src/tools/clippy/clippy_lints/src/types/option_option.rs

   1 use clippy_utils::diagnostics::span_lint;
   2 use clippy_utils::{path_def_id, qpath_generic_tys};
   3 use if_chain::if_chain;
   4 use rustc_hir::{self as hir, def_id::DefId, QPath};
   5 use rustc_lint::LateContext;
   6 use rustc_span::symbol::sym;
   7
   8 use super::OPTION_OPTION;
   9
  10 pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_>, def_id: DefId) -> bool {
  11     if_chain! {
  12         if cx.tcx.is_diagnostic_item(sym::Option, def_id);
  13         if let Some(arg) = qpath_generic_tys(qpath).next();
  14         if path_def_id(cx, arg) == Some(def_id);
  15         then {
  16             span_lint(
  17                 cx,
  18                 OPTION_OPTION,
  19                 hir_ty.span,
  20                 "consider using `Option<T>` instead of `Option<Option<T>>` or a custom \
  21                                      enum if you need to distinguish all 3 cases",
  22             );
  23             true
  24         } else {
  25             false
  26         }
  27     }
  28 }