dbu are sometimes incorrect.

[jevillegasd]

The database units are always read from the technology definition, instead of the actual layout, and this often results in wrong behaviour whenever the layout units don't match the technology default db units.

I am guessing in general the db units are defined by the foundry and therefore you don't want to have your units to not match that of the fabrication process, but I guess it's still good if the shape generation works despite the units mismatch. Would it be reasonable to change the core to allow this? (I think this would need changes in the get_technology() function only).

Example: Here is a path, and the same path after transforming it into a waveguide while using the layout units as 0.002 um

Originally posted by @jevillegasd in #177

[lukasc-ubc]

This could be changed, but indeed the foundries usually only accept one dbu, so that should be defined in the technology.