#116 diffutils not handling VMS versions from DCL

[John Malmberg]

GNV's 3.5 version of diff (and maybe other versions greater than 3.0) no longer
evaluates the feature logical DECC$FILENAME_UNIX_ONLY. But there is a new
feature to determine VMS file specifications, but it isn't triggered by a
version suffix. Any chance to either get the feature logical back or to
recognize a version as a VMS file specification? Or is there a GNV feature
logical to turn on evaluation of DECC feature logicals? :-)

On an I64/V8.4 system, if that matters:

$ gdiff -v
diff (GNU diffutils) 3.0
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Paul Eggert, Mike Haertel, David Hayes,
Richard Stallman, and Len Tower.
$
$ gdiff messages.properties;-1 messages.properties
/DSA202/USR/GNV/gdiff.exe: messages.properties;-1: no such file or directory
$ gdiff []messages.properties;-1 messages.properties
/DSA202/USR/GNV/gdiff.exe: []messages.properties;-1: no such file or directory
$
$ def DECC$FILENAME_UNIX_ONLY DISABLE/user
$ gdiff messages.properties;-1 messages.properties;
428,429c428,431
...
$

On Eisner:

On Eisner
$ gdiff -v
diff (GNU diffutils) 3.5
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Paul Eggert, Mike Haertel, David Hayes,
Richard Stallman, and Len Tower.
$
$
$ gdiff symbols.com;-1 symbols.com
diff: symbols.com;-1: no such file or directory
$
$ def DECC$FILENAME_UNIX_ONLY DISABLE/user
$ gdiff symbols.com;-1 symbols.com
diff: symbols.com;-1: no such file or directory
$
$ gdiff []symbols.com;-1 symbols.com
11c11
< $ gdiff       :==     mc gnv$gnu:[bin]diff
---
> $ gdiff       :==     mc gnv$gnu:[usr.bin]diff
$

[John Malmberg]

I am getting a worse behavior when the fles are different.

{code}
LION> gdiff -- vms_crtl_init.lis;-1 vms_crtl_init.lis;
diff: vms_crtl_init.lis;-1: illegal seek
LION> gdiff -- []vms_crtl_init.lis;-1 vms_crtl_init.lis;
diff: []vms_crtl_init.lis;-1: illegal seek
LION> gdiff vms_crtl_init.lis;2 vms_crtl_init.lis;1
diff: vms_crtl_init.lis;2: illegal seek
LION> gdiff vms_crtl_init.lis;2 vms_crtl_init.lis
LION> gdiff vms_crtl_init.lis;2 vms_crtl_init.lis;1
diff: vms_crtl_init.lis;2: illegal seek
LION> gdiff vms_crtl_init.lis vms_crtl_init.lis;1
diff: vms_crtl_init.lis: illegal seek
LION> gdiff vms_crtl_init.lis vms_crtl_init.lis;1
diff: vms_crtl_init.lis: illegal seek
LION> gdiff vms_crtl_init.lis;1 vms_crtl_init.lis;1
LION> gdiff vms_crtl_init.lis;2 vms_crtl_init.lis;2
LION> gdiff vms_crtl_init.lis;-1 vms_crtl_init.lis;-1
{code}