entry: Mark all extern "C" function-pointer calls unsafe

We don't mark any of the extern calls to Vulkan function-pointers safe
except for a few `Entry` functions.  Their safety contract was easy to
validate, but now that we exposed a constructor function to let the user
provide function pointers in the form of `Entry::from_parts_1_1()` it is
no longer safe to assume that we are calling the function that adheres
to the contract specified in the Vulkan reference.

Because we don't rigorously do this validation and safe-marking anywhere
else either, mark these function calls as `unsafe`.

Related discussion chain: https://github.com/ash-rs/ash/pull/748#discussion_r1186794284

Changelog.md

@@ -16,7 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added `VK_EXT_shader_object` device extension (#732)
 - Added missing `Device::get_device_queue2()` wrapper (#736)
 - Exposed `FramebufferCreateInfo::attachment_count()` builder for `vk::FramebufferCreateFlags::IMAGELESS` (#747)
-- Allow building `Entry`/`Instance`/`Device` from handle+fns (#748)
+- Allow building `Entry`/`Instance`/`Device` from handle+fns (see their `from_parts_1_x()` associated functions) (#748)
 
 ### Changed
 

ash/src/entry.rs

@@ -184,7 +184,7 @@ impl Entry {
     /// # use ash::{Entry, vk};
     /// # fn main() -> Result<(), Box<dyn std::error::Error>> {
     /// let entry = Entry::linked();
-    /// match entry.try_enumerate_instance_version()? {
+    /// match unsafe { entry.try_enumerate_instance_version() }? {
     ///     // Vulkan 1.1+
     ///     Some(version) => {
     ///         let major = vk::version_major(version);
@@ -197,8 +197,7 @@ impl Entry {
     /// # Ok(()) }
     /// ```
     #[inline]
-    pub fn try_enumerate_instance_version(&self) -> VkResult<Option<u32>> {
+    pub unsafe fn try_enumerate_instance_version(&self) -> VkResult<Option<u32>> {
-        unsafe {
         let mut api_version = 0;
         let enumerate_instance_version: Option<vk::PFN_vkEnumerateInstanceVersion> = {
             let name = CStr::from_bytes_with_nul_unchecked(b"vkEnumerateInstanceVersion\0");
@@ -208,13 +207,11 @@ impl Entry {
             ))
         };
         if let Some(enumerate_instance_version) = enumerate_instance_version {
-                (enumerate_instance_version)(&mut api_version)
+            (enumerate_instance_version)(&mut api_version).result_with_success(Some(api_version))
-                    .result_with_success(Some(api_version))
         } else {
             Ok(None)
         }
     }
-    }
 
     /// <https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/vkCreateInstance.html>
     ///
@@ -240,21 +237,18 @@ impl Entry {
 
     /// <https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/vkEnumerateInstanceLayerProperties.html>
     #[inline]
-    pub fn enumerate_instance_layer_properties(&self) -> VkResult<Vec<vk::LayerProperties>> {
+    pub unsafe fn enumerate_instance_layer_properties(&self) -> VkResult<Vec<vk::LayerProperties>> {
-        unsafe {
         read_into_uninitialized_vector(|count, data| {
             (self.entry_fn_1_0.enumerate_instance_layer_properties)(count, data)
         })
     }
-    }
 
     /// <https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/vkEnumerateInstanceExtensionProperties.html>
     #[inline]
-    pub fn enumerate_instance_extension_properties(
+    pub unsafe 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)(
                 layer_name.map_or(ptr::null(), |str| str.as_ptr()),
@@ -263,7 +257,6 @@ impl Entry {
             )
         })
     }
-    }
 
     /// <https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/vkGetInstanceProcAddr.html>
     #[inline]
@@ -288,13 +281,11 @@ impl Entry {
     ///
     /// Please use [`try_enumerate_instance_version()`][Self::try_enumerate_instance_version()] instead.
     #[inline]
-    pub fn enumerate_instance_version(&self) -> VkResult<u32> {
+    pub unsafe fn enumerate_instance_version(&self) -> VkResult<u32> {
-        unsafe {
         let mut api_version = 0;
         (self.entry_fn_1_1.enumerate_instance_version)(&mut api_version)
             .result_with_success(api_version)
     }
-    }
 }
 
 #[cfg(feature = "linked")]