Rework missing_docs_in_private_items (#14741)

This is blocking #14724 as it triggers the debug
assertions it adds.

The inter item span parsing was introduced to solve
#12197. This is better handled by just not linting
anything within bodies.

changelog: [`missing_docs_in_private_items`]: Don't lint items in bodies
and automatically derived impls
changelog: [`missing_docs_in_private_items`]: Better detect when things
are accessible from the crate root
changelog: [`missing_docs_in_private_items`]: Lint unnameable items
which are accessible outside the crate

Author: y21

clippy_lints/src/missing_doc.rs

@@ -265,7 +265,14 @@ fn item_search_pat(item: &Item<'_>) -> (Pat, Pat) {
         ItemKind::Trait(_, IsAuto::Yes, ..) => (Pat::Str("auto"), Pat::Str("}")),
         ItemKind::Trait(..) => (Pat::Str("trait"), Pat::Str("}")),
         ItemKind::Impl(_) => (Pat::Str("impl"), Pat::Str("}")),
-        _ => return (Pat::Str(""), Pat::Str("")),
+        ItemKind::Mod(..) => (Pat::Str("mod"), Pat::Str("")),
+        ItemKind::Macro(_, def, _) => (
+            Pat::Str(if def.macro_rules { "macro_rules" } else { "macro" }),
+            Pat::Str(""),
+        ),
+        ItemKind::TraitAlias(..) => (Pat::Str("trait"), Pat::Str(";")),
+        ItemKind::GlobalAsm { .. } => return (Pat::Str("global_asm"), Pat::Str("")),
+        ItemKind::Use(..) => return (Pat::Str(""), Pat::Str("")),
     };
     if item.vis_span.is_empty() {
         (start_pat, end_pat)