Replace ExtensionChain with a simple iterator

examples/src/lib.rs

@@ -4,7 +4,6 @@ extern crate ash;
 extern crate winapi;
 
 extern crate winit;
-
 #[cfg(target_os = "macos")]
 extern crate cocoa;
 #[cfg(target_os = "macos")]
@@ -408,9 +407,9 @@ impl ExampleBase {
                 .build()];
 
             let mut variable_pointers =
-                vk::PhysicalDeviceVariablePointerFeatures::builder().variable_pointers(true);
+                vk::PhysicalDeviceVariablePointerFeatures::builder().variable_pointers(true).build();
             let mut corner = vk::PhysicalDeviceCornerSampledImageFeaturesNV::builder()
-                .corner_sampled_image(true);
+                .corner_sampled_image(true).build();
             let mut device_create_info = vk::DeviceCreateInfo::builder()
                 .next(&mut corner)
                 .next(&mut variable_pointers)
@@ -419,24 +418,12 @@ impl ExampleBase {
                 .enabled_features(&features)
                 .build();
 
-            let mut chain =
+            for ptr in vk::ptr_chain_iter(&mut device_create_info){
-                vk::ExtensionChain::from_ptr(&mut device_create_info as *mut _ as *mut _);
+                println!("{:?}", ptr);
-            println!("{}", (*chain).s_type);
-            println!("{:?}", (*chain).p_next);
-            unsafe {
-                loop {
-                    chain = vk::ExtensionChain::from_ptr((*chain).p_next as *mut _);
-                    println!("{}", (*chain).s_type);
-                    println!("{:?}", (*chain).p_next);
-                    if (*chain).p_next.is_null() {
-                        break;
-                    }
-                }
             }
-            use std::ops::Deref;
             println!("--");
-            println!("{:?}", corner.deref() as *const _);
+            println!("{:?}", &corner as *const _);
-            println!("{:?}", variable_pointers.deref() as *const _);
+            println!("{:?}", &variable_pointers as *const _);
             let device: Device = instance
                 .create_device(pdevice, &device_create_info, None)
                 .unwrap();

generator/src/lib.rs

@@ -1596,11 +1596,13 @@ pub fn derive_setters(_struct: &vkxml::Struct) -> Option<Tokens> {
 
     let next_function = if has_next {
         quote! {
-            pub fn next<T: #extends_name>(mut self, next: &'a mut impl ::std::ops::DerefMut<Target = T>) -> #name_builder<'a> {
+            pub fn next<T: #extends_name>(mut self, next: &'a mut T) -> #name_builder<'a> {
                 unsafe{
-                    let ptr = &mut self.inner as *mut _ as *mut c_void;
+                    let last_extension = ptr_chain_iter(&mut self.inner)
-                    let last_extension = ExtensionChain::last_chain(ptr);
+                        .last()
-                    (*last_extension).p_next = next.deref_mut() as *mut T as *mut c_void;
+                        .expect("Initial ptr was null");
+                    // Append the extension at the end
+                    (*last_extension).p_next = next as *mut T as *mut _;
                 }
                 self
             }
@@ -2145,33 +2147,23 @@ pub fn write_source_code(path: &Path) {
     let source_code = quote! {
         use std::fmt;
         use std::os::raw::*;
-
+        /// `T` has to be a valid xxx_create_info struct. Addtionally all the pointer chains in
-        #[repr(C)]
+        /// this iterator are mutable. Make sure that all the objects in this pointer chain have an
-        #[derive(Debug, Copy, Clone)]
+        /// active `&mut` borrow if you want to update those objects.
-        pub struct ExtensionChain {
+        pub unsafe fn ptr_chain_iter<T>(ptr: &mut T) -> impl Iterator<Item = *mut BaseOutStructure> {
-            pub s_type: StructureType,
+            use std::ptr::null_mut;
-            pub p_next: *mut c_void
+            let ptr: *mut BaseOutStructure = ::std::mem::transmute(ptr);
-        }
+            (0..).scan(ptr, |p_ptr, _|{
-
+                if *p_ptr == null_mut() {
-        impl ExtensionChain {
+                    return None;
-            pub unsafe fn from_ptr(ptr: *mut c_void) -> *mut Self {
-                ::std::mem::transmute(ptr)
-            }
-            pub unsafe fn last_chain(ptr: *mut c_void) -> *mut Self {
-                assert!(!ptr.is_null());
-                let mut extension = ExtensionChain::from_ptr(ptr);
-                while !(*extension).p_next.is_null() {
-                    extension = ExtensionChain::from_ptr((*extension).p_next);
                 }
-                extension
+                let n_ptr = (**p_ptr).p_next as *mut BaseOutStructure;
-            }
+                let old = *p_ptr;
-        }
+                *p_ptr = n_ptr;
-        #[repr(C)]
+                Some(old)
-        #[derive(Debug, Copy, Clone)]
+            })
-        pub struct ExtensionChainMut {
-            pub s_type: StructureType,
-            pub p_next: *mut c_void
         }
+
         pub trait Handle {
             const TYPE: ObjectType;
             fn as_raw(self) -> u64;