fix: repositories using ref-tables will be recognised.

Author: Byron

gix-discover/src/is.rs

@@ -1,6 +1,5 @@
-use std::{borrow::Cow, ffi::OsStr, path::Path};
-
 use crate::{DOT_GIT_DIR, MODULES};
+use std::{borrow::Cow, ffi::OsStr, path::Path};
 
 /// Returns true if the given `git_dir` seems to be a bare repository.
 ///
@@ -67,21 +66,30 @@ pub(crate) fn git_with_metadata(
 
     {
         // Fast-path: avoid doing the complete search if HEAD is already not there.
-        // TODO(reftable): use a ref-store to lookup HEAD if ref-tables should be supported, or detect ref-tables beforehand.
-        //                 Actually ref-tables still keep a specially marked `HEAD` around, so nothing might be needed here
-        //                 Even though our head-check later would fail without supporting it.
         if !dot_git.join("HEAD").exists() {
             return Err(crate::is_git::Error::MissingHead);
         }
         // We expect to be able to parse any ref-hash, so we shouldn't have to know the repos hash here.
-        // With ref-table, the has is probably stored as part of the ref-db itself, so we can handle it from there.
+        // With ref-table, the hash is probably stored as part of the ref-db itself, so we can handle it from there.
         // In other words, it's important not to fail on detached heads here because we guessed the hash kind wrongly.
         let refs = gix_ref::file::Store::at(dot_git.as_ref().into(), Default::default());
-        let head = refs.find_loose("HEAD")?;
-        if head.name.as_bstr() != "HEAD" {
-            return Err(crate::is_git::Error::MisplacedHead {
-                name: head.name.into_inner(),
-            });
+        match refs.find_loose("HEAD") {
+            Ok(head) => {
+                if head.name.as_bstr() != "HEAD" {
+                    return Err(crate::is_git::Error::MisplacedHead {
+                        name: head.name.into_inner(),
+                    });
+                }
+            }
+            Err(gix_ref::file::find::existing::Error::Find(gix_ref::file::find::Error::ReferenceCreation {
+                source: _,
+                relative_path,
+            })) if relative_path == Path::new("HEAD") => {
+                // It's fine as long as the reference is found is `HEAD`.
+            }
+            Err(err) => {
+                return Err(err.into());
+            }
         }
     }
 

gix-discover/tests/discover/is_git/mod.rs

@@ -133,8 +133,8 @@ fn split_worktree_using_configuration() -> crate::Result {
 
 #[test]
 fn reftable() -> crate::Result {
-    let repo = gix_testtools::scripted_fixture_read_only("make_reftable_repo.sh")?.join("reftable-clone");
-    let kind = gix_discover::is_git(&repo)?;
+    let repo_path = gix_testtools::scripted_fixture_read_only("make_reftable_repo.sh")?.join("reftable-clone/.git");
+    let kind = gix_discover::is_git(&repo_path)?;
     assert_eq!(kind, gix_discover::repository::Kind::WorkTree { linked_git_dir: None });
     Ok(())
 }