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use super::utils::get_hint_if_single_char_arg;
use clippy_utils::diagnostics::span_lint_and_sugg;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_span::symbol::Symbol;
use super::SINGLE_CHAR_PATTERN;
const PATTERN_METHODS: [(&str, usize); 24] = [
("contains", 0),
("starts_with", 0),
("ends_with", 0),
("find", 0),
("rfind", 0),
("split", 0),
("split_inclusive", 0),
("rsplit", 0),
("split_terminator", 0),
("rsplit_terminator", 0),
("splitn", 1),
("rsplitn", 1),
("split_once", 0),
("rsplit_once", 0),
("matches", 0),
("rmatches", 0),
("match_indices", 0),
("rmatch_indices", 0),
("strip_prefix", 0),
("strip_suffix", 0),
("trim_start_matches", 0),
("trim_end_matches", 0),
("replace", 0),
("replacen", 0),
];
/// lint for length-1 `str`s for methods in `PATTERN_METHODS`
pub(super) fn check(
cx: &LateContext<'_>,
_expr: &hir::Expr<'_>,
method_name: Symbol,
receiver: &hir::Expr<'_>,
args: &[hir::Expr<'_>],
) {
for &(method, pos) in &PATTERN_METHODS {
if_chain! {
if let ty::Ref(_, ty, _) = cx.typeck_results().expr_ty_adjusted(receiver).kind();
if *ty.kind() == ty::Str;
if method_name.as_str() == method && args.len() > pos;
let arg = &args[pos];
let mut applicability = Applicability::MachineApplicable;
if let Some(hint) = get_hint_if_single_char_arg(cx, arg, &mut applicability);
then {
span_lint_and_sugg(
cx,
SINGLE_CHAR_PATTERN,
arg.span,
"single-character string constant used as pattern",
"try using a `char` instead",
hint,
applicability,
);
}
}
}
}
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