From ee5e651cf334de1891220dbd4dd9cbb8bc0b0afc Mon Sep 17 00:00:00 2001
From: Marijn Suijten <marijn@traverseresearch.nl>
Date: Fri, 26 May 2023 10:46:03 +0200
Subject: [PATCH] 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     |  2 +-
 ash/src/entry.rs | 69 +++++++++++++++++++++---------------------------
 2 files changed, 31 insertions(+), 40 deletions(-)

diff --git a/Changelog.md b/Changelog.md
index 8ce05df1b..a95074f98 100644
--- a/Changelog.md
+++ b/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
 
diff --git a/ash/src/entry.rs b/ash/src/entry.rs
index f3052e2c7..695d7b27f 100644
--- a/ash/src/entry.rs
+++ b/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);
@@ -197,22 +197,19 @@ impl Entry {
     /// # Ok(()) }
     /// ```
     #[inline]
-    pub 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");
-                mem::transmute((self.static_fn.get_instance_proc_addr)(
-                    vk::Instance::null(),
-                    name.as_ptr(),
-                ))
-            };
-            if let Some(enumerate_instance_version) = enumerate_instance_version {
-                (enumerate_instance_version)(&mut api_version)
-                    .result_with_success(Some(api_version))
-            } else {
-                Ok(None)
-            }
+    pub unsafe fn try_enumerate_instance_version(&self) -> VkResult<Option<u32>> {
+        let mut api_version = 0;
+        let enumerate_instance_version: Option<vk::PFN_vkEnumerateInstanceVersion> = {
+            let name = CStr::from_bytes_with_nul_unchecked(b"vkEnumerateInstanceVersion\0");
+            mem::transmute((self.static_fn.get_instance_proc_addr)(
+                vk::Instance::null(),
+                name.as_ptr(),
+            ))
+        };
+        if let Some(enumerate_instance_version) = enumerate_instance_version {
+            (enumerate_instance_version)(&mut api_version).result_with_success(Some(api_version))
+        } else {
+            Ok(None)
         }
     }
 
@@ -240,29 +237,25 @@ 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>> {
-        unsafe {
-            read_into_uninitialized_vector(|count, data| {
-                (self.entry_fn_1_0.enumerate_instance_layer_properties)(count, data)
-            })
-        }
+    pub unsafe fn enumerate_instance_layer_properties(&self) -> VkResult<Vec<vk::LayerProperties>> {
+        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()),
-                    count,
-                    data,
-                )
-            })
-        }
+        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()),
+                count,
+                data,
+            )
+        })
     }
 
     /// <https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/vkGetInstanceProcAddr.html>
@@ -288,12 +281,10 @@ impl Entry {
     ///
     /// Please use [`try_enumerate_instance_version()`][Self::try_enumerate_instance_version()] instead.
     #[inline]
-    pub 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)
-        }
+    pub unsafe fn enumerate_instance_version(&self) -> VkResult<u32> {
+        let mut api_version = 0;
+        (self.entry_fn_1_1.enumerate_instance_version)(&mut api_version)
+            .result_with_success(api_version)
     }
 }