mirror_zfs/config/always-no-unused-but-set-variable.m4
Brian Behlendorf 2e08aedba4 Always check -Wno-unused-but-set-variable gcc support
The previous commit 8a7e1ceefa wasn't
quite right.  This check applies to both the user and kernel space
build and as such we must make sure it runs regardless of what
the --with-config option is set too.

For example, if --with-config=kernel then the autoconf test does
not run and we generate build warnings when compiling the kernel
packages.
2011-06-14 16:40:35 -07:00

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dnl #
dnl # Check if gcc supports -Wno-unused-but-set-variable option.
dnl #
dnl # We actually invoke gcc with the -Wunused-but-set-variable option
dnl # and infer the 'no-' version does or doesn't exist based upon
dnl # the results. This is required because when checking any of
dnl # no- prefixed options gcc always returns success.
dnl #
AC_DEFUN([ZFS_AC_CONFIG_ALWAYS_NO_UNUSED_BUT_SET_VARIABLE], [
AC_MSG_CHECKING([for -Wno-unused-but-set-variable support])
saved_flags="$CFLAGS"
CFLAGS="$CFLAGS -Wunused-but-set-variable"
AC_RUN_IFELSE(AC_LANG_PROGRAM( [], []),
[
NO_UNUSED_BUT_SET_VARIABLE=-Wno-unused-but-set-variable
AC_MSG_RESULT([yes])
],
[
NO_UNUSED_BUT_SET_VARIABLE=
AC_MSG_RESULT([no])
])
CFLAGS="$saved_flags"
AC_SUBST([NO_UNUSED_BUT_SET_VARIABLE])
])