Ports should no longer use pyhelp_print_obj but instead should define
MICROPY_PY_BUILTINS_HELP to 1 and then specify their help text using
MICROPY_PY_BUILTINS_HELP_TEXT.
This happens with some compilers on some architectures, which don't define
size_t as unsigned int. MicroPython's printf() dooesn't support obscure
format specifiers for size_t, so the obvious choice is to explicitly cast
to unsigned, to match %u used in printf().
In order to have more fine-grained control over how builtin functions are
constructed, the MP_DECLARE_CONST_FUN_OBJ macros are made more specific,
with suffix of _0, _1, _2, _3, _VAR, _VAR_BETEEN or _KW. These names now
match the MP_DEFINE_CONST_FUN_OBJ macros.
Now there is just one function to allocate a new vstr, namely vstr_new
(in addition to vstr_init etc). The caller of this function should know
what initial size to allocate for the buffer, or at least have some policy
or config option, instead of leaving it to a default (as it was before).
"Forced exit" is treated as soft-reboot (Ctrl+D). But expected effect of
calling sys.exit() is termination of the current script, not any further
and more serious actions like mentioned soft reboot.
This new config option allows to control whether MicroPython uses its own
internal printf or not (if not, an external one should be linked in).
Accompanying this new option is the inclusion of lib/utils/printf.c in the
core list of source files, so that ports no longer need to include it
themselves.
Several ports use identical code for the 1-argument form of the builtin
help function. Move this code to a library function to allow easier
re-use by ports.