Identity parse failure : Some libyang warnings when use the version v0.16-r2

[Prasann1506]

Following libyang warnings are coming while loading some yang modules.
We tried to identify the root cause but it is little hard for us to find out the exact root cause.
Please help us to identify the issue.

Version used : v0.16-r2

libyang[1]: Identity found, but in a non-implemented module "iana-if-type".
libyang[1]: Failed to resolve identityref "iana-if-type:ieee8023adLag". (path: /openconfig-interfaces:type)
libyang[1]: Previous warning generated by XPath subexpression[95] "openconfig-interfaces:type = 'iana-if-type:ieee8023adLag'".

libyang[1]: Identity used as identityref value is not implemented. (path: /openconfig-interfaces:type)
libyang[1]: Failed to resolve identityref "openconfig-if-types:IF_AGGREGATE". (path: /openconfig-interfaces:type)
libyang[1]: Previous warning generated by XPath subexpression[251] "openconfig-interfaces:type = 'openconfig-if-types:IF_AGGREGATE'".

libyang[1]: Failed to resolve identityref "PATH_SETUP_RSVP". (path: /openconfig-mpls:signaling-protocol)
libyang[1]: Previous warning generated by XPath subexpression[50] "signaling-protocol = 'PATH_SETUP_RSVP'".
libyang[1]: Identityref "signaling-protocol" comparison with identity "PATH_SETUP_RSVP" without prefix, consider adding a prefix or best using "derived-from(-or-self)()" functions.

Thanks,
Prasann

[Prasann1506]

I did not get these issues for the same data model when I use older libyang (version v0.11)
But when I use the latest released version then these issues are exposed

[michalvasko]

Hi,
you did not get the warnings because in v0.11 there were much less checks. For the first 2 warnings, it just means that when these modules were parsed some other modules that included definitions of some identities used in XPath expressions of the original modules and were not implemented. That means that these identities could never be instantiated in data. However, these warnings can easily be false positives, the important thing is, in this specific example, to have iana-if-type and openconfig-if-types modules implemented in the output of sysrepoctl -l.

The last warning just mentions a possible problem in the model because an identity is used without prefix in an XPath expression. The problem is that XPath has only 4 types so this is parsed as a literal (string) and it may not be interpreted correctly. The solution is described in the warning.

Regards,
Michal

[Prasann1506]

Thank you Michal for this information!!!

[Prasann1506]

Issue:1

In the above must condition we get libyang warning as <Incompatible types of operands "name" and "tag" for comparison.>
As per the rfc integer can depend on string. It looks like this must condition is a valid statement. But we want to know why this warning is reported by libyang ?

Issue:2
Also please let us know why this libyang warning is coming for the below entry.
From our understanding we know the below data model definition is correct.
Warning: Node type list "test-list" used as operand.

Thanks,
Prasann

[michalvasko]

Hi,
yes, for the first issue you are right that there is no error and that is why the message is only warning. You should be able to fix it by, for example, using string(current()) instead of current() if you are certain you know what you are doing.

For the second issue, that seems to be an invalid warning but when I tried to reproduce it in the current libyang with your model, it did not appear. Are you using a recent libyang version?

Regards,
Michal

[Prasann1506]

Thanks Michal, 1st is verified and there is no warning reported by libyang.
For the 2nd issue we are using libyang version 0.15 r1
Can you please suggest if any fix is done by libyang for the 2nd issue after version 0.15-r1 ?

Regards,
Prasann

[michalvasko]

Hi,
I have suggested what to do and do not want to waste my time going over all the changes since 0.15 to find what commit fixed this. You can do that yourself.

Regards,
Michal