Fix potential termination with noexcept specifier (#2865)

Author: yosh-matsuda

include/xtensor/core/xaccessible.hpp

@@ -36,7 +36,7 @@ namespace xt
         using const_reference = typename inner_types::const_reference;
         using size_type = typename inner_types::size_type;
 
-        size_type size() const noexcept;
+        size_type size() const noexcept(noexcept(derived_cast().shape()));
         size_type dimension() const noexcept;
         size_type shape(size_type index) const;
 
@@ -138,7 +138,7 @@ namespace xt
      * Returns the size of the expression.
      */
     template <class D>
-    inline auto xconst_accessible<D>::size() const noexcept -> size_type
+    inline auto xconst_accessible<D>::size() const noexcept(noexcept(derived_cast().shape())) -> size_type
     {
         return compute_size(derived_cast().shape());
     }