place shallow git dependencies into a different directory.

That way, we avoid any danger with older cargo's not being able
to handle such a repository correctly.

src/cargo/sources/git/source.rs

@@ -29,7 +29,13 @@ impl<'cfg> GitSource<'cfg> {
         assert!(source_id.is_git(), "id is not git, id={}", source_id);
 
         let remote = GitRemote::new(source_id.url());
-        let ident = ident(&source_id);
+        let ident = ident_shallow(
+            &source_id,
+            config
+                .cli_unstable()
+                .gitoxide
+                .map_or(false, |gix| gix.fetch && gix.shallow_deps),
+        );
 
         let source = GitSource {
             remote,
@@ -76,6 +82,14 @@ fn ident(id: &SourceId) -> String {
     format!("{}-{}", ident, short_hash(id.canonical_url()))
 }
 
+fn ident_shallow(id: &SourceId, is_shallow: bool) -> String {
+    let mut ident = ident(id);
+    if is_shallow {
+        ident.push_str("-shallow");
+    }
+    ident
+}
+
 impl<'cfg> Debug for GitSource<'cfg> {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         write!(f, "git repo at {}", self.remote.url())?;

tests/testsuite/git.rs

@@ -2092,15 +2092,20 @@ fn gitoxide_clones_git_dependency_with_shallow_protocol_and_follow_up_fetch_main
         .masquerade_as_nightly_cargo(&["unstable features must be available for -Z gitoxide"])
         .run();
 
-    let db_clone = gix::open_opts(
-        glob::glob(paths::home().join(".cargo/git/db/bar-*").to_str().unwrap())?
-            .next()
-            .unwrap()?,
+    let shallow_db_clone = gix::open_opts(
+        glob::glob(
+            paths::home()
+                .join(".cargo/git/db/bar-*-shallow")
+                .to_str()
+                .unwrap(),
+        )?
+        .next()
+        .unwrap()?,
         gix::open::Options::isolated(),
     )?;
-    assert!(db_clone.is_shallow());
+    assert!(shallow_db_clone.is_shallow());
     assert_eq!(
-        db_clone
+        shallow_db_clone
             .rev_parse_single("origin/master")?
             .ancestors()
             .all()?
@@ -2145,16 +2150,24 @@ fn gitoxide_clones_git_dependency_with_shallow_protocol_and_follow_up_fetch_main
         .masquerade_as_nightly_cargo(&["unstable features must be available for -Z gitoxide"])
         .run();
 
+    let db_clone = gix::open_opts(
+        glob::glob(paths::home().join(".cargo/git/db/bar-*").to_str().unwrap())?
+            .map(Result::unwrap)
+            .filter(|p| !p.to_string_lossy().ends_with("-shallow"))
+            .next()
+            .unwrap(),
+        gix::open::Options::isolated(),
+    )?;
     assert_eq!(
         db_clone
             .rev_parse_single("origin/master")?
             .ancestors()
             .all()?
             .count(),
-        2,
-        "the new commit was fetched into our DB clone"
+        3,
+        "we created an entirely new non-shallow clone"
     );
-    assert!(db_clone.is_shallow());
+    assert!(!db_clone.is_shallow());
     assert_eq!(
         dep_checkout.head_id()?.ancestors().all()?.count(),
         1,
@@ -2168,8 +2181,14 @@ fn gitoxide_clones_git_dependency_with_shallow_protocol_and_follow_up_fetch_main
             .unwrap(),
     )?
     .map(|path| -> anyhow::Result<usize> {
-        let dep_checkout = gix::open_opts(path?, gix::open::Options::isolated())?;
-        assert!(dep_checkout.is_shallow());
+        let path = path?;
+        let dep_checkout = gix::open_opts(&path, gix::open::Options::isolated())?;
+        dbg!(dep_checkout.git_dir());
+        assert_eq!(
+            dep_checkout.is_shallow(),
+            path.to_string_lossy().contains("-shallow"),
+            "checkouts of shallow db repos are shallow as well"
+        );
         let depth = dep_checkout.head_id()?.ancestors().all()?.count();
         Ok(depth)
     })
@@ -2178,8 +2197,8 @@ fn gitoxide_clones_git_dependency_with_shallow_protocol_and_follow_up_fetch_main
     .expect("two checkout repos");
 
     assert_eq!(
-        max_history_depth, 2,
-        "the new checkout sees all commits of the DB"
+        max_history_depth, 3,
+        "we see the previous shallow checkout as well as new new unshallow one"
     );
 
     Ok(())