(j3.2006) Is a parenthesized polymorphic defined operation apolymorphic primary?

[Malcolm Cohen]

Of course it's polymorphic.  Parenthesising something does not change the 
declared type, dynamic type, or any of the type parameters.

I mean sure we don't come right out and say ANY of that stuff, but it's implicit 
in the common and mathematical meanings of parentheses.  We don't even say that 
(1.5) is type REAL for goodness sake, that doesn't mean that it becomes 
CHARACTER with LEN=3.

The user is absolutely correct.  It would be sheer madness to have
  O1 + O2 + O3
have a type different from
  (O1 + O2) + O3

You write
<<<
Because defining when a
parenthesized expression is polymorphic would require
consideration of the nature of the contained expression
that is not spelled out in the standard
>>>

no it does not require any special consideration.  "(anything)" has the same 
type, type parameters, and value, as "anything".  Parenthesising something is 
not an operation ***therefore it cannot change anything about the parenthesised 
entity*** other than potentially changing it from a object reference into an 
object value.

Cheers,

-----Original Message----- 
From: Robert Corbett
Date: ?? 27?3?24? 16:10
To: j3
Subject: (j3.2006) Is a parenthesized polymorphic defined operation apolymorphic 
primary?

A user has written a program in which he has used parentheses
to group the operands of an expression that consists of
two applications of a polymorphic defined operation:

       O4 = O1 + (O2 + O3)

The operations turn into calls of a function that has a
polymorphic allocatable result variable.  Oracle Solaris
Studio Fortran assumes that the parenthesized expression is
not polymorphic, and so considers the dynamic type of the
parenthesized expression to be the same as the declared
type of the function result variable.  The user assumes
the dynamic type of the parenthesized expression should
be the same as the dynamic type of the expression without
the parentheses.

Paragraph 2 of Clause 7.1.9.1 of the Fortran 2008 standard
states:

       If an expression is a polymorphic primary or
       defined operation, the type parameters and the
       declared and dynamic types of the expression
       are the same as those of the primary or defined
       operation.

The question of whether the dynamic type of a parenthesized
expression is the same as the declared type or the dynamic
type of the contained expression depends on whether the
parenthesized expression is considered a polymorphic
primary.  The standard does not appear to supply an explicit
answer to that question.  Because defining when a
parenthesized expression is polymorphic would require
consideration of the nature of the contained expression
that is not spelled out in the standard, I assume that a
parenthesized expression is not intended to be a
polymorphic primary.

Robert Corbett
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-- 
................................Malcolm Cohen, Nihon NAG, Tokyo.