more precise reason

[ufcpp]

now:

var origin = new X();
var copy = origin; // NoCopy

origion.ByValExtensionMethod(); // NoCopy

ref readonly var ro = ref origin;
ro.Method(); // NoCopy

Should be changed?

var origin = new X();
var copy = origin; // assingment error

origion.ByValExtensionMethod(); // pass-by-value error

ref readonly var ro = ref origin;
ro.Method(); // readonly defensive copy error

[ufcpp]

done