Inch(1)*Inch(2)

[bc0n]

 Inch(1)*Inch(2)
ERROR: MethodError: no method matching *(::Inch, ::Inch)
The function `*` exists, but no method is defined for this combination of argument types.

[bc0n]

The problem here is that @relateMeasures adds the relations for Meter*Meter=Meter2, but since Inch is defined after that the *() is never defined on Inch.
Fix it by broadening *() from x::Meter to x::AbstractLength, with the penalty that Inch*Inch=Meter2, and this can't be avoided because we can't dispatch on return type. The choice is defining AbstractAbstract=Base, or defining every InchInch=Inch2, Foot*Lbs=FootLbs, ...