I just installed 2.0.0 Beta 2 on a Fedora Core 4 system. I am getting the
following warning:

/usr/local/include/mysql++/noexceptions.h: In member function
mysqlpp::NoExceptions& mysqlpp::NoExceptions:perator=(const
mysqlpp::NoExceptions&):
/usr/local/include/mysql++/noexceptions.h:129: warning: no return
statement in function returning non-void


And the offending line of code seems to be at the end of:


private:
OptionalExceptions& assoc_;
bool exceptions_were_enabled_;

// Hidden assignment operator and copy ctor, because we should not
// be copied.
NoExceptions(const NoExceptions&);
NoExceptions& operator=(const NoExceptions&) { }

As defined in that last line, operator= should return a NoExceptions
reference but it does not. I am not an expert programmer, should the "{
}" just become ";" ?

If not, what should I do? I am including mysqlpp as follows:

#include <mysql++.h>

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On Thu, 21 Jul 2005, Carlos M. Gutierrez wrote:

BTW, I am compiling with -Wall as in:

g++ -g -Wall -fPIC -I/usr/local/mysql/include/mysql
-I/usr/local/include/mysql++ -c -o TFixcountsApp.o TFixcountsApp.cc

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On Thu, Jul 21, 2005 at 12:58:19PM -0400, Carlos M. Gutierrez wrote:
Yes.

The latest SVN version has this "fixed", but incorrectly in my
opinion. It currently just returns *this, whereas I don't think
operator=() should be defined at all, just declared.

- Chris


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Chris Frey wrote:
Does this actually suppress the compiler-generated version?

Regardless, operator= does normally return *this, so the only problem
with doing it this way is that it generates a tiny bit more code than if
it were only declared and not defined.

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On Thu, Jul 21, 2005 at 06:29:03PM -0600, Warren Young wrote:
Yep.

tmp $ cat oe.cc
class A
{
private:
A(const A&);
A& operator=(const A&);

int i;

public:
A() : i(5) {}
};

int main()
{
A a, b;
a = b;
return 0;
}

tmp $ g++ -Wall -o oe oe.cc
oe.cc: In function `int main()':
oe.cc:5: error: `A& A:perator=(const A&)' is private
oe.cc:16: error: within this context


This also flags an error for derived classes too. The thing you want
to be careful about is if you're doing virtual operator=(), with a
base class as the const reference argument. For example:

class A {
public:
virtual A& operator=(const A&); // this overrides the default
};

class B : public A {
public:
virtual A& operator=(const A&); // this does not
// there is a hidden, automatic, operator=(const B&) here too!
// and the automatic operator=() will call the user-defined
// A:perator=() for us.
};



I think all we care about is the compiler warning, so no copy is done
accidentally.

- Chris


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