fix!: allow querying Repository::submodules() in an unborn repository.

It's a breaking change merely because the error type changed.

Author: Byron

gix/src/repository/submodule.rs

@@ -26,7 +26,7 @@ impl Repository {
         )?))
     }
 
-    /// Return a shared [`.gitmodules` file](crate::submodule::File) which is updated automatically if the in-memory snapshot
+    /// Return a shared [`.gitmodules` file](submodule::File) which is updated automatically if the in-memory snapshot
     /// has become stale as the underlying file on disk has changed. The snapshot based on the file on disk is shared across all
     /// clones of this repository.
     ///
@@ -54,12 +54,20 @@ impl Repository {
                 }) {
                     Some(id) => id,
                     None => match self
-                        .head_commit()?
-                        .tree()?
-                        .find_entry(submodule::MODULES_FILE)
-                        .map(|entry| entry.inner.oid)
+                        .head()?
+                        .try_peel_to_id_in_place()?
+                        .map(|id| -> Result<Option<_>, submodule::modules::Error> {
+                            Ok(id
+                                .object()?
+                                .peel_to_commit()?
+                                .tree()?
+                                .find_entry(submodule::MODULES_FILE)
+                                .map(|entry| entry.inner.oid.to_owned()))
+                        })
+                        .transpose()?
+                        .flatten()
                     {
-                        Some(id) => id.to_owned(),
+                        Some(id) => id,
                         None => return Ok(None),
                     },
                 };

gix/src/status/index_worktree.rs

@@ -226,13 +226,6 @@ mod submodule_status {
                     v
                 }
                 Ok(None) => Vec::new(),
-                Err(crate::submodule::modules::Error::FindHeadCommit(
-                    crate::reference::head_commit::Error::PeelToCommit(
-                        crate::head::peel::to_commit::Error::PeelToObject(
-                            crate::head::peel::to_object::Error::Unborn { .. },
-                        ),
-                    ),
-                )) => Vec::new(),
                 Err(err) => return Err(err),
             };
             Ok(Self {

gix/src/submodule/errors.rs

@@ -23,8 +23,12 @@ pub mod modules {
         OpenIndex(#[from] crate::worktree::open_index::Error),
         #[error("Could not find the .gitmodules file by id in the object database")]
         FindExistingBlob(#[from] crate::object::find::existing::Error),
-        #[error("Did not find commit in current HEAD to access its tree")]
-        FindHeadCommit(#[from] crate::reference::head_commit::Error),
+        #[error(transparent)]
+        FindHeadRef(#[from] crate::reference::find::existing::Error),
+        #[error(transparent)]
+        PeelHeadRef(#[from] crate::head::peel::Error),
+        #[error(transparent)]
+        PeelObjectToCommit(#[from] crate::object::peel::to_kind::Error),
         #[error(transparent)]
         TreeFromCommit(#[from] crate::object::commit::Error),
     }

gix/tests/fixtures/generated-archives/make_submodules.tar

@@ -144,3 +144,5 @@ git clone with-submodules not-a-submodule
   mv modules.bak .gitmodules
   git add m1 && git commit -m "no submodule in index and commit, but in configuration"
 )
+
+git init unborn

gix/tests/fixtures/make_submodules.sh

@@ -340,6 +340,17 @@ mod open {
         Ok(())
     }
 
+    #[test]
+    fn in_unborn() -> crate::Result {
+        let repo = repo("unborn")?;
+        assert_eq!(
+            repo.submodules()?.into_iter().flatten().count(),
+            0,
+            "there is nothing, and that is fine"
+        );
+        Ok(())
+    }
+
     #[test]
     #[cfg(feature = "revision")]
     fn submodule_worktrees() -> crate::Result {