Fix label leak (#3053)

Cargo.lock

@@ -337,12 +337,6 @@ dependencies = [
  "web-sys",
 ]
 
-[[package]]
-name = "copyless"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2df960f5d869b2dd8532793fde43eb5427cceb126c929747a26823ab0eeb536"
-
 [[package]]
 name = "core-foundation"
 version = "0.9.3"
@@ -2249,7 +2243,6 @@ dependencies = [
  "bitflags",
  "cfg_aliases",
  "codespan-reporting",
- "copyless",
  "fxhash",
  "log",
  "naga",

wgpu-hal/src/metal/command.rs

@@ -102,12 +102,12 @@ impl crate::CommandEncoder<super::Api> for super::CommandEncoder {
             } else {
                 queue.new_command_buffer_with_unretained_references()
             };
+            if let Some(label) = label {
+                cmd_buf_ref.set_label(label);
+            }
             cmd_buf_ref.to_owned()
         });
 
-        if let Some(label) = label {
-            raw.set_label(label);
-        }
         self.raw_cmd_buf = Some(raw);
 
         Ok(())

wgpu-hal/src/metal/device.rs

@@ -376,7 +376,9 @@ impl crate::Device<super::Api> for super::Device {
                 },
             );
             if let Some(label) = desc.label {
-                raw.set_label(label);
+                objc::rc::autoreleasepool(|| {
+                    raw.set_label(label);
+                });
             }
             raw
         };