Forgive me, but can you be clearer than "mentioned"? Is the mangling required to contain template parameters for return types?
> In this case though the underlying reason is that its part of the type (system) not because of the mangle specifically.
I'm not sure. The compiler knows it will always be the same type, so under many uses of this function I could easily imagine a compiler that doesn't actually fill in .value until runtime.
Sorry, I meant parameters that only are being returned, and not passed in.
So in the example several layers above, T uniquely identifies the function. I don't see any need to involve std::integral_constant<int, x> in the mangling.