Fix removing unused function declarations

Author: lxsmnsyc

packages/start/src/directives/bubble-function-declaration.ts

@@ -8,17 +8,6 @@ export function bubbleFunctionDeclaration(path: babel.NodePath<t.FunctionDeclara
     const block = (path.findParent(current => current.isBlockStatement()) ||
       path.scope.getProgramParent().path) as babel.NodePath<t.BlockStatement>;
 
-    const [tmp] = block.unshiftContainer(
-      "body",
-      t.variableDeclaration("const", [
-        t.variableDeclarator(
-          decl.id,
-          t.functionExpression(decl.id, decl.params, decl.body, decl.generator, decl.async),
-        ),
-      ]),
-    );
-    path.scope.registerDeclaration(tmp);
-    // tmp.skip();
     if (path.parentPath.isExportNamedDeclaration()) {
       path.parentPath.replaceWith(
         t.exportNamedDeclaration(undefined, [t.exportSpecifier(decl.id, decl.id)]),
@@ -28,5 +17,17 @@ export function bubbleFunctionDeclaration(path: babel.NodePath<t.FunctionDeclara
     } else {
       path.remove();
     }
+
+    const [tmp] = block.unshiftContainer(
+      "body",
+      t.variableDeclaration("const", [
+        t.variableDeclarator(
+          decl.id,
+          t.functionExpression(decl.id, decl.params, decl.body, decl.generator, decl.async),
+        ),
+      ]),
+    );
+    block.scope.registerDeclaration(tmp);
+    tmp.skip();
   }
 }

packages/start/src/directives/remove-unused-variables.ts

@@ -1,5 +1,6 @@
 import type * as babel from "@babel/core";
 import * as t from "@babel/types";
+import { generateUniqueName } from "./generate-unique-name.ts";
 import { isPathValid } from "./paths.ts";
 
 export function removeUnusedVariables(program: babel.NodePath<t.Program>) {
@@ -31,6 +32,24 @@ export function removeUnusedVariables(program: babel.NodePath<t.Program>) {
                   } else {
                     binding.path.remove();
                   }
+
+                /**
+                 * TODO (Alexis):
+                 * For some reason, we can't directly remove function declarations,
+                 * Babel yields an error that is entirely on its fault.
+                 * 
+                 * For now, we replace this with an unused variable and that variable
+                 * will then get removed on the next cycle.
+                 * 
+                 * (Although weirdly enough, this should've been a variable
+                 * in the first phase during the earlier function bubbling phase)
+                 */
+                } else if (binding.kind === 'hoisted') {
+                  binding.path.replaceWith(
+                    t.variableDeclaration("const", [
+                      t.variableDeclarator(generateUniqueName(binding.path, "var")),
+                    ]),
+                  );
                 } else {
                   binding.path.remove();
                 }