(j3.2006) binding labels and global identifiers

[Van Snyder]

On Sun, 2011-06-19 at 04:22 -0700, Bill Long wrote:
> 
> On 6/19/11 2:36 AM, mickistjames at gmail.com wrote:
> > Robert Corbett wrote:
> >
> >  >Is the program presented above intended to be standard-
> >  >conforming?
> >
> > I would agree with Malcolm and answer no.
> >
> 

16.2p1 says that a binding label is a global identifier, and the name of
an external procedure is a global identifier.  16.2p2 says two global
identifiers can't be the same.

Neither paragraph addresses the question of an identifier the processor
derives from the identifiers specified by the standard.

So if the processor mangles an identifier that the standard says is a
global identifier, and manages to create one that's the same as a
different global identifier specified in your program, I'd be inclined
to say the processor, not the program or the standard, is the culprit.

> While one might imagine some scheme to allow the case in the original 
> example to work (since global variables and procedures are different 
> sorts of objects), the even worse example of an interface block for a 
> function with a binding label of subr_ and a function named subr seems 
> intractable in an environment where the Fortran processor appends an 
> underscore to the end of a procedure name.  The irony is that the 
> convention of adding an underscore was designed to prevent (accidental) 
> interoperability.

This was a bad idea from the outset.  It's a shame it got perpetuated.

> 
> 
> > R303 says that underscores may be used as a significant
> > character in a name, but I see no provision for low lines,
> > so if "_" in a binding label is a low line then the functionality
> > to bind to C names with underscores is simply missing.
> >
> > Okay, that may have been a joke, but
> > "subr_" is not a name in the line
> > REAL, BIND(C, NAME="subr_") :: x = 0.1
> 
> Right, it is a "binding label".
> 
> > it is a scalar-char-initialization-expr or some such, so
> > an implementation that wants to outlaw scalar-char-initialization-expr's
> > that mimic linker-constructed names with low lines would seem
> > to be on narrow but reasonable ground. Is there any expectation that
> > absolutely
> > any initialization expr is legal?
> 
> No. The string has to be legal as a name of the corresponding object in C.
> 
> Cheers,
> Bill
> 
> > Seems like control characters
> > are legal in initialization expr's but not in names, if so that would
> > already be a special case to handle.
> >
> > Micki
>