clippy_lints/src/methods/single_char_insert_string.rs

   1 use crate::methods::get_hint_if_single_char_arg;
   2 use crate::utils::{snippet_with_applicability, span_lint_and_sugg};
   3 use rustc_errors::Applicability;
   4 use rustc_hir as hir;
   5 use rustc_lint::LateContext;
   6
   7 use super::SINGLE_CHAR_ADD_STR;
   8
   9 /// lint for length-1 `str`s as argument for `insert_str`
  10 pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
  11     let mut applicability = Applicability::MachineApplicable;
  12     if let Some(extension_string) = get_hint_if_single_char_arg(cx, &args[2], &mut applicability) {
  13         let base_string_snippet =
  14             snippet_with_applicability(cx, args[0].span.source_callsite(), "_", &mut applicability);
  15         let pos_arg = snippet_with_applicability(cx, args[1].span, "..", &mut applicability);
  16         let sugg = format!("{}.insert({}, {})", base_string_snippet, pos_arg, extension_string);
  17         span_lint_and_sugg(
  18             cx,
  19             SINGLE_CHAR_ADD_STR,
  20             expr.span,
  21             "calling `insert_str()` using a single-character string literal",
  22             "consider using `insert` with a character literal",
  23             sugg,
  24             applicability,
  25         );
  26     }
  27 }