Fix cross build from macos to msvc

godot-bindings/build.rs

@@ -10,7 +10,7 @@
 // It's the only purpose of this build.rs file. If a better solution is found, this file can be removed.
 
 #[rustfmt::skip]
-fn main() {    
+fn main() {
     let mut count = 0;
     if cfg!(feature = "api-custom") { count += 1; }
     if cfg!(feature = "api-custom-json") { count += 1; }

godot-bindings/src/import.rs

@@ -60,6 +60,66 @@ pub use gdextension_api::version_4_5 as prebuilt;
 // ]]
 // [version-sync] [[
 //  [include] current.minor
-//  [line] pub use gdextension_api::version_$snakeVersion as prebuilt;
-pub use gdextension_api::version_4_5 as prebuilt;
+//  [line] pub use gdextension_api as prebuilt;
+pub use gdextension_api as prebuilt;
 // ]]
+
+// Platform-specific header loading for cross-compilation support.
+// The prebuilt module is compiled for HOST (not TARGET) when used as a build-dependency,
+// so we determine the platform at runtime based on CARGO_CFG_TARGET_* environment variables.
+#[cfg(not(any(feature = "api-custom", feature = "api-custom-json")))]
+pub(crate) mod prebuilt_platform {
+    use std::borrow::Cow;
+    use std::path::PathBuf;
+
+    /// Load platform-specific prebuilt bindings based on the TARGET platform (not HOST).
+    ///
+    /// Since godot-bindings is a build-dependency, it's compiled for HOST, but we need bindings for TARGET.
+    /// We detect the target platform using CARGO_CFG_TARGET_* environment variables available during
+    /// build script execution, then read the corresponding file from the gdextension-api dependency.
+    pub fn load_gdextension_header_rs_for_target() -> Cow<'static, str> {
+        // Determine TARGET platform from environment variables
+        let target_family = std::env::var("CARGO_CFG_TARGET_FAMILY").ok();
+        let target_os = std::env::var("CARGO_CFG_TARGET_OS").ok();
+
+        // Select platform suffix matching gdextension-api's file naming
+        let platform = match (target_family.as_deref(), target_os.as_deref()) {
+            (Some("windows"), _) => "windows",
+            (_, Some("macos" | "ios")) => "macos",
+            _ => "linux", // Linux, Android, and other Unix-like systems
+        };
+
+        // Get the Godot version string from prebuilt module
+        let version = super::prebuilt::GODOT_VERSION_STRING;
+
+        // Read the file from gdextension-api dependency
+        load_platform_file(platform, version)
+    }
+
+    /// Load platform-specific bindings file from the gdextension-api dependency.
+    ///
+    /// Uses the DEP_GDEXTENSION_API_ROOT environment variable exported by gdextension-api's build script
+    /// to locate the correct platform-specific bindings file.
+    fn load_platform_file(platform: &str, _version: &str) -> Cow<'static, str> {
+        // Get the gdextension-api root directory from the build script
+        let dep_root = std::env::var("DEP_GDEXTENSION_API_ROOT")
+            .expect("DEP_GDEXTENSION_API_ROOT not set. This should be exported by gdextension-api's build script.");
+
+        // The 4.x branches have files directly in res/, not versions/{version}/res/
+        let file_path = PathBuf::from(dep_root)
+            .join("res")
+            .join(format!("gdextension_interface_{}.rs", platform));
+
+        match std::fs::read_to_string(&file_path) {
+            Ok(contents) => Cow::Owned(contents),
+            Err(e) => panic!(
+                "Failed to load platform-specific bindings for platform '{}'.\n\
+                 Tried to read: {}\n\
+                 Error: {}\n\
+                 \n\
+                 This is likely a cross-compilation issue or the gdextension-api version doesn't support this platform.",
+                platform, file_path.display(), e
+            ),
+        }
+    }
+}

godot-bindings/src/lib.rs

@@ -129,7 +129,11 @@ mod depend_on_prebuilt {
             .unwrap_or_else(|e| panic!("failed to write gdextension_interface.h: {e}"));
         watch.record("write_header_h");
 
-        let rs_contents = prebuilt::load_gdextension_header_rs();
+        // CROSS-COMPILATION FIX:
+        // Since godot-bindings is a build-dependency, it and gdextension-api are compiled for the HOST platform.
+        // The #[cfg] attributes in gdextension-api::load_gdextension_header_rs() evaluate for HOST, not TARGET.
+        // We read CARGO_CFG_TARGET_* environment variables to select the correct bindings at runtime.
+        let rs_contents = crate::import::prebuilt_platform::load_gdextension_header_rs_for_target();
         std::fs::write(rs_path, rs_contents.as_ref())
             .unwrap_or_else(|e| panic!("failed to write gdextension_interface.rs: {e}"));
         watch.record("write_header_rs");