Improve the Server Actions SWC transform (part 2) (#62052)

This fills the last piece in the puzzle and it's based on #61001. In
"use server" file. And this PR extends that to a "use server" file so
exported values are automatically handled just like before, but any
other definitions including nested ones will be hoisted and marked
correctly now.

```ts
'use server'

let a, f

export async function action0(b, c, ...g) { // <- Handled like before.
  return async function action1(d) {        // <- Renamed, marked and hoisted.
    'use server'
    let f
    console.log(...window, { window })
    console.log(a, b, action2)

    async function action2(e) {             // <- Renamed, marked and hoisted.
      'use server'
      console.log(a, c, d, e, f, g)
    }

    return [
      action2,
      async function action3(e) {           // <- Renamed, marked and hoisted.
        'use server'
        action2(e)
        console.log(a, c, d, e)
      },
    ]
  }
}
```

Closes NEXT-2491

packages/next-swc/crates/next-custom-transforms/src/transforms/server_actions.rs

@@ -132,7 +132,7 @@ impl<C: Comments> ServerActions<C> {
                     self.config.enabled,
                 );
 
-                if is_action_fn && !self.config.is_react_server_layer {
+                if is_action_fn && !self.config.is_react_server_layer && !self.in_action_file {
                     HANDLER.with(|handler| {
                         handler
                             .struct_span_err(
@@ -459,7 +459,8 @@ impl<C: Comments> VisitMut for ServerActions<C> {
             });
         }
 
-        if !self.in_action_file {
+        if !(self.in_action_file && self.in_export_decl) {
+            // It's an action function. If it doesn't have a name, give it one.
             match f.ident.as_mut() {
                 None => {
                     let action_name = gen_ident(&mut self.action_cnt);
@@ -541,7 +542,7 @@ impl<C: Comments> VisitMut for ServerActions<C> {
             });
         }
 
-        if !self.in_action_file {
+        if !(self.in_action_file && self.in_export_decl) {
             // Collect all the identifiers defined inside the closure and used
             // in the action function. With deduplication.
             retain_names_from_declared_idents(&mut child_names, &current_declared_idents);
@@ -1022,6 +1023,8 @@ impl<C: Comments> VisitMut for ServerActions<C> {
 
         if self.has_action {
             let mut actions = self.export_actions.clone();
+
+            // All exported values are considered as actions if the file is an action file.
             if self.in_action_file {
                 actions.extend(self.exported_idents.iter().map(|e| e.1.clone()));
             };

packages/next-swc/crates/next-custom-transforms/tests/fixture/server-actions/client/5/input.js

@@ -0,0 +1,26 @@
+'use server'
+
+let a, f
+
+export async function action0(b, c, ...g) {
+  return async function action1(d) {
+    'use server'
+    let f
+    console.log(...window, { window })
+    console.log(a, b, action2)
+
+    async function action2(e) {
+      'use server'
+      console.log(a, c, d, e, f, g)
+    }
+
+    return [
+      action2,
+      async function action3(e) {
+        'use server'
+        action2(e)
+        console.log(a, c, d, e)
+      },
+    ]
+  }
+}

packages/next-swc/crates/next-custom-transforms/tests/fixture/server-actions/server/30/input.js

@@ -0,0 +1,26 @@
+'use server'
+
+let a, f
+
+export async function action0(b, c, ...g) {
+  return async function action1(d) {
+    'use server'
+    let f
+    console.log(...window, { window })
+    console.log(a, b, action2)
+
+    async function action2(e) {
+      'use server'
+      console.log(a, c, d, e, f, g)
+    }
+
+    return [
+      action2,
+      async function action3(e) {
+        'use server'
+        action2(e)
+        console.log(a, c, d, e)
+      },
+    ]
+  }
+}

packages/next-swc/crates/next-custom-transforms/tests/fixture/server-actions/server/30/output.js

@@ -0,0 +1,46 @@
+/* __next_internal_action_entry_do_not_use__ {"0090eaf4e1f08a2d94f6be401e54a2ded399b87c":"action0","188d5d945750dc32e2c842b93c75a65763d4a922":"$$ACTION_1","6d53ce510b2e36499b8f56038817b9bad86cabb4":"$$ACTION_0","9878bfa39811ca7650992850a8751f9591b6a557":"$$ACTION_2"} */ import { registerServerReference } from "private-next-rsc-server-reference";
+import { encryptActionBoundArgs, decryptActionBoundArgs } from "private-next-rsc-action-encryption";
+let a, f;
+export async function action0(b, c, ...g) {
+    return registerServerReference("9878bfa39811ca7650992850a8751f9591b6a557", $$ACTION_2).bind(null, encryptActionBoundArgs("9878bfa39811ca7650992850a8751f9591b6a557", [
+        c,
+        g,
+        b
+    ]));
+}
+export async function $$ACTION_0($$ACTION_CLOSURE_BOUND, e) {
+    var [$$ACTION_ARG_0, $$ACTION_ARG_1, $$ACTION_ARG_2, $$ACTION_ARG_3] = await decryptActionBoundArgs("6d53ce510b2e36499b8f56038817b9bad86cabb4", $$ACTION_CLOSURE_BOUND);
+    console.log(a, $$ACTION_ARG_0, $$ACTION_ARG_1, e, $$ACTION_ARG_2, $$ACTION_ARG_3);
+}
+export async function $$ACTION_1($$ACTION_CLOSURE_BOUND, e) {
+    var [$$ACTION_ARG_0, $$ACTION_ARG_1, $$ACTION_ARG_2] = await decryptActionBoundArgs("188d5d945750dc32e2c842b93c75a65763d4a922", $$ACTION_CLOSURE_BOUND);
+    $$ACTION_ARG_0(e);
+    console.log(a, $$ACTION_ARG_1, $$ACTION_ARG_2, e);
+}
+export async function $$ACTION_2($$ACTION_CLOSURE_BOUND, d) {
+    var [$$ACTION_ARG_0, $$ACTION_ARG_1, $$ACTION_ARG_2] = await decryptActionBoundArgs("9878bfa39811ca7650992850a8751f9591b6a557", $$ACTION_CLOSURE_BOUND);
+    let f;
+    console.log(...window, {
+        window
+    });
+    console.log(a, $$ACTION_ARG_2, action2);
+    var action2 = registerServerReference("6d53ce510b2e36499b8f56038817b9bad86cabb4", $$ACTION_0).bind(null, encryptActionBoundArgs("6d53ce510b2e36499b8f56038817b9bad86cabb4", [
+        $$ACTION_ARG_0,
+        d,
+        f,
+        $$ACTION_ARG_1
+    ]));
+    return [
+        action2,
+        registerServerReference("188d5d945750dc32e2c842b93c75a65763d4a922", $$ACTION_1).bind(null, encryptActionBoundArgs("188d5d945750dc32e2c842b93c75a65763d4a922", [
+            action2,
+            $$ACTION_ARG_0,
+            d
+        ]))
+    ];
+}
+import { ensureServerEntryExports } from "private-next-rsc-action-validate";
+ensureServerEntryExports([
+    action0
+]);
+registerServerReference("0090eaf4e1f08a2d94f6be401e54a2ded399b87c", action0);

packages/next-swc/crates/next-custom-transforms/tests/fixture/server-actions/server/4/output.js

@@ -1,18 +1,19 @@
-/* __next_internal_action_entry_do_not_use__ {"1ab723c80dcca470e0410b4b2a2fc2bf21f41476":"c","6e7bc104e4d6e7fda190c4a51be969cfd0be6d6d":"a","d1f7eb64271d7c601dfef7d4d7053de1c2ca4338":"b"} */ import { createActionProxy } from "private-next-rsc-action-proxy";
+/* __next_internal_action_entry_do_not_use__ {"1ab723c80dcca470e0410b4b2a2fc2bf21f41476":"c","6d53ce510b2e36499b8f56038817b9bad86cabb4":"$$ACTION_0","6e7bc104e4d6e7fda190c4a51be969cfd0be6d6d":"a","d1f7eb64271d7c601dfef7d4d7053de1c2ca4338":"b"} */ import { registerServerReference } from "private-next-rsc-server-reference";
 import { encryptActionBoundArgs, decryptActionBoundArgs } from "private-next-rsc-action-encryption";
 export async function a() {}
 export async function b() {}
 export async function c() {}
 function d() {}
 function Foo() {
-    async function e() {}
+    var e = registerServerReference("6d53ce510b2e36499b8f56038817b9bad86cabb4", $$ACTION_0);
 }
+export async function $$ACTION_0() {}
 import { ensureServerEntryExports } from "private-next-rsc-action-validate";
 ensureServerEntryExports([
     a,
     b,
     c
 ]);
-createActionProxy("6e7bc104e4d6e7fda190c4a51be969cfd0be6d6d", a);
-createActionProxy("d1f7eb64271d7c601dfef7d4d7053de1c2ca4338", b);
-createActionProxy("1ab723c80dcca470e0410b4b2a2fc2bf21f41476", c);
+registerServerReference("6e7bc104e4d6e7fda190c4a51be969cfd0be6d6d", a);
+registerServerReference("d1f7eb64271d7c601dfef7d4d7053de1c2ca4338", b);
+registerServerReference("1ab723c80dcca470e0410b4b2a2fc2bf21f41476", c);