[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 --- Comment #13 from Jonathan Wakely --- It's so crazy, it just might work.
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 Harald van Dijk changed: What|Removed |Added CC||harald at gigawatt dot nl --- Comment #12 from Harald van Dijk --- (In reply to Jonathan Wakely from comment #11) > No, probably not. Comment 2 doesn't work because -Wsystem-headers can't be > enabled and disabled using pragmas. It doesn't work like other warnings. However, the internal version of the #line directive, # [line number] [file name] [flags] could be used to mark a region of a system header as non-system header, which should achieve the same result, right? It might need a bit of cleanup to be maintainable, but this seems to work as a proof of concept: --- bits/unique_ptr.h +++ bits/unique_ptr.h @@ -82,7 +82,9 @@ "can't delete pointer to incomplete type"); static_assert(sizeof(_Tp)>0, "can't delete pointer to incomplete type"); +# 86 __FILE__ delete __ptr; +# 88 __FILE__ 3 } };
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 Jonathan Wakely changed: What|Removed |Added See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=64399 --- Comment #11 from Jonathan Wakely --- (In reply to DB from comment #10) > Sorry to pester, but is this likely to get anywhere, any time soon? No, probably not. Comment 2 doesn't work because -Wsystem-headers can't be enabled and disabled using pragmas. It doesn't work like other warnings. I don't think this can be fixed in the library. > I presume the same goes for std::shared_ptr, too. No, because shared_ptr type-erases the deleter and so deletes the dynamic type even if the stored pointer is upcast to a different static type.
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 Jonathan Wakely changed: What|Removed |Added Status|ASSIGNED|NEW Assignee|redi at gcc dot gnu.org|unassigned at gcc dot gnu.org
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 DB changed: What|Removed |Added CC||db0451 at gmail dot com --- Comment #10 from DB --- Sorry to pester, but is this likely to get anywhere, any time soon? I fixed a bug in one of my projects recently by using AddressSanitizer, which this would've caught if it warned on non-polymorphic deletion via unique_ptr, so it'd be nice to see. I presume the same goes for std::shared_ptr, too.
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 --- Comment #9 from Matthew Woehlke mw_triad at users dot sourceforge.net --- (In reply to Jonathan Wakely from comment #8) No, really, that's not how make_unique works. You do not use 'new' with make_unique, that's the whole point [...] D'oh, sorry :-). Not sure what I was thinking. I think I meant 'unique_ptrA(new B)', like to the original example. That said... unique_ptrA p = make_uniqueB(); ...this is also a good example that I would like to see warn. (I think this has the same problems; the warning would need to trigger in the conversion operator, otherwise the knowledge of the true type is lost by the time the unique_ptrA is destroyed.)
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 --- Comment #6 from Jonathan Wakely redi at gcc dot gnu.org --- (In reply to Matthew Woehlke from comment #5) Actually, this may be required for 'make_uniqueA(new B)' to warn, since That's not how make_unique works.
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 --- Comment #7 from Matthew Woehlke mw_triad at users dot sourceforge.net --- (In reply to Jonathan Wakely from comment #6) (In reply to Matthew Woehlke from comment #5) Actually, this may be required for 'make_uniqueA(new B)' to warn, since That's not how make_unique works. ...and I'm suggesting it *should* be. (How else are you going to warn? After that executes, the pointer no longer knows that it really contains a B, unless you teach the compiler some fancy extra tricks, which seems overly complicated. Conversely, I feel that 'make_uniqueA(new B)' should warn if it's going to result in failing to call B's dtor. I might even go so far as to say 'even if the compiler can prove that B's dtor is trivial', though I'd be willing to delegate that to a different and more pedantic warning.)
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 --- Comment #8 from Jonathan Wakely redi at gcc dot gnu.org --- No, really, that's not how make_unique works. You do not use 'new' with make_unique, that's the whole point, so you would say make_uniqueB() to create a B. Your motivating examples should be valid C++ of you want to convince anyone, so maybe: unique_ptrA p = make_uniqueB();
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876
Matthew Woehlke mw_triad at users dot sourceforge.net changed:
What|Removed |Added
CC||mw_triad at users dot
sourceforge.
||net
--- Comment #5 from Matthew Woehlke mw_triad at users dot sourceforge.net ---
See also bug 64399, which proposes that a) the conversion itself should
generate a warning, and b) the presence of other virtual methods in A should
not be required for the warning to trip. (This could be achieved by something
like static_assert except to emit a warning, combined with
std::has_virtual_destructor, without otherwise having to fiddle with pragmas.)
Actually, this may be required for 'make_uniqueA(new B)' to warn, since the
conversion of a B* ('new B') to an A* (which is what is passed to make_unique /
unique_ptr::unique_ptr) should not warn. (IOW, unique_ptr / make_unique would
need overloads taking any pointer type and doing the conversion inside STL so
that std::has_virtual_destructor can be checked against the actual pointer
type.)
...or alternatively gcc would need to detect when a converted pointer is passed
to unique_ptr / make_unique, which seems like it would be harder.
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 Bug 58876 depends on bug 59304, which changed state. Bug 59304 Summary: #pragma diagnostic pop after warning fails for options unspecified in the command-line and disabled by default https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59304 What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 Bug 58876 depends on bug 61600, which changed state. Bug 61600 Summary: #pragma GCC diagnostic pop leaves warnings enabled https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61600 What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |DUPLICATE
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Keywords||diagnostic Status|UNCONFIRMED |NEW Last reconfirmed||2013-10-30 Component|c++ |libstdc++ Ever confirmed|0 |1 --- Comment #1 from Jonathan Wakely redi at gcc dot gnu.org --- This is because warnings are suppressed by default in system headers, and the undefined delete operation occurs in a system header. You get the warning if you use -Wsystem-headers I don't see an easy way to force the warning to always be emitted though.
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876
Jonathan Wakely redi at gcc dot gnu.org changed:
What|Removed |Added
Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org
--- Comment #2 from Jonathan Wakely redi at gcc dot gnu.org ---
Actually we can use this around the definition of default_delete
#pragma GCC diagnostic push
#pragma GCC diagnostic warning -Wsystem-headers
/// Primary template of default_delete, used by unique_ptr
templatetypename _Tp
struct default_delete
{
...
};
#pragma GCC diagnostic pop
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 --- Comment #3 from Paolo Carlini paolo.carlini at oracle dot com --- At some point Ian Taylor filed a Bugzilla about these issues, I think it's still open. Not sure what we should do in this area...
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Status|NEW |ASSIGNED
[Bug libstdc++/58876] No non-virtual-dtor warning in std::unique_ptr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58876 --- Comment #4 from Jonathan Wakely redi at gcc dot gnu.org --- Yes, I should dig Ian's bug out and have another look. I'm planning to throw some ideas around on the mailing list ...
