From f5cb4d8e1266eb6c184a01b3fe20da3de13f09bb Mon Sep 17 00:00:00 2001
From: Jinlei Li <jinleili0@outlook.com>
Date: Mon, 6 Jun 2022 15:29:16 +0800
Subject: [PATCH] metal: check if in the main thread when calling
 `create_surface`

---
 wgpu-hal/src/metal/surface.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/wgpu-hal/src/metal/surface.rs b/wgpu-hal/src/metal/surface.rs
index a0ca46ab358..820805505a5 100644
--- a/wgpu-hal/src/metal/surface.rs
+++ b/wgpu-hal/src/metal/surface.rs
@@ -9,7 +9,7 @@ use objc::{
     declare::ClassDecl,
     msg_send,
     rc::autoreleasepool,
-    runtime::{Class, Object, Sel, BOOL, YES},
+    runtime::{Class, Object, Sel, BOOL, NO, YES},
     sel, sel_impl,
 };
 use parking_lot::Mutex;
@@ -84,6 +84,11 @@ impl super::Surface {
             panic!("window does not have a valid contentView");
         }
 
+        let is_main_thread: BOOL = msg_send![class!(NSThread), isMainThread];
+        if is_main_thread == NO {
+            panic!("create_surface cannot be called in non-ui thread.");
+        }
+
         let main_layer: *mut Object = msg_send![view, layer];
         let class = class!(CAMetalLayer);
         let is_valid_layer: BOOL = msg_send![main_layer, isKindOfClass: class];