BYTES_NTH;
pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, recv: &'tcx Expr<'tcx>, n_arg: &'tcx Expr<'tcx>) {
let ty = cx.typeck_results().expr_ty(recv).peel_refs();
let caller_type = if ty.is_str() {
"str"
} else if is_type_lang_item(cx, ty, LangItem::String) {
"String"
} else {
return;
};
let mut applicability = Applicability::MachineApplicable;
let receiver = snippet_with_applicability(cx, recv.span, "..", &mut applicability);
let n = snippet_with_applicability(cx, n_arg.span, "..", &mut applicability);
if let Some(parent) = clippy_utils::get_parent_expr(cx, expr)
&& let Some((name, _, _, _, _)) = method_call(parent)
&& name == "unwrap" {
span_lint_and_sugg(
cx,
BYTES_NTH,
parent.span,
&format!("called `.bytes().nth().unwrap()` on a `{caller_type}`"),
"try",
format!("{receiver}.as_bytes()[{n}]",),
applicability
);
} else {
span_lint_and_sugg(
cx,
BYTES_NTH,
expr.span,
&format!("called `.bytes().nth()` on a `{caller_type}`"),
"try",
format!("{receiver}.as_bytes().get({n}).copied()"),
applicability
);
};
}
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