Pull the is_external test out of the loop

Author: tylerjw

clippy_lints/src/matches/match_wild_enum.rs

@@ -3,7 +3,6 @@ use clippy_utils::ty::is_type_diagnostic_item;
 use clippy_utils::{is_refutable, peel_hir_pat_refs, recurse_or_patterns};
 use rustc_errors::Applicability;
 use rustc_hir::def::{CtorKind, DefKind, Res};
-use rustc_hir::def_id::DefId;
 use rustc_hir::{Arm, Expr, PatKind, PathSegment, QPath, Ty, TyKind};
 use rustc_lint::LateContext;
 use rustc_middle::ty::{self, VariantDef};
@@ -46,11 +45,12 @@ pub(crate) fn check(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
 
     // Accumulate the variants which should be put in place of the wildcard because they're not
     // already covered.
-    let has_hidden_external = adt_def.variants().iter().any(|x| is_external_and_hidden(cx, x));
+    let is_external = adt_def.did().as_local().is_none();
+    let has_external_hidden = is_external && adt_def.variants().iter().any(|x| is_hidden(cx, x));
     let mut missing_variants: Vec<_> = adt_def
         .variants()
         .iter()
-        .filter(|x| !is_external_and_hidden(cx, x))
+        .filter(|x| !(is_external && is_hidden(cx, x)))
         .collect();
 
     let mut path_prefix = CommonPrefixSearcher::None;
@@ -138,7 +138,7 @@ pub(crate) fn check(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
 
     match missing_variants.as_slice() {
         [] => (),
-        [x] if !adt_def.is_variant_list_non_exhaustive() && !has_hidden_external => span_lint_and_sugg(
+        [x] if !adt_def.is_variant_list_non_exhaustive() && !has_external_hidden => span_lint_and_sugg(
             cx,
             MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
             wildcard_span,
@@ -149,7 +149,7 @@ pub(crate) fn check(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
         ),
         variants => {
             let mut suggestions: Vec<_> = variants.iter().copied().map(format_suggestion).collect();
-            let message = if adt_def.is_variant_list_non_exhaustive() || has_hidden_external {
+            let message = if adt_def.is_variant_list_non_exhaustive() || has_external_hidden {
                 suggestions.push("_".into());
                 "wildcard matches known variants and will also match future added variants"
             } else {
@@ -196,14 +196,6 @@ impl<'a> CommonPrefixSearcher<'a> {
     }
 }
 
-fn is_external_and_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
-    is_external(variant_def.def_id) && is_hidden(cx, variant_def)
-}
-
 fn is_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
     cx.tcx.is_doc_hidden(variant_def.def_id) || cx.tcx.has_attr(variant_def.def_id, sym::unstable)
 }
-
-fn is_external(def_id: DefId) -> bool {
-    def_id.as_local().is_none()
-}