Path: utzoo!mnetor!uunet!husc6!mailrus!nrl-cmf!ames!umd5!uvaarpa!virginia!scl
From: scl@virginia.acc.virginia.edu (Steve Losen)
Newsgroups: comp.lang.pascal
Subject: Scope question
Message-ID: <718@virginia.acc.virginia.edu>
Date: 29 Mar 88 19:40:24 GMT
Organization: Academic Computing Center, University of Va.
Lines: 56

The following pascal program compiles and outputs "10" with the Berkeley
pascal compiler "pc".

program test(output);
	const c = 10;

procedure junk;
	const c = c;  { Shouldn't this be an error ? }
begin
	writeln(c)
end;

begin
	junk
end.

According the the ISO pascal standard:

"The occurrence of an identifier in a constant-definition of a
constant-definition-part of a block shall constitute its defining-point
for the region that is the block.  The constant in a constant-definition
shall not contain an applied occurrence of the identifier in the
constant-definition."

constant-definition-part = [ "const" constant-definition ";"
	{ constant-definition ";" } ] .

constant-definition = identifier "=" constant .

constant = [ sign ] ( unsigned-number | constant-identifier ) |
	character-string .

constant-identifier = identifier .


As far as I can tell, then, the pascal fragment

const c = c;

should not be allowed even if c is a constant defined in an enclosing
block.  Is my interpretation of the pascal standard correct?  Since I'm
writing a pascal compiler, I need to have this issue cleared up.

A further note:

	The Berkeley pascal compiler also accepts fragments like this:

type thing = array [1..10] of thing; { where "thing" is a type defined
	in an enclosing block }

This also appears to be illegal according to the ISO pascal standard.

Does anyone out there agree/disagree/care?
-- 
Steve Losen     scl@virginia.edu
University of Virginia Academic Computing Center