Re: Wrong order of preprocessor and compiler flags

On 2022-03-23, Zack Weinberg <[email protected]> wrote:
> On Wed, Mar 23, 2022, at 11:31 AM, Evgeny Grin wrote:
>> I've found that everywhere in autoconf scripts flags are used like:
>> $CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&AS_MESSAGE_LOG_FD
>> while automake and libtool use flags in the other order:
>> $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS)
>> $(AM_CFLAGS) $(CFLAGS)
>
> I agree that this should be made consistent, but before we change
> anything, we need to check what the rules *built into GNU and BSD
> Make* do with CFLAGS and CPPFLAGS (and also CXXFLAGS, OBJCFLAGS, etc)
> because those are much much harder to get changed than anything in
> Automake or Autoconf, so we should aim to harmonize everything with
> them.

Practically all make implementations use the $(CFLAGS) $(CPPFLAGS)
ordering in their builtin .c.o inference rules.

However, GNU coding standards state that CFLAGS should be the last
item on compilation commands, so it would appear that this is a case
where traditional "make" behaviour contrasts with GNU standards (which
Automake is following).

Cheers,
  Nick