Don't lint about missing code examples in derived traits

Fixes #81775

Author: hnj2

src/librustdoc/passes/doc_test_lints.rs

@@ -96,6 +96,7 @@ crate fn should_have_doc_example(cx: &DocContext<'_>, item: &clean::Item) -> boo
 
     if cx.tcx.hir().attrs(hir_id).lists(sym::doc).has_word(sym::hidden)
         || inherits_doc_hidden(cx.tcx, hir_id)
+        || cx.tcx.hir().span(hir_id).in_derive_expansion()
     {
         return false;
     }

src/test/rustdoc-ui/lint-missing-doc-code-example.rs

@@ -78,6 +78,15 @@ impl Clone for Struct {
 }
 
 
+
+/// doc
+///
+/// ```
+/// println!("hello");
+/// ```
+#[derive(Clone)]
+pub struct NiceStruct;
+
 #[doc(hidden)]
 pub mod foo {
     pub fn bar() {}