Change depth arg to at_root.

This will facilitate a subsequent refactoring.

Author: nnethercote

compiler/rustc_builtin_macros/src/test_harness.rs

@@ -171,15 +171,15 @@ impl<'a> Visitor<'a> for InnerItemLinter<'_> {
 
 // Beware, this is duplicated in librustc_passes/entry.rs (with
 // `rustc_hir::Item`), so make sure to keep them in sync.
-fn entry_point_type(item: &ast::Item, depth: usize) -> EntryPointType {
+fn entry_point_type(item: &ast::Item, at_root: bool) -> EntryPointType {
     match item.kind {
         ast::ItemKind::Fn(..) => {
             if attr::contains_name(&item.attrs, sym::start) {
                 EntryPointType::Start
             } else if attr::contains_name(&item.attrs, sym::rustc_main) {
                 EntryPointType::RustcMainAttr
             } else if item.ident.name == sym::main {
-                if depth == 0 {
+                if at_root {
                     // This is a top-level function so can be 'main'
                     EntryPointType::MainNamed
                 } else {
@@ -210,7 +210,7 @@ impl<'a> MutVisitor for EntryPointCleaner<'a> {
         // Remove any #[rustc_main] or #[start] from the AST so it doesn't
         // clash with the one we're going to add, but mark it as
         // #[allow(dead_code)] to avoid printing warnings.
-        let item = match entry_point_type(&item, self.depth) {
+        let item = match entry_point_type(&item, self.depth == 0) {
             EntryPointType::MainNamed | EntryPointType::RustcMainAttr | EntryPointType::Start => {
                 item.map(|ast::Item { id, ident, attrs, kind, vis, span, tokens }| {
                     let allow_dead_code = attr::mk_attr_nested_word(