One of the most tricky ASN.1 excerpt :

E-RABDataForwardingItemIEs S1AP-PROTOCOL-IES ::= {
    { ID id-E-RABDataForwardingItem   CRITICALITY ignore   TYPE E-RABDataForwardingItem PRESENCE mandatory },
    ...
}

E-RABSubjecttoDataForwardingList ::= E-RAB-IE-ContainerList { {E-RABDataForwardingItemIEs} }

E-RAB-IE-ContainerList { S1AP-PROTOCOL-IES : IEsSetParam } ::=
    ProtocolIE-ContainerList { 1, maxnoofE-RABs, {IEsSetParam} }

ProtocolIE-ContainerList {INTEGER : lowerBound, INTEGER : upperBound, S1AP-PROTOCOL-IES : IEsSetParam} ::=
    SEQUENCE (SIZE (lowerBound..upperBound)) OF
    ProtocolIE-SingleContainer {{IEsSetParam}}

ProtocolIE-SingleContainer {S1AP-PROTOCOL-IES : IEsSetParam} ::=
    ProtocolIE-Field {{IEsSetParam}}

ProtocolIE-Field {S1AP-PROTOCOL-IES : IEsSetParam} ::= SEQUENCE {
    id          S1AP-PROTOCOL-IES.&id           ({IEsSetParam}),
    criticality S1AP-PROTOCOL-IES.&criticality  ({IEsSetParam}{@id}),
    value       S1AP-PROTOCOL-IES.&Value        ({IEsSetParam}{@id})
}

Fix 'FATAL: Does not look like criticality is a CLASS field reference (xxxx) denoting a type one line xxx'

In Module_1,

	Criticality ::= ENUMERATED { reject, ignore, notify }

In Module_2,

	IMPORTS
		Criticality
	FROM Module_1

		someMessage SOME-CLASS ::= {
			CRITICALITY	ignore
		}

This pull request add the capability to resolve 'reject', 'ignore' and 'notify'
in Module_2.

The aforementioned error message displayed during processing the following ASN.1 excerpt.

S1AP-ELEMENTARY-PROCEDURES S1AP-ELEMENTARY-PROCEDURE ::= {
    S1AP-ELEMENTARY-PROCEDURES-CLASS-1 |
    S1AP-ELEMENTARY-PROCEDURES-CLASS-2,
    ...
}

S1AP-ELEMENTARY-PROCEDURES-CLASS-1 S1AP-ELEMENTARY-PROCEDURE ::= {
    handoverPreparation                |
...
    writeReplaceWarning,
    ...,
    uERadioCapabilityMatch             |
....
    uEContextResume
}

S1AP-ELEMENTARY-PROCEDURES-CLASS-2 S1AP-ELEMENTARY-PROCEDURE ::= {
    handoverNotification               |
...
    privateMessage,
    ...,
    downlinkUEAssociatedLPPaTransport  |
...
    mMECPRelocationIndication
}

Because S1AP-ELEMENTARY-PROCEDURES-CLASS-1 and S1AP-ELEMENTARY-PROCEDURES-CLASS-2
are resolved 'after' S1AP-ELEMENTARY-PROCEDURES, so the ioc tables of them are not
available during resolving S1AP-ELEMENTARY-PROCEDURES. So we can not drop the
latter's containedSubtype field at first pass of asn1f_resolve_constraints of fix
process.

We also add second pass of asn1f_resolve_constraints to have a chance to combine
ioc tables of S1AP-ELEMENTARY-PROCEDURES-CLASS-1 and
S1AP-ELEMENTARY-PROCEDURES-CLASS-2.

../../libasn1print/asn1print.c:59:5: error: ‘ret’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

oer_support.c:66:24: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]

From Travis logs:
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.

Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received

OCTET_STRING.c:1896:46: error: signed and unsigned type in conditional expression [-Werror=sign-compare]

oer_support.c:38:22: error: comparison between signed and unsigned integer expressions [-Werror=s

constr_SEQUENCE.c:1438:24: error: signed and unsigned type in conditional expression [-Werror=sign-compare]

NativeReal.c:366:13: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
NativeReal.c:370:13: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]

BIT_STRING.c:494:45: error: signed and unsigned type in conditional expression [-Werror=sign-compare]
BIT_STRING.c:580:46: error: signed and unsigned type in conditional expression [-Werror=sign-compare]

error: ISO C90 does not support the ‘z’ gnu_printf length modifier