On login with external user ID (Oauth2) ensure an external login is created

[zeripath]

Gitea has an external login user table which only gets used for linked accounts. This appears to be a longstanding mistake and a bug, as they should be created for all external users.

Close #1143

[codecov-commenter]

Codecov Report

Merging #23501 (f971cd1) into main (f521e88) will decrease coverage by 0.02%.
The diff coverage is 42.63%.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@            Coverage Diff             @@
##             main   #23501      +/-   ##
==========================================
- Coverage   47.14%   47.12%   -0.02%     
==========================================
  Files        1149     1154       +5     
  Lines      151446   152198     +752     
==========================================
+ Hits        71397    71726     +329     
- Misses      71611    72002     +391     
- Partials     8438     8470      +32     

Impacted Files	Coverage Δ
cmd/dump.go	0.67% <0.00%> (ø)
models/actions/run.go	1.64% <0.00%> (-0.08%)	⬇️
models/packages/package.go	45.45% <0.00%> (-1.13%)	⬇️
models/user/search.go	77.50% <0.00%> (-6.29%)	⬇️
modules/actions/github.go	0.00% <0.00%> (ø)
modules/actions/workflows.go	0.00% <0.00%> (ø)
modules/doctor/storage.go	31.93% <0.00%> (ø)
modules/setting/git.go	45.45% <ø> (ø)
modules/storage/minio.go	1.51% <0.00%> (-0.06%)	⬇️
modules/structs/user.go	100.00% <ø> (ø)
... and 35 more

... and 11 files with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[lunny]

Suggested change

	}
	if !errors.Is(err, util.ErrAlreadyExist) {
	if err != nil && !errors.Is(err, util.ErrAlreadyExist) {
	log.Error("LinkAccountToUser failed: %v", err)
	}
	} else {

[wxiaoguang]

I guess we go back to history:

• Create external user for new OAuth2 user #21276 (comment)

That may not be correct. If I understand the existing code an ExternalLoginUser

makes the connecting between some existing user and additional external login sources

From the code this type is only inserted if an external login is used for an existing user but not if the user is created with/by that source. In this case User.LoginType has a specific value and no ExternalLoginUser is needed. (?)

ps: I haven't read the code and don't understand the problem, it's just unclear to me about what the design was and what's the expected behavior.