[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 Jonathan Wakely changed: What|Removed |Added Keywords||diagnostic Status|UNCONFIRMED |NEW Last reconfirmed||2021-08-31 Ever confirmed|0 |1 --- Comment #8 from Jonathan Wakely --- See https://wg21.link/p2413 which proposes to make this conversion ill-formed.
[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 --- Comment #4 from Jonathan Wakely redi at gcc dot gnu.org --- It might be valid with a custom deleter, but the example shown has undefined behaviour.
[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 --- Comment #5 from Jonathan Wakely redi at gcc dot gnu.org --- N.B. we definitely want -Wdelete-non-virtual-dtor not the less useful -Wnon-virtual-dtor
[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 --- Comment #6 from Marc Glisse glisse at gcc dot gnu.org --- (In reply to Jonathan Wakely from comment #4) It might be valid with a custom deleter, but the example shown has undefined behaviour. When the derived class does not add any member or redefine any important functionality, it is not an uncommon technique to call the base class destructor on a derived class. It might pedantically be illegal, but it is useful, and I believe some people would like to avoid the warning when the two destructors are equivalent.
[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 --- Comment #7 from Matthew Woehlke mw_triad at users dot sourceforge.net --- (In reply to Thiago Macieira from comment #3) Because it's not a bug. This is a totally valid scenario. Valid in what way? I constructed a Y but arranged, probably by accident, that its dtor is never called. I fail to see how that's not likely a bug in my code that reasonably warrants a diagnostic. (Note that I'm talking about a *warning*, and possibly one that isn't even on by default, not an error.) (In reply to Marc Glisse from comment #6) It might pedantically be illegal, but it is useful, and I believe some people would like to avoid the warning when the two destructors are equivalent. However, the compiler doesn't know that here, because I didn't provided a definition thereof; Y's dtor, even in this example, could have important side effects. Even if the compiler *can* prove equivalence, I'd be suspicious whether this was intended, but I'd be okay with a different (i.e. more pedantic) warning in that case. (I'd also point out that it's not unreasonable to require the user to somehow annotate if this is intentional if they care about avoiding the warning when it's enabled.) Anyway, I still get no warning if Y has members that need to be destroyed, which definitely causes bad behavior when its dtor isn't called.
[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 --- Comment #1 from Jonathan Wakely redi at gcc dot gnu.org --- PR 58876
[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 --- Comment #2 from Matthew Woehlke mw_triad at users dot sourceforge.net --- (In reply to Jonathan Wakely from comment #1) PR 58876 *Almost*, except I am proposing that -Wnon-virtual-dtor should trip even if X does not otherwise have virtual methods. (Just why you'd be writing such code, I'm not sure, but...) Odd that didn't turn up in my search for existing bugs...
[Bug libstdc++/64399] g++ does not diagnose when upcasting owning pointer (e.g. unique_ptr) with non-virtual destructor
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64399 Thiago Macieira thiago at kde dot org changed: What|Removed |Added CC||thiago at kde dot org --- Comment #3 from Thiago Macieira thiago at kde dot org --- Because it's not a bug. This is a totally valid scenario.
