Conditional nothrow/safe/nogc/etc?

[Matt Elkins via Digitalmars-d-learn]

Is there any way to specify that a generic function is 
conditionally nothrow (or other function decorators), based on 
whether the template instantiation is nothrow? I'm looking for 
something akin to C++'s noexcept(noexcept(<expr>)), e.g.:

template <class T> void foo() noexcept(noexcept(T())) {}

I don't see anything about it on the functions grammar page 
(https://dlang.org/spec/function.html). I do see something to do 
with nothrow_ on the std.traits page, but I'm not sure how to use 
it to achieve this or whether that is the right approach.

My actual use case is a non-generic method opAssign inside of a 
generic struct.