Enabling Debug port "Serial" results in compile error

[probonopd]

In most (all?) sketches that use Wi-Fi, enabling Debug port "Serial" results in a compile error.

For example, using the mDNS_Web_Server.ino sketch and enabling Debug port "Serial" results in a compile error:

Arduino: 1.6.7 Hourly Build 2015/12/17 04:29 (Linux), Board: "Generic ESP8266 Module, Serial, 80 MHz, 40MHz, DIO, 921600, 4M (3M SPIFFS), nodemcu, Serial, All"

Build options changed, rebuilding all
In file included from /home/me/.arduino15/packages/esp8266/hardware/esp8266/2.1.0-rc1/libraries/ESP8266WiFi/src/ESP8266WiFiMulti.cpp:26:0:
/home/me/.arduino15/packages/esp8266/hardware/esp8266/2.1.0-rc1/libraries/ESP8266WiFi/src/ESP8266WiFiMulti.cpp: In member function 'wl_status_t ESP8266WiFiMulti::run()':
/home/me/.arduino15/packages/esp8266/hardware/esp8266/2.1.0-rc1/libraries/ESP8266WiFi/src/ESP8266WiFiMulti.h:37:66: error: cannot pass objects of non-trivially-copyable type 'class String' through '...'
 #define DEBUG_WIFI_MULTI(...) DEBUG_ESP_PORT.printf( __VA_ARGS__ )

                                                                  ^
/home/me/.arduino15/packages/esp8266/hardware/esp8266/2.1.0-rc1/libraries/ESP8266WiFi/src/ESP8266WiFiMulti.cpp:130:25: note: in expansion of macro 'DEBUG_WIFI_MULTI'
                         DEBUG_WIFI_MULTI("[WIFI] SSID: %s\n", WiFi.SSID());

                         ^
exit status 1
Error compiling.

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[andig]

Duplicate of #1369