In SBE, there is a function sbe::value::makeNewString(StringData) to create new string values.
As StringData can be implicitly created from an std::string, it is allowed to call the function is called with an std::string parameter as well.

There were some places in the code that unnecessarily call this function with an std::string parameter where this isn't necessary, for example:

            std::string str = str::stream() << value::bitcastTo<int32_t>(operandVal);
            auto [strTag, strVal] = value::makeNewString(str);

Here we are creating a StringBuilder instance to build the stringified version of the number, and then copy the StringBuilder 's contents into an std::string, which is then passed into sbe::value::makeNewString().
We could instead use a StringData object to point into the StringBuilder 's internal buffer, and thus avoid creating the std::string altogether:

            str::stream str;
            str << value::bitcastTo<int32_t>(operandVal);
            auto [strTag, strVal] = value::makeNewString(StringData(str));

Similarly, objects of the Value class can also be constructed from StringData and std::string inputs alike. The Value constructor that takes an std::string input simply casts it to a StringData and delegates to the StringData parameter constructor.
Creating a Value object from a temporary std::string input provides no benefit, and we can instead create the Value object directly from a StringData object to avoid the potentially expensive std::string creation.