submodule.path & submodule.branch is empty

[sigurdblueface]

I've added two submodules:

 git submodule add https://mygitlab/prometheus monitoring
 git submodule add https://mygitlab/prometheus-rules

.gitmodules file:

[submodule "monitoring"]
	path = monitoring
	url = https://mygitlab/prometheus
[submodule "prometheus-rules"]
	path = prometheus-rules
	url = https://mygitlab/prometheus-rules

go test code snippet:

func FindSubmodules() error {
	repo, err := git.PlainOpen(".")
	if err != nil {
		return err
	}
	cfg, err := repo.Config()
	if err != nil {
		return err
	}
	for key, submodule := range cfg.Submodules{
		log.Printf("key: %s, name: %s, path: %s, url: %s, branch: %s", key, submodule.Name, submodule.Path, submodule.URL, submodule.Branch)
	}
	return nil
}

func TestFindSubmodules(t *testing.T) {
	err := FindSubmodules()
	if err != nil {
		t.Error(err)
	}
}

output of the above code is

=== RUN   TestFindSubmodules
2021/09/08 13:02:16 key: prometheus-rules, name: prometheus-rules, path: , url: https://mygitlab/prometheus-rules, branch: 
2021/09/08 13:02:16 key: monitoring, name: monitoring, path: , url: https://mygitlab/prometheus, branch: 

Please clarify if it's expected.

[andrewpollock]

I'm seeing something related, where the repo's submodule status is different after code has examined it, than before.

Steps to reproduce:

$ git clone https://github.com/charlesneimog/pd-server.git
Cloning into 'pd-server'...
remote: Enumerating objects: 849, done.
remote: Counting objects: 100% (10/10), done.
remote: Compressing objects: 100% (8/8), done.
remote: Total 849 (delta 2), reused 4 (delta 2), pack-reused 839
Receiving objects: 100% (849/849), 2.12 MiB | 2.56 MiB/s, done.
Resolving deltas: 100% (371/371), done.
$ cd pd-server
$ git submodule update --init --recursive
Submodule 'pd-lib-builder' (https://github.com/pure-data/pd-lib-builder) registered for path 'pd-lib-builder'
Submodule 'src/cpp-httplib' (https://github.com/yhirose/cpp-httplib) registered for path 'src/cpp-httplib'
Submodule 'src/json' (https://github.com/nlohmann/json) registered for path 'src/json'
Submodule 'src/websocketpp' (https://github.com/zaphoyd/websocketpp) registered for path 'src/websocketpp'
Cloning into '/tmp/pd-server/pd-lib-builder'...
Cloning into '/tmp/pd-server/src/cpp-httplib'...
Cloning into '/tmp/pd-server/src/json'...
Cloning into '/tmp/pd-server/src/websocketpp'...
Submodule path 'pd-lib-builder': checked out '5c2e137f7a7a03f4007494954ccb3e23753e7807'
Submodule path 'src/cpp-httplib': checked out '227d2c20509f85a394133e2be6d0b0fc1fda54b2'
Submodule path 'src/json': checked out '4c6cde72e533158e044252718c013a48bcff346c'
Submodule path 'src/websocketpp': checked out '1b11fd301531e6df35a6107c1e8665b1e77a2d8e'
$ git submodule status
 5c2e137f7a7a03f4007494954ccb3e23753e7807 pd-lib-builder (v0.6.0-28-g5c2e137)
 227d2c20509f85a394133e2be6d0b0fc1fda54b2 src/cpp-httplib (v0.11.3-6-g227d2c2)
 4c6cde72e533158e044252718c013a48bcff346c src/json (v3.11.2-39-g4c6cde72)
 1b11fd301531e6df35a6107c1e8665b1e77a2d8e src/websocketpp (0.8.2-1-g1b11fd3)
[run the code in https://github.com/google/osv-scanner/pull/581 against the repo]
$ go run ./cmd/osv-scanner -r /tmp/pd-server/
Scanning dir /tmp/pd-server/
Scanning /tmp/pd-server/ at commit cf3f15a841ca21b53c6de654c9981a30ae0b590c
Scanning submodule src/cpp-httplib at commit 0000000000000000000000000000000000000000
Scanning submodule pd-lib-builder at commit 5c2e137f7a7a03f4007494954ccb3e23753e7807
Scanning submodule src/json at commit 0000000000000000000000000000000000000000
Scanning submodule src/websocketpp at commit 0000000000000000000000000000000000000000
.
.
.
$ git submodule status
 5c2e137f7a7a03f4007494954ccb3e23753e7807 pd-lib-builder (v0.6.0-28-g5c2e137)
 227d2c20509f85a394133e2be6d0b0fc1fda54b2 src/cpp-httplib ()
 4c6cde72e533158e044252718c013a48bcff346c src/json ()
 1b11fd301531e6df35a6107c1e8665b1e77a2d8e src/websocketpp ()
$ git status
On branch master
Your branch is up to date with 'origin/master'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
  (commit or discard the untracked or modified content in submodules)
        modified:   src/cpp-httplib (untracked content)
        modified:   src/json (untracked content)
        modified:   src/websocketpp (untracked content)

[andrewpollock]

For reasons not yet clear to me, using SubmoduleStatus Expected instead of Current seems to do the right thing.

Credit to @another-rex for identifying this.

[andrewpollock]

So while using Expected instead of Current addresses the unexpected functional issues I was encountering, it does not address the unexpected side-effects to the current state of the submodules.

[pjbgf]

@andrewpollock We could improve the documentation to highlight the behaviour. Would you be keen on proposing a PR to that effect?

[andrewpollock]

@pjbgf Unfortunately I don't feel like I (yet) have enough of a handle on what's actually going on under the hood to be able to do that.

[andrewpollock]

Latest debugging for the unexpected side-effects, I have a narrower reproduction case in https://gist.github.com/andrewpollock/0c51ca92fdb77f1b0671a69c8187d949

$ git clone --recursive https://github.com/charlesneimog/pd-server
Cloning into 'pd-server'...
remote: Enumerating objects: 852, done.
remote: Counting objects: 100% (13/13), done.
remote: Compressing objects: 100% (11/11), done.
remote: Total 852 (delta 3), reused 7 (delta 2), pack-reused 839
Receiving objects: 100% (852/852), 2.12 MiB | 2.26 MiB/s, done.
Resolving deltas: 100% (372/372), done.
Submodule 'pd-lib-builder' (https://github.com/pure-data/pd-lib-builder) registered for path 'pd-lib-builder'
Submodule 'src/cpp-httplib' (https://github.com/yhirose/cpp-httplib) registered for path 'src/cpp-httplib'
Submodule 'src/json' (https://github.com/nlohmann/json) registered for path 'src/json'
Submodule 'src/websocketpp' (https://github.com/zaphoyd/websocketpp) registered for path 'src/websocketpp'
Cloning into '/tmp/pd-server/pd-lib-builder'...
remote: Enumerating objects: 711, done.
remote: Counting objects: 100% (126/126), done.
remote: Compressing objects: 100% (58/58), done.
remote: Total 711 (delta 82), reused 80 (delta 68), pack-reused 585
Receiving objects: 100% (711/711), 176.16 KiB | 751.00 KiB/s, done.
Resolving deltas: 100% (356/356), done.
Cloning into '/tmp/pd-server/src/cpp-httplib'...
remote: Enumerating objects: 4723, done.
remote: Counting objects: 100% (4723/4723), done.
remote: Compressing objects: 100% (1505/1505), done.
remote: Total 4723 (delta 3214), reused 4586 (delta 3168), pack-reused 0
Receiving objects: 100% (4723/4723), 2.79 MiB | 3.91 MiB/s, done.
Resolving deltas: 100% (3214/3214), done.
Cloning into '/tmp/pd-server/src/json'...
remote: Enumerating objects: 36542, done.
remote: Counting objects: 100% (812/812), done.
remote: Compressing objects: 100% (217/217), done.
remote: Total 36542 (delta 386), reused 736 (delta 356), pack-reused 35730
Receiving objects: 100% (36542/36542), 177.61 MiB | 21.22 MiB/s, done.
Resolving deltas: 100% (22578/22578), done.
Cloning into '/tmp/pd-server/src/websocketpp'...
remote: Enumerating objects: 12791, done.
remote: Counting objects: 100% (1549/1549), done.
remote: Compressing objects: 100% (197/197), done.
remote: Total 12791 (delta 1504), reused 1353 (delta 1352), pack-reused 11242
Receiving objects: 100% (12791/12791), 8.37 MiB | 8.28 MiB/s, done.
Resolving deltas: 100% (7985/7985), done.
Submodule path 'pd-lib-builder': checked out '5c2e137f7a7a03f4007494954ccb3e23753e7807'
Submodule path 'src/cpp-httplib': checked out 'a609330e4c6374f741d3b369269f7848255e1954'
Submodule path 'src/json': checked out '4c6cde72e533158e044252718c013a48bcff346c'
Submodule path 'src/websocketpp': checked out '1b11fd301531e6df35a6107c1e8665b1e77a2d8e'

$ go run ./gitsubmodulestatusdebug/gsmsd.go 
Hello, world.
[]*git.Repository{(*git.Repository)(0xc00018e0c0), (*git.Repository)(0xc00018e450), (*git.Repository)(0xc00018e750), (*git.Repository)(0xc00018ed50)}

$ git submodule status
 5c2e137f7a7a03f4007494954ccb3e23753e7807 pd-lib-builder (v0.6.0-28-g5c2e137)
 a609330e4c6374f741d3b369269f7848255e1954 src/cpp-httplib ()
 4c6cde72e533158e044252718c013a48bcff346c src/json ()
 1b11fd301531e6df35a6107c1e8665b1e77a2d8e src/websocketpp ()

So the misbehaviour is somewhere within

go-git/submodule.go

Line 102 in 6252084

func (s *Submodule) Repository() (*Repository, error) {

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