Variable package version in Build-Depends

[Steve M]

Hello,

My package "swiftlang" has a build dependency on itself of the same
version or the prior version. So when building swiftlang 6.1.3 the
Build-Depends in d/rule are:

Build-Depends: debhelper-compat (= 13),
               swiftlang (>=6.0.3),
               swiftlang-dev (>=6.0.3),

What I would like to do is have the swiftlang Build-Depends resolve as
above but have swiftlang-dev be required to match the version of
swiftlang. Something like this:

Build-Depends: debhelper-compat (= 13),
               swiftlang (>=6.0.3),
               swiftlang-dev (=${swiftlang:Version}),

I've not had any success in using d/substvar or changes to d/rules
(such as overriding dh_auto_configure or dh_gencontrol) as dpkg-source
runs before any of this takes place.

Is there a way to create this version match requirement in Build-
Depends?


Thanks
-Steve