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* [Bug c++/12277] New: Warn on dynamic casts with known NULL results.
@ 2003-09-14 16:55 tilps at hotmail dot com
2003-09-14 17:23 ` [Bug c++/12277] " pinskia at gcc dot gnu dot org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: tilps at hotmail dot com @ 2003-09-14 16:55 UTC (permalink / raw)
To: gcc-bugs
PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12277
Summary: Warn on dynamic casts with known NULL results.
Product: gcc
Version: 3.4
Status: UNCONFIRMED
Severity: enhancement
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tilps at hotmail dot com
CC: gcc-bugs at gcc dot gnu dot org
While this can not be done generally - if the inheritence relation between the
type being cast from and the type being cast to is known at the time of use,
there are some cases where a dynamic cast can be sure to return NULL. I can not
think of any valid use of a dynamic cast which will always return NULL - so
therefore I suggest that a warning be given.
The specific case which bothered me (and hence why i'm writing this) is
upcasting through private inheritence always gives NULL for dynamic cast.
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug c++/12277] Warn on dynamic casts with known NULL results. 2003-09-14 16:55 [Bug c++/12277] New: Warn on dynamic casts with known NULL results tilps at hotmail dot com @ 2003-09-14 17:23 ` pinskia at gcc dot gnu dot org 2003-09-15 0:42 ` bangerth at dealii dot org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2003-09-14 17:23 UTC (permalink / raw) To: gcc-bugs PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12277 pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |diagnostic ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/12277] Warn on dynamic casts with known NULL results. 2003-09-14 16:55 [Bug c++/12277] New: Warn on dynamic casts with known NULL results tilps at hotmail dot com 2003-09-14 17:23 ` [Bug c++/12277] " pinskia at gcc dot gnu dot org @ 2003-09-15 0:42 ` bangerth at dealii dot org 2004-05-20 12:12 ` pinskia at gcc dot gnu dot org 2004-05-20 13:25 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: bangerth at dealii dot org @ 2003-09-15 0:42 UTC (permalink / raw) To: gcc-bugs PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12277 bangerth at dealii dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Ever Confirmed| |1 Last reconfirmed|0000-00-00 00:00:00 |2003-09-15 00:15:55 date| | ------- Additional Comments From bangerth at dealii dot org 2003-09-15 00:15 ------- Seems reasonable. W. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/12277] Warn on dynamic casts with known NULL results. 2003-09-14 16:55 [Bug c++/12277] New: Warn on dynamic casts with known NULL results tilps at hotmail dot com 2003-09-14 17:23 ` [Bug c++/12277] " pinskia at gcc dot gnu dot org 2003-09-15 0:42 ` bangerth at dealii dot org @ 2004-05-20 12:12 ` pinskia at gcc dot gnu dot org 2004-05-20 13:25 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2004-05-20 12:12 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2004-05-19 13:30 ------- *** Bug 15541 has been marked as a duplicate of this bug. *** -- What |Removed |Added ---------------------------------------------------------------------------- CC| |bangerth at dealii dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12277 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/12277] Warn on dynamic casts with known NULL results. 2003-09-14 16:55 [Bug c++/12277] New: Warn on dynamic casts with known NULL results tilps at hotmail dot com ` (2 preceding siblings ...) 2004-05-20 12:12 ` pinskia at gcc dot gnu dot org @ 2004-05-20 13:25 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2004-05-20 13:25 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2004-05-19 13:31 ------- And here is an example: struct Base { virtual ~Base () {} }; class Derived : Base { friend int main (); }; #include <cassert> int main () { Base * p = new Derived; assert(dynamic_cast<Derived *>(p)); // fails } -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12277 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2004-05-19 13:32 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2003-09-14 16:55 [Bug c++/12277] New: Warn on dynamic casts with known NULL results tilps at hotmail dot com 2003-09-14 17:23 ` [Bug c++/12277] " pinskia at gcc dot gnu dot org 2003-09-15 0:42 ` bangerth at dealii dot org 2004-05-20 12:12 ` pinskia at gcc dot gnu dot org 2004-05-20 13:25 ` pinskia at gcc dot gnu dot org
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