warning when compile: returning reference to temporary [wreturn local addr]

[lenguyenvu007]

when compile the code, usually happen the warning: returning reference to temporary [wreturn local addr] and firebase will not return any description, if firebase error occur.

We should change the function in Firebase.cpp like this, then OK.
Please test it by your self, and update below function the file "Firebase.cpp" if helpful.

const String& FirebaseArduino::error() {
static const String& s = error_.message().c_str();
return s;
}

[proppy]

Yes, we should store the ref as an Arduino String and just return a reference to it

[lenguyenvu007]

yes, thank you @proppy but this solution is not completed yet. Because I used "static const String& s" then it always return firebase error at the first time. (mean the next error also return the first error message). But if not declare "static" is no warning while compile, but error return nothing.

[proppy]

@lenguyenvu007 thanks for the followup, I meant that we could store the message_ as a String instead of a std::string in https://github.com/firebase/firebase-arduino/blob/master/src/FirebaseError.h#L21

And then just return a reference to it, instead of a ref to a temporary copy.