src/tools/clippy/clippy_lints/src/methods/filter_map_identity.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::{is_expr_identity_function, is_trait_method};
   3 use rustc_errors::Applicability;
   4 use rustc_hir as hir;
   5 use rustc_lint::LateContext;
   6 use rustc_span::{source_map::Span, sym};
   7
   8 use super::FILTER_MAP_IDENTITY;
   9
  10 pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, filter_map_arg: &hir::Expr<'_>, filter_map_span: Span) {
  11     if is_trait_method(cx, expr, sym::Iterator) && is_expr_identity_function(cx, filter_map_arg) {
  12         span_lint_and_sugg(
  13             cx,
  14             FILTER_MAP_IDENTITY,
  15             filter_map_span.with_hi(expr.span.hi()),
  16             "use of `filter_map` with an identity function",
  17             "try",
  18             "flatten()".to_string(),
  19             Applicability::MachineApplicable,
  20         );
  21     }
  22 }