adding == operator to fixed_shape.

Author: vakokako

include/xtensor/xstorage.hpp

@@ -1697,6 +1697,18 @@ namespace xt
     constexpr typename fixed_shape<X...>::cast_type fixed_shape<X...>::m_array;
 #endif
 
+    template <std::size_t... X1, std::size_t... X2>
+    XTENSOR_FIXED_SHAPE_CONSTEXPR bool operator==(const fixed_shape<X1...>& lhs, const fixed_shape<X2...>& rhs)
+    {
+        return std::is_same<fixed_shape<X1...>, fixed_shape<X2...>>::value;
+    }
+
+    template <std::size_t... X1, std::size_t... X2>
+    XTENSOR_FIXED_SHAPE_CONSTEXPR bool operator!=(const fixed_shape<X1...>& lhs, const fixed_shape<X2...>& rhs)
+    {
+        return !(lhs == rhs);
+    }
+
 #undef XTENSOR_FIXED_SHAPE_CONSTEXPR
 
     template <class E, std::ptrdiff_t Start, std::ptrdiff_t End = -1>

test/test_xreducer.cpp

@@ -939,14 +939,6 @@ namespace xt
         EXPECT_EQ(b.dimension(), 0u);
         EXPECT_EQ(minmax(b)(), (A{1.2, 1.2}));
     }
-    
-    template <std::size_t... I, std::size_t... J>
-    bool operator==(fixed_shape<I...>, fixed_shape<J...>)
-    {
-        std::array<std::size_t, sizeof...(I)> ix = {I...};
-        std::array<std::size_t, sizeof...(J)> jx = {J...};
-        return sizeof...(J) == sizeof...(I) && std::equal(ix.begin(), ix.end(), jx.begin());
-    }
 
     TEST(xreducer, keep_dims)
     {