Path: utzoo!attcan!uunet!modcomp!joe
From: joe@modcomp.UUCP
Newsgroups: comp.lang.fortran
Subject: Re: Dubious Fortran Construct
Message-ID: <11800009@modcomp>
Date: 14 Dec 88 03:13:00 GMT
References: <22994@sgi.SGI.COM>
Lines: 29
Nf-ID: #R:sgi.SGI.COM:22994:modcomp:11800009:000:1233
Nf-From: modcomp.UUCP!joe    Dec 13 22:13:00 1988


Dave Seaman (ags@j.cc.purdue.edu) writes:

> In article <44400031@hcx2> bill@hcx2.SSD.HARRIS.COM writes:
> >
> >The X3J3 FORTRAN committee has considered this question, and an
> >official interpretation will be published sometime in the near future,
> 
> I was surprised to see this, because I see nothing ambiguous in the
> standard.  [...]  Here are the relevant statements:
> 
>	11.10.1 _Range_of_a_DO-Loop_.  [...] More than one DO-loop may
>	have the same terminal statement.
> 
> This means that the CONTINUE statement in the example is part of the
> range of both loops.  The GOTO statement in the example is not part of
> the range of the inner DO-loop.

Because the CONTINUE statement is being used as the terminating statement of
two scopes, an ambiguity exists, since GOTO can only branch into a single
scope.  Which scope is selected is not stated by the f77 standard.  Your
implied intepretation of "select that scope which makes sense for the GOTO
in question" is a nice feature that Smart Compilers (like mine (:->)) can
implement.  However, wording to *require* that behavior is not present in
the standard.  Hence any program that makes use of the ambiguity is
nonstandard conforming.
--
joe korty
uunet!modcomp!joe