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.
{
        if (!arguments[0]->isValueRepresentedByNumber())
            throw Exception("Illegal type " + arguments[0]->getName() + " of argument of function " + getName(),
                ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
        return std::make_shared<DataTypeNumber<typename Impl::ReturnType>>();
    }
    bool useDefaultImplementationForConstants() const override { return true; }
    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & ) const override { return false; }
    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t ) const override
    {
        const IDataType * from_type = arguments[0].type.get();
        WhichDataType which(from_type);
        if (which.isUInt8())
            return executeType<UInt8>(arguments);
        else if (which.isUInt16())
            return executeType<UInt16>(arguments);
        else if (which.isUInt32())
            return executeType<UInt32>(arguments);
        else if (which.isUInt64())
            return executeType<UInt64>(arguments);
        else if (which.isInt8())
            return executeType<Int8>(arguments);
        else if (which.isInt16())
            return executeType<Int16>(arguments);
        else if (which.isInt32())
            return executeType<Int32>(arguments);
        else if (which.isInt64())
            return executeType<Int64>(arguments);
        else if (which.isDate())
            return executeType<UInt16>(arguments);