Guest CODEOWNERS unable to approve MR

Summary

A user with guest access who's listed in the CODEOWNERS file can't see the Approve button on the merge request page.

This is originally reported by a premium customer (internal link only) and is reproducible in 12.10.7-ee, 12.9.8-ee, and 12.7.0-ee.

Steps to reproduce

  1. Create a new project P.
  2. Add user X as a guest member to project P.
  3. Add user Y as a maintainer member to project P.
  4. Create a CODEOWNERS file mentioning X in the list of approvers.
  5. As user Y, Commit changes to project P and create an MR.
  6. User X will show in the list of approvers.
  7. Impersonate user X.
  8. User X can't see the approve button.

What is the current bug behavior?

The Approve button is not visible for Guests listed in CODEOWNERS.

What is the expected correct behavior?

The Approve button is visible for Guests listed in CODEOWNERS.

Relevant logs and/or screenshots

approvalmissing

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info 
System information
System:		Ubuntu 18.04
Proxy:		no
Current User:	git
Using RVM:	no
Ruby Version:	2.6.6p146
Gem Version:	2.7.10
Bundler Version:1.17.3
Rake Version:	12.3.3
Redis Version:	5.0.7
Git Version:	2.26.2
Sidekiq Version:5.2.7
Go Version:	unknown

GitLab information
Version:	12.10.7-ee
Revision:	80b99e43cfc
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	11.7
URL:		https://rhassanein.do.gitlap.com
HTTP Clone URL:	https://rhassanein.do.gitlap.com/some-group/some-project.git
SSH Clone URL:	git@rhassanein.do.gitlap.com:some-group/some-project.git
Elasticsearch:	yes
Geo:		no
Using LDAP:	yes
Using Omniauth:	yes
Omniauth Providers: 

GitLab Shell
Version:	12.2.0
Repository storage paths:
- default: 	/var/opt/gitlab/git-data/repositories
GitLab Shell path:		/opt/gitlab/embedded/service/gitlab-shell
Git:		/opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check 
Checking GitLab subtasks ...

Checking GitLab Shell ...


GitLab Shell: ... GitLab Shell version >= 12.2.0 ? ... OK (12.2.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Internal API available: OK
Redis available via internal API: OK
gitlab-shell self-check successful


Checking GitLab Shell ... Finished


Checking Gitaly ...


Gitaly: ... default ... OK


Checking Gitaly ... Finished


Checking Sidekiq ...


Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1


Checking Sidekiq ... Finished


Checking Incoming Email ...


Incoming Email: ... Reply by email is disabled in config/gitlab.yml


Checking Incoming Email ... Finished


Checking LDAP ...


LDAP: ... Server: ldapmain
Deprecation warning: Net::LDAP::ConnectionRefused will be deprecated. Use Errno::ECONNREFUSED instead.
Deprecation warning: Net::LDAP::ConnectionRefused will be deprecated. Use Errno::ECONNREFUSED instead.
Could not connect to the LDAP server: Connection refused - connect(2) for 127.0.0.1:389


Checking LDAP ... Finished


Checking GitLab App ...


Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... yes
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
1/1 ... yes
7/2 ... yes
7/3 ... yes
7/4 ... yes
7/5 ... yes
7/6 ... yes
7/7 ... yes
7/8 ... yes
7/9 ... yes
7/10 ... yes
8/11 ... yes
8/12 ... yes
8/13 ... yes
8/14 ... yes
1/15 ... yes
7/16 ... yes
1/17 ... yes
6/18 ... yes
1/20 ... yes
1/21 ... yes
1/30 ... yes
1/31 ... yes
1/32 ... yes
1/33 ... yes
1/34 ... yes
14/35 ... yes
17/36 ... yes
1/37 ... yes
1/38 ... yes
27/39 ... yes
29/40 ... yes
30/41 ... yes
32/42 ... yes
34/43 ... yes
36/44 ... yes
38/45 ... yes
40/46 ... yes
42/47 ... yes
44/48 ... yes
45/49 ... yes
47/50 ... yes
49/51 ... yes
51/52 ... yes
53/53 ... yes
1/54 ... yes
1/55 ... yes
1/56 ... yes
1/57 ... yes
55/58 ... yes
1/59 ... yes
21/60 ... yes
1/61 ... yes
1/62 ... yes
1/63 ... yes
1/64 ... yes
1/65 ... yes
1/66 ... yes
1/67 ... yes
1/68 ... yes
1/69 ... yes
1/70 ... yes
1/71 ... yes
1/72 ... yes
1/73 ... yes
1/74 ... yes
1/75 ... yes
1/76 ... yes
1/77 ... yes
Redis version >= 4.0.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.6)
Git version >= 2.22.0 ? ... yes (2.26.2)
Git user has default SSH configuration? ... yes
Active users: ... 8
Is authorized keys file accessible? ... yes
Elasticsearch version 5.6 - 6.x? ... yes (6.8.5)


Checking GitLab App ... Finished


Checking GitLab subtasks ... Finished

Possible fixes

Give guest user at least developer access, but that's probably can't be an accpetable workaround in many cases.

Edited by Rehab