https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78826
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jason at gcc dot gnu.org
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Krzysztof Laskowski from comment #3)
> (In reply to Jonathan Wakely from comment #2)
> > I assume GCC 4.5 stopped diagnosing it due to the revised specification
> > which only cares about trivial constructor or trivial destructor, not
> > PODness.
> I couldn't actually find any clause allowing jump over trivially constructed
> variable in ISO/IEC 14882:1998 nor ISO/IEC 14882:2003. Moreover, icc (13,
> 16, 17) and clang (3.0-3.9) warn and err, respectively, on example.
I didn't suggest you'd find it in C++03.
> It seems to correlate with introducing c++0x support in gcc.
Yes, obviously. Because the refined rule was introduced for C++11. That's what
I meant by revised specification.
> https://gcc.gnu.org/gcc-4.5/changes.html
> "Diagnostics that used to complain about passing non-POD types to ... or
> jumping past the declaration of a non-POD variable now check for triviality
> rather than PODness, as per C++0x."
So it's even documented as being deliberate, isn't that clear?
> > Giving a diagnostic here would just be pedantic and unhelpful.
> I agree it's harmless to bypass trivially constructed variable. Does it mean
> that it's a deliberate deviation from standard for the sake of ease of c++11
> implementation at the cost of portability/conformance?
No, not for the ease of implementation. For the benefit of users.
I repeat: Giving a diagnostic here would just be pedantic and unhelpful.
The old rule doesn't prevent bugs, it doesn't make code faster, it has no
advantages. The only reason the C++03 rule was in terms of POD was because we
didn't have a better property to use. What matters is whether non-trivial
initialization or destruction gets bypassed, and with modern C++ we are able to
express the rule more precisely.
Jason, do you see any advantage to making this a pedwarn for -std=c++98, or
should we just close as WONTFIX?
