Why add_dependencies() doesn't have any effect?

The EternalTerminal project contains the add_dependencies statement here but the generated Makefile doesn’t contain the line that the target et-lib depends on the target generated-code.

Docs say that add_dependencies appeared in 3.3
This project’s CMakeLists.txt has cmake_minimum_required(VERSION 3.0.2). I think that this means that cmake only has features enabled that were available in version 3.0.2 (?)

Why then add_dependencies() doesn’t cause an error and doesn’t work?

Is this a bug in cmake that it just ignores add_dependencies() ?

cmake-3.23.2

FreeBSD 13.1

It is certainly odd. Could you try to distill it down to a simpler case that still shows the problem?