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, path_def_id};
   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::{self, DefIdTree};
  10
  11 /// Wrapper fn for `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints.
  12 pub(super) fn check(
  13     cx: &LateContext<'_>,
  14     info: &crate::methods::BinaryExprInfo<'_>,
  15     chain_methods: &[&str],
  16     lint: &'static Lint,
  17     suggest: &str,
  18 ) -> bool {
  19     if_chain! {
  20         if let Some(args) = method_chain_args(info.chain, chain_methods);
  21         if let hir::ExprKind::Call(fun, [arg_char]) = info.other.kind;
  22         if let Some(id) = path_def_id(cx, fun).and_then(|ctor_id| cx.tcx.parent(ctor_id));
  23         if Some(id) == cx.tcx.lang_items().option_some_variant();
  24         then {
  25             let mut applicability = Applicability::MachineApplicable;
  26             let self_ty = cx.typeck_results().expr_ty_adjusted(&args[0][0]).peel_refs();
  27
  28             if *self_ty.kind() != ty::Str {
  29                 return false;
  30             }
  31
  32             span_lint_and_sugg(
  33                 cx,
  34                 lint,
  35                 info.expr.span,
  36                 &format!("you should use the `{}` method", suggest),
  37                 "like this",
  38                 format!("{}{}.{}({})",
  39                         if info.eq { "" } else { "!" },
  40                         snippet_with_applicability(cx, args[0][0].span, "..", &mut applicability),
  41                         suggest,
  42                         snippet_with_applicability(cx, arg_char.span, "..", &mut applicability)),
  43                 applicability,
  44             );
  45
  46             return true;
  47         }
  48     }
  49
  50     false
  51 }