aCC warnings when end of function reached without a return?

[simon moore]

Hi There,

how can I get aCC (v 3.50) to warn when it encounters the following situation (no return).

Any help much appreciated.

Thanks

Simon


int f(int i)
{
if (42 == i)
{
return i;
}
else
{
cout << "not returning" << endl;
// return nothing
}
}

[Antoniov.]

Hi Simon,
a int function return always a value; in c (R&K and ANSI) doesn't exist NULL value for int.
However I use code like follow:

#define NULLINT 0x80000000
int f(int i)
{ if (i==42) /* Test my value */
return (i); /* return valid value */
else
return (NULLINT); /* invalid value */
}
In this example I suppose 32bit int; you could set a value 0x08 followed by zero until pad the size.
Also your caller code must be recognize the NULLINT value (for example):
i=f(10);
if (i==NULLINT)
/* here do noting */
If you ise ANSIC you could use macro MININT (if I remember);
Notice, in this way, negative vale ha min suca as positive value; for example using 16 bit int your valid value are -32678..32767; using my hint valid value are -32767..32767 because -32768 id NULL value.

H.T.H.
Antoniov

[simon moore]

I should add that I have a rather large code base and I need a compiler switch to detect this situation as the behaviour of what gets returned is not only 'undefined' but it is differently undefined in statically and dynamically linked programs.

Simon

[A. Clay Stephenson · Accepted solution]

There is no pragma or switch to do this in aCC. Compiling with +w (full warnings) does not flag this as a warning either. Ironically, this would have been "duck soup" with lint but lint doesn't understand C++. You really nned a lint that speaks C++ and runs on HP-UX. One such lint is FlexeLint from Gimpel although it's not free:
http://www.gimpel.com/html/flex.htm

It would be quite easy to add a FlexeLint call to all your makefiles before invoking aCC.

[simon moore]

Ironically, g++ -Wall -pedantic -ansi flags this, as does VC++.

Why doesn't aCC? It's infuriating!!!! And it took a helluva lot of time to track down the behavioural differenced between static and dynamic builds.

Can anyone from HP answer?

Thanks

Simon