From owner-sc22wg5+sc22wg5-dom9=www.open-std.org@open-std.org Wed Sep 18 11:20:35 2024 Return-Path: X-Original-To: sc22wg5-dom9 Delivered-To: sc22wg5-dom9@www.open-std.org Received: by www.open-std.org (Postfix, from userid 521) id 11A37357015; Wed, 18 Sep 2024 11:20:35 +0200 (CEST) Delivered-To: sc22wg5@open-std.org X-Greylist: delayed 397 seconds by postgrey-1.34 at www5.open-std.org; Wed, 18 Sep 2024 11:20:33 CEST Received: from nag-j.co.jp (bvdeuz19.secure.ne.jp [180.222.80.19]) by www.open-std.org (Postfix) with SMTP id CFB14356F3A for ; Wed, 18 Sep 2024 11:20:33 +0200 (CEST) Received: (qmail 65736 invoked from network); 18 Sep 2024 18:13:51 +0900 Received: from unknown (HELO Maru10) (218.42.159.105) by 0 with SMTP; 18 Sep 2024 18:13:51 +0900 From: "Malcolm Cohen" To: "'WG5'" References: In-Reply-To: Subject: RE: [ukfortran] [SC22WG5.6604] intent(in) and value Date: Wed, 18 Sep 2024 18:13:51 +0900 Message-ID: <002101db09ab$14305110$3c90f330$@nag-j.co.jp> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0022_01DB09F6.84190A80" X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQH/9fLaKj7MZ/xChKmAc+pwsbYi4LITZm8A Content-Language: ja Sender: owner-sc22wg5@open-std.org Precedence: bulk This is a multipart message in MIME format. ------=_NextPart_000_0022_01DB09F6.84190A80 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi Jeff, It is called "unspecified INTENT" not "default INTENT". That is because it is not a default, it is that it is not specified. (ASIDE: I don't think we use the phrase in the standard itself, but we do when talking about it.) R828 by itself does not define the INTENT attribute, it defines some syntax - and that is the syntax for specified intent (it's even called "intent-spec". The whole of 8.5.10 defines the INTENT attribute, and indeed, there is a paragraph about unspecified intent. INTENT(INOUT) is very different indeed from unspecified intent. In particular, INOUT requires that the actual argument be a definable variable. There is no such requirement for unspecified intent. With unspecified intent you simply have to get it right, viz not reference the dummy argument unless it is defined, and not define the dummy argument unless it is definable. This is the world before the invention of INTENT. To summarise: with no intent-spec, the intent is not "INOUT", or "INOUT except stuff", it is "unspecified", and has the same capabilities and limitations that it had before Fortran 90. Cheers, -- ..............Malcolm Cohen, NAG Oxford/Tokyo. From: owner-sc22wg5@open-std.org On Behalf Of Jeff Hammond Sent: Wednesday, September 18, 2024 4:12 PM To: WG5 Subject: [ukfortran] [SC22WG5.6604] intent(in) and value 8.5.10 R828 says that INTENT is IN, OUT or INOUT. 8.5.19 C868 says that VALUE cannot be INTENT(OUT) or INTENT(INOUT) Should I understand that dummy arguments without an INTENT do not have an implicit intent corresponding to any of the explicit INTENT types? I have always assumed that the default INTENT was INOUT, but that cannot be true since that would conflict with VALUE in the example below. It seems the default INTENT is "INOUT, unless VALUE, in which case it's IN-but-also-assignable". subroutine foo(a,b) implicit none integer, value, intent(in) :: a integer, value :: b ! integer, value, intent(inout) :: c ! not allowed ! integer, value, intent(out) :: d ! not allowed ! a = 21 ! can't assign because intent(in) b = 23 ! can assign end subroutine foo Thanks Jeff ------=_NextPart_000_0022_01DB09F6.84190A80 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi = Jeff,

It is called = “unspecified INTENT” not “default INTENT”. That = is because it is not a default, it is that it is not specified. (ASIDE: = I don’t think we use the phrase in the standard itself, but we do = when talking about it.)

R828 by = itself does not define the INTENT attribute, it defines some syntax = – and that is the syntax for specified intent (it’s even = called “intent-spec”. The whole of 8.5.10 defines the INTENT = attribute, and indeed, there is a paragraph about unspecified = intent.

INTENT(INOUT)= is very different indeed from unspecified intent. In particular, INOUT = requires that the actual argument be a definable variable. There is no = such requirement for unspecified intent. With unspecified intent you = simply have to get it right, viz not reference the dummy argument unless = it is defined, and not define the dummy argument unless it is definable. = This is the world before the invention of = INTENT.

To = summarise: with no intent-spec, the intent is not “INOUT”, = or “INOUT except stuff”, it is “unspecified”, = and has the same capabilities and limitations that it had before Fortran = 90.

Cheers,<= /o:p>

--

..............Malcolm Cohen, NAG Oxford/Tokyo.

From: owner-sc22wg5@open-std.org <owner-sc22wg5@open-std.org> = On Behalf Of Jeff Hammond
Sent: Wednesday, September = 18, 2024 4:12 PM
To: WG5 = <sc22wg5@open-std.org>
Subject: [ukfortran] = [SC22WG5.6604] intent(in) and value

8.5.10 R828 says that INTENT is IN, OUT or = INOUT.

8.5.19 C868 says that VALUE cannot be INTENT(OUT) or = INTENT(INOUT)

Should I understand that dummy arguments without an INTENT = do not have an implicit intent corresponding to any of the explicit = INTENT types? I have always assumed that the default INTENT was = INOUT, but that cannot be true since that would conflict with VALUE in = the example below. It seems the default INTENT is “INOUT, = unless VALUE, in which case it’s = IN-but-also-assignable”.

subroutine = foo(a,b)

implicit none

integer, value, = intent(in) :: a

integer, value :: = b

! integer, value, intent(inout) :: c ! = not allowed

! integer, value, intent(out) :: d ! not = allowed

! a =3D 21 ! can't assign because = intent(in)

b =3D 23 ! can = assign

end = subroutine foo

Thanks

Jeff

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