Fix conflict with declaration in std lib and gcc version > 4.9.2. See issue #4002

[jlbirccyn]

See issue #4002

[sandeepmistry]

@jlbirccyn thank you for submitting this!

I just tried it with gcc-arm-none-eabi-5_3-2016q1, but get the following build error:

/Users/smistry/Documents/Arduino/hardware/arduino/sam/cores/arduino/itoa.c:124:14: error: conflicting types for 'utoa'
 extern char* utoa( unsigned long value, char *string, int radix )
              ^
In file included from /Users/smistry/Documents/Arduino/hardware/arduino/sam/cores/arduino/itoa.c:19:0:
/Users/smistry/Documents/Arduino/hardware/arduino/sam/cores/arduino/itoa.h:38:14: note: previous declaration of 'utoa' was here
 extern char* utoa( unsigned value, char *string, int radix ) ;
              ^
exit status 1
Error compiling for board Arduino Due (Programming Port).

Is there any reason why the equivalent change from itoa.h is not in itoa.c?

[joshingyou]

Agree with @sandeepmistry just tried your change and got the same error about conflicting declaration of utoa

[cmaglie]

The latest newlib provides itoa too, also this function should be put under guards. Weird that the compiler doesn't throw errors on itoa, maybe because in this case the stub has the exact same signature as the lib function.

arm-none-eabi/include$ grep [iu]toa -r *
stdlib.h:char * _EXFUN(__itoa,(int, char *, int));
stdlib.h:char * _EXFUN(__utoa,(unsigned, char *, int));
stdlib.h:char * _EXFUN(itoa,(int, char *, int));
stdlib.h:char * _EXFUN(utoa,(unsigned, char *, int));

[cmaglie]

Fixed with #5480.
The implementation of itoa and utoa inside the Arduino core will be removed when the bundled arm-gcc will be upgraded.