https://github.com/ClickHouse/ClickHouse/blob/9a48cf0da8badfc5f3da08611eb44961aa28e3f6/src/Functions/FunctionsHashing.h#L669-L671

There's a call to `blake3_free_char_pointer` that passes ownership of the pointer back to Rust (which then frees the memory), then there's a call to `std::string`'s constructor that accepts that now-freed pointer.
static auto apply(const char * s, const size_t len) { return NAMESPACE_FOR_HASH_FUNCTIONS::Hash64(s, len); }
    static constexpr bool use_int_hash_for_pods = true;
};
struct ImplMetroHash64
{
    static constexpr auto name = "metroHash64";
    using ReturnType = UInt64;
    using uint128_t = CityHash_v1_0_2::uint128;
    static auto combineHashes(UInt64 h1, UInt64 h2) { return CityHash_v1_0_2::Hash128to64(uint128_t(h1, h2)); }
    static auto apply(const char * s, const size_t len)
    {
        union
        {
            UInt64 u64;
            uint8_t u8[sizeof(u64)];
        };
        metrohash64_1(reinterpret_cast<const uint8_t *>(s), len, 0, u8);
        return u64;
    }
    static constexpr bool use_int_hash_for_pods = true;
};
struct ImplXxHash32
{
    static constexpr auto name = "xxHash32";
    using ReturnType = UInt32;
    static auto apply(const char * s, const size_t len) { return XXH_INLINE_XXH32(s, len, 0); }