To: J3                                                J3/13-226
From: Dick Hendrickson
Subject: Interp from c.l.f
Date: 2013 January 01

NUMBER: F08/ZZZZ
TITLE: Can an allocate with SOURCE= have side-effects
in a Pure procedure?
KEYWORDS: Allocate, SOURCE=, PURE, side-effects
DEFECT TYPE: Erratum
STATUS: Under J3 consideration

QUESTION:

On comp.lang.fortran Ian Harvey brought up a pointer/PURE
question.

Given a type definition like

 type :: int_ptr
    integer, pointer :: i
 end type int_ptr
And a PURE function like
PURE function FUN (arg)
type(int_ptr), intent(in) :: arg
type(int_ptr), allocatable :: tmp
  FUN = 1
  allocate (tmp, source=arg)
  tmp%i = 2

end function fun

Is FUN standard conforming?

Doesn't the use of source=arg allow the function to
modify a global entity via the tmp%i  =  ...?  There
don't seem to be any constraints on what arg%i can
point to, which means that the assignment to tmp%i

can have side effects.

C1283(1) prevents usage like
    arg%i = 2
ANSWER
Of course it isn't standard conforming!
Words modeled after C1283(4) will be added.

EDITS
Add to C1283:  "..."

SUBMITTED BY: Dick Hendrickson

HISTORY: 13-WWW    m200  F08/ZZZZ submitted