Invalid conversion from 'void (*)()' to 'void (*)(char*) compilation errors

[Twilight-Logic]

..does not compile. Errors are
AR488-0-45-10:758: error: invalid conversion from 'void ()()' to 'void ()(char*)' [-fpermissive]
plenty of them..
AR488-0-45-10:758: error: invalid conversion from 'void ()()' to 'void ()(char*)' [-fpermissive]

UPDATE:
error handling seems to have been downgraded to warnings after updating Arduino IDE fro 1.6.5 to 1.8.19
Kutte

[Twilight-Logic]

Have tested with the standalone IDE version 1.8.7 and 1.8.8 downloaded directly from the Arduino site and did not receive the errors or warnings. However, then tested with v1.8.8/1.8.19.0 downloaded from the Windows 10 store and discovered that these warnings do indeed appear.

Will investigate further to see whether the code can be adjusted to avoid them.

[Twilight-Logic]

Line 413: changed the expression NULL to character expression '\0'.
This seemed to resolve the warnings and the code compiled cleanly.

[Twilight-Logic]

Further warnings reported by Kutte:

Y:\USB_16GB\Voltage reference\GPIB\ar488-arduino\ar488\AR488.ino:153:0: warning: "SPE" redefined

#define SPE 0x18

In file included from c:\program files (x86)\arduino\hardware\tools\avr\avr\include\avr\io.h:272:0,
from c:\program files (x86)\arduino\hardware\tools\avr\avr\include\avr\pgmspace.h:90,
from C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/Arduino.h:28,
from sketch\AR488.ino.cpp:1:
c:\program files (x86)\arduino\hardware\tools\avr\avr\include\avr\iom328p.h:294:0: note: this is the location of the previous definition
#define SPE 6
Y:\USB_16GB\Voltage reference\GPIB\ar488-arduino\ar488\AR488.ino:758:1: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]

Y:\USB_16GB\Voltage reference\GPIB\ar488-arduino\ar488\AR488.ino:758:1: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]

Y:\USB_16GB\Voltage reference\GPIB\ar488-arduino\ar488\AR488.ino:758:1: warning: invalid conversion from 'void ()()' to 'void ()(char*)' [-fpermissive]

Y:\USB_16GB\Voltage reference\GPIB\ar488-arduino\ar488\AR488.ino:758:1: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]

[Twilight-Logic]

In the new release of the code (0.46.01), the names of the #define variables related to GPIB commands (e.g. SPE) have been changed to avoid clashes with other Arduino modules.

[Twilight-Logic]

Further corrections made to the code to remove all warnings. By default it seems that this setting is now set to None, so all warnings were hidden. Compilation is now done with the Arduino IDE set to show ALL compiler warnings.