entry: Allow querying enumerate_instance_extension_properties() by layer name (#574)

Changelog.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 
 - extensions/khr: Drop `_khr` suffix from `get_memory_fd_properties_khr` in `ExternalMemoryFd` (#580)
+- entry: Allow querying `enumerate_instance_extension_properties()` by layer name (#574)
 
 ### Added
 

ash/src/entry.rs

@@ -238,11 +238,15 @@ impl Entry {
     /// <https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/vkEnumerateInstanceExtensionProperties.html>
     pub fn enumerate_instance_extension_properties(
         &self,
+        layer_name: Option<&CStr>,
     ) -> VkResult<Vec<vk::ExtensionProperties>> {
         unsafe {
             read_into_uninitialized_vector(|count, data| {
-                self.entry_fn_1_0
-                    .enumerate_instance_extension_properties(ptr::null(), count, data)
+                self.entry_fn_1_0.enumerate_instance_extension_properties(
+                    layer_name.map_or(ptr::null(), |str| str.as_ptr()),
+                    count,
+                    data,
+                )
             })
         }
     }