kvdb+watchtower: fix unreachable code

[undefinedor]

Change Description

fix unreachable code

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[mohamedawnallah]

Thanks @undefinedor for the PR! The changes look good to me but please review our contribution guidelines on how to write commit messages.

BTW there is another unreachable code here:

lnd/watchtower/wtclient/session_negotiator.go

Lines 336 to 340 in 1422df2

	// Success.
	return
	}
	}

[mohamedawnallah]

I wonder if we could detect this automatically in our CI linting to ensure it doesn't happen again. I've found go vet package which is capable of detecting these kinds of issues.

For instance, running go vet ./... on all packages available revealed several issues, including unreachable code analysis:

➜  lnd git:(master) go vet ./...
# github.com/lightningnetwork/lnd/internal/musig2v040
# [github.com/lightningnetwork/lnd/internal/musig2v040]
internal/musig2v040/musig2_test.go:402:2: struct field tag `json:"expected_error` not compatible with reflect.StructTag.Get: bad syntax for struct tag value
internal/musig2v040/musig2_test.go:1065:6: call to (*testing.T).Fatalf from a non-test goroutine
internal/musig2v040/musig2_test.go:1069:6: call to (*testing.T).Fatalf from a non-test goroutine
# github.com/lightningnetwork/lnd/contractcourt
# [github.com/lightningnetwork/lnd/contractcourt]
contractcourt/briefcase_test.go:354:20: assignment copies lock value to contestTimeout: github.com/lightningnetwork/lnd/contractcourt.htlcTimeoutResolver contains sync.Mutex
contractcourt/briefcase_test.go:359:20: assignment copies lock value to contestSuccess: github.com/lightningnetwork/lnd/contractcourt.htlcSuccessResolver contains sync.Mutex
# github.com/lightningnetwork/lnd/watchtower/wtclient
# [github.com/lightningnetwork/lnd/watchtower/wtclient]
watchtower/wtclient/session_negotiator.go:338:3: unreachable code
watchtower/wtclient/session_negotiator.go:397:2: unreachable code

[undefinedor]

I wonder if we could detect this automatically in our CI linting to ensure it doesn't happen again. I've found go vet package which is capable of detecting these kinds of issues.

For instance, running go vet ./... on all packages available revealed several issues, including unreachable code analysis:

➜  lnd git:(master) go vet ./...
# github.com/lightningnetwork/lnd/internal/musig2v040
# [github.com/lightningnetwork/lnd/internal/musig2v040]
internal/musig2v040/musig2_test.go:402:2: struct field tag `json:"expected_error` not compatible with reflect.StructTag.Get: bad syntax for struct tag value
internal/musig2v040/musig2_test.go:1065:6: call to (*testing.T).Fatalf from a non-test goroutine
internal/musig2v040/musig2_test.go:1069:6: call to (*testing.T).Fatalf from a non-test goroutine
# github.com/lightningnetwork/lnd/contractcourt
# [github.com/lightningnetwork/lnd/contractcourt]
contractcourt/briefcase_test.go:354:20: assignment copies lock value to contestTimeout: github.com/lightningnetwork/lnd/contractcourt.htlcTimeoutResolver contains sync.Mutex
contractcourt/briefcase_test.go:359:20: assignment copies lock value to contestSuccess: github.com/lightningnetwork/lnd/contractcourt.htlcSuccessResolver contains sync.Mutex
# github.com/lightningnetwork/lnd/watchtower/wtclient
# [github.com/lightningnetwork/lnd/watchtower/wtclient]
watchtower/wtclient/session_negotiator.go:338:3: unreachable code
watchtower/wtclient/session_negotiator.go:397:2: unreachable code

You're correct.
I've eliminated all unreachable code.
Next, I'll submit another pull request to update the CI linting.

[mohamedawnallah]

Thanks @undefinedor! The changes look good to me 🎉!

[guggero]

LGTM, thanks!

[ellemouton]

Lgtm! nice clean up :)

Pls add a release notes entry 🙏

[undefinedor]

Lgtm! nice clean up :)

Pls add a release notes entry 🙏

done

[guggero]

You're correct. I've eliminated all unreachable code. Next, I'll submit another pull request to update the CI linting.

We do have a linter (golangci-lint, check .golangci.yml in the repo). But that only looks at new code starting at a specific commit, because previous code would generate way too many warnings.

But if you want, you can comment out the new-from-rev: 8c66353e4c02329abdacb5a8df29998035ec2e24 part and run the linter locally. The output will likely be massive and a lot of non-critical stuff.
PRs for linter fixes for old commits are accepted, if they're easy to review and small risk. Ideally we'd be able to remove the new-from-rev at some point, but don't think that's going to happen any time soon.