segfaulting: DebugUtilsMessengerCallbackDataEXT::pMessageIdName may be null in debug callback (#1487)

* vulkano: DebugUtilsMessengerCallbackDataEXT::pMessageIdName may be null in debug callback

- https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkDebugUtilsMessengerCallbackDataEXT.html#VUID-VkDebugUtilsMessengerCallbackDataEXT-pMessageIdName-parameter

* make `Message::layer_prefix` an Option

CHANGELOG_VULKANO.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- **Breaking** `Message::layer_prefix` turned to Option to prevent segfaults when Vulkan message didn't provide `pMessageIdName` value
 - **Breaking** On `AutoCommandBufferBuilder`, methods that bind a descriptor set now take a `dynamic_offsets` parameter
 - **Breaking** On `AutoCommandBufferBuilder` and `SyncCommandBufferBuilder`, the `update_buffer` method now takes `data` by reference
 - **Breaking** Made `PipelineLayoutDescTweaks` public, for use with compute pipelines

examples/src/bin/debug.rs

@@ -99,7 +99,10 @@ fn main() {
 
         println!(
             "{} {} {}: {}",
-            msg.layer_prefix, ty, severity, msg.description
+            msg.layer_prefix.unwrap_or("unknown"),
+            ty,
+            severity,
+            msg.description
         );
     })
     .ok();

vulkano/src/instance/debug.rs

@@ -96,9 +96,12 @@ impl DebugCallback {
                 let user_callback = user_data as *mut Box<dyn Fn()> as *const _;
                 let user_callback: &Box<dyn Fn(&Message)> = &*user_callback;
 
-                let layer_prefix = CStr::from_ptr((*callback_data).pMessageIdName)
+                let layer_prefix = (*callback_data).pMessageIdName.as_ref().map(|msg_id_name| {
+                    CStr::from_ptr(msg_id_name)
                         .to_str()
-                    .expect("debug callback message not utf-8");
+                        .expect("debug callback message not utf-8")
+                });
+
                 let description = CStr::from_ptr((*callback_data).pMessage)
                     .to_str()
                     .expect("debug callback message not utf-8");
@@ -231,8 +234,8 @@ pub struct Message<'a> {
     pub severity: MessageSeverity,
     /// Type of message,
     pub ty: MessageType,
-    /// Prefix of the layer that reported this message.
-    pub layer_prefix: &'a str,
+    /// Prefix of the layer that reported this message or `None` if unknown.
+    pub layer_prefix: Option<&'a str>,
     /// Description of the message.
     pub description: &'a str,
 }