+ Autoconf Macro: ax_cflags_gcc

+ Description +

+ AX_CFLAGS_GCC_OPTION(-fvomit-frame) would show a message as like "checking + CFLAGS for gcc -fvomit-frame ... yes" and adds the optionflag to CFLAGS if + it is understood. You can override the shellvar-default of CFLAGS of + course. The order of arguments stems from the explicit macros like AX_CFLAGS_WARN_ALL. +

+ The cousin AX_CXXFLAGS_GCC_OPTION would check for an option to add to + CXXFLAGS - and it uses the autoconf setup for C++ instead of C (since it is + possible to use different compilers for C and C++). +

+ The macro is a lot simpler than any special AX_CFLAGS_* macro (or + ac_cxx_rtti.m4 macro) but allows to check for arbitrary options. However, + if you use this macro in a few places, it would be great if you would make + up a new function-macro and submit it to the ac-archive. +

+  - $1 option-to-check-for : required ("-option" as non-value)
+  - $2 shell-variable-to-add-to : CFLAGS (or CXXFLAGS in the other case)
+  - $3 action-if-found : add value to shellvariable
+  - $4 action-if-not-found : nothing
+

+ Note: in earlier versions, $1-$2 were swapped. We try to detect the + situation and accept a $2=~/-/ as being the old option-to-check-for. +

+ There are other variants that emerged from the original macro variant which + did just test an option to be possibly added. However, some compilers + accept an option silently, or possibly for just another option that was not + intended. Therefore, we have to do a generic test for a compiler family. + For gcc we check "-pedantic" being accepted which is also understood by + compilers who just want to be compatible with gcc even when not being made + from gcc sources. +

+ Author +

+ Last Modified +

+ Cross References +

+ M4 Source Code +

+AC_DEFUN([AX_CFLAGS_GCC_OPTION_OLD], [dnl
+AS_VAR_PUSHDEF([FLAGS],[CFLAGS])dnl
+AS_VAR_PUSHDEF([VAR],[ac_cv_cflags_gcc_option_$2])dnl
+AC_CACHE_CHECK([m4_ifval($1,$1,FLAGS) for gcc m4_ifval($2,$2,-option)],
+VAR,[VAR="no, unknown"
+ AC_LANG_SAVE
+ AC_LANG_C
+ ac_save_[]FLAGS="$[]FLAGS"
+for ac_arg dnl
+in "-pedantic -Werror % m4_ifval($2,$2,-option)"  dnl   GCC
+   "-pedantic % m4_ifval($2,$2,-option) %% no, obsolete"  dnl new GCC
+   #
+do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
+   AC_TRY_COMPILE([],[return 0;],
+   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+done
+ FLAGS="$ac_save_[]FLAGS"
+ AC_LANG_RESTORE
+])
+case ".$VAR" in
+     .ok|.ok,*) m4_ifvaln($3,$3) ;;
+   .|.no|.no,*) m4_ifvaln($4,$4) ;;
+   *) m4_ifvaln($3,$3,[
+   if echo " $[]m4_ifval($1,$1,FLAGS) " | grep " $VAR " 2>&1 >/dev/null
+   then AC_RUN_LOG([: m4_ifval($1,$1,FLAGS) does contain $VAR])
+   else AC_RUN_LOG([: m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"])
+                      m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"
+   fi ]) ;;
+esac
+AS_VAR_POPDEF([VAR])dnl
+AS_VAR_POPDEF([FLAGS])dnl
+])
+
+
+dnl the only difference - the LANG selection... and the default FLAGS
+
+AC_DEFUN([AX_CXXFLAGS_GCC_OPTION_OLD], [dnl
+AS_VAR_PUSHDEF([FLAGS],[CXXFLAGS])dnl
+AS_VAR_PUSHDEF([VAR],[ac_cv_cxxflags_gcc_option_$2])dnl
+AC_CACHE_CHECK([m4_ifval($1,$1,FLAGS) for gcc m4_ifval($2,$2,-option)],
+VAR,[VAR="no, unknown"
+ AC_LANG_SAVE
+ AC_LANG_CPLUSPLUS
+ ac_save_[]FLAGS="$[]FLAGS"
+for ac_arg dnl
+in "-pedantic -Werror % m4_ifval($2,$2,-option)"  dnl   GCC
+   "-pedantic % m4_ifval($2,$2,-option) %% no, obsolete"  dnl new GCC
+   #
+do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
+   AC_TRY_COMPILE([],[return 0;],
+   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+done
+ FLAGS="$ac_save_[]FLAGS"
+ AC_LANG_RESTORE
+])
+case ".$VAR" in
+     .ok|.ok,*) m4_ifvaln($3,$3) ;;
+   .|.no|.no,*) m4_ifvaln($4,$4) ;;
+   *) m4_ifvaln($3,$3,[
+   if echo " $[]m4_ifval($1,$1,FLAGS) " | grep " $VAR " 2>&1 >/dev/null
+   then AC_RUN_LOG([: m4_ifval($1,$1,FLAGS) does contain $VAR])
+   else AC_RUN_LOG([: m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"])
+                      m4_ifval($1,$1,FLAGS)="$m4_ifval($1,$1,FLAGS) $VAR"
+   fi ]) ;;
+esac
+AS_VAR_POPDEF([VAR])dnl
+AS_VAR_POPDEF([FLAGS])dnl
+])
+
+dnl -------------------------------------------------------------------------
+
+AC_DEFUN([AX_CFLAGS_GCC_OPTION_NEW], [dnl
+AS_VAR_PUSHDEF([FLAGS],[CFLAGS])dnl
+AS_VAR_PUSHDEF([VAR],[ac_cv_cflags_gcc_option_$1])dnl
+AC_CACHE_CHECK([m4_ifval($2,$2,FLAGS) for gcc m4_ifval($1,$1,-option)],
+VAR,[VAR="no, unknown"
+ AC_LANG_SAVE
+ AC_LANG_C
+ ac_save_[]FLAGS="$[]FLAGS"
+for ac_arg dnl
+in "-pedantic -Werror % m4_ifval($1,$1,-option)"  dnl   GCC
+   "-pedantic % m4_ifval($1,$1,-option) %% no, obsolete"  dnl new GCC
+   #
+do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
+   AC_TRY_COMPILE([],[return 0;],
+   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+done
+ FLAGS="$ac_save_[]FLAGS"
+ AC_LANG_RESTORE
+])
+case ".$VAR" in
+     .ok|.ok,*) m4_ifvaln($3,$3) ;;
+   .|.no|.no,*) m4_ifvaln($4,$4) ;;
+   *) m4_ifvaln($3,$3,[
+   if echo " $[]m4_ifval($2,$2,FLAGS) " | grep " $VAR " 2>&1 >/dev/null
+   then AC_RUN_LOG([: m4_ifval($2,$2,FLAGS) does contain $VAR])
+   else AC_RUN_LOG([: m4_ifval($2,$2,FLAGS)="$m4_ifval($2,$2,FLAGS) $VAR"])
+                      m4_ifval($2,$2,FLAGS)="$m4_ifval($2,$2,FLAGS) $VAR"
+   fi ]) ;;
+esac
+AS_VAR_POPDEF([VAR])dnl
+AS_VAR_POPDEF([FLAGS])dnl
+])
+
+
+dnl the only difference - the LANG selection... and the default FLAGS
+
+AC_DEFUN([AX_CXXFLAGS_GCC_OPTION_NEW], [dnl
+AS_VAR_PUSHDEF([FLAGS],[CXXFLAGS])dnl
+AS_VAR_PUSHDEF([VAR],[ac_cv_cxxflags_gcc_option_$1])dnl
+AC_CACHE_CHECK([m4_ifval($2,$2,FLAGS) for gcc m4_ifval($1,$1,-option)],
+VAR,[VAR="no, unknown"
+ AC_LANG_SAVE
+ AC_LANG_CPLUSPLUS
+ ac_save_[]FLAGS="$[]FLAGS"
+for ac_arg dnl
+in "-pedantic -Werror % m4_ifval($1,$1,-option)"  dnl   GCC
+   "-pedantic % m4_ifval($1,$1,-option) %% no, obsolete"  dnl new GCC
+   #
+do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
+   AC_TRY_COMPILE([],[return 0;],
+   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+done
+ FLAGS="$ac_save_[]FLAGS"
+ AC_LANG_RESTORE
+])
+case ".$VAR" in
+     .ok|.ok,*) m4_ifvaln($3,$3) ;;
+   .|.no|.no,*) m4_ifvaln($4,$4) ;;
+   *) m4_ifvaln($3,$3,[
+   if echo " $[]m4_ifval($2,$2,FLAGS) " | grep " $VAR " 2>&1 >/dev/null
+   then AC_RUN_LOG([: m4_ifval($2,$2,FLAGS) does contain $VAR])
+   else AC_RUN_LOG([: m4_ifval($2,$2,FLAGS)="$m4_ifval($2,$2,FLAGS) $VAR"])
+                      m4_ifval($2,$2,FLAGS)="$m4_ifval($2,$2,FLAGS) $VAR"
+   fi ]) ;;
+esac
+AS_VAR_POPDEF([VAR])dnl
+AS_VAR_POPDEF([FLAGS])dnl
+])
+
+AC_DEFUN([AX_CFLAGS_GCC_OPTION],[ifelse(m4_bregexp([$2],[-]),-1,
+[AX_CFLAGS_GCC_OPTION_NEW($@)],[AX_CFLAGS_GCC_OPTION_OLD($@)])])
+
+AC_DEFUN([AX_CXXFLAGS_GCC_OPTION],[ifelse(m4_bregexp([$2],[-]),-1,
+[AX_CXXFLAGS_GCC_OPTION_NEW($@)],[AX_CXXFLAGS_GCC_OPTION_OLD($@)])])
+

+ License +

+ This program is free software; you can redistribute it and/or modify it + under the terms of the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at your option) + any later version. +

+ This program is distributed in the hope that it will be useful, but WITHOUT + ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + more details. +

+ You should have received a copy of the GNU General Public License along + with this program; if not, write to the Free Software Foundation, Inc., 59 + Temple Place - Suite 330, Boston, MA 02111-1307, USA. +

+ As a special exception, the respective Autoconf Macro's copyright owner + gives unlimited permission to copy, distribute and modify the configure + scripts that are the output of Autoconf when processing the Macro. You need + not follow the terms of the GNU General Public License when using or + distributing such scripts, even though portions of the text of the Macro + appear in them. The GNU General Public License (GPL) does govern all other + use of the material that constitutes the Autoconf Macro. +

+ This special exception to the GPL applies to versions of the Autoconf Macro + released by the Autoconf Macro Archive. When you make and distribute a + modified version of the Autoconf Macro, you may extend this special + exception to the GPL to apply to your modified version as well. +