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Re: When is the complete type of an external definition known?

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On 19-Aug-12 10:22 PM, Keith Thompson wrote:
> Vlad from Moscow <vlad.moscow@mail.ru> writes:
>> понедельник, 20 августа 2012 г., 1:56:49 UTC+4 пользователь Ike Naar написал:
>>> On 2012-08-19, Vlad from Moscow <vlad.moscow@mail.ru> wrote:
> [...]
>>>    static int a[];
>>>
>>> violates 6.9.2 p3:
>>>
>>> "If the declaration of an identifier for an object is a tentative
>>> definition and has internal linkage, the declared type shall not be
>>> an incomplete type."
>
> ... (more precisely a constraint violation).

Actually that paragraph is in a Semantics section, not in a Constraints 
section.  It's plain undefined behaviour without a promise of a diagnostic.

Out of curiosity, does anybody know the reason for this restriction?  It 
sounds like a useful thing to be able to do.  (And I have to admit that 
did it more than once, before I knew about this.)  Is it because 
different compilers used to interpret it differently back in the day, 
and the standard didn't want to break them?  The Rationale doesn't seem 
to mention "tentative" at all.

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When is the complete type of an external definition known? Vlad from Moscow <vlad.moscow@mail.ru> - 2012-08-19 13:40 -0700
  Re: When is the complete type of an external definition known? Keith Thompson <kst-u@mib.org> - 2012-08-19 14:06 -0700
    Re: When is the complete type of an external definition known? Vlad from Moscow <vlad.moscow@mail.ru> - 2012-08-19 14:30 -0700
      Re: When is the complete type of an external definition known? Ike Naar <ike@iceland.freeshell.org> - 2012-08-19 21:56 +0000
        Re: When is the complete type of an external definition known? Vlad from Moscow <vlad.moscow@mail.ru> - 2012-08-19 16:42 -0700
          Re: When is the complete type of an external definition known? Keith Thompson <kst-u@mib.org> - 2012-08-19 19:22 -0700
            Re: When is the complete type of an external definition known? Wojtek Lerch <wojtek_l@yahoo.ca> - 2012-08-20 10:57 -0400
              Re: When is the complete type of an external definition known? Keith Thompson <kst-u@mib.org> - 2012-08-20 13:01 -0700
                Re: When is the complete type of an external definition known? Wojtek Lerch <wojtek_l@yahoo.ca> - 2012-08-20 16:58 -0400
              Re: When is the complete type of an external definition known? pacman@kosh.dhis.org (Alan Curry) - 2012-08-21 00:44 +0000
          Re: When is the complete type of an external definition known? Ike Naar <ike@sverige.freeshell.org> - 2012-08-20 05:57 +0000
            Re: When is the complete type of an external definition known? Vlad from Moscow <vlad.moscow@mail.ru> - 2012-08-20 03:22 -0700
              Re: When is the complete type of an external definition known? Ike Naar <ike@sverige.freeshell.org> - 2012-08-20 12:27 +0000
                Re: When is the complete type of an external definition known? Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-20 17:04 +0200
                Re: When is the complete type of an external definition known? Ike Naar <ike@iceland.freeshell.org> - 2012-08-20 16:35 +0000
                Re: When is the complete type of an external definition known? Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-20 20:43 +0200
          Re: When is the complete type of an external definition known? James Kuyper <jameskuyper@verizon.net> - 2012-08-20 08:46 -0400
  Re: When is the complete type of an external definition known? Vlad from Moscow <vlad.moscow@mail.ru> - 2012-08-19 14:24 -0700
  Re: When is the complete type of an external definition known? "Ersek, Laszlo" <lacos@caesar.elte.hu> - 2012-08-19 23:36 +0200
    Re: When is the complete type of an external definition known? Vlad from Moscow <vlad.moscow@mail.ru> - 2012-08-19 14:46 -0700

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