[Due] pgm_read_ptr causes error

[bobc]

Arduino IDE 1.6.8
Arduino AVR Boards 1.6.10
Arduino SAM Boards 1.6.9

On Mega2560, the following sketch compiles OK:

void setup() {
  // put your setup code here, to run once:
  char str_debug_1[] PROGMEM = "ECHO";
  Serial.print((char*)pgm_read_ptr(&str_debug_1));
}

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

On Due, the same sketch has a compile error :

In file included from C:\Users\bob\AppData\Local\Arduino15\packages\arduino\hardware\sam\1.6.9\cores\arduino/Arduino.h:31:0,

                 from C:\Users\bob\AppData\Local\Temp\build3a01f77cc023d803352a39f55ca441db.tmp\sketch\sketch_pgm_read_test.ino.cpp:1:

C:\Users\bob\Documents\Arduino\sketch_pgm_read_test\sketch_pgm_read_test.ino: In function 'void setup()':

C:\Users\bob\AppData\Local\Arduino15\packages\arduino\hardware\sam\1.6.9\cores\arduino/avr/pgmspace.h:106:49: error: 'const void*' is not a pointer-to-object type

 #define pgm_read_ptr(addr) (*(const void *)(addr))

                                                 ^

C:\Users\bob\Documents\Arduino\sketch_pgm_read_test\sketch_pgm_read_test.ino:6:23: note: in expansion of macro 'pgm_read_ptr'

   Serial.print((char*)pgm_read_ptr(&str_debug_1));

                       ^

exit status 1
Error compiling for board Arduino Due (Programming Port).

Inspection of pgm_read_ptr (in avr/pgmspace.h) for Due shows : -
#define pgm_read_ptr(addr) (*(const void *)(addr))

This macro casts the argument void *, then tries to dereference a void *, which is guaranteed to never work.

Probably, the cast to (void *) is not needed.

[agdl]

This issue was moved to arduino/ArduinoCore-sam#21