------- Comment #9 from wotte at dre dot vanderbilt dot edu 2006-03-09 22:44
-------
In some cases, this warning can also be impossible to address and may be
buggy/erroneous. Consider the following example:
========
struct A
{
A ();
};
struct B : virtual A
{
B ();
};
struct C : virtual B
{
C ();
};
template <typename Base>
struct E : Base
{
E ();
E (E const &)
{
};
};
E<C> foo;
E<C> bar (foo);
====
Produces the following diagnostic:
test.cpp: In copy constructor 'E<Base>::E(const E<Base>&) [with Base = C]':
test.cpp:27: instantiated from here
test.cpp:21: warning: base class 'struct A' should be explicitly initialized in
the copy constructor
test.cpp:21: warning: base class 'struct B' should be explicitly initialized in
the copy constructor
test.cpp:21: warning: base class 'struct C' should be explicitly initialized in
the copy constructor
If I make an immediately obvious fix by explicitly initializing Base:
========
struct A
{
A ();
};
struct B : virtual A
{
B ();
};
struct C : virtual B
{
C ();
};
template <typename Base>
struct E : Base
{
E ();
E (E const &)
: Base ()
{
};
};
E<C> foo;
E<C> bar (foo);
====
I am presented with the following diagnostic:
test.cpp: In copy constructor 'E<Base>::E(const E<Base>&) [with Base = C]':
test.cpp:28: instantiated from here
test.cpp:21: warning: base class 'struct A' should be explicitly initialized in
the copy constructor
test.cpp:21: warning: base class 'struct B' should be explicitly initialized in
the copy constructor
In this case, E can't explicitly initialize A or B, because E can't assume that
either is present as a parent of Base. This is also likely erroneous because E
shouldn't have to explicitly initialize the parents of Base... That should be
handled by the copy constructor of Base.
--
wotte at dre dot vanderbilt dot edu changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |wotte at dre dot vanderbilt
| |dot edu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11159
