clippy_lints/src/methods/chars_cmp.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::source::snippet_with_applicability;
   3 use clippy_utils::{method_chain_args, single_segment_path};
   4 use if_chain::if_chain;
   5 use rustc_errors::Applicability;
   6 use rustc_hir as hir;
   7 use rustc_lint::LateContext;
   8 use rustc_lint::Lint;
   9 use rustc_middle::ty;
  10 use rustc_span::sym;
  11
  12 /// Wrapper fn for `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints.
  13 pub(super) fn check(
  14     cx: &LateContext<'_>,
  15     info: &crate::methods::BinaryExprInfo<'_>,
  16     chain_methods: &[&str],
  17     lint: &'static Lint,
  18     suggest: &str,
  19 ) -> bool {
  20     if_chain! {
  21         if let Some(args) = method_chain_args(info.chain, chain_methods);
  22         if let hir::ExprKind::Call(ref fun, ref arg_char) = info.other.kind;
  23         if arg_char.len() == 1;
  24         if let hir::ExprKind::Path(ref qpath) = fun.kind;
  25         if let Some(segment) = single_segment_path(qpath);
  26         if segment.ident.name == sym::Some;
  27         then {
  28             let mut applicability = Applicability::MachineApplicable;
  29             let self_ty = cx.typeck_results().expr_ty_adjusted(&args[0][0]).peel_refs();
  30
  31             if *self_ty.kind() != ty::Str {
  32                 return false;
  33             }
  34
  35             span_lint_and_sugg(
  36                 cx,
  37                 lint,
  38                 info.expr.span,
  39                 &format!("you should use the `{}` method", suggest),
  40                 "like this",
  41                 format!("{}{}.{}({})",
  42                         if info.eq { "" } else { "!" },
  43                         snippet_with_applicability(cx, args[0][0].span, "..", &mut applicability),
  44                         suggest,
  45                         snippet_with_applicability(cx, arg_char[0].span, "..", &mut applicability)),
  46                 applicability,
  47             );
  48
  49             return true;
  50         }
  51     }
  52
  53     false
  54 }