clippy_lints/src/methods/filter_map_next.rs

   1 use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
   2 use clippy_utils::source::snippet;
   3 use clippy_utils::{is_trait_method, meets_msrv};
   4 use rustc_errors::Applicability;
   5 use rustc_hir as hir;
   6 use rustc_lint::LateContext;
   7 use rustc_semver::RustcVersion;
   8 use rustc_span::sym;
   9
  10 use super::FILTER_MAP_NEXT;
  11
  12 const FILTER_MAP_NEXT_MSRV: RustcVersion = RustcVersion::new(1, 30, 0);
  13
  14 pub(super) fn check<'tcx>(
  15     cx: &LateContext<'tcx>,
  16     expr: &'tcx hir::Expr<'_>,
  17     recv: &'tcx hir::Expr<'_>,
  18     arg: &'tcx hir::Expr<'_>,
  19     msrv: Option<&RustcVersion>,
  20 ) {
  21     if is_trait_method(cx, expr, sym::Iterator) {
  22         if !meets_msrv(msrv, &FILTER_MAP_NEXT_MSRV) {
  23             return;
  24         }
  25
  26         let msg = "called `filter_map(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
  27                    `.find_map(..)` instead";
  28         let filter_snippet = snippet(cx, arg.span, "..");
  29         if filter_snippet.lines().count() <= 1 {
  30             let iter_snippet = snippet(cx, recv.span, "..");
  31             span_lint_and_sugg(
  32                 cx,
  33                 FILTER_MAP_NEXT,
  34                 expr.span,
  35                 msg,
  36                 "try this",
  37                 format!("{}.find_map({})", iter_snippet, filter_snippet),
  38                 Applicability::MachineApplicable,
  39             );
  40         } else {
  41             span_lint(cx, FILTER_MAP_NEXT, expr.span, msg);
  42         }
  43     }
  44 }