please try this program (generic resolution) [Fortran]

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From: Herman D. Knoble on 10 Apr 2008 11:11

From: Bil Kleb on 10 Apr 2008 11:38

robert.corbett(a)sun.com wrote:
> According to my understanding of Section 14.1.2.4.1 of the Fortran 95
> standard and Section 12.4.4.1 of the Fortran 2003 standard, the
> program [..]
>
> I would like to know if other compilers get it right.

Your team should have a compiler gauntlet? (We find ours extremely
valuable for finding compiler bugs and for detecting questionable code.)

gcc version 4.0.3 (g95 0.90!) Mar 7 2008
$ g95 corbett.f90 && ./a.out
1.

gcc version 4.1.1 20070105 (Red Hat 4.1.1-52)
% gfortran corbett.f90 && ./a.out
1.000000

ifort (IFORT) 10.1 20071116
% ifort corbett.f90 && ./a.out
2.000000

f95: Sun Fortran 95 8.3 Linux_i386 Patch 127145-01 2007/07/31
% f95 corbett.f90 && ./a.out
2.0

gcc version 4.0.1 (g95!) Jan 12 2006
% g95 corbett.f90 && ./a.out
1.

Lahey/Fujitsu Fortran 95 Express Release L6.20d
% lf95 corbett.f90 && ./a.out
Encountered 0 errors, 0 warnings in file corbett.f90.
1.00000000

Compaq Fortran Compiler V1.2.0-1882-48BBF
a2n9% fort corbett.f90 && ./a.out
2.000000

pgf90 6.1-2 32-bit target on x86 Linux
% pgf95 corbett.f90 && ./a.out
PGF90-S-0126-Name cos is not an intrinsic function (corbett.f90: 9)

PathScale EKOPath(TM) Compiler Suite: Version 2.5
% pathf90 corbett.f90 && ./a.out
2.

NAGWare Fortran 95 compiler Release 5.0(347)
% f95 corbett.f90 && ./a.out
Warning: corbett.f90, line 16: Unused dummy argument X
detected at END@<end-of-statement>
[f95 continuing despite warning messages]
1.0000000

Lahey/Fujitsu Linux64 Fortran Express Release L8.00a
% lf95 corbett.f90 && ./a.out
Encountered 0 errors, 0 warnings in file corbett.f90.
1.00000000

pgf95 7.1-5 64-bit target on x86-64 Linux -tp k8-64e
% pgf95 corbett.f90 && ./a.out
PGF90-S-0126-Name cos is not an intrinsic function (corbett.f90: 9)

NAGWare Fortran 95 compiler Release 5.1(347,355,357-364,365)
% f95 corbett.f90 && ./a.out
Warning: corbett.f90, line 16: Unused dummy argument X
detected at END@<end-of-statement>
[f95 continuing despite warning messages]
1.0000000

Absoft 64-bit Fortran 95 10.1.2
% af95 corbett.f90 && ./a.out
2.00000

Intel(R) Fortran Compiler for 32-bit applications, Version 9.1 Build 20070109Z (9.1.041)
% ifort corbett.f90 && ./a.out
2.000000

Regards,
--
Bil Kleb
http://fun3d.larc.nasa.gov

From: Herman D. Knoble on 10 Apr 2008 12:08

On Thu, 10 Apr 2008 11:11:06 -0400, Herman D. Knoble <SkipKnobleLESS(a)SPAMpsu.DOT.edu>
wrote:

-|-|$ ifort --version
-|-|ifort (IFORT) 10.1 20070913
-|-|Copyright (C) 1985-2007 Intel Corporation. All rights reserved.
-|-|
-|-|gives 2.0 (wrong?)
-|Try using ifort options: -O0 -fltconsistency
-|
-|Skip Knoble

Sorry. The options I previously suggested have
no effect on the results.

Skip

From: Steve Lionel on 10 Apr 2008 16:42

On Thu, 10 Apr 2008 01:21:52 -0700 (PDT), robert.corbett(a)sun.com wrote:

>According to my understanding of Section 14.1.2.4.1 of the Fortran 95
>standard and Section 12.4.4.1 of the Fortran 2003 standard, the
>program

>
>or something else like it. The third item in the lists in the cited
>sections of
>the cited standards says that the call of the generic function COS in
>the
>PRINT statement should call the intrinsic specific function COS, not
>the
>external procedure MYCOS.

Bob,

My reading is somewhat different from yours. The actual wording of the
section you cite is this:

19 (3) If (1) and (2) do not apply, if the scoping unit contains either an
INTRINSIC attribute
20 specification for that name or a USE statement that makes that name
accessible from a
21 module in which the corresponding name is specified to have the INTRINSIC
attribute, and
22 if the reference is consistent with the interface of that intrinsic
procedure, the reference is
23 to that intrinsic procedure.

Note the initial clause "If (1) and (2) do not apply". (1) is:

8 (1) If the reference is consistent with a nonelemental reference to one of
the specific interfaces of
9 a generic interface that has that name and either is in the scoping unit in
which the reference
10 appears or is made accessible by a USE statement in the scoping unit, the
reference is to
11 the specific procedure in the interface block that provides that interface.
The rules in 16.2.3
12 ensure that there can be at most one such specific procedure.

In your program, the reference COS(0.0) *is* consistent with a nonelemental
reference to one of the specific interfaces of the visible generic COS,
therefore (3) does not apply and it would be correct to call MYCOS.

I also found this:

2 C547 (R503) (R1216) If the name of a generic intrinsic procedure is
explicitly declared to have the
3 INTRINSIC attribute, and it is also the generic name in one or more generic
interfaces (12.3.2.1)
4 accessible in the same scoping unit, the procedures in the interfaces and
the specific intrinsic
5 procedures shall all be functions or all be subroutines, and the
characteristics of the specific
6 intrinsic procedures and the procedures in the interfaces shall differ as
specified in 16.2.3.

My head was spinning when I read this, but I interpret it as saying that your
program is non-standard because it explicitly declares COS as INTRINSIC in a
scope where a generic interface containing a procedure that has the same
signature as the intrinsic COS.

If this reading is correct, the proper behavior would be to issue a standards
violation diagnostic for the INTRINSIC COS, but otherwise calling MYCOS (and
printing 2.0) is right.

I am not as steeped in the standard as some so I welcome counterarguments.

--
Steve Lionel
Developer Products Division
Intel Corporation
Nashua, NH

For email address, replace "invalid" with "com"

User communities for Intel Software Development Products
http://softwareforums.intel.com/
Intel Fortran Support
http://support.intel.com/support/performancetools/fortran
My Fortran blog
http://www.intel.com/software/drfortran

From: John Harper on 10 Apr 2008 18:23

In article <29usv3l33ltn44h1tnfvb7nlttuh1168ci(a)4ax.com>,
Steve Lionel <Steve.Lionel(a)intel.invalid> wrote:
>
>I also found this:
[complicated standard-speak followed by]
>6 intrinsic procedures and the procedures in the interfaces shall differ as
>specified in 16.2.3.
>
>My head was spinning when I read this, but I interpret it as saying that your
>program is non-standard because it explicitly declares COS as INTRINSIC in a
>scope where a generic interface containing a procedure that has the same
>signature as the intrinsic COS.
>
>If this reading is correct, the proper behavior would be to issue a standards
>violation diagnostic for the INTRINSIC COS, but otherwise calling MYCOS (and
>printing 2.0) is right.

F2003 16.2.3 refers one to C.11.2, which reduces the head-spinning
rate and would seem to support Steve's interpretation, but of course
it's a nonnormative note.

-- John Harper, School of Mathematics, Statistics and Computer Science,
Victoria University, PO Box 600, Wellington 6140, New Zealand
e-mail john.harper(a)vuw.ac.nz phone (+64)(4)463 6780 fax (+64)(4)463 5045

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