Build warnings -- [-Wignored-qualifiers]

[henrygab]

original log example

click to expand

/home/runner/.arduino15/packages/adafruit/hardware/samd/1.6.0/cores/arduino/Reset.cpp: In function 'void banzai()':
/home/runner/.arduino15/packages/adafruit/hardware/samd/1.6.0/cores/arduino/Reset.cpp:32:55: warning: type qualifiers ignored on cast result type [-Wignored-qualifiers]
   32 | #define APP_START ((volatile uint32_t)(&__text_start__) + 4)
      |                                                       ^
/home/runner/.arduino15/packages/adafruit/hardware/samd/1.6.0/cores/arduino/Reset.cpp:77:6: note: in expansion of macro 'APP_START'
   77 |  if (APP_START < (0x200 + 4)) {
      |      ^~~~~~~~~

/home/runner/.arduino15/packages/adafruit/hardware/samd/1.6.0/cores/arduino/Reset.cpp:32:55: warning: type qualifiers ignored on cast result type [-Wignored-qualifiers]
   32 | #define APP_START ((volatile uint32_t)(&__text_start__) + 4)
      |                                                       ^
/home/runner/.arduino15/packages/adafruit/hardware/samd/1.6.0/cores/arduino/Reset.cpp:87:46: note: in expansion of macro 'APP_START'
   87 |  NVMCTRL->ADDR.reg  = (uintptr_t)&NVM_MEMORY[APP_START / 4];
      |                                              ^~~~~~~~~

/home/runner/.arduino15/packages/adafruit/hardware/samd/1.6.0/cores/arduino/Reset.cpp: In function 'void banzai()':
/home/runner/.arduino15/packages/adafruit/hardware/samd/1.6.0/cores/arduino/Reset.cpp:32:55: warning: type qualifiers ignored on cast result type [-Wignored-qualifiers]
   32 | #define APP_START ((volatile uint32_t)(&__text_start__) + 4)
      |                                                       ^

See https://github.com/adafruit/ArduinoCore-samd/runs/965558867.

Simplified log

.../samd/1.6.0/cores/arduino/Reset.cpp: In function 'void banzai()':

.../samd/1.6.0/cores/arduino/Reset.cpp:32:55: 
    warning: type qualifiers ignored on cast result type [-Wignored-qualifiers]
   32 | #define APP_START ((volatile uint32_t)(&__text_start__) + 4)
      |                                                       ^
.../samd/1.6.0/cores/arduino/Reset.cpp:77:6:
    note: in expansion of macro 'APP_START'
   77 |  if (APP_START < (0x200 + 4)) {
      |      ^~~~~~~~~

.../samd/1.6.0/cores/arduino/Reset.cpp:32:55:
    warning: type qualifiers ignored on cast result type [-Wignored-qualifiers]
   32 | #define APP_START ((volatile uint32_t)(&__text_start__) + 4)
      |                                                       ^
..../samd/1.6.0/cores/arduino/Reset.cpp:87:46:
    note: in expansion of macro 'APP_START'
   87 |  NVMCTRL->ADDR.reg  = (uintptr_t)&NVM_MEMORY[APP_START / 4];
      |                                              ^~~~~~~~~

-Wignored-qualifiers information

Best explanation may be in another github comment.

Interpretation

Basically, casting to a volatile uint32_t doesn't make sense, as it's treated as a standard uint32_t?

Recommendation

tbd