Async2sync and write_aiger -vmap

[widlarizer]

I opened a bug report for this, since it’s undesirable behavior and could be fixed

async2sync doesn't copy src attributes consistently

There’s also related upcoming work that should eliminate these problems across the board:

Consistent source location transfer with Patch

The greatest source of loss of source attributes is synthesis with abc, but not all users use abc and there’s a lot of gaps in Yosys passes. To address this, there’s two major features I think we need. Patch I have started prototyping a data structure called Patch that allows passes to prepare rewrites to the design and that will come with automatic source transfer. Potential future benefits is higher functional clarity, lower reliance on opt_clean to garbage collect design objects and cheaper …