fix bool, add tests

Author: kalenedrael

include/xsimd/arch/xsimd_scalar.hpp

@@ -1208,9 +1208,15 @@ namespace xsimd
     template <class T_out, class T_in>
     XSIMD_INLINE constexpr T_out batch_cast(T_in const& val) noexcept
     {
-        static_assert(std::is_same<T_in, bool>::value ^ std::is_same<T_in, bool>::value, "cannot convert to/from bool; use !x or x != 0");
+        static_assert(!std::is_same<T_out, bool>::value, "cannot convert to bool, use !x or x != 0");
         return static_cast<T_out>(val);
     }
+
+    template <class T>
+    XSIMD_INLINE constexpr bool batch_cast(bool b) noexcept
+    {
+        return b;
+    }
 }
 
 #endif

test/test_batch_cast.cpp

@@ -341,6 +341,7 @@ struct batch_cast_test
             T_out scalar_ref = static_cast<T_out>(in_test_value);
             T_out scalar_res = res.get(0);
             CHECK_SCALAR_EQ(scalar_ref, scalar_res);
+            CHECK_SCALAR_EQ(scalar_ref, xsimd::batch_cast<T_out>(in_test_value));
         }
     }
 
@@ -353,14 +354,22 @@ struct batch_cast_test
         using B_common_out = xsimd::batch_bool<T_out>;
 
         B_common_in all_true_in(true);
-        B_common_out all_true_res = xsimd::batch_bool_cast<T_out>(all_true_in);
+        B_common_out all_true_res0 = xsimd::batch_bool_cast<T_out>(all_true_in);
+        B_common_out all_true_res1 = xsimd::batch_cast<T_out>(all_true_in);
         INFO(name);
-        CHECK_SCALAR_EQ(all_true_res.get(0), true);
+        CHECK_SCALAR_EQ(all_true_res0.get(0), true);
+        CHECK_SCALAR_EQ(all_true_res1.get(0), true);
+        CHECK_SCALAR_EQ(xsimd::batch_bool_cast<B_out>(true), true);
+        CHECK_SCALAR_EQ(xsimd::batch_cast<B_out>(true), true);
 
         B_common_in all_false_in(false);
-        B_common_out all_false_res = xsimd::batch_bool_cast<T_out>(all_false_in);
+        B_common_out all_false_res0 = xsimd::batch_bool_cast<T_out>(all_false_in);
+        B_common_out all_false_res1 = xsimd::batch_cast<T_out>(all_false_in);
         INFO(name);
-        CHECK_SCALAR_EQ(all_false_res.get(0), false);
+        CHECK_SCALAR_EQ(all_false_res0.get(0), false);
+        CHECK_SCALAR_EQ(all_false_res1.get(0), false);
+        CHECK_SCALAR_EQ(xsimd::batch_bool_cast<B_out>(false), false);
+        CHECK_SCALAR_EQ(xsimd::batch_cast<B_out>(false), false);
     }
 };