Hassan Sajjad
That's incorrect: build2 had support for header units (with include translation) from 2021:
Thank you for informing me. I did not know about it. Can you give bigger examples? Is it used in production anywhere?
I will assume your questions refer to build2 in general rather than to its header units support specifically (which is not very usable at the moment due to compiler deficiencies). Yes, you can see more substantial examples on cppget.org (packages) or the build2-packaging GitHub org (package repositories), which, in particular, include both Boost and Qt (and I agree with Andrey, SFML, which is also there, is not a particularly complex library). And yes, build2 is used in production, including in large (many hundreds of libraries), successful commercial projects. And speaking of Boost (not to make this reply completely off-topic), in Hmake's README you say:
HMake 1.0 will only be released when, few of the mega projects like UE5, AOSP, Qt etc. could be supported.
I would suggest that you include Boost on this list. While libraries like Qt give good "depth-wise" reality check (i.e., relatively few libraries with very complex builds), Boost gives a unique "breadth-wise" challenge with its 140+ heavily interdependent libraries with dependency chains at times 20+ levels deep. If you want to see what kind of issues a build system may run into while trying to deal with something like this, take a looks at this bug report: https://github.com/build2/build2/issues/184