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.
/*
       With current implementation with more than 1 arguments it will give the results
       non-reproducible from outside of CH. (see comment on ImplXxHash32).
     */
    static auto combineHashes(UInt64 h1, UInt64 h2) { return CityHash_v1_0_2::Hash128to64(uint128_t(h1, h2)); }
    static constexpr bool use_int_hash_for_pods = false;
};
struct ImplXXH3
{
    static constexpr auto name = "xxh3";
    using ReturnType = UInt64;
    using uint128_t = CityHash_v1_0_2::uint128;
    static auto apply(const char * s, const size_t len) { return XXH_INLINE_XXH3_64bits(s, len); }
    /*
       With current implementation with more than 1 arguments it will give the results
       non-reproducible from outside of CH. (see comment on ImplXxHash32).
     */
    static auto combineHashes(UInt64 h1, UInt64 h2) { return CityHash_v1_0_2::Hash128to64(uint128_t(h1, h2)); }
    static constexpr bool use_int_hash_for_pods = false;
};
struct ImplBLAKE3
{
    static constexpr auto name = "BLAKE3";
    enum { length = 32 };