Potential Regression in xt::drop

[nosracd]

There appears to have been a regression in xt::drop between the 0.26.0 and 0.27.0 releases.

Consider the following source code:

#include <xtensor/containers/xarray.hpp>
#include <xtensor/views/xview.hpp>

int main() {
	auto my_array       = xt::xtensor<double, 1>({1, 2, 3});

	// This compiles.
	xt::view(my_array, xt::drop(1));

	// This does not compile in 0.27.0.
	size_t index = 1;
	xt::view(my_array, xt::drop(index));
}

The first xt::drop call builds fine in both versions of xtensor. However, the second xt::drop call fails to compile in xtensor 0.27.0 (but builds fine in 0.26.0). Specifically, I get a compiler error like:

views/xslice.hpp:506:46: error: type 'decay_t<unsigned long &>' (aka 'unsigned long') cannot be used prior to '::' because it has no members
  506 |             return xdrop_slice<typename std::decay_t<T>::value_type>(std::forward<T>(indices));
      |                                         ~~~~~^
../xtensor_test.cpp:12:25: note: in instantiation of function template specialization 'xt::drop<long, unsigned long &>' requested here
   12 |         xt::view(my_array, xt::drop(index));
      |                                ^
1 error generated.

The compiler error happens for other integer types (e.g. int) as well.