add WEBUSB_URL_DEF() to avoid using flexible array member in C++

Author: hathach

examples/WebUSB/webusb_serial/webusb_serial.ino

@@ -31,7 +31,7 @@
 Adafruit_USBD_WebUSB usb_web;
 
 // Landing Page: scheme (0: http, 1: https), url
-const tusb_desc_webusb_url_t landingPage = TUD_WEBUSB_URL_DESCRIPTOR(1 /*https*/, "adafruit.github.io/Adafruit_TinyUSB_Arduino/examples/webusb-serial");
+WEBUSB_URL_DEF(landingPage, 1 /*https*/, "adafruit.github.io/Adafruit_TinyUSB_Arduino/examples/webusb-serial");
 
 int led_pin = LED_BUILTIN;
 

src/Adafruit_USBD_WebUSB.h

@@ -27,6 +27,14 @@
 
 #include "Adafruit_TinyUSB_Core.h"
 
+#define WEBUSB_URL_DEF(_name, _scheme, _url) \
+  struct TU_ATTR_PACKED {                    \
+    uint8_t bLength;                         \
+    uint8_t bDescriptorType;                 \
+    uint8_t bScheme;                         \
+    char    url[3 + sizeof(_url)];           \
+  } const _name = { 3 + sizeof(_url) - 1, 3, _scheme, _url }
+
 class Adafruit_USBD_WebUSB : public Stream, Adafruit_USBD_Interface
 {
   public: