To: J3                                                     J3/21-127
From: Malcolm Cohen & Yasuharu Hayashi
Subject: NOTE for CONTIGUOUS and assumed-shape
Date: 2021-March-01

1. Introduction

The standard is somewhat cryptic re passing discontiguous actual arguments
to CONTIGUOUS assumed-shape dummies. This is understandable, as the issue
is the same as passing discontiguous to explicit-shape or assumed-size, but
especially for those who are less familiar with the traditions and were not
there for the discussions, it is unclear whether it is allowed or not, and
whether the processor needs to do copy-in/out or not.

Therefore this paper suggests adding a NOTE or two to make this clearer.


2. Edits to 21-007

[100:2-] 8.5.7 CONTIGUOUS attribute, at the very end of the subclause,
         insert a new NOTE:
   "NOTE 3
    If an assumed-shape or assumed-rank dummy argument has the CONTIGUOUS
    attribute, there is no requirement for the actual argument to be
    contiguous. This is the same as for dummy arguments that have explicit
    shape or assumed size. The dummy argument will be contiguous even when
    the actual argument is not."

[317:12-] 15.5.2.4 Ordinary dummy variables, at the end of the subclause,
          insert a new NOTE:
   "NOTE 6
    If an effective argument is a discontiguous array, and the dummy
    argument is an assumed-shape array with the CONTIGUOUS attribute, an
    assumed-rank dummy data object with the CONTIGUOUS attribute, an
    explicit-shape array, or an assumed-size array, the processor might
    need to use the so-called copy-in/copy-out argument passing mechanism,
    so as to ensure that the dummy array is contiguous even when the actual
    argument is not."

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