Building installable pkg of toolchain's debug source

Hello, Swift community!

I am looking a way to build with standard util build scripts an installable pkg file not only for toolchain but for toolchain's debug source. Like here. I learnt keyword keys which take on this role:

--darwin-install-extract-symbols (specified key will extract symbols with dsymutil)

**--install-destdir=**PATH (specified key will put folder PATH with compiled toolchain)

**--install-symroot=**PATH (specified key will put folder PATH with debug syms)

**--installable-package=**PATH (specified key will do tar-gz archive with install-destdir which with compiled toolchain)

**--symbols-package=**PATH (specified key will do tar-gz archive with install-symroot which with debug symbols)

**--darwin-toolchain-installer-package=**PATH (specified key will make installable pkg with install-destdir which with compiled toolchain)

But I couldn't find the key which will help to make installable pkg with install-symroot path (which with debug symbols). Something like **--darwin-toolchain-symbols-package=**PATH key. Yes, there is no problem to add this key to build-script-impl file but I am thinking I miss something. Does something know this key?

It is easy to use pkgbuild console util (like in toolchain-installer file) and make pkg installable archive from folder manually, but I am thinking possible to do this operation with build-script-impl.

Andrey Efremov