add test 3, fmt and lint

Author: quangcito

clippy_lints/src/missing_doc.rs

@@ -263,17 +263,12 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
     }
 
     fn check_field_def(&mut self, cx: &LateContext<'tcx>, sf: &'tcx hir::FieldDef<'_>) {
-        if !sf.is_positional() {
-            // Skip checking if the field starts with an underscore and allow_unused is enabled
-            if self.allow_unused && sf.ident.as_str().starts_with('_') {
-                self.prev_span = Some(sf.span);
-                return;
-            }
-
+        if !(sf.is_positional()
+            || is_from_proc_macro(cx, sf)
+            || self.allow_unused && sf.ident.as_str().starts_with('_'))
+        {
             let attrs = cx.tcx.hir_attrs(sf.hir_id);
-            if !is_from_proc_macro(cx, sf) {
-                self.check_missing_docs_attrs(cx, sf.def_id, attrs, sf.span, "a", "struct field");
-            }
+            self.check_missing_docs_attrs(cx, sf.def_id, attrs, sf.span, "a", "struct field");
         }
         self.prev_span = Some(sf.span);
     }

tests/ui-toml/missing_docs_allow_unused/missing_docs_allow_unused.rs

@@ -16,4 +16,11 @@ struct Test2 {
     _field2: i32, // This should not trigger a warning
 }
 
+struct Test3 {
+    //~^ missing_docs_in_private_items
+    /// This field is documented although this is not mandatory
+    _unused: i32, // This should not trigger a warning because it starts with an underscore
+    field2: i32, //~ missing_docs_in_private_items
+}
+
 fn main() {}

tests/ui-toml/missing_docs_allow_unused/missing_docs_allow_unused.stderr

@@ -17,5 +17,22 @@ LL | |     _field2: i32, // This should not trigger a warning
 LL | | }
    | |_^
 
-error: aborting due to 2 previous errors
+error: missing documentation for a struct
+  --> tests/ui-toml/missing_docs_allow_unused/missing_docs_allow_unused.rs:19:1
+   |
+LL | / struct Test3 {
+LL | |
+LL | |     /// This field is documented although this is not mandatory
+LL | |     _unused: i32, // This should not trigger a warning because it starts with an underscore
+LL | |     field2: i32,
+LL | | }
+   | |_^
+
+error: missing documentation for a struct field
+  --> tests/ui-toml/missing_docs_allow_unused/missing_docs_allow_unused.rs:23:5
+   |
+LL |     field2: i32,
+   |     ^^^^^^^^^^^
+
+error: aborting due to 4 previous errors