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Check for -Wno-unused-but-set-variable gcc support Gcc versions 4.3.2 and earlier do not support the compiler flag -Wno-unused-but-set-variable. This can lead to build failures on older Linux platforms such as Debian Lenny. Since this is an optional build argument this changes add a new autoconf check for the option. If it is supported by the installed version of gcc then it is used otherwise it is omited. See commit's 12c1acde76683108441827ae9affba1872f3afe5 and 79713039a2b6e0ed223d141b4a8a8455f282d2f2 for the reason the -Wno-unused-but-set-variable options was originally added.
2011-06-14 18:02:13 +00:00
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 #
Always check -Wno-unused-but-set-variable gcc support The previous commit 8a7e1ceefa430988c8f888ca708ab307333b4464 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 22:09:05 +00:00
AC_DEFUN([ZFS_AC_CONFIG_ALWAYS_NO_UNUSED_BUT_SET_VARIABLE], [
Check for -Wno-unused-but-set-variable gcc support Gcc versions 4.3.2 and earlier do not support the compiler flag -Wno-unused-but-set-variable. This can lead to build failures on older Linux platforms such as Debian Lenny. Since this is an optional build argument this changes add a new autoconf check for the option. If it is supported by the installed version of gcc then it is used otherwise it is omited. See commit's 12c1acde76683108441827ae9affba1872f3afe5 and 79713039a2b6e0ed223d141b4a8a8455f282d2f2 for the reason the -Wno-unused-but-set-variable options was originally added.
2011-06-14 18:02:13 +00:00
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])
])