http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50477
Bug #: 50477
Summary: -Wunused-parameter should not warn about virtual
method declarations with bodies
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: trivial
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: mi...@gnu.org
In the following code:
struct X { virtual void f (int a) { } };
One gets a warning from -Wunused-parameter, "unused parameter 'a'".
While this is understandable, I think it's undesirable -- clearly the parameter
'a' will often be used by overrides of X::f, and the parameter name 'a' serves
a valuable documentation purpose here, even if it's not strictly required.
The basic problem of course, is that in this case, f is both a virtual method
declaration which covers overriding methods as well, and a definition of X's
definition of it.
One can avoid this by defining X::f outside the class definition, but for
trivial definitions like the above, this would seem like annoying make-work if
done only to shut up -Wunused-parameter.
My current method of avoiding the warning is to comment out the parameter name:
virtual void f (int /* a */) { }
but this again seems like an annoying wart, rather than natural code -- it's
both less readable (especially when the parameter has a funny type like a
function pointer) and yields a slightly confusing inconsistency ("why do
comment-out some method parameter names but not others?!" "oh it's just to shut
up -Wunused-parameter... :(").
Anyway, the current behavior seems wrong to me; I think -Wunused-parameter
shoul d stay silent for method virtual definitions inside the class definition.
[If this were a very rare scenario, I suppose I wouldn't care about the need to
work around it, but it seems to happen all the time for me...]
Thanks,
-Miles
