@node ax_check_preproc_flag
@unnumberedsec ax_check_preproc_flag

@majorheading Synopsis

@smallexample
AX_CHECK_PREPROC_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
@end smallexample

@majorheading Description

Check whether the given FLAG works with the current language's
preprocessor or gives an error.  (Warnings, however, are ignored)

ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
success/failure.

If EXTRA-FLAGS is defined, it is added to the preprocessor's default
flags when the check is done.  The check is thus made with the flags:
"CPPFLAGS EXTRA-FLAGS FLAG".  This can for example be used to force the
preprocessor to issue an error when a bad flag is given.

INPUT gives an alternative input source to AC_PREPROC_IFELSE.

NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
macro in sync with AX_CHECK_@{COMPILE,LINK@}_FLAG.

@majorheading Source Code

Download the
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_check_preproc_flag.m4,latest
version of @file{ax_check_preproc_flag.m4}} or browse
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=history;f=m4/ax_check_preproc_flag.m4,the
macro's revision history}.

@majorheading License

@w{Copyright @copyright{} 2008 Guido U. Draheim @email{guidod@@gmx.de}} @* @w{Copyright @copyright{} 2011 Maarten Bosmans @email{mkbosmans@@gmail.com}}

Copying and distribution of this file, with or without modification, are
permitted in any medium without royalty provided the copyright notice
and this notice are preserved.  This file is offered as-is, without any
warranty.