Nios2 SDRAM+LAN bus sharing

I agree with gmm... I would expect Quiartus to give a compilation error becaue of a mis-matched bus width; you are attempting to throw away 4 address lines but Quartus doesn't know that.

You should try this in case you're seeing such a compilation error:

addr ( from SOPCB ) ---- name the bus "my_addr"----x

the 'x' means that you don't connect the line to anything. then, to get to your pin, make a separate named bus wire like this:

   x----name this one "my_addr"--------<<--IO named "my_addr-->>

Then quartus knows explicity that you want to connect 11..0 on your IO to 11..0 on the bus coming from the SOPCB module.