Fix fallout in similar_names

Author: flip1995

clippy_lints/src/non_expressive_names.rs

@@ -5,6 +5,7 @@ use rustc_ast::ast::{
 use rustc_ast::attr;
 use rustc_ast::visit::{walk_block, walk_expr, walk_pat, Visitor};
 use rustc_lint::{EarlyContext, EarlyLintPass};
+use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::{Ident, SymbolStr};
@@ -354,12 +355,20 @@ impl<'a, 'tcx> Visitor<'tcx> for SimilarNamesLocalVisitor<'a, 'tcx> {
 
 impl EarlyLintPass for NonExpressiveNames {
     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
+        if in_external_macro(cx.sess, item.span) {
+            return;
+        }
+
         if let ItemKind::Fn(_, ref sig, _, Some(ref blk)) = item.kind {
             do_check(self, cx, &item.attrs, &sig.decl, blk);
         }
     }
 
     fn check_impl_item(&mut self, cx: &EarlyContext<'_>, item: &AssocItem) {
+        if in_external_macro(cx.sess, item.span) {
+            return;
+        }
+
         if let AssocItemKind::Fn(_, ref sig, _, Some(ref blk)) = item.kind {
             do_check(self, cx, &item.attrs, &sig.decl, blk);
         }