cpp: Fallback to evmc::is_zero() in case the deprecated ::is_zero() i…

…s used

The deprecated is_zero() is removed, but evmc.hpp is included in helpers.hpp in a way that allows using is_zero() as before. This is more user-friendly solution because now evmc::is_zero() can be used also for C types. Before, the deprecated overloading was selected by the compiler.

include/evmc/helpers.hpp

@@ -12,11 +12,13 @@
  */
 #pragma once
 
-#include <evmc/evmc.h>
+#include <evmc/evmc.hpp>
 
 #include <cstring>
 #include <functional>
 
+using evmc::is_zero;
+
 /// The comparator for std::map<evmc_address, ...>.
 EVMC_DEPRECATED
 inline bool operator<(const evmc_address& a, const evmc_address& b)
@@ -45,22 +47,6 @@ inline bool operator==(const evmc_bytes32& a, const evmc_bytes32& b)
     return std::memcmp(a.bytes, b.bytes, sizeof(a.bytes)) == 0;
 }
 
-/// Check if the address is zero (all bytes are zeros).
-EVMC_DEPRECATED
-inline bool is_zero(const evmc_address& address) noexcept
-{
-    constexpr auto zero = evmc_address{};
-    return std::memcmp(address.bytes, zero.bytes, sizeof(zero.bytes)) == 0;
-}
-
-/// Check if the hash is zero (all bytes are zeros).
-EVMC_DEPRECATED
-inline bool is_zero(const evmc_bytes32& x) noexcept
-{
-    constexpr auto zero = evmc_bytes32{};
-    return std::memcmp(x.bytes, zero.bytes, sizeof(zero.bytes)) == 0;
-}
-
 /// Parameters for the fnv1a hash function, specialized by the hash result size (size_t).
 ///
 /// The values for the matching size are taken from