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_diagnostic_item;
   5 use rustc_errors::Applicability;
   6 use rustc_hir::Expr;
   7 use rustc_lint::LateContext;
   8 use rustc_span::sym;
   9
  10 use super::REPEAT_ONCE;
  11
  12 pub(super) fn check<'tcx>(
  13     cx: &LateContext<'tcx>,
  14     expr: &'tcx Expr<'_>,
  15     recv: &'tcx Expr<'_>,
  16     repeat_arg: &'tcx Expr<'_>,
  17 ) {
  18     if constant_context(cx, cx.typeck_results()).expr(repeat_arg) == Some(Constant::Int(1)) {
  19         let ty = cx.typeck_results().expr_ty(recv).peel_refs();
  20         if ty.is_str() {
  21             span_lint_and_sugg(
  22                 cx,
  23                 REPEAT_ONCE,
  24                 expr.span,
  25                 "calling `repeat(1)` on str",
  26                 "consider using `.to_string()` instead",
  27                 format!("{}.to_string()", snippet(cx, recv.span, r#""...""#)),
  28                 Applicability::MachineApplicable,
  29             );
  30         } else if ty.builtin_index().is_some() {
  31             span_lint_and_sugg(
  32                 cx,
  33                 REPEAT_ONCE,
  34                 expr.span,
  35                 "calling `repeat(1)` on slice",
  36                 "consider using `.to_vec()` instead",
  37                 format!("{}.to_vec()", snippet(cx, recv.span, r#""...""#)),
  38                 Applicability::MachineApplicable,
  39             );
  40         } else if is_type_diagnostic_item(cx, ty, sym::String) {
  41             span_lint_and_sugg(
  42                 cx,
  43                 REPEAT_ONCE,
  44                 expr.span,
  45                 "calling `repeat(1)` on a string literal",
  46                 "consider using `.clone()` instead",
  47                 format!("{}.clone()", snippet(cx, recv.span, r#""...""#)),
  48                 Applicability::MachineApplicable,
  49             );
  50         }
  51     }
  52 }