Thank you

vicente_polo (at) yahoo (dot) es patch has been tested and confirmed.
It has been included in Vim 8.2-2298 version.

Don't worry, it's working with the changes I did... no problems since then.

Thank you anyway.

I have recently installed VSI VMS 8.4 on Alpha and could not reproduce 
the issue.
Seems, it is just IA64 specific... but I do not have access to any 
IA64 environment running VSI VMS... I cannot help with this issue - 
you are on your own :(

VMS DIFF between original and modified
   676           // Seems it is a regular file, let's find out it is 
pure Unix fspec
   677           if(
   678               (strchr(instring,'[')==NULL) && 
(strchr(instring,'<')==NULL) &&
   679               (strchr(instring,']')==NULL) && 
(strchr(instring,'>')==NULL) &&
   680               (strchr(instring,':')==NULL)
   681           ){
   682               // It must be a truly unix filename no mixed
   683               decc$to_vms(instring, vms_fspec_proc, 0, 0);
   684
   685           } else {
   686               // Contains characters of VMS file spec... and also /
   687               // so it is mixed
   688               vms_unix_mixed_filespec(instring, buf);
   689           }
   690
   691       }
******
File DKA2:[VIM.vim82-222-vms.src]os_vms.c;1
   674           // Seems it is a regular file, let guess that it is 
pure Unix fspec
   675           if (decc$to_vms(instring, vms_fspec_proc, 0, 0) <= 0)
   676               // No... it must be mixed
   677               vms_unix_mixed_filespec(instring, buf);
   678       }

The fact is that I can actually create a directory with name
CREATE/DIRECTORY [.DKA2^:^[VIM^.VIM82^]syntax] works and creates 
directory DKA2^:^[VIM^.VIM82^]syntax.DIR;1

On HPE OpenVMS 8.3-1H1 (HP Rx2660 ODS5 Disk) the command
CREATE/DIRECTORY [.DKA2^:^[VIM^.VIM82^]syntax] fails

On HPE OpenVMS 8.4 (HP Rx2800 i2 ODS5 Disk) the command works!
So I wonder if last HPE version is also affected by the issue.

Check if you can create such a directory

Regards,

Thank you for the investigation.
I haven't run VSI OpenVMS at all... and on HPE VMS I have tested on 
ODS5 and it worked.

I have no idea how to solve this issue quickly - but if you have a 
functional patch, please submit to the community - as for me it will 
take some time to get an Itanium server with VSI OpenVMS on it.

I am sorry

Sorry, didn't include OS version and it does matter... it is a VSI 
OpenVMS 8.4-2L1on HP Integrity Rx2800 i4

I looked at it... it's related to decc$to_vms

In OS_VMS.C
     {
         // Seems it is a regular file, let guess that it is pure Unix fspec
         // VPOLO decc$to_vms not failing with mixed unix/vms path...
         // so stick to vms_unix_mixed_filespec func
         // and comment line below
         // if (decc$to_vms(instring, vms_fspec_proc, 0, 0) <= 0)
             // No... it must be mixed
             vms_unix_mixed_filespec(instring, buf);
     }

the return of decc$to_vms was something

-Before vms_fixfilename = DKA2:[VIM.VIM82]syntax/syntax.vim
-After    vms_fixfilename = [.DKA2^:^[VIM^.VIM82^]syntax]syntax.vim

I'll take a look soon.

Tested and working on a ia64 system in an ODS2 disk.
Not working on a ODS5.
The errors are of type, can't access file.
I thought it could be due to case sensitive but tested with SET 
PROCESS/CASE=SENSITIVE and SET PROCESS/CASE=BLIND with identical result.
  DKA2:[VIM.vim82]syntax/syntax.vim can't open file