Fix helpers internal fns names conflict resolution (#16130)

* Add test

* Fix it

packages/babel-helpers/src/index.ts

@@ -191,6 +191,7 @@ function permuteHelperAST(
 
   const toRename: Record<string, string> = {};
   const bindings = new Set(localBindings || []);
+  if (id.type === "Identifier") bindings.add(id.name);
   localBindingNames.forEach(name => {
     let newName = name;
     while (bindings.has(newName)) newName = "_" + newName;

packages/babel-helpers/test/fixtures/misc/declaration-name-conflict-helper-entrypoint/input.js

@@ -0,0 +1,6 @@
+// We'll add the helper `set`. It needs to be renamed to `_set` to avoid
+// conflicting with the variable name `set` in this file.
+// However, the `set` helper declares a `_set` function itself, which will
+// need to be renamed to avoid conflicts.
+
+let set;

packages/babel-helpers/test/fixtures/misc/declaration-name-conflict-helper-entrypoint/options.json

@@ -0,0 +1,4 @@
+{
+  "minNodeVersion": "12.22.0",
+  "plugins": ["./plugin"]
+}

packages/babel-helpers/test/fixtures/misc/declaration-name-conflict-helper-entrypoint/plugin.js

@@ -0,0 +1,9 @@
+export default function () {
+  return {
+    visitor: {
+      VariableDeclaration(path) {
+        this.addHelper("set");
+      },
+    },
+  };
+}