src/tools/clippy/clippy_lints/src/methods/repeat_once.rs

   1 use clippy_utils::consts::{constant_context, Constant};
   2 use clippy_utils::diagnostics::span_lint_and_sugg;
   3 use clippy_utils::source::snippet;
   4 use clippy_utils::ty::is_type_lang_item;
   5 use rustc_errors::Applicability;
   6 use rustc_hir::{Expr, LangItem};
   7 use rustc_lint::LateContext;
   8
   9 use super::REPEAT_ONCE;
  10
  11 pub(super) fn check<'tcx>(
  12     cx: &LateContext<'tcx>,
  13     expr: &'tcx Expr<'_>,
  14     recv: &'tcx Expr<'_>,
  15     repeat_arg: &'tcx Expr<'_>,
  16 ) {
  17     if constant_context(cx, cx.typeck_results()).expr(repeat_arg) == Some(Constant::Int(1)) {
  18         let ty = cx.typeck_results().expr_ty(recv).peel_refs();
  19         if ty.is_str() {
  20             span_lint_and_sugg(
  21                 cx,
  22                 REPEAT_ONCE,
  23                 expr.span,
  24                 "calling `repeat(1)` on str",
  25                 "consider using `.to_string()` instead",
  26                 format!("{}.to_string()", snippet(cx, recv.span, r#""...""#)),
  27                 Applicability::MachineApplicable,
  28             );
  29         } else if ty.builtin_index().is_some() {
  30             span_lint_and_sugg(
  31                 cx,
  32                 REPEAT_ONCE,
  33                 expr.span,
  34                 "calling `repeat(1)` on slice",
  35                 "consider using `.to_vec()` instead",
  36                 format!("{}.to_vec()", snippet(cx, recv.span, r#""...""#)),
  37                 Applicability::MachineApplicable,
  38             );
  39         } else if is_type_lang_item(cx, ty, LangItem::String) {
  40             span_lint_and_sugg(
  41                 cx,
  42                 REPEAT_ONCE,
  43                 expr.span,
  44                 "calling `repeat(1)` on a string literal",
  45                 "consider using `.clone()` instead",
  46                 format!("{}.clone()", snippet(cx, recv.span, r#""...""#)),
  47                 Applicability::MachineApplicable,
  48             );
  49         }
  50     }
  51 }