g++ not allowing returned objects as references

Millenniumman · 06-08-2007, 08:47 PM

I am porting some code from Windows to Linux. I am starting to see a lot of problems relating to g++ not allowing returned objects to be passed as references. For example:

Code:

//functions
string alterString( string & inputString );
void doSomethingWithAlteredString(string & inputString);

//implementation
doSomethingWithAlteredString(alterString(aString));

With the above, doSomethingWithAlteredString will not work. g++ apparently will not accept the return of a function as a reference to an object, and complains that I am passing a string to function that takes a string&. Microsoft's compiler accepts this.

Is there any way to deal with this without making code changes wherever this occurs? Maybe a g++ compiler flag?

I know I could store the output of alterString in a variable, but this would require changes to a lot of code, and I don't see how I could do it in a function definition with default values.

tuxdev · 06-08-2007, 09:07 PM

You're trying to use the "const reference input object" optimization idiom, but forgot the const. You need the const because you're trying to push a temporary object into the method, and temporary objects are considered const.

Microsoft VC++ is once again very broken and non-compliant.

Millenniumman · 06-08-2007, 10:56 PM

I'll first note that I didn't write this code.

Second, where does the const go? The function definition? And this is the only way to solve this?

Thanks.

tuxdev · 06-08-2007, 11:43 PM

Code:

string alterString(const string & inputString );
void doSomethingWithAlteredString(const string & inputString);

dmail · 06-09-2007, 03:01 AM

"Microsoft's compiler accepts this."
"Microsoft VC++ is once again very broken and non-compliant."

Did you try with language extensions turned off?
Although this normally means MS code will not compile