I need help with SoftwareSerial

Using Arduino Programming Questions
#1

I am not the original author of the sketch plus the syntax of the SoftwareSerial command has changed since it was originally written. There is 1 main sketch and about 15 sub sketches.
I am only posting here the sub-sketch that used Software Serial and only portions of it.
Plus I dont understand the use of the → 

while (ss->available())

I made changes to enable it to compile.

Common to both:

#include "Circum.h"

// serial configuration for GPS
#define GPS_TX_PIN (-1) // none
#define GPS_RX_PIN 12
#define GPS_INVERT false
#define GPS_BUFSIZE 512
#define GPS_BAUD 9600

Original sketch part:

// create serial connection to GPS board
 resetWatchdog();
 ss = new SoftwareSerial (GPS_RX_PIN, GPS_TX_PIN, GPS_INVERT, GPS_BUFSIZE);
 ss->begin(GPS_BAUD);

My changed code:

// create serial connection to GPS board
 resetWatchdog();
 SoftwareSerial ss(GPS_RX_PIN, GPS_TX_PIN);
 ss.begin(GPS_BAUD);

Original code:

 while (ss->available()) {

My code: I am especially concerned that this is functionally the same.

  while (Serial.available()) {
#2

You have changed from ss to Serial. How can this be the same?

#3

looks like the original code instantiated (i.e constructed) the serial interface at run time using a pointer

 ss = new SoftwareSerial (GPS_RX_PIN, GPS_TX_PIN, GPS_INVERT, GPS_BUFSIZE);

the change defined it statically as a variable

SoftwareSerial ss(GPS_RX_PIN, GPS_TX_PIN);

hence the use of "->" and "."

i'm curious what the compiler error was

#4

gcjr:
looks like the original code instantiated (i.e constructed) the serial interface at run time using a pointer

 ss = new SoftwareSerial (GPS_RX_PIN, GPS_TX_PIN, GPS_INVERT, GPS_BUFSIZE);

the change defined it statically as a variable

SoftwareSerial ss(GPS_RX_PIN, GPS_TX_PIN);

hence the use of "->" and "."

i'm curious what the compiler error was

This is the statement that the compiler highlighted.

ss = new SoftwareSerial (GPS_RX_PIN, GPS_TX_PIN, GPS_INVERT, GPS_BUFSIZE);

Here is the original sketch compiled and its error. I think that the new syntax is only looking for 2 parameters rather than 4.

Arduino: 1.8.5 (Linux), Board: "Adafruit Feather HUZZAH ESP8266, 80 MHz, Flash, Legacy (new can return nullptr), All SSL ciphers (most compatible), 4MB (FS:2MB OTA:~1019KB), v2 Lower Memory, Disabled, None, Only Sketch, 115200"

sketch/Circum.cpp: In constructor 'Circum::Circum()':
Circum.cpp:21: error: no matching function for call to 'SoftwareSerial::SoftwareSerial(int, int, bool, int)'
  ss = new SoftwareSerial (GPS_RX_PIN, GPS_TX_PIN, GPS_INVERT, GPS_BUFSIZE);
                                                                          ^
sketch/Circum.cpp:21:74: note: candidates are:
In file included from sketch/Circum.h:5:0,
                 from sketch/Circum.cpp:5:
/home/hexdump/Arduino-1.8.5/hardware/esp8266com/esp8266/libraries/SoftwareSerial/src/SoftwareSerial.h:94:5: note: SoftwareSerial::SoftwareSerial(int8_t, int8_t, bool)
     SoftwareSerial(int8_t rxPin, int8_t txPin = -1, bool invert = false);
     ^
Multiple libraries were found for "SoftwareSerial.h"
 Used: /home/hexdump/Arduino-1.8.5/hardware/esp8266com/esp8266/libraries/SoftwareSerial
 Not used: /home/hexdump/Arduino-1.8.5/Sketches/libraries/EspSoftwareSerial
/home/hexdump/Arduino-1.8.5/hardware/esp8266com/esp8266/libraries/SoftwareSerial/src/SoftwareSerial.h:94:5: note:   candidate expects 3 arguments, 4 provided
/home/hexdump/Arduino-1.8.5/hardware/esp8266com/esp8266/libraries/SoftwareSerial/src/SoftwareSerial.h:90:5: note: SoftwareSerial::SoftwareSerial()
     SoftwareSerial();
     ^
/home/hexdump/Arduino-1.8.5/hardware/esp8266com/esp8266/libraries/SoftwareSerial/src/SoftwareSerial.h:90:5: note:   candidate expects 0 arguments, 4 provided
exit status 1
no matching function for call to 'SoftwareSerial::SoftwareSerial(int, int, bool, int)'

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
#5 
I think that I got it working like this

[code}
[b]Original code[/b]
	ss = new SoftwareSerial (GPS_RX_PIN, GPS_TX_PIN, GPS_INVERT, GPS_BUFSIZE);
	ss->begin(GPS_BAUD);

[b]Changed to:[/b]
 ss = new SoftwareSerial (GPS_RX_PIN, GPS_TX_PIN);
 ss->begin(GPS_BAUD);
#6

that would be consistent with the error

#7