* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
@ 2007-03-30 23:43 ` fang at csl dot cornell dot edu
2007-04-07 23:58 ` bangerth at dealii dot org
` (10 subsequent siblings)
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From: fang at csl dot cornell dot edu @ 2007-03-30 23:43 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from fang at csl dot cornell dot edu 2007-03-31 00:43 -------
Do you mean -Woverloaded-virtual? (see man page)
The diagostic reports when a derived class's method 'hides' the base class's.
--
fang at csl dot cornell dot edu changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |fang at csl dot cornell dot
| |edu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
2007-03-30 23:43 ` [Bug c++/31397] " fang at csl dot cornell dot edu
@ 2007-04-07 23:58 ` bangerth at dealii dot org
2009-07-08 10:23 ` Thomas dot Lange at sun dot com
` (9 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: bangerth at dealii dot org @ 2007-04-07 23:58 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from bangerth at dealii dot org 2007-04-08 00:58 -------
(In reply to comment #1)
> Do you mean -Woverloaded-virtual? (see man page)
> The diagostic reports when a derived class's method 'hides' the base class's.
No, he simply wants to know that "it doesn't matter from a semantic point,
but just to make the declaration clearer, why don't you add a 'virtual'
to your destructor and int f(int) functions, because they are implicitly
virtual anyway'.
Confirmed.
W.
--
bangerth at dealii dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bangerth at dealii dot org
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |diagnostic
Last reconfirmed|0000-00-00 00:00:00 |2007-04-08 00:58:22
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
2007-03-30 23:43 ` [Bug c++/31397] " fang at csl dot cornell dot edu
2007-04-07 23:58 ` bangerth at dealii dot org
@ 2009-07-08 10:23 ` Thomas dot Lange at sun dot com
2009-07-08 10:30 ` Thomas dot Lange at sun dot com
` (8 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Thomas dot Lange at sun dot com @ 2009-07-08 10:23 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from Thomas dot Lange at sun dot com 2009-07-08 10:23 -------
(In reply to comment #2)
> why don't you add a 'virtual'
> to your destructor and int f(int) functions, because they are implicitly
> virtual anyway'.
That is exactly the point this is about!
I want a way so the compiler enforces to add 'virtual' to ~B and B::f, and thus
help to write better understandable code.
This is in order for large derived trees or a big source code. It is for the
one looking at the declaration (and not anymore or not at all familiar with the
code!) to not miss that those functions are virtual.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (2 preceding siblings ...)
2009-07-08 10:23 ` Thomas dot Lange at sun dot com
@ 2009-07-08 10:30 ` Thomas dot Lange at sun dot com
2009-07-13 11:48 ` jwakely dot gcc at gmail dot com
` (7 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Thomas dot Lange at sun dot com @ 2009-07-08 10:30 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from Thomas dot Lange at sun dot com 2009-07-08 10:30 -------
Side note: Of course having such an option is much more useful where the
declaration of class A and B are in different header files and probably even in
different modules.
(For example: such cases are often found in the OpenOffice.org source code...
^_-)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (3 preceding siblings ...)
2009-07-08 10:30 ` Thomas dot Lange at sun dot com
@ 2009-07-13 11:48 ` jwakely dot gcc at gmail dot com
2009-07-13 11:57 ` Thomas dot Lange at sun dot com
` (6 subsequent siblings)
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From: jwakely dot gcc at gmail dot com @ 2009-07-13 11:48 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from jwakely dot gcc at gmail dot com 2009-07-13 11:48 -------
(In reply to comment #0)
>
> What I/we at OOo would like to have is a warning when a when a function in a
> derived class is overloaded without specifing 'virtual'.
To avoid further misunderstanding: you mean overridden, not overloaded.
This seems like the sort of thing that could be put in a plugin or other static
analysis tool rather than the compiler, because it warns about a preference in
coding style.
--
jwakely dot gcc at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jwakely dot gcc at gmail dot
| |com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (4 preceding siblings ...)
2009-07-13 11:48 ` jwakely dot gcc at gmail dot com
@ 2009-07-13 11:57 ` Thomas dot Lange at sun dot com
2009-07-13 12:00 ` rguenth at gcc dot gnu dot org
` (5 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Thomas dot Lange at sun dot com @ 2009-07-13 11:57 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from Thomas dot Lange at sun dot com 2009-07-13 11:56 -------
(In reply to comment #5)
No. I do mean overloaded!
It might be nice to have a warning for overloading virtual functions of base
classes as well. But my point is that the compiler should help to enforce that
every virtual function has the 'virtual' keyword set in its declaration.
Thus effectively removing those implicit virtual functions that are allowed in
C++.
The goal is: Either a function should be explicitly declared virtual in its
declaration or not be virtual at all.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (5 preceding siblings ...)
2009-07-13 11:57 ` Thomas dot Lange at sun dot com
@ 2009-07-13 12:00 ` rguenth at gcc dot gnu dot org
2009-07-13 12:02 ` Thomas dot Lange at sun dot com
` (4 subsequent siblings)
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From: rguenth at gcc dot gnu dot org @ 2009-07-13 12:00 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from rguenth at gcc dot gnu dot org 2009-07-13 11:59 -------
Your example is overriding A::f, not overloading it. Overloading would be
int f(int x, int y);
do you want a warning for that as well?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (6 preceding siblings ...)
2009-07-13 12:00 ` rguenth at gcc dot gnu dot org
@ 2009-07-13 12:02 ` Thomas dot Lange at sun dot com
2009-07-13 12:07 ` Thomas dot Lange at sun dot com
` (3 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Thomas dot Lange at sun dot com @ 2009-07-13 12:02 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from Thomas dot Lange at sun dot com 2009-07-13 12:02 -------
(In reply to comment #6)
Ooops... Sorry!
I just was told that I confused those two terms. >_<
(That might happen to non-native speakers)
My apologies!
Yes you are correct. It is about overwriting.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (7 preceding siblings ...)
2009-07-13 12:02 ` Thomas dot Lange at sun dot com
@ 2009-07-13 12:07 ` Thomas dot Lange at sun dot com
2009-07-13 16:47 ` jwakely dot gcc at gmail dot com
` (2 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Thomas dot Lange at sun dot com @ 2009-07-13 12:07 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from Thomas dot Lange at sun dot com 2009-07-13 12:07 -------
(In reply to comment #6)
I'm not concerned about that case.
Thank you for your time!
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (8 preceding siblings ...)
2009-07-13 12:07 ` Thomas dot Lange at sun dot com
@ 2009-07-13 16:47 ` jwakely dot gcc at gmail dot com
2009-07-21 10:51 ` jwakely dot gcc at gmail dot com
2009-08-11 14:16 ` jwakely dot gcc at gmail dot com
11 siblings, 0 replies; 18+ messages in thread
From: jwakely dot gcc at gmail dot com @ 2009-07-13 16:47 UTC (permalink / raw)
To: gcc-bugs
------- Comment #10 from jwakely dot gcc at gmail dot com 2009-07-13 16:46 -------
(In reply to comment #8)
>
> Ooops... Sorry!
> I just was told that I confused those two terms. >_<
> (That might happen to non-native speakers)
> My apologies!
> Yes you are correct. It is about overwriting.
Overriding :-)
I'm using the terminology of the C++ standard, but I do have the advantage that
it's written in my native language
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (9 preceding siblings ...)
2009-07-13 16:47 ` jwakely dot gcc at gmail dot com
@ 2009-07-21 10:51 ` jwakely dot gcc at gmail dot com
2009-08-11 14:16 ` jwakely dot gcc at gmail dot com
11 siblings, 0 replies; 18+ messages in thread
From: jwakely dot gcc at gmail dot com @ 2009-07-21 10:51 UTC (permalink / raw)
To: gcc-bugs
------- Comment #11 from jwakely dot gcc at gmail dot com 2009-07-21 10:51 -------
There is a lot of overlap between this warning and the functionality described
by http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2852.html (which
will be updated by N2928 in a couple of weeks.)
It might make sense to add attributes rather than a -W switch, as that might
make it easier to implement the C++0x [[base_check]] and [[override]]
attributes. It would also be easier for user code to transition from GNU-style
__attribute__((override)) to C++0x-style [[override]]
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
2007-03-30 9:49 [Bug c++/31397] New: Useful compiler warning missing (virtual functions in derived classes used without 'virtual') Thomas dot Lange at sun dot com
` (10 preceding siblings ...)
2009-07-21 10:51 ` jwakely dot gcc at gmail dot com
@ 2009-08-11 14:16 ` jwakely dot gcc at gmail dot com
11 siblings, 0 replies; 18+ messages in thread
From: jwakely dot gcc at gmail dot com @ 2009-08-11 14:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #12 from jwakely dot gcc at gmail dot com 2009-08-11 14:16 -------
revised 'Explicit Virtual Function Overrides' paper:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2928.htm
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
[not found] <bug-31397-4@http.gcc.gnu.org/bugzilla/>
@ 2011-06-21 16:13 ` redi at gcc dot gnu.org
2011-07-09 12:55 ` ville.voutilainen at gmail dot com
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From: redi at gcc dot gnu.org @ 2011-06-21 16:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-06-21 16:12:42 UTC ---
G++ 4.7 implements C++0x explicit override control so you can add 'override'
class B : public A
{
B( int y );
~B();
int f( int x ) override;
};
and you'll get an error if it doesn't actually override a virtual function from
a base class.
It's not *quite* what you want, but you could use it to check whether B::f
overrides a virtual (and so you want to add 'virtual' to it) without checking
the declaration of A::f
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
[not found] <bug-31397-4@http.gcc.gnu.org/bugzilla/>
2011-06-21 16:13 ` redi at gcc dot gnu.org
@ 2011-07-09 12:55 ` ville.voutilainen at gmail dot com
2013-05-22 8:20 ` ethouris at gmail dot com
` (2 subsequent siblings)
4 siblings, 0 replies; 18+ messages in thread
From: ville.voutilainen at gmail dot com @ 2011-07-09 12:55 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
Ville Voutilainen <ville.voutilainen at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ville.voutilainen at gmail
| |dot com
--- Comment #14 from Ville Voutilainen <ville.voutilainen at gmail dot com> 2011-07-09 12:54:40 UTC ---
"[[base_check]]" or "explicit" on a class might've been helpful for this, but
even those facilities were never supposed to require annotations on
destructors.
The committee ended up removing that part because there were grammar problems
for "new" on members, and we didn't want to add base_check/explicit that
would check only overrides.
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
[not found] <bug-31397-4@http.gcc.gnu.org/bugzilla/>
2011-06-21 16:13 ` redi at gcc dot gnu.org
2011-07-09 12:55 ` ville.voutilainen at gmail dot com
@ 2013-05-22 8:20 ` ethouris at gmail dot com
2015-01-06 2:05 ` tbsaunde at gcc dot gnu.org
2021-08-11 23:48 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 18+ messages in thread
From: ethouris at gmail dot com @ 2013-05-22 8:20 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
Michal Malecki <ethouris at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ethouris at gmail dot com
--- Comment #15 from Michal Malecki <ethouris at gmail dot com> ---
But it would be nice to add a warning, valid in C++11 mode only, when a method
is overridden without 'override' keyword, or an overloaded method is defined,
which does not override without explicit 'new'. For example,
-Wimplicit-override. Additionally, if [[base_check]] has been withdrawn, the
same idea can be additionally added as __attribute__((warn_implicit_override))
(or, in C++11, [[gnu::warn_implicit_override]]).
I don't think forcing a 'virtual' keyword would do things any better -
'virtual' can always mean starting a new virtual method in this class, which
does not override anything.
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
[not found] <bug-31397-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2013-05-22 8:20 ` ethouris at gmail dot com
@ 2015-01-06 2:05 ` tbsaunde at gcc dot gnu.org
2021-08-11 23:48 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 18+ messages in thread
From: tbsaunde at gcc dot gnu.org @ 2015-01-06 2:05 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
--- Comment #16 from tbsaunde at gcc dot gnu.org ---
Author: tbsaunde
Date: Tue Jan 6 02:02:47 2015
New Revision: 219213
URL: https://gcc.gnu.org/viewcvs?rev=219213&root=gcc&view=rev
Log:
implement -Wsuggest-override
c-family/
PR c++/31397
* c.opt (Wsuggest-override): New option.
cp/
PR c++/31397
* class.c (check_for_override): Warn when a virtual function is an
override not marked override.
gcc/
PR c++/31397
* doc/invoke.texi: Document -Wsuggest-override.
Added:
trunk/gcc/testsuite/g++.dg/warn/Wsuggest-override.C
Modified:
trunk/gcc/ChangeLog
trunk/gcc/c-family/ChangeLog
trunk/gcc/c-family/c.opt
trunk/gcc/cp/ChangeLog
trunk/gcc/cp/class.c
trunk/gcc/doc/invoke.texi
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* [Bug c++/31397] Useful compiler warning missing (virtual functions in derived classes used without 'virtual')
[not found] <bug-31397-4@http.gcc.gnu.org/bugzilla/>
` (3 preceding siblings ...)
2015-01-06 2:05 ` tbsaunde at gcc dot gnu.org
@ 2021-08-11 23:48 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 18+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-11 23:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31397
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|NEW |RESOLVED
Target Milestone|--- |5.0
--- Comment #17 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed in GCC 5 with -Wsuggest-override.
^ permalink raw reply [flat|nested] 18+ messages in thread