Option parsing: warn if both an option and its alias are specified for a module

[felixfontein]

SUMMARY

Currently, if both an option and its alias are provided in module options, the value of the alias overwrites the value of the option. (If multiple aliases of that option are specified, the last one appearing in the aliases list wins.)

I think there should be a warning if that happens. This PR implements such a warning:

Example:

 - argtest:
      l: 1,2,3
      lalias: 1,2,3,4
      x:
        y: 1
        yy: 2

with argument_spec=dict(l=dict(type='list', elements='int', aliases=['lalias']), x=dict(type='dict', options=dict(y=dict(type='str', aliases=['yy'])))) results in

 [WARNING]: Both option l and its alias lalias are set.
 [WARNING]: Both option x.y and its alias x.yy are set.

ISSUE TYPE

• Bugfix Pull Request
• Feature Pull Request

COMPONENT NAME

lib/ansible/module_utils/basic.py
lib/ansible/module_utils/common/parameters.py

[felixfontein]

About the question on IRC on why alias_warnings is carried around: this is because aliases are handled very early on, and calling self.warn() directly will do a call to self.log(), which is potentially bad since self.no_log hasn't been set up yet (see comment in except block):
https://github.com/ansible/ansible/blob/69df7ba6329d3cc60419dade008fcc44c7f4a6b0/lib/ansible/module_utils/basic.py#L764-L771

[bcoca]

inject the warnings directly into the 'warnings' list and you don't have to deal with log

[felixfontein]

If it's ok that they're not sent to log, sure, that makes it a lot easier :-)

[felixfontein]

The CI failures seem to be totally unrelated to this PR.

ready_for_review

[felixfontein]

ready_for_review

[felixfontein]

Re-triggering CI.

[felixfontein]

@bcoca can you take another look? It has been a while... :)

[felixfontein]

rebuild_merge

[felixfontein]

bot_status

[ansibot]

Components

changelogs/fragments/53698-alias-collision-warning.yaml
support: community
maintainers:

lib/ansible/module_utils/basic.py
support: core
maintainers:

lib/ansible/module_utils/common/parameters.py
support: core
maintainers:

test/units/module_utils/basic/test_argument_spec.py
support: core
maintainers:

Metadata

waiting_on: felixfontein
changes_requested_by: null
needs_info: False
needs_revision: True
needs_rebase: False
merge_commits: []
too many files or commits: False
mergeable_state: unstable
shippable_status: pending
maintainer_shipits (module maintainers): False
community_shipits (namespace maintainers): False
ansible_shipits (core team members): False
shipit_actors (maintainer or core team member): None
shipit_actors_other:
automerge: automerge shipit test failed

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[felixfontein]

@bcoca and everyone on IRC who helped with this: thanks for reviewing!