picolib: stdio.h is missing extern "C"

[nolange]

This should be fixed since 1.8.7: picolibc/picolibc@c4b55b0

including stdio.h or cstdio will result in subtle to obvious breakage:

#include <stdio.h>

#ifdef FDEV_SETUP_STREAM

namespace {

int sample_putc(char c, FILE *file)
{
	(void) file;		/* Not used in this function */
	// __uart_putc(c);		/* Defined by underlying system */
	return c;
}

int sample_getc(FILE *file)
{
	unsigned char c = '\0';
	(void) file;		/* Not used in this function */
	// c = __uart_getc();	/* Defined by underlying system */
	return c;
}
FILE __stdio = FDEV_SETUP_STREAM(sample_putc,
					sample_getc,
					NULL,
					_FDEV_SETUP_RW);

} // namespace
extern "C" {
FILE *const stdin = &__stdio; __strong_reference(stdin, stdout); __strong_reference(stdin, stderr);
}

#endif // FDEV_SETUP_STREAM

[voltur01]

Hi, this fix should be available in the builds from the main branch now or you can rebuild llvm-19 branch with updated picolibc revision in https://github.com/ARM-software/LLVM-embedded-toolchain-for-Arm/blob/llvm-19/versions.json