Removing use of static mut reference

Author: ryan-summers

src/lib.rs

@@ -134,10 +134,11 @@ pub mod endpoint;
 /// To implement USB support for your own project, the required code is usually as follows:
 ///
 /// ``` ignore
+/// use core::cell::UnsafeCell;
 /// use usb_device::prelude::*;
 /// use usb_serial; // example class crate (not included)
 ///
-/// static mut CONTROL_BUFFER: [u8; 128] = [0; 128];
+/// static mut CONTROL_BUFFER: UnsafeCell<[u8; 128]> = UnsafeCell::new([0; 128]);
 ///
 /// // Create the device-specific USB peripheral driver. The exact name and arguments are device
 /// // specific, so check the documentation for your device driver crate.
@@ -153,7 +154,7 @@ pub mod endpoint;
 /// // pair. Additional builder arguments can specify parameters such as device class code or
 /// // product name. If using an existing class, remember to check the class crate documentation
 /// // for correct values.
-/// let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x5824, 0x27dd), unsafe { &mut CONTROL_BUFFER })
+/// let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x5824, 0x27dd), unsafe { CONTROL_BUFFER.get_mut() })
 ///     .strings(&[StringDescriptors::new(LangID::EN)
 ///         .product("Serial port")])
 ///         .expect("Failed to set strings")

src/test_class.rs

@@ -1,9 +1,9 @@
 #![allow(missing_docs)]
 
 use crate::class_prelude::*;
-use crate::descriptor::lang_id::LangID;
 use crate::device::{StringDescriptors, UsbDevice, UsbDeviceBuilder, UsbVidPid};
 use crate::Result;
+use core::cell::UnsafeCell;
 use core::cmp;
 
 #[cfg(feature = "test-class-high-speed")]
@@ -22,7 +22,7 @@ mod sizes {
     pub const INTERRUPT_ENDPOINT: u16 = 31;
 }
 
-static mut CONTROL_BUFFER: [u8; 256] = [0; 256];
+static mut CONTROL_BUFFER: UnsafeCell<[u8; 256]> = UnsafeCell::new([0; 256]);
 
 /// Test USB class for testing USB driver implementations. Supports various endpoint types and
 /// requests for testing USB peripheral drivers on actual hardware.
@@ -114,14 +114,16 @@ impl<B: UsbBus> TestClass<'_, B> {
         &self,
         usb_bus: &'a UsbBusAllocator<B>,
     ) -> UsbDeviceBuilder<'a, B> {
-        UsbDeviceBuilder::new(usb_bus, UsbVidPid(VID, PID), unsafe { &mut CONTROL_BUFFER })
-            .strings(&[StringDescriptors::default()
-                .manufacturer(MANUFACTURER)
-                .product(PRODUCT)
-                .serial_number(SERIAL_NUMBER)])
-            .unwrap()
-            .max_packet_size_0(sizes::CONTROL_ENDPOINT)
-            .unwrap()
+        UsbDeviceBuilder::new(usb_bus, UsbVidPid(VID, PID), unsafe {
+            CONTROL_BUFFER.get_mut()
+        })
+        .strings(&[StringDescriptors::default()
+            .manufacturer(MANUFACTURER)
+            .product(PRODUCT)
+            .serial_number(SERIAL_NUMBER)])
+        .unwrap()
+        .max_packet_size_0(sizes::CONTROL_ENDPOINT)
+        .unwrap()
     }
 
     /// Must be called after polling the UsbDevice.