remove recursive walk in the visitor

Author: estebank

compiler/rustc_expand/src/expand.rs

@@ -1274,10 +1274,9 @@ impl InvocationCollectorNode for P<ast::Item> {
         res
     }
     fn declared_names(&self) -> Vec<Ident> {
-        struct ItemNameVisitor(Vec<Ident>, u8);
+        struct ItemNameVisitor(Vec<Ident>);
         impl Visitor<'_> for ItemNameVisitor {
             fn visit_item(&mut self, i: &ast::Item) {
-                self.1 += 1;
                 if let ItemKind::Use(ut) = &i.kind {
                     fn collect_use_tree_leaves(ut: &ast::UseTree, idents: &mut Vec<Ident>) {
                         match &ut.kind {
@@ -1295,19 +1294,10 @@ impl InvocationCollectorNode for P<ast::Item> {
                 } else {
                     self.0.push(i.ident);
                 }
-                if self.1 < 4 {
-                    // We only visit up to 3 levels of nesting from this item, like if we were
-                    // looking at `mod a`, we'd find item `a::b::c`. We have this limit to guard
-                    // against deeply nested modules behind `cfg` flags, where we could spend
-                    // significant time collecting this information purely for a potential
-                    // diagnostic improvement.
-                    visit::walk_item(self, i);
-                }
-                self.1 -= 1;
             }
         }
 
-        let mut v = ItemNameVisitor(vec![], 0);
+        let mut v = ItemNameVisitor(vec![]);
         v.visit_item(self);
         v.0
     }

tests/ui/cfg/diagnostics-reexport.rs

@@ -1,7 +1,7 @@
 pub mod inner {
-    #[cfg(FALSE)] //~ NOTE the item is gated here
+    #[cfg(FALSE)]
     mod gone {
-        pub fn uwu() {} //~ NOTE found an item that was configured out
+        pub fn uwu() {}
     }
 
     #[cfg(FALSE)] //~ NOTE the item is gated here

tests/ui/cfg/diagnostics-reexport.stderr

@@ -50,16 +50,6 @@ error[E0425]: cannot find function `uwu` in module `inner`
 LL |     inner::uwu();
    |            ^^^ not found in `inner`
    |
-note: found an item that was configured out
-  --> $DIR/diagnostics-reexport.rs:4:16
-   |
-LL |         pub fn uwu() {}
-   |                ^^^
-note: the item is gated here
-  --> $DIR/diagnostics-reexport.rs:2:5
-   |
-LL |     #[cfg(FALSE)]
-   |     ^^^^^^^^^^^^^
 note: found an item that was configured out
   --> $DIR/diagnostics-reexport.rs:8:20
    |