optional_depends gtk+2 \
                 "NO_GTK=" \
                 "NO_GTK=1" \
                 "for GTK+2 support" &&

optional_depends audit \
                 "NO_LIBAUDIT=" \
                 "NO_LIBAUDIT=1" \
                 "for trace tool support" &&

optional_depends LIBELF \
                 "NO_LIBELF=" \
                 "NO_LIBELF=1" \
                 "for probe tool support" &&

optional_depends perl \
                 "NO_LIBPERL=" \
                 "NO_LIBPERL=1" \
                 "for Perl scripting support" &&

optional_depends python \
                 "NO_LIBPYTHON=" \
                 "NO_LIBPYTHON=1" \
                 "for Python support" &&

optional_depends slang \
                 "NO_SLANG=" \
                 "NO_SLANG=1" \
                 "for TUI support" &&

optional_depends SSL \
                 "NO_LIBCRYPTO=" \
                 "NO_LIBCRYPTO=1" \
                 "for jitted code injection" &&

optional_depends libunwind \
                 "NO_LIBUNWIND=" \
                 "NO_LIBUNWIND=1" \
                 "for post unwind support" &&

optional_depends zlib \
                 "NO_ZLIB=" \
                 "NO_ZLIB=1" \
                 "for kernel module decompression support" &&

optional_depends xz-utils \
                 "NO_LZMA=" \
                 "NO_LZMA=1" \
                 "for xz kernel module decompression support" &&

optional_depends asciidoc "" "" "to build documentation" &&

if is_depends_enabled ${SPELL} asciidoc; then
  depends xmlto
fi
