SDCC version > 3.6.0 error 91: extern definition for 'putchar' mismatches with declaration

[ghost]

When you want to compile the source without error, with a version of SDCC > 3.6.0, you need to change the putchar() function prototype to fit SDCC, bacause it was changed. I tested it on SDCC v4.0 (Linux Fedora 33).

In display.h

#ifndef LOCAL
//void putchar(char c);
int putchar(int c);
#endif

and in display.c

/* sdcc provides printf if we provide this */
//void putchar(char c)
int putchar(int c)
{
 ....
 return(c);
}

[samyk]

Thanks - do you know the exact version it needs to be adjusted or have a link with further info on the version with the change? Adjusting that fails to compile on sdcc 3.4.0 so would like some ifdefs to support both.

[ghost]

The change of putchar() prototype was made in version 3.7.0

SDCC 3.7.0 Feature List:

• Changed putchar() prototype from void putchar(char) to int putchar(int) to improve standard-compliance and allow error reporting.

It was a fix of an issue from 2016-06-16 (SDCC changelog):

• Make putchar() prototype standard-compliant, fix bug #2505.

[samyk]

Cool, it will now check version of sdcc to decide what to do. Hopefully that resolves it!

[Ivan275g4]

I'm not sure that actually fixed it at least not for me under Windows/Linux with SDCC 4.0.0 I will start by saying I don't know wtf I'm doing but.... Shouldn't #if (SDCC_VERSION_HI == 3 && SDCC_VERSION_LO >= 7) || (SDCC_VERSION_HI >= 4) be #if (__SDCC_VERSION_MAGOR == 3 && __SDCC_VERSION_MINOR >= 7) || (__SDCC_VERSION_MAJOR >= 4)

also both in display C and H, the declaration and use of putchar() needs to be fixed for >3.7. With the code above the Int/Int that is expected turns to int/char with the current code. Adding PUTCHAR_TYPE2 fixes that. But I'm not a fan of that name.

display.h

// sdcc 3.7.0+ uses int putchar
#if (__SDCC_VERSION_MAGOR == 3 && __SDCC_VERSION_MINOR >= 7) || (__SDCC_VERSION_MAJOR >= 4)
  #define PUTCHAR_INT
  #define PUTCHAR_TYPE int
  #define PUTCHAR_TYPE2 int
#else
  #define PUTCHAR_TYPE void
  #define PUTCHAR_TYPE2 char
#endif

display.h

#ifndef LOCAL
	PUTCHAR_TYPE putchar(PUTCHAR_TYPE2 c);
#endif

display.c

/* sdcc provides printf if we provide this */
PUTCHAR_TYPE putchar(PUTCHAR_TYPE2 c)
{
#ifdef SIMULATOR
	while (!TI); /*  wait end of last transmission */
	TI = 0;
	SBUF = c; /*  transmit to serial */
#else
	u8 i;
	c &= 0x7f;
	if (c >= FONT_OFFSET)
	{
		for (i = 0; i < FONT_WIDTH; i++)
			txData(font[c - FONT_OFFSET][i] ^ (reverseTxt ? 0xff : 0));
		txData(reverseTxt ? 0xff : 0x00);
	}
#endif
#ifdef PUTCHAR_INT
  return c;
#endif
}