Is there a way to make a struct without a distinction between constant, immutable, and mutable?

[Liam McGillivray]

I am doing work on the `units-d` library. This library contains 
some struct templates which don't contain any variables. Because 
of this, all instances are effectively constant. However, when 
they are placed as arguments in other templates, it causes 
problems when one is unexpectedly `const`.

Is there a way to make it so that this struct has only one 
qualifier? No distinction?