-use crate::consts::{constant_context, Constant};
-use crate::utils::{in_macro, span_lint_and_sugg};
+use clippy_utils::consts::{constant_context, Constant};
+use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet;
use clippy_utils::ty::is_type_diagnostic_item;
use if_chain::if_chain;
use rustc_span::sym;
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `.repeat(1)` and suggest the following method for each types.
+ /// ### What it does
+ /// Checks for usage of `.repeat(1)` and suggest the following method for each types.
/// - `.to_string()` for `str`
/// - `.clone()` for `String`
/// - `.to_vec()` for `slice`
///
- /// **Why is this bad?** For example, `String.repeat(1)` is equivalent to `.clone()`. If cloning the string is the intention behind this, `clone()` should be used.
+ /// The lint will evaluate constant expressions and values as arguments of `.repeat(..)` and emit a message if
+ /// they are equivalent to `1`. (Related discussion in [rust-clippy#7306](https://github.com/rust-lang/rust-clippy/issues/7306))
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Why is this bad?
+ /// For example, `String.repeat(1)` is equivalent to `.clone()`. If cloning
+ /// the string is the intention behind this, `clone()` should be used.
///
+ /// ### Example
/// ```rust
/// fn main() {
/// let x = String::from("hello world").repeat(1);
/// let x = String::from("hello world").clone();
/// }
/// ```
+ #[clippy::version = "1.47.0"]
pub REPEAT_ONCE,
complexity,
"using `.repeat(1)` instead of `String.clone()`, `str.to_string()` or `slice.to_vec()` "
impl<'tcx> LateLintPass<'tcx> for RepeatOnce {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
if_chain! {
- if let ExprKind::MethodCall(path, _, [receiver, count], _) = &expr.kind;
+ if let ExprKind::MethodCall(path, [receiver, count], _) = &expr.kind;
if path.ident.name == sym!(repeat);
- if let Some(Constant::Int(1)) = constant_context(cx, cx.typeck_results()).expr(&count);
- if !in_macro(receiver.span);
+ if constant_context(cx, cx.typeck_results()).expr(count) == Some(Constant::Int(1));
+ if !receiver.span.from_expansion();
then {
- let ty = cx.typeck_results().expr_ty(&receiver).peel_refs();
+ let ty = cx.typeck_results().expr_ty(receiver).peel_refs();
if ty.is_str() {
span_lint_and_sugg(
cx,
format!("{}.to_vec()", snippet(cx, receiver.span, r#""...""#)),
Applicability::MachineApplicable,
);
- } else if is_type_diagnostic_item(cx, ty, sym::string_type) {
+ } else if is_type_diagnostic_item(cx, ty, sym::String) {
span_lint_and_sugg(
cx,
REPEAT_ONCE,