enableWiFiAtBootTime() should be declared in ESP8266WiFi.h (#7993)

Author: dok-net

cores/esp8266/core_esp8266_features.h

@@ -105,8 +105,6 @@ uint64_t micros64(void);
 void delay(unsigned long);
 void delayMicroseconds(unsigned int us);
 
-void enableWiFiAtBootTime (void) __attribute__((noinline));
-
 #if defined(F_CPU) || defined(CORE_MOCK)
 #ifdef __cplusplus
 constexpr

doc/esp8266wifi/generic-class.rst

@@ -61,7 +61,7 @@ linker).
 
 .. code:: cpp
 
-    #include <ESP8266WiFi.h>    // necessary to avoid a linker error
+    #include <ESP8266WiFi.h>
 
     void setup () {
     #ifdef WIFI_IS_OFF_AT_BOOT

libraries/ESP8266WiFi/src/ESP8266WiFi.h

@@ -53,6 +53,7 @@ extern "C" {
 #define DEBUG_WIFI(...) do { (void)0; } while (0)
 #endif
 
+extern "C" void enableWiFiAtBootTime (void) __attribute__((noinline));
 
 class ESP8266WiFiClass : public ESP8266WiFiGenericClass, public ESP8266WiFiSTAClass, public ESP8266WiFiScanClass, public ESP8266WiFiAPClass {
     public: