Gary V. Vaughan wrote: > But why emit a warning when > we can just fix-up the definition on the fly? ... > This changeset fixes AC_PROG_CC_C99 > (and effectively AC_PROG_CC_STDC) whether it is called before or > after gl_EARLY, directly or by AC_PROG_CC_STDC, or even not at all! > ... > +[AC_PROVIDE_IFELSE([AC_PROG_CC_C99], > + [AC_DEFUN([AC_PROG_CC_C99])], > + [AC_DEFUN([AC_PROG_CC_C99], > + m4_defn([AC_PROG_CC_C99])[AC_DEFUN([AC_PROG_CC_C99])])])])
We can't use this. AC_PROVIDE_IFELSE is undocumented. > By putting the fix in gl_EARLY rather than autoconf itself, there's > still the possibility of getting multiple expansions with something > like: > > AC_PROG_CC > AC_PROG_CC_C99 > AC_PROG_CC_STDC > gl_EARLY > > But that seems pathological to me in any case, so I haven't tried to > address that. That's why I think it should be addressed in Autoconf. > * m4/gnulib-common (gl_PROG_CC_C99_ONCE): New macro to automatically > neuter AC_PROG_CC_C99 after first invocation. We didn't say that we want to enable C99 for all programs. See <http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00441.html> > +2011-09-30 Gary V. Vaughan <g...@gnu.org> > + > + stdarg: don't expand AC_PROG_CC_C99 multiple times. If a change affects gnulib-tool, the ChangeLog entry shouldn't pretend that it affects only the 'stdarg' module. I'm applying this for now. Maybe you have a more acceptable workaround against the "$CC gets augmented twice" problem? 2011-09-30 Bruno Haible <br...@clisp.org> Centralize C99 requirement. * m4/gnulib-common.m4 (gl_PROG_CC_C99): New macro. * modules/stdarg (configure.ac-early): Invoke it instead of AC_PROG_CC_STDC. Reported by Gary V. Vaughan and Paul Eggert. --- m4/gnulib-common.m4.orig Fri Sep 30 11:46:01 2011 +++ m4/gnulib-common.m4 Fri Sep 30 11:43:50 2011 @@ -1,4 +1,4 @@ -# gnulib-common.m4 serial 30 +# gnulib-common.m4 serial 31 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -211,6 +211,29 @@ [m4_define([AS_VAR_IF], [AS_IF([test x"AS_VAR_GET([$1])" = x""$2], [$3], [$4])])]) +# gl_PROG_CC_C99 +# Modifies the value of the shell variable CC in an attempt to make $CC +# understand ISO C99 source code. +# This is like AC_PROG_CC_C99, except that +# - AC_PROG_CC_C99 did not exist in Autoconf versions < 2.60, +# - AC_PROG_CC_C99 does not mix well with AC_PROG_CC_STDC +# <http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00367.html>, +# but many more packages use AC_PROG_CC_STDC than AC_PROG_CC_C99 +# <http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00441.html>. +# Remaining problems: +# - When AC_PROG_CC_STDC is invoked twice, it adds the C99 enabling options +# to CC twice +# <http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00431.html>. +# - AC_PROG_CC_STDC is likely to change when C1X is an ISO standard. +AC_DEFUN([gl_PROG_CC_C99], +[ + dnl Change that version number to the minimum Autoconf version that supports + dnl mixing AC_PROG_CC_C99 calls with AC_PROG_CC_STDC calls. + m4_version_prereq([9.0], + [AC_REQUIRE([AC_PROG_CC_C99])], + [AC_REQUIRE([AC_PROG_CC_STDC])]) +]) + # gl_PROG_AR_RANLIB # Determines the values for AR, ARFLAGS, RANLIB that fit with the compiler. # The user can set the variables AR, ARFLAGS, RANLIB if he wants to override --- modules/stdarg.orig Fri Sep 30 11:46:01 2011 +++ modules/stdarg Fri Sep 30 11:37:20 2011 @@ -11,9 +11,9 @@ configure.ac-early: dnl Some compilers (e.g., AIX 5.3 cc) need to be in c99 mode dnl for the builtin va_copy to work. With Autoconf 2.60 or later, -dnl AC_PROG_CC_STDC arranges for this. With older Autoconf AC_PROG_CC_STDC +dnl gl_PROG_CC_C99 arranges for this. With older Autoconf gl_PROG_CC_C99 dnl shouldn't hurt, though installers are on their own to set c99 mode. -AC_REQUIRE([AC_PROG_CC_STDC]) +gl_PROG_CC_C99 configure.ac: gl_STDARG_H -- In memoriam Kelsang Namtso <http://en.wikipedia.org/wiki/Nangpa_La_shooting_incident>
