From 68bccbaeeefe1ec007b7fe4caa2302afe06158e8 Mon Sep 17 00:00:00 2001
From: Omar Emara <mail@OmarEmara.dev>
Date: Mon, 15 Sep 2025 09:09:43 +0200
Subject: [PATCH] Nodes: Recursively apply usage inference

This patch extends the usage_by_menu method to also consider the usage
of the menu socket in the make available and usage inference callbacks.
This essentially means that if a socket depends on menu B which, in
turn, depends on menu A, it will be sufficiently to check the value of
menu B, while A will be checked recursively.

The single variant of the usage_by_menu function is now implemented in
terms of its overloaded vector variant for code deduplication since the
new code increase the size quite a bit.

Pull Request: https://projects.blender.org/blender/blender/pulls/146141
---
 .../blender/nodes/intern/node_declaration.cc  | 62 +++++++++++++------
 1 file changed, 44 insertions(+), 18 deletions(-)

diff --git a/source/blender/nodes/intern/node_declaration.cc b/source/blender/nodes/intern/node_declaration.cc
index f8bc5a9ca19..e31ed25b89a 100644
--- a/source/blender/nodes/intern/node_declaration.cc
+++ b/source/blender/nodes/intern/node_declaration.cc
@@ -825,7 +825,7 @@ BaseSocketDeclarationBuilder &BaseSocketDeclarationBuilder::usage_by_single_menu
     const bNodeSocket &socket = find_single_menu_input(params.node);
     if (const std::optional<bool> any_output_used = params.any_output_is_used()) {
       if (!*any_output_used) {
-        /* If no output is used, none if the inputs is used either. */
+        /* If no output is used, none of the inputs is used either. */
         return false;
       }
     }
@@ -842,16 +842,8 @@ BaseSocketDeclarationBuilder &BaseSocketDeclarationBuilder::usage_by_single_menu
 BaseSocketDeclarationBuilder &BaseSocketDeclarationBuilder::usage_by_menu(
     const StringRef menu_input_identifier, const int menu_value)
 {
-  this->make_available([menu_input_identifier, menu_value](bNode &node) {
-    bNodeSocket &socket = *blender::bke::node_find_socket(node, SOCK_IN, menu_input_identifier);
-    bNodeSocketValueMenu *value = socket.default_value_typed<bNodeSocketValueMenu>();
-    value->value = menu_value;
-  });
-  this->usage_inference(
-      [menu_input_identifier, menu_value](
-          const socket_usage_inference::InputSocketUsageParams &params) -> std::optional<bool> {
-        return params.menu_input_may_be(menu_input_identifier, menu_value);
-      });
+  Array<int> menu_values = {menu_value};
+  this->usage_by_menu(menu_input_identifier, menu_values);
   return *this;
 }
 
@@ -859,20 +851,54 @@ BaseSocketDeclarationBuilder &BaseSocketDeclarationBuilder::usage_by_menu(
     const StringRef menu_input_identifier, const Array<int> menu_values)
 {
   this->make_available([menu_input_identifier, menu_values](bNode &node) {
-    bNodeSocket &socket = *blender::bke::node_find_socket(node, SOCK_IN, menu_input_identifier);
-    bNodeSocketValueMenu *value = socket.default_value_typed<bNodeSocketValueMenu>();
+    bNodeSocket &menu_socket = *blender::bke::node_find_socket(
+        node, SOCK_IN, menu_input_identifier);
+    const SocketDeclaration &socket_declaration = *menu_socket.runtime->declaration;
+    socket_declaration.make_available(node);
+    bNodeSocketValueMenu *value = menu_socket.default_value_typed<bNodeSocketValueMenu>();
     value->value = menu_values[0];
   });
   this->usage_inference(
       [menu_input_identifier, menu_values](
           const socket_usage_inference::InputSocketUsageParams &params) -> std::optional<bool> {
-        for (const int menu_value : menu_values) {
-          const bool might_be = params.menu_input_may_be(menu_input_identifier, menu_value);
-          if (might_be) {
-            return true;
+        if (const std::optional<bool> any_output_used = params.any_output_is_used()) {
+          if (!*any_output_used) {
+            /* If no output is used, none of the inputs is used either. */
+            return false;
           }
         }
-        return false;
+        else {
+          /* It's not known if any output is used yet. This function will be called again once new
+           * information about output usages is available. */
+          return std::nullopt;
+        }
+
+        /* Check if the menu might be any of the given values. */
+        bool menu_might_be_any_value = false;
+        for (const int menu_value : menu_values) {
+          menu_might_be_any_value = params.menu_input_may_be(menu_input_identifier, menu_value);
+          if (menu_might_be_any_value) {
+            break;
+          }
+        }
+
+        const bNodeSocket &menu_socket = *blender::bke::node_find_socket(
+            params.node, SOCK_IN, menu_input_identifier);
+        const SocketDeclaration &menu_socket_declaration = *menu_socket.runtime->declaration;
+        if (!menu_socket_declaration.usage_inference_fn) {
+          return menu_might_be_any_value;
+        }
+
+        /* If the menu socket has a usage inference function, check if it might be used. */
+        const std::optional<bool> menu_might_be_used =
+            (*menu_socket_declaration.usage_inference_fn)(params);
+        if (!menu_might_be_used.has_value()) {
+          return menu_might_be_any_value;
+        }
+
+        /* The input is only used if the menu might be any of the values and the menu itself is
+         * used. */
+        return *menu_might_be_used && menu_might_be_any_value;
       });
   return *this;
 }