Constructing IPAddress crashes ESP. Since 2.5.0. Works in 2.4.2.

[crndn2018]

Basic Infos

• This issue complies with the issue POLICY doc.
• 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).
• I have searched the issue tracker for a similar issue.
• If there is a stack dump, I have decoded it.
• I have filled out all fields below.

Platform

• Hardware: [ESP-12]
• Core Version: [773f306]
• Development Env: [Arduino IDE]
• Operating System: [Windows]

Settings in IDE

• Module: [Generic ESP8266 Module]
• Flash Mode: [qio]
• Flash Size: [4MB]
• lwip Variant: [v2 Lower Memory]
• Reset Method: [ck]
• Flash Frequency: [40Mhz]
• CPU Frequency: [80Mhz]
• Upload Using: [SERIAL]
• Upload Speed: [115200] (serial upload only)

Problem Description

This sketch works fine with Core 2.4.2. With 2.5.0 it throws Exceptions.

MCVE Sketch

#include <ESP8266WiFi.h>

struct NetworkEthernetSetup 
{
  byte bMac[6];
  byte bIp[4];
  byte bDns[4];
  byte bGateway[4];
  byte bNetmask[4];
};

NetworkEthernetSetup nes;

void setup() {
  Serial1.begin(115200);
  
  nes.bMac[0] = 0xA;
  nes.bMac[1] = 0xB;
  nes.bMac[2] = 0xC;
  nes.bMac[3] = 0xD;
  nes.bMac[4] = 0xE;
  nes.bMac[5] = 0xF;

  nes.bIp[0] = 192;
  nes.bIp[1] = 168;
  nes.bIp[2] = 16;
  nes.bIp[3] = 1;
  
  nes.bDns[0] = 192;
  nes.bDns[1] = 168;
  nes.bDns[2] = 16;
  nes.bDns[3] = 2;

  nes.bGateway[0] = 192;
  nes.bGateway[1] = 168;
  nes.bGateway[2] = 16;
  nes.bGateway[3] = 3;

  nes.bNetmask[0] = 255;
  nes.bNetmask[1] = 255;
  nes.bNetmask[2] = 255;
  nes.bNetmask[3] = 0;
}

void loop() {
  
  Serial1.println("Livebeat");
  IPAddress ipa = IPAddress(nes.bIp);    // Here is the problem !
  delay(1000);
}

### Debug Messages

Exception (9):
epc1=0x402027d3 epc2=0x00000000 epc3=0x00000000 excvaddr=0x3ffee61e depc=0x00000000

>>>stack>>>

ctx: cont
sp: 3ffffd90 end: 3fffffc0 offset: 01a0
3fffff30:  3fffdad0 00000008 3ffee630 40202630
3fffff40:  3fffdad0 00000000 3ffee630 40202835
3fffff50:  3ffe887c 0000001c 00000000 40202835
3fffff60:  3ffe8870 feefeffe 3ffee630 40202850
3fffff70:  3fffdad0 00000001 3ffee630 40202874
3fffff80:  0001c200 00000000 3ffee684 402025ab
3fffff90:  feefeffe 00000000 3ffee684 40202528
3fffffa0:  feefeffe feefeffe feefeffe 40202c54
3fffffb0:  feefeffe feefeffe 3ffe8500 40100a35
<<<stack<<<

 ets Jan  8 2013,rst cause:2, boot mode:(3,6)

load 0x4010f000, len 1384, room 16
tail 8
chksum 0x2d
csum 0x2d
v00000000
~ld

[d-a-v]

reproduced, fix on its way #5421.
Thanks