Re: Warnings for unhandled c++ exceptions?

["Wesley W. Terpstra" <terpstra@ito.tu-darmstadt.de>]

On Mon, Feb 03, 2003 at 04:11:07PM -0200, Alexandre Oliva wrote:
> On Feb  3, 2003, "Wesley W. Terpstra" <terpstra@ito.tu-darmstadt.de> wrote:
> 
> > I suggested an optional flag to be used for compiler-assisted bug-tracking
> > and quality code writing. (refer to the earlier portion of the message)
> 
> /me thinks such a warning would be mostly useless
> 
> I actually find this sad, but if you consider that most of the C++
> code out there, as well as the C library whose declarations are
> brought into C++, have no throw() declarations at all, you'd quickly
> drown into warning due to calling methods that could throw anything
> but that in reality don't, and it would be very difficult to tell what
> warnings are actually significant.

Yes, but you missed the fine print in my options' descriptions.

        -Wthrow-clause-violated
                If a method throws an exception which is not listed in it's
                throw () clause, or calls a method whose throw clause is not
                handled or not included, generate a warning.

(by not included I meant not included in our throw clause)

        -Wthrow-clause-missing
                If a method throws an exception or calls a method which
                declares a throw clause, but has no throw-clause itself,
                a warning is generated.
                Implies -Wthrow-clause-violated

The first one does not warn about functions which might throw but don't
include a throw () clause. Nor does it warn about calling them.

The second will only warn about things defined within your translation unit.
... excepting inline methods of course... and I see that the libstdc++ does
this. Perhaps the above throw-clause-missing should be ignored for inlined
methods.

Therefore, these warnings will NOT be issued by including other people's
no-throw-declared headers. Only when misusing throw () declared methods and
writing bad methods yourself.

Neither warning is triggered by:

void foo(); // defined elsewhere and actually throws ints

void bar()
{
	foo();
}

In a large enough software project, you probably won't be calling many of
these out-of-project methods (and such calls are suspect anyways), so the
warnings are still useful in the context you describe.

---
Wes

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