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Date: Fri, 21 May 2021 21:47:36 -0400
From: Mike Frysinger <vapier@gentoo.org>
To: "naohirot@fujitsu.com" <naohirot@fujitsu.com>
Cc: "libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Subject: Re: [PATCH v4] configure: Replaced obsolete AC_TRY_COMPILE
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On 22 May 2021 01:32, naohirot@fujitsu.com wrote:
> > On 11 May 2021 01:34, Naohiro Tamura wrote:
> > > --- a/configure.ac
> > > +++ b/configure.ac
> > >
> > > -[AC_TRY_COMPILE([], [
> > > +[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
> > >  #ifdef _FORTIFY_SOURCE
> > >  # error bogon
> > > -#endif],
> > > +#endif]])],
> > 
> > this can be AC_PREPROC_IFELSE
> 
> In case of _FORTIFY_SOURCE, it requires compiler optimize option more than -O1.
> 
> $ man  FEATURE_TEST_MACROS
> 
>    If _FORTIFY_SOURCE is set to 1, with compiler optimization level 1 (gcc -O1) and above, checks that shouldn't change the behavior  of  con‐
>    forming programs are performed.  With _FORTIFY_SOURCE set to 2, some more checking is added, but some conforming programs might fail.

you'll want to leave a dnl in there explaining why so the next person doesn't
try to "fix" it.
-mike