gentoo-x86/eclass/flag-o-matic.eclass

# Copyright 1999-2011 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: /var/cvsroot/gentoo-x86/eclass/flag-o-matic.eclass,v 1.158 2011/11/14 20:29:03 vapier Exp $

# @ECLASS: flag-o-matic.eclass
# @MAINTAINER:
# toolchain@gentoo.org
# @BLURB: common functions to manipulate and query toolchain flags
# @DESCRIPTION:
# This eclass contains a suite of functions to help developers sanely
# and safely manage toolchain flags in their builds.

inherit eutils toolchain-funcs multilib

################ DEPRECATED functions ################
# The following are still present to avoid breaking existing
# code more than necessary; however they are deprecated. Please
# use gcc-specs-* from toolchain-funcs.eclass instead, if you
# need to know which hardened techs are active in the compiler.
# See bug #100974
#
# has_hardened
# has_pie
# has_pic
# has_ssp_all
# has_ssp


# {C,CXX,F,FC}FLAGS that we allow in strip-flags
# Note: shell globs and character lists are allowed
setup-allowed-flags() {
        if [[ -z ${ALLOWED_FLAGS} ]] ; then
                export ALLOWED_FLAGS="-pipe"
                export ALLOWED_FLAGS="${ALLOWED_FLAGS} -O -O0 -O1 -O2 -mcpu -march -mtune"
                export ALLOWED_FLAGS="${ALLOWED_FLAGS} -fstack-protector -fstack-protector-all"
                export ALLOWED_FLAGS="${ALLOWED_FLAGS} -fbounds-checking -fno-strict-overflow"
                export ALLOWED_FLAGS="${ALLOWED_FLAGS} -fno-PIE -fno-pie -fno-unit-at-a-time"
                export ALLOWED_FLAGS="${ALLOWED_FLAGS} -g -g[0-9] -ggdb -ggdb[0-9] -gstabs -gstabs+"
                export ALLOWED_FLAGS="${ALLOWED_FLAGS} -fno-ident -fpermissive"
                export ALLOWED_FLAGS="${ALLOWED_FLAGS} -W* -w"
        fi
        # allow a bunch of flags that negate features / control ABI
        ALLOWED_FLAGS="${ALLOWED_FLAGS} -fno-stack-protector -fno-stack-protector-all \
                -fno-strict-aliasing -fno-bounds-checking -fstrict-overflow -fno-omit-frame-pointer"
        ALLOWED_FLAGS="${ALLOWED_FLAGS} -mregparm -mno-app-regs -mapp-regs \
                -mno-mmx -mno-sse -mno-sse2 -mno-sse3 -mno-ssse3 -mno-sse4 -mno-sse4.1 \
                -mno-sse4.2 -mno-avx -mno-aes -mno-pclmul -mno-sse4a -mno-3dnow \
                -mno-popcnt -mno-abm \
                -mips1 -mips2 -mips3 -mips4 -mips32 -mips64 -mips16 -mplt \
                -msoft-float -mno-soft-float -mhard-float -mno-hard-float -mfpu \
                -mieee -mieee-with-inexact -mschedule -mfloat-gprs -mspe -mno-spe \
                -mtls-direct-seg-refs -mno-tls-direct-seg-refs \
                -mflat -mno-flat -mno-faster-structs -mfaster-structs \
                -m32 -m64 -mx32 -mabi -mlittle-endian -mbig-endian -EL -EB -fPIC \
                -mlive-g0 -mcmodel -mstack-bias -mno-stack-bias \
                -msecure-plt -m*-toc -D* -U*"

        # 4.5
        ALLOWED_FLAGS="${ALLOWED_FLAGS} -mno-fma4 -mno-movbe -mno-xop -mno-lwp"
        # 4.6
        ALLOWED_FLAGS="${ALLOWED_FLAGS} -mno-fsgsbase -mno-rdrnd -mno-f16c \
                -mno-bmi -mno-tbm"

        # {C,CXX,F,FC}FLAGS that we are think is ok, but needs testing
        # NOTE:  currently -Os have issues with gcc3 and K6* arch's
        export UNSTABLE_FLAGS="-Os -O3 -freorder-blocks"
        return 0
}

# inverted filters for hardened compiler.  This is trying to unpick
# the hardened compiler defaults.
_filter-hardened() {
        local f
        for f in "$@" ; do
                case "${f}" in
                        # Ideally we should only concern ourselves with PIE flags,
                        # not -fPIC or -fpic, but too many places filter -fPIC without
                        # thinking about -fPIE.
                        -fPIC|-fpic|-fPIE|-fpie|-Wl,pie|-pie)
                                gcc-specs-pie || continue
                                is-flagq -nopie || append-flags -nopie;;
                        -fstack-protector)
                                gcc-specs-ssp || continue
                                is-flagq -fno-stack-protector || append-flags $(test-flags -fno-stack-protector);;
                        -fstack-protector-all)
                                gcc-specs-ssp-to-all || continue
                                is-flagq -fno-stack-protector-all || append-flags $(test-flags -fno-stack-protector-all);;
                        -fno-strict-overflow)
                                gcc-specs-nostrict || continue
                                is-flagq -fstrict-overflow || append-flags $(test-flags -fstrict-overflow);;
                esac
        done
}

# Remove occurrences of strings from variable given in $1
# Strings removed are matched as globs, so for example
# '-O*' would remove -O1, -O2 etc.
_filter-var() {
        local f x VAR VAL
        declare -a new

        VAR=$1
        shift
        eval VAL=\${${VAR}}
        for f in ${VAL}; do
                for x in "$@"; do
                        # Note this should work with globs like -O*
                        [[ ${f} == ${x} ]] && continue 2
                done
                eval new\[\${\#new\[@]}]=\${f}
        done
        eval export ${VAR}=\${new\[*]}
}

# @FUNCTION: filter-flags
# @USAGE: <flags>
# @DESCRIPTION:
# Remove particular <flags> from {C,CPP,CXX,F,FC}FLAGS.  Accepts shell globs.
filter-flags() {
        _filter-hardened "$@"
        _filter-var CFLAGS "$@"
        _filter-var CPPFLAGS "$@"
        _filter-var CXXFLAGS "$@"
        _filter-var FFLAGS "$@"
        _filter-var FCFLAGS "$@"
        return 0
}

# @FUNCTION: filter-lfs-flags
# @DESCRIPTION:
# Remove flags that enable Large File Support.
filter-lfs-flags() {
        [[ $# -ne 0 ]] && die "filter-lfs-flags takes no arguments"
        # http://www.gnu.org/s/libc/manual/html_node/Feature-Test-Macros.html
        # _LARGEFILE_SOURCE: enable support for new LFS funcs (ftello/etc...)
        # _LARGEFILE64_SOURCE: enable support for 64bit variants (off64_t/fseeko64/etc...)
        # _FILE_OFFSET_BITS: default to 64bit variants (off_t is defined as off64_t)
        filter-flags -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE
}

# @FUNCTION: append-cppflags
# @USAGE: <flags>
# @DESCRIPTION:
# Add extra <flags> to the current CPPFLAGS.
append-cppflags() {
        [[ $# -eq 0 ]] && return 0
        export CPPFLAGS="${CPPFLAGS} $*"
        return 0
}

# @FUNCTION: append-cflags
# @USAGE: <flags>
# @DESCRIPTION:
# Add extra <flags> to the current CFLAGS.
append-cflags() {
        [[ $# -eq 0 ]] && return 0
        export CFLAGS=$(test-flags-CC ${CFLAGS} "$@")
        return 0
}

# @FUNCTION: append-cxxflags
# @USAGE: <flags>
# @DESCRIPTION:
# Add extra <flags> to the current CXXFLAGS.
append-cxxflags() {
        [[ $# -eq 0 ]] && return 0
        export CXXFLAGS=$(test-flags-CXX ${CXXFLAGS} "$@")
        return 0
}

# @FUNCTION: append-fflags
# @USAGE: <flags>
# @DESCRIPTION:
# Add extra <flags> to the current {F,FC}FLAGS.
append-fflags() {
        [[ $# -eq 0 ]] && return 0
        export FFLAGS=$(test-flags-F77 ${FFLAGS} "$@")
        export FCFLAGS=$(test-flags-FC ${FCFLAGS} "$@")
        return 0
}

# @FUNCTION: append-lfs-flags
# @DESCRIPTION:
# Add flags that enable Large File Support.
append-lfs-flags() {
        [[ $# -ne 0 ]] && die "append-lfs-flags takes no arguments"
        # see comments in filter-lfs-flags func for meaning of these
        append-cppflags -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE
}

# @FUNCTION: append-flags
# @USAGE: <flags>
# @DESCRIPTION:
# Add extra <flags> to your current {C,CXX,F,FC}FLAGS.
append-flags() {
        [[ $# -eq 0 ]] && return 0
        append-cflags "$@"
        append-cxxflags "$@"
        append-fflags "$@"
        return 0
}

# @FUNCTION: replace-flags
# @USAGE: <old> <new>
# @DESCRIPTION:
# Replace the <old> flag with <new>.  Accepts shell globs for <old>.
replace-flags() {
        [[ $# != 2 ]] \
                && echo && eerror "Usage: replace-flags <old flag> <new flag>" \
                && die "replace-flags takes 2 arguments, not $#"

        local f fset
        declare -a new_CFLAGS new_CXXFLAGS new_FFLAGS new_FCFLAGS

        for fset in CFLAGS CXXFLAGS FFLAGS FCFLAGS; do
                # Looping over the flags instead of using a global
                # substitution ensures that we're working with flag atoms.
                # Otherwise globs like -O* have the potential to wipe out the
                # list of flags.
                for f in ${!fset}; do
                        # Note this should work with globs like -O*
                        [[ ${f} == ${1} ]] && f=${2}
                        eval new_${fset}\[\${\#new_${fset}\[@]}]=\${f}
                done
                eval export ${fset}=\${new_${fset}\[*]}
        done

        return 0
}

# @FUNCTION: replace-cpu-flags
# @USAGE: <old> <new>
# @DESCRIPTION:
# Replace cpu flags (like -march/-mcpu/-mtune) that select the <old> cpu
# with flags that select the <new> cpu.  Accepts shell globs for <old>.
replace-cpu-flags() {
        local newcpu="$#" ; newcpu="${!newcpu}"
        while [ $# -gt 1 ] ; do
                # quote to make sure that no globbing is done (particularly on
                # ${oldcpu}) prior to calling replace-flags
                replace-flags "-march=${1}" "-march=${newcpu}"
                replace-flags "-mcpu=${1}" "-mcpu=${newcpu}"
                replace-flags "-mtune=${1}" "-mtune=${newcpu}"
                shift
        done
        return 0
}

_is_flagq() {
        local x
        for x in ${!1} ; do
                [[ ${x} == $2 ]] && return 0
        done
        return 1
}

# @FUNCTION: is-flagq
# @USAGE: <flag>
# @DESCRIPTION:
# Returns shell true if <flag> is in {C,CXX,F,FC}FLAGS, else returns shell false.  Accepts shell globs.
is-flagq() {
        [[ -n $2 ]] && die "Usage: is-flag <flag>"
        _is_flagq CFLAGS $1 || _is_flagq CXXFLAGS $1 || _is_flagq FFLAGS $1 || _is_flagq FCFLAGS $1
}

# @FUNCTION: is-flag
# @USAGE: <flag>
# @DESCRIPTION:
# Echo's "true" if flag is set in {C,CXX,F,FC}FLAGS.  Accepts shell globs.
is-flag() {
        is-flagq "$@" && echo true
}

# @FUNCTION: is-ldflagq
# @USAGE: <flag>
# @DESCRIPTION:
# Returns shell true if <flag> is in LDFLAGS, else returns shell false.  Accepts shell globs.
is-ldflagq() {
        [[ -n $2 ]] && die "Usage: is-ldflag <flag>"
        _is_flagq LDFLAGS $1
}

# @FUNCTION: is-ldflag
# @USAGE: <flag>
# @DESCRIPTION:
# Echo's "true" if flag is set in LDFLAGS.  Accepts shell globs.
is-ldflag() {
        is-ldflagq "$@" && echo true
}

# @FUNCTION: filter-mfpmath
# @USAGE: <math types>
# @DESCRIPTION:
# Remove specified math types from the fpmath flag.  For example, if the user
# has -mfpmath=sse,386, running `filter-mfpmath sse` will leave the user with
# -mfpmath=386.
filter-mfpmath() {
        local orig_mfpmath new_math prune_math

        # save the original -mfpmath flag
        orig_mfpmath=$(get-flag -mfpmath)
        # get the value of the current -mfpmath flag
        new_math=$(get-flag mfpmath)
        new_math=" ${new_math//,/ } "
        # figure out which math values are to be removed
        prune_math=""
        for prune_math in "$@" ; do
                new_math=${new_math/ ${prune_math} / }
        done
        new_math=$(echo ${new_math})
        new_math=${new_math// /,}

        if [[ -z ${new_math} ]] ; then
                # if we're removing all user specified math values are
                # slated for removal, then we just filter the flag
                filter-flags ${orig_mfpmath}
        else
                # if we only want to filter some of the user specified
                # math values, then we replace the current flag
                replace-flags ${orig_mfpmath} -mfpmath=${new_math}
        fi
        return 0
}

# @FUNCTION: strip-flags
# @DESCRIPTION:
# Strip C[XX]FLAGS of everything except known good/safe flags.
strip-flags() {
        local x y flag NEW_CFLAGS NEW_CXXFLAGS NEW_FFLAGS NEW_FCFLAGS

        setup-allowed-flags

        local NEW_CFLAGS=""
        local NEW_CXXFLAGS=""
        local NEW_FFLAGS=""
        local NEW_FCFLAGS=""

        # Allow unstable C[XX]FLAGS if we are using unstable profile ...
        if has "~$(tc-arch)" ${ACCEPT_KEYWORDS} ; then
                ALLOWED_FLAGS="${ALLOWED_FLAGS} ${UNSTABLE_FLAGS}"
        fi

        set -f  # disable pathname expansion

        for x in ${CFLAGS}; do
                for y in ${ALLOWED_FLAGS}; do
                        flag=${x%%=*}
                        if [ "${flag%%${y}}" = "" ] ; then
                                NEW_CFLAGS="${NEW_CFLAGS} ${x}"
                                break
                        fi
                done
        done

        for x in ${CXXFLAGS}; do
                for y in ${ALLOWED_FLAGS}; do
                        flag=${x%%=*}
                        if [ "${flag%%${y}}" = "" ] ; then
                                NEW_CXXFLAGS="${NEW_CXXFLAGS} ${x}"
                                break
                        fi
                done
        done

        for x in ${FFLAGS}; do
                for y in ${ALLOWED_FLAGS}; do
                        flag=${x%%=*}
                        if [ "${flag%%${y}}" = "" ] ; then
                                NEW_FFLAGS="${NEW_FFLAGS} ${x}"
                                break
                        fi
                done
        done

        for x in ${FCFLAGS}; do
                for y in ${ALLOWED_FLAGS}; do
                        flag=${x%%=*}
                        if [ "${flag%%${y}}" = "" ] ; then
                                NEW_FCFLAGS="${NEW_FCFLAGS} ${x}"
                                break
                        fi
                done
        done

        # In case we filtered out all optimization flags fallback to -O2
        if [ "${CFLAGS/-O}" != "${CFLAGS}" -a "${NEW_CFLAGS/-O}" = "${NEW_CFLAGS}" ]; then
                NEW_CFLAGS="${NEW_CFLAGS} -O2"
        fi
        if [ "${CXXFLAGS/-O}" != "${CXXFLAGS}" -a "${NEW_CXXFLAGS/-O}" = "${NEW_CXXFLAGS}" ]; then
                NEW_CXXFLAGS="${NEW_CXXFLAGS} -O2"
        fi
        if [ "${FFLAGS/-O}" != "${FFLAGS}" -a "${NEW_FFLAGS/-O}" = "${NEW_FFLAGS}" ]; then
                NEW_FFLAGS="${NEW_FFLAGS} -O2"
        fi
        if [ "${FCFLAGS/-O}" != "${FCFLAGS}" -a "${NEW_FCFLAGS/-O}" = "${NEW_FCFLAGS}" ]; then
                NEW_FCFLAGS="${NEW_FCFLAGS} -O2"
        fi

        set +f  # re-enable pathname expansion

        export CFLAGS="${NEW_CFLAGS}"
        export CXXFLAGS="${NEW_CXXFLAGS}"
        export FFLAGS="${NEW_FFLAGS}"
        export FCFLAGS="${NEW_FCFLAGS}"
        return 0
}

test-flag-PROG() {
        local comp=$1
        local flags="$2"

        [[ -z ${comp} || -z ${flags} ]] && return 1

        # use -c so we can test the assembler as well
        local PROG=$(tc-get${comp})
        ${PROG} ${flags} -c -o /dev/null -xc /dev/null \
                > /dev/null 2>&1
}

# @FUNCTION: test-flag-CC
# @USAGE: <flag>
# @DESCRIPTION:
# Returns shell true if <flag> is supported by the C compiler, else returns shell false.
test-flag-CC() { test-flag-PROG "CC" "$1"; }

# @FUNCTION: test-flag-CXX
# @USAGE: <flag>
# @DESCRIPTION:
# Returns shell true if <flag> is supported by the C++ compiler, else returns shell false.
test-flag-CXX() { test-flag-PROG "CXX" "$1"; }

# @FUNCTION: test-flag-F77
# @USAGE: <flag>
# @DESCRIPTION:
# Returns shell true if <flag> is supported by the Fortran 77 compiler, else returns shell false.
test-flag-F77() { test-flag-PROG "F77" "$1"; }

# @FUNCTION: test-flag-FC
# @USAGE: <flag>
# @DESCRIPTION:
# Returns shell true if <flag> is supported by the Fortran 90 compiler, else returns shell false.
test-flag-FC() { test-flag-PROG "FC" "$1"; }

test-flags-PROG() {
        local comp=$1
        local flags
        local x

        shift

        [[ -z ${comp} ]] && return 1

        for x in "$@" ; do
                test-flag-${comp} "${x}" && flags="${flags}${flags:+ }${x}"
        done

        echo "${flags}"

        # Just bail if we dont have any flags
        [[ -n ${flags} ]]
}

# @FUNCTION: test-flags-CC
# @USAGE: <flags>
# @DESCRIPTION:
# Returns shell true if <flags> are supported by the C compiler, else returns shell false.
test-flags-CC() { test-flags-PROG "CC" "$@"; }

# @FUNCTION: test-flags-CXX
# @USAGE: <flags>
# @DESCRIPTION:
# Returns shell true if <flags> are supported by the C++ compiler, else returns shell false.
test-flags-CXX() { test-flags-PROG "CXX" "$@"; }

# @FUNCTION: test-flags-F77
# @USAGE: <flags>
# @DESCRIPTION:
# Returns shell true if <flags> are supported by the Fortran 77 compiler, else returns shell false.
test-flags-F77() { test-flags-PROG "F77" "$@"; }

# @FUNCTION: test-flags-FC
# @USAGE: <flags>
# @DESCRIPTION:
# Returns shell true if <flags> are supported by the Fortran 90 compiler, else returns shell false.
test-flags-FC() { test-flags-PROG "FC" "$@"; }

# @FUNCTION: test-flags
# @USAGE: <flags>
# @DESCRIPTION:
# Short-hand that should hopefully work for both C and C++ compiler, but
# its really only present due to the append-flags() abomination.
test-flags() { test-flags-CC "$@"; }

# @FUNCTION: test_version_info
# @USAGE: <version>
# @DESCRIPTION:
# Returns shell true if the current C compiler version matches <version>, else returns shell false.
# Accepts shell globs.
test_version_info() {
        if [[ $($(tc-getCC) --version 2>&1) == *$1* ]]; then
                return 0
        else
                return 1
        fi
}

# @FUNCTION: strip-unsupported-flags
# @DESCRIPTION:
# Strip {C,CXX,F,FC}FLAGS of any flags not supported by the active toolchain.
strip-unsupported-flags() {
        export CFLAGS=$(test-flags-CC ${CFLAGS})
        export CXXFLAGS=$(test-flags-CXX ${CXXFLAGS})
        export FFLAGS=$(test-flags-F77 ${FFLAGS})
        export FCFLAGS=$(test-flags-FC ${FCFLAGS})
}

# @FUNCTION: get-flag
# @USAGE: <flag>
# @DESCRIPTION:
# Find and echo the value for a particular flag.  Accepts shell globs.
get-flag() {
        local f findflag="$1"

        # this code looks a little flaky but seems to work for
        # everything we want ...
        # for example, if CFLAGS="-march=i686":
        # `get-flag -march` == "-march=i686"
        # `get-flag march` == "i686"
        for f in ${CFLAGS} ${CXXFLAGS} ${FFLAGS} ${FCFLAGS} ; do
                if [ "${f/${findflag}}" != "${f}" ] ; then
                        printf "%s\n" "${f/-${findflag}=}"
                        return 0
                fi
        done
        return 1
}

# DEAD FUNCS.  Remove by Dec 2011.
test_flag()    { die "$0: deprecated, please use test-flags()!" ; }
has_hardened() { die "$0: deprecated, please use gcc-specs-{relro,now}()!" ; }
has_pic()      { die "$0: deprecated, please use gcc-specs-pie()!" ; }
has_pie()      { die "$0: deprecated, please use gcc-specs-pie()!" ; }
has_ssp_all()  { die "$0: deprecated, please use gcc-specs-ssp()!" ; }
has_ssp()      { die "$0: deprecated, please use gcc-specs-ssp()!" ; }

# @FUNCTION: has_m64
# @DESCRIPTION:
# This doesn't test if the flag is accepted, it tests if the flag actually
# WORKS. Non-multilib gcc will take both -m32 and -m64. If the flag works
# return code is 0, else the return code is 1.
has_m64() {
        # this doesnt test if the flag is accepted, it tests if the flag
        # actually -WORKS-. non-multilib gcc will take both -m32 and -m64!
        # please dont replace this function with test_flag in some future
        # clean-up!

        local temp="$(emktemp)"
        echo "int main() { return(0); }" > "${temp}".c
        MY_CC=$(tc-getCC)
        ${MY_CC/ .*/} -m64 -o "$(emktemp)" "${temp}".c > /dev/null 2>&1
        local ret=$?
        rm -f "${temp}".c
        [[ ${ret} != 1 ]] && return 0
        return 1
}

# @FUNCTION: has_m32
# @DESCRIPTION:
# This doesn't test if the flag is accepted, it tests if the flag actually
# WORKS. Non-mulilib gcc will take both -m32 and -64. If the flag works return
# code is 0, else return code is 1.
has_m32() {
        # this doesnt test if the flag is accepted, it tests if the flag
        # actually -WORKS-. non-multilib gcc will take both -m32 and -m64!
        # please dont replace this function with test_flag in some future
        # clean-up!

        [ "$(tc-arch)" = "amd64" ] && has_multilib_profile && return 0

        local temp=$(emktemp)
        echo "int main() { return(0); }" > "${temp}".c
        MY_CC=$(tc-getCC)
        ${MY_CC/ .*/} -m32 -o "$(emktemp)" "${temp}".c > /dev/null 2>&1
        local ret=$?
        rm -f "${temp}".c
        [[ ${ret} != 1 ]] && return 0
        return 1
}

# @FUNCTION: replace-sparc64-flags
# @DESCRIPTION:
# Sets mcpu to v8 and uses the original value as mtune if none specified.
replace-sparc64-flags() {
        local SPARC64_CPUS="ultrasparc3 ultrasparc v9"

        if [ "${CFLAGS/mtune}" != "${CFLAGS}" ]; then
                for x in ${SPARC64_CPUS}; do
                        CFLAGS="${CFLAGS/-mcpu=${x}/-mcpu=v8}"
                done
        else
                for x in ${SPARC64_CPUS}; do
                        CFLAGS="${CFLAGS/-mcpu=${x}/-mcpu=v8 -mtune=${x}}"
                done
        fi

        if [ "${CXXFLAGS/mtune}" != "${CXXFLAGS}" ]; then
                for x in ${SPARC64_CPUS}; do
                        CXXFLAGS="${CXXFLAGS/-mcpu=${x}/-mcpu=v8}"
                done
        else
                for x in ${SPARC64_CPUS}; do
                        CXXFLAGS="${CXXFLAGS/-mcpu=${x}/-mcpu=v8 -mtune=${x}}"
                done
        fi

        export CFLAGS CXXFLAGS
}

# @FUNCTION: append-libs
# @USAGE: <libs>
# @DESCRIPTION:
# Add extra <libs> to the current LIBS.
append-libs() {
        [[ $# -eq 0 ]] && return 0
        local flag
        for flag in "$@"; do
                [[ ${flag} == -l* ]] && flag=${flag#-l}
                export LIBS="${LIBS} -l${flag}"
        done

        return 0
}

# @FUNCTION: append-ldflags
# @USAGE: <flags>
# @DESCRIPTION:
# Add extra <flags> to the current LDFLAGS.
append-ldflags() {
        [[ $# -eq 0 ]] && return 0
        local flag
        for flag in "$@"; do
                [[ ${flag} == -l* ]] && \
                        ewarn "Appending a library link instruction (${flag}); libraries to link to should not be passed through LDFLAGS"
        done

        export LDFLAGS="${LDFLAGS} $*"
        return 0
}

# @FUNCTION: filter-ldflags
# @USAGE: <flags>
# @DESCRIPTION:
# Remove particular <flags> from LDFLAGS.  Accepts shell globs.
filter-ldflags() {
        _filter-var LDFLAGS "$@"
        return 0
}

# @FUNCTION: raw-ldflags
# @USAGE: [flags]
# @DESCRIPTION:
# Turn C style ldflags (-Wl,-foo) into straight ldflags - the results
# are suitable for passing directly to 'ld'; note LDFLAGS is usually passed
# to gcc where it needs the '-Wl,'.
#
# If no flags are specified, then default to ${LDFLAGS}.
raw-ldflags() {
        local x input="$@"
        [[ -z ${input} ]] && input=${LDFLAGS}
        set --
        for x in ${input} ; do
                x=${x#-Wl,}
                set -- "$@" ${x//,/ }
        done
        echo "$@"
}

# @FUNCTION: no-as-needed
# @RETURN: Flag to disable asneeded behavior for use with append-ldflags.
no-as-needed() {
        case $($(tc-getLD) -v 2>&1 </dev/null) in
                *GNU*) # GNU ld
                echo "-Wl,--no-as-needed" ;;
        esac
}

# Some tests for when we screw with things and want to make
# sure we didn't break anything
#TESTS() {
#       CFLAGS="-a -b -c=1"
#       CXXFLAGS="-x -y -z=2"
#       LDFLAGS="-l -m -n=3"
#
#       die() { exit 1; }
#       (is-flag 1 2 3) && die
#       (is-ldflag 1 2 3) && die
#
#       is-flagq -l && die
#       is-ldflagq -a && die
#       is-flagq -a || die
#       is-flagq -x || die
#       is-ldflagq -n=* || die
#       is-ldflagq -n && die
#
#       strip-unsupported-flags
#       [[ ${CFLAGS} == "-c=1" ]] || die
#       [[ ${CXXFLAGS} == "-y -z=2" ]] || die
#
#       echo "All tests pass"
#}
#TESTS