lua-users home
lua-l archive

[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index] [Thread Index]

It was thus said that the Great Philipp Janda once stated:
> Am 24.11.18 um 00:28 schröbte Sean Conner:
> >It was thus said that the Great Viacheslav Usov once stated:
> >>
> >> The very first message of mine in this thread explained how having
> >> multiple definitions of external linkage identifiers in an "entire
> >> program" is undefined behaviour, quoting the standard.
> >
> >   That was 6.9#5, which I quoted a portion of, but here's the full quote:
> >
> >	5 An external definition is an external declaration that is also a
> >	  definition of a function (other than an inline definition) or an
> >	  object. If an identifier declared with external linkage is used in
> >	  an expression (other than as part of the operand of a sizeof
> >	  operator whose result is an integer constant), somewhere in the
> >	  entire program there shall be exactly one external definition for
> >	  the identifier; otherwise, there shall be no more than one.
> >
> >   I'm not reading "undefined behavior" there, I see "error" there. Annex
> > J of the C99 standard lists all the unspecified, undefined,
> > implementation-defined and locale-specific behaviors.  Nowhere is this
> > addresses.
> This one is easy. Very first bullet point in Annex J.2.1:
> 	J.2 Undefined behavior
> 	1 The behavior is undefined in the following circumstances: — A
> 	‘‘shall’’ or ‘‘shall not’’ requirement that appears outside of a
> 	constraint is violated (clause 4).
> Which refers to 4.2 in the normative part of the standard:
> 	2 If a ‘‘shall’’ or ‘‘shall not’’ requirement that appears outside
> 	of a constraint is violated, the behavior is undefined. Undefined
> 	behavior is otherwise indicated in this International Standard by
> 	the words ‘‘undefined behavior’’ or by the omission of any explicit
> 	definition of behavior. There is no difference in emphasis among
> 	these three; they all describe ‘‘behavior that is undefined’’.

  Fair enough, I stand corrected on that point.

> >   -spc (So did I use two non-comformant compilers for this experiment 
> >   then?)

> Philipp

  No answer to my question though?