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From: ags@s.cc.purdue.edu (Dave Seaman)
Newsgroups: comp.lang.fortran
Subject: Re: Dubious Fortran Construct
Summary: Standard is perfectly clear
Message-ID: <3680@s.cc.purdue.edu>
Date: 12 Dec 88 20:17:16 GMT
References: <22994@sgi.SGI.COM> <44400031@hcx2>
Reply-To: ags@s.cc.purdue.edu (Dave Seaman)
Organization: Purdue University
Lines: 43

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.  It may be that the committee did not specifically intend to make
the construct illegal, but the words they used are quite clear and
explicit.  Here are the relevant statements:

	11.10.1 _Range_of_a_DO-Loop_.  The _range_of_a_DO-Loop_ consists of
	all of the executable statements that appear following the DO
	statement that specifies the DO-Loop, up to and including the terminal
	statement of the DO-loop.

	If a DO statement appears within the range of a DO-loop, the range
	of the DO-loop specified by that DO statement must be contained
	entirely within the range of the outer 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.  To complete the analysis, only one more fact is
needed:

	11.10.8 _Transfer_into_the_Range_of_a_DO-Loop_.  Transfer of
	control into the range of a DO-loop from outside the range is not
	permitted.

I did not leave anything out.  What you just read is the entirety of what
the standard says about transferring into the range of a DO-loop.  I don't
see how anything could possibly be clearer than that.

If the Supreme Court can rule that the First Amendment does not mean what
it says, then I suppose there is nothing to stop the X3J3 committee from
ruling that the standard does not mean what it says.  That is the only way
I can make sense of the claim that an "official interpretation" is needed.
But if the committee decides that the construct is illegal, then exactly
how could they go about rewording the standard to make it any clearer than
it is now?  
-- 
Dave Seaman	  					
ags@j.cc.purdue.edu