CWG2602 asks for this text in [dcl.constexpr]/3:

A function is constexpr-suitable if:

• it is not a coroutine (9.5.4 [dcl.fct.def.coroutine]), and
• if the function is a constructor or destructor, its class does not have any virtual base classes.

The second bullet does fit well into the enclosing context ("A function is constexpr-suitable if, [...] if the function [...]"). This would be easier to read if rephrased:

A function is constexpr-suitable if:

• it is not a coroutine (9.5.4 [dcl.fct.def.coroutine]), and
• if the function either it is not a constructor or destructor, or its class does not have any virtual base classes.

or

A function is constexpr-suitable if:

• it is not a coroutine (9.5.4 [dcl.fct.def.coroutine]), and
• if the function it is not a constructor or destructor, its of a class does not have any with virtual base classes.