Problem with Wifi persistent connection

[uhfband]

Basic Infos

• [x] This issue complies with the issue POLICY doc.
• [x] I have read the documentation at readthedocs and the issue is not addressed there.
• [ ] I have tested that the issue is present in current master branch (aka latest git).
• [x] I have searched the issue tracker for a similar issue.
• [ ] If there is a stack dump, I have decoded it.
• [x] I have filled out all fields below.

Platform

• Hardware: [ESP-07]
• Core Version: [3.1.1/NONOSDK22x_191122 ]
• Development Env: [Arduino IDE]
• Operating System: [Windows]

Settings in IDE

• Module: [Generic ESP8266 Module]
• Flash Mode: [dout]
• Flash Size: [1MB]
• lwip Variant: [v2 Lower Memory]
• Reset Method: [dtr]
• Flash Frequency: [40Mhz]
• CPU Frequency: [80Mhz]
• Upload Using: [SERIAL]
• Upload Speed: [115200)

Problem Description

Wifi persistent connection option did not work for me, each reconnection took a long time (4500 ms). I started debugging and found that threshold property does not preserved when station config saved to flash then loaded.

Sketch

#include "ESP8266WiFi.h"

void setup() {
  Serial.begin(115200);
  
  struct station_config conf;

  strcpy((char*)conf.ssid, "testAP");
  strcpy((char*)conf.password, "password");
  conf.bssid_set = 0;
  conf.threshold.authmode = AUTH_WPA_PSK;
  conf.threshold.rssi = -127;

  WiFi.persistent(true);
  WiFi.mode(WIFI_STA);
  int res = wifi_station_set_config(&conf);

  memset(&conf, 0, sizeof(station_config));
  
  wifi_station_get_config_default(&conf);

  Serial.print("\r\n");
  Serial.printf(PSTR("  ssid:      %s\n"), conf.ssid);
  Serial.printf(PSTR("  password:  %s\n"), conf.password);
  Serial.printf(PSTR("  bssid_set: %d\n"), conf.bssid_set);
  Serial.printf(PSTR("  bssid:     %02x:%02x:%02x:%02x:%02x\n"), 
       conf.bssid[0], conf.bssid[1], conf.bssid[2],
       conf.bssid[3], conf.bssid[4], conf.bssid[5]);
  Serial.printf(PSTR("  threshold.rssi: %d\n"), conf.threshold.rssi);
  Serial.printf(PSTR("  threshold.authmode: %d\n"), (uint8_t)conf.threshold.authmode);

}

void loop() {
  // put your main code here, to run repeatedly:

}

Debug Messages

  ssid:      testAP
  password:  password
  bssid_set: 0
  bssid:     21:66:d8:15:8c
  threshold.rssi: 0
  threshold.authmode: 0

For this reason next code always return false https://github.com/esp8266/Arduino/blob/badb407bbb7f6dec18d4dd7fd83785b88ec7e6f2/libraries/ESP8266WiFi/src/ESP8266WiFiSTA.cpp#L89-L95

I commented out this lines, and it worked as it should, reconnection become much faster (700ms). Is it bug, SDK issue, or my environment settings problem?

[mcspr]

Argument-less WiFi.begin() can be used instead, which won't compare existing settings? But, the issue is there, that's true. Threshold should not be compared if it is not comparable