mergerfs/buildtools/install-build-pkgs

#!/bin/sh

set -e

BUILD_ENV=/tmp/build-env

write_gcc_env()
{
    {
        printf 'export CC=%s\n' "$1"
        printf 'export CXX=%s\n' "$2"
    } > "$BUILD_ENV"
}

write_toolset_env()
{
    {
        printf '. %s\n' "$1"
        printf 'export CC=gcc\n'
        printf 'export CXX=g++\n'
    } > "$BUILD_ENV"
}

latest_apt_gxx()
{
    apt-cache --names-only search '^g[+][+]-[0-9]' \
        | sed -n 's/^\(g++-[0-9][0-9]*\) .*/\1/p' \
        | sort -t- -k2,2V \
        | tail -n 1
}

latest_dnf_toolset()
{
    dnf -q list --showduplicates 'gcc-toolset-*-gcc-c++' 2>/dev/null \
        | sed -n 's/^gcc-toolset-\([0-9][0-9]*\)-gcc-c++\..*/\1/p' \
        | sort -V \
        | tail -n 1
}

latest_yum_toolset()
{
    yum -q list available 'devtoolset-*-gcc-c++' 2>/dev/null \
        | sed -n 's/^devtoolset-\([0-9][0-9]*\)-gcc-c++\..*/\1/p' \
        | sort -V \
        | tail -n 1
}

version_gt()
{
    highest="$(printf '%s\n%s\n' "$1" "$2" | sort -V | tail -n 1)"
    [ "$highest" = "$1" ] && [ "$1" != "$2" ]
}

check_cxx20()
{
    cxx="${CXX:-g++}"
    test_src=/tmp/mergerfs-cxx20-check.cpp
    test_bin=/tmp/mergerfs-cxx20-check

    cat > "$test_src" <<'EOF'
template <typename T>
concept Incrementable = requires(T value) { value + 1; };

static_assert(Incrementable<int>);

int main()
{
    return 0;
}
EOF

    if ! "$cxx" -std=c++20 "$test_src" -o "$test_bin" >/dev/null 2>&1; then
        echo "error: $cxx does not support C++20" >&2
        exit 1
    fi

    rm -f "$test_src" "$test_bin"
}

: > "$BUILD_ENV"

if [ -e /usr/bin/apt-get ]; then
    export DEBIAN_FRONTEND=noninteractive
    apt-get -qy update
    cxx_pkg="$(latest_apt_gxx)"
    if [ -n "$cxx_pkg" ]; then
        gcc_pkg="gcc-${cxx_pkg#g++-}"
        compiler_pkgs="$gcc_pkg $cxx_pkg"
        write_gcc_env "$gcc_pkg" "$cxx_pkg"
    else
        compiler_pkgs="g++"
        write_gcc_env gcc g++
    fi
    apt-get -qy --force-yes --no-install-suggests --no-install-recommends \
	    install \
            ca-certificates \
            build-essential \
            dpkg-dev \
            git \
            $compiler_pkgs \
            debhelper \
            lsb-release \
            fakeroot
    . "$BUILD_ENV"
    check_cxx20
elif [ -e /usr/bin/dnf ]; then
    dnf -y update
    toolset="$(latest_dnf_toolset)"
    dnf -y install \
        git rpm-build gcc-c++ make which libatomic
    default_gxx_major="$(g++ -dumpversion | cut -f1 -d.)"
    if [ -n "$toolset" ] && version_gt "$toolset" "$default_gxx_major"; then
        dnf -y install \
            "gcc-toolset-${toolset}-gcc" \
            "gcc-toolset-${toolset}-gcc-c++"
        write_toolset_env "/opt/rh/gcc-toolset-${toolset}/enable"
    else
        write_gcc_env gcc g++
    fi
    . "$BUILD_ENV"
    check_cxx20
elif [ -e /usr/bin/yum ]; then
    yum -y update
    yum -y install \
        git rpm-build gcc-c++ make which
    yum -y install centos-release-scl || true
    yum -y update
    toolset="$(latest_yum_toolset)"
    default_gxx_major="$(g++ -dumpversion | cut -f1 -d.)"
    if [ -n "$toolset" ] && version_gt "$toolset" "$default_gxx_major"; then
        yum -y install \
            "devtoolset-${toolset}-gcc" \
            "devtoolset-${toolset}-gcc-c++"
        write_toolset_env "/opt/rh/devtoolset-${toolset}/enable"
    else
        write_gcc_env gcc g++
    fi
    . "$BUILD_ENV"
    check_cxx20
elif [ -e /usr/bin/zypper ]; then
    zypper update -y
    zypper install -y \
           git rpm-build gcc-c++ make which
    write_gcc_env gcc g++
    . "$BUILD_ENV"
    check_cxx20
elif [ -e /sbin/apk ]; then
    apk add \
        abuild git gcc g++ make \
        linux-headers
    write_gcc_env gcc g++
    . "$BUILD_ENV"
    check_cxx20
elif [ -e /usr/sbin/pkg ]; then
    pkg install \
        git gmake gcc
elif [ -e /usr/bin/pacman ]; then
    pacman -Sy --noconfirm base-devel git fakeroot
    write_gcc_env gcc g++
    . "$BUILD_ENV"
    check_cxx20
fi