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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_MATCH_FROM(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,imap1.dmz-prg2.suse.org:helo] X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org On 4/24/26 6:21 PM, Tom Tromey wrote: > Tom> + Instead of factoring out a base class, we could use something like this: > Tom> + > Tom> + template > Tom> + struct next_iterator > Tom> + { > Tom> + ... > Tom> + self_type &operator++ () > Tom> + { > Tom> + m_item = m_item->*F; > Tom> + return *this; > Tom> + } > Tom> + ... > Tom> + } > Tom> + > Tom> + but that has the drawback that it doesn't work with incomplete T. */ > > I am curious about this because I wonder how the current code could work > with an incomplete T -- since the code references T::next directly. Yeah, that's a good question. I wrote the following stand-alone demonstrator: ... $ cat test.c #include #include #include #include #include "gdbsupport/next-iterator.h" struct list; void print_pointer (list *l) { auto begin = next_iterator (l); for (auto elem : next_range (begin)) printf ("%p\n", elem); } struct list { int i; struct list *next; }; void print_int (list *l) { auto begin = next_iterator (l); for (auto elem : next_range (begin)) printf ("%d\n", elem->i); } struct list a = { 1, nullptr }; struct list b = { 2, &a }; struct list c = { 3, &b }; int main () { print_pointer (&c); print_int (&c); return 0; } $ g++ test.c -I . $ ./a.out 0x404040 0x404030 0x404020 3 2 1 $ ... I asked an LLM about this, and it explained that this is deferred or delayed template instantiation at work. Basically the operator++ is used in print_pointer, but not yet instantiated, so we don't have to know the details of the incomplete type at that point. Thanks, - Tom