[lamestllama]

What

lyplg_type_validate_tree_instanceid() in src/plugins_types/instanceid.c now returns LY_EVALID when a required instance-identifier target does not exist, with the existing error item (LYVE_DATA, app-tag instance-required, message Invalid instance-identifier "..." value - required instance not found.). Before, it passed on the return value of ly_path_eval(), which is always LY_ENOTFOUND on failure. The leafref plugin already uses LY_EVALID for the same situation (src/plugins_types/leafref.c).

Why

A missing required target is invalid data. RFC 7950, section 9.9.3: "If "require-instance" is "true", it means that the instance being referred to MUST exist for the data to be valid." log.h sets the validation code together with LY_EVALID, and the error item already carries LYVE_DATA; only the return code differed.

The code also changed the behaviour of LYD_VALIDATE_MULTI_ERROR: LY_VAL_ERR_GOTO() in validation.c continues only after LY_EVALID, so validation stopped at the instance-identifier error and the errors after it were lost. With this schema:

leaf t {
  type string;
}
leaf lr {
  type leafref {
    path "/ri:t";
  }
}
leaf ii {
  type instance-identifier;
}

and the data <lr>x</lr><ii>/ri:t</ii>, multi-error validation returned 5 with only the instance-identifier error; it now returns 7 with both errors.

Callers checked: ly_path_eval() returns only LY_SUCCESS or LY_ENOTFOUND, so no other error is masked. The union plugin tries the next member type after any failure of a member, whatever the code (union_find_type()), and then reports LY_EVALID. lyd_value_validate_incomplete(), lyd_value_validate3() and their callers (validation.c, path.c, xpath.c, tree_schema_common.c) treat any non-zero code as a failure and do not test for LY_ENOTFOUND. The only code that relied on it is in the unit tests: five expectations in tests/utests/types/instanceid.c and one in tests/utests/extensions/test_structure.c, updated to LY_EVALID.

Fixes #2608

Test

• New test_require_instance in tests/utests/data/test_validation.c: a missing leafref target and a missing instance-identifier target are each refused with LY_EVALID and the instance-required app-tag, and with LYD_VALIDATE_MULTI_ERROR both errors are reported.
• test_data_xml in tests/utests/types/instanceid.c and test_parse in tests/utests/extensions/test_structure.c now expect LY_EVALID.

Before the fix (updated tests, unchanged library): utest_validation fails test_require_instance (22 of 23 pass), utest_instanceid fails test_data_xml (2 of 3) and utest_structure fails test_parse (4 of 5). After the fix, all three pass, and the whole ctest run passes (69 of 69; Debug build, GCC 13.3, aarch64).