Re: INSTALL should tell about particular systems, HP-UX cc

[Ralf Wildenhues]

* Bruno Haible wrote on Sun, Apr 13, 2008 at 05:17:43PM CEST:
> Ralf Wildenhues wrote:
> 
> > c.m4 _AC_PROG_CC_C89 already checks for -Ae, so I don't understand
> > why it's not used automatically (AC_PROG_CC calls that macro).
> 
> In the particular case of HP-UX:
> 
>   - On a system where the expensive HP C compiler is not installed, the
>     autoconf test certainly tried "cc -Ae" and this failed, so -Ae was
>     not added to CC or the CFLAGS.

OK, IIUC then we don't need to care about this case at all, right?

>   - On a system where the expensive HP C compiler is installed:
>     If it's a HP-UX 10 system, "cc" is only K&R C, so _AC_PROG_CC_C89 will
>     add -Ae; good.

OK.

>     If it's a HP-UX 11 system, "cc" understands ANSI C, so _AC_PROG_CC_C89
>     does nothing:
[...]
> But -Ae is generally needed on HP-UX, so that system functions get declared
> in the header files. AC_USE_SYSTEM_EXTENSIONS cares about it in the case of
> GNU systems and Solaris systems, but not for HP-UX.

This sounds like there's a  bug in either _AC_PROG_CC_C89 or
AC_USE_SYSTEM_EXTENSIONS, or both.  This isn't a part of Autoconf code
I know very well, so I'd appreciate if somebody else could take a look.

> I can agree to dropping the recommendation to try CC="cc -Ae" if
> 
>   1) AC_USE_SYSTEM_EXTENSIONS is modified to add -Ae on HP-UX with cc, if
>      it is not already present in $CC.

Is there an "or" or an "and" connecting (1) and (2)?

>   2) The "checking whether the C compiler works..." test is made sharper,
>      to reject compilers which support only K&R C and not ANSI C. Today,
>      even GCC and Emacs use ANSI C features. The guy in [1] (presumably
>      on a HP-UX 10 system, where "cc" was only K&R C and "cc -Ae" did not
>      work) should have received a message about his C compiler not working,
>      instead of bugging the Amanda developers who then bugged the gnulib
>      developers.

Judging from the manual, I'd expect AC_PROG_CC_STDC to achieve this
(so if it doesn't, it should be fixed).

Cheers,
Ralf