Match branches with worktrees always, even with slashes

src/grm/main.rs

@@ -502,25 +502,9 @@ fn main() {
                         None => None,
                     };
 
-                    let mut name: &str = &action_args.name;
-                    let subdirectory;
-                    let split = name.split_once('/');
-                    match split {
-                        None => subdirectory = None,
-                        Some(split) => {
-                            if split.0.is_empty() || split.1.is_empty() {
-                                print_error("Worktree name cannot start or end with a slash");
-                                process::exit(1);
-                            } else {
-                                (subdirectory, name) = (Some(Path::new(split.0)), split.1);
-                            }
-                        }
-                    }
-
                     match worktree::add_worktree(
                         &cwd,
-                        name,
+                        &action_args.name,
-                        subdirectory,
                         track,
                         action_args.no_track,
                     ) {

src/tree.rs

@@ -222,7 +222,7 @@ fn sync_repo(root_path: &Path, repo: &repo::Repo, init_worktree: bool) -> Result
     if newly_created && repo.worktree_setup && init_worktree {
         match repo_handle.default_branch() {
             Ok(branch) => {
-                worktree::add_worktree(&repo_path, &branch.name()?, None, None, false)?;
+                worktree::add_worktree(&repo_path, &branch.name()?, None, false)?;
             }
             Err(_error) => print_repo_error(
                 &repo.name,

src/worktree.rs

@@ -21,10 +21,17 @@ pub const GIT_MAIN_WORKTREE_DIRECTORY: &str = ".git-main-working-tree";
 pub fn add_worktree(
     directory: &Path,
     name: &str,
-    subdirectory: Option<&Path>,
     track: Option<(&str, &str)>,
     no_track: bool,
 ) -> Result<(), String> {
+    // A branch name must never start or end with a slash. Everything else is ok.
+    if name.starts_with('/') || name.ends_with('/') {
+        return Err(format!(
+            "Invalid worktree name: {}. It cannot start or end with a slash",
+            name
+        ));
+    }
+
     let repo = repo::RepoHandle::open(directory, true).map_err(|error| match error.kind {
         repo::RepoErrorKind::NotFound => {
             String::from("Current directory does not contain a worktree setup")
@@ -38,11 +45,6 @@ pub fn add_worktree(
         return Err(format!("Worktree {} already exists", &name));
     }
 
-    let path = match subdirectory {
-        Some(dir) => directory.join(dir).join(name),
-        None => directory.join(Path::new(name)),
-    };
-
     let mut remote_branch_exists = false;
 
     let mut target_branch = match repo.find_local_branch(name) {
@@ -193,10 +195,80 @@ pub fn add_worktree(
         }
     }
 
-    if let Some(subdirectory) = subdirectory {
+    // We have to create subdirectories first, otherwise adding the worktree
-        std::fs::create_dir_all(subdirectory).map_err(|error| error.to_string())?;
+    // will fail
+    if name.contains('/') {
+        let path = Path::new(&name);
+        if let Some(base) = path.parent() {
+            // This is a workaround of a bug in libgit2 (?)
+            //
+            // When *not* doing this, we will receive an error from the `Repository::worktree()`
+            // like this:
+            //
+            // > failed to make directory '/{repo}/.git-main-working-tree/worktrees/dir/test
+            //
+            // This is a discrepancy between the behaviour of libgit2 and the
+            // git CLI when creating worktrees with slashes:
+            //
+            // The git CLI will create the worktree's configuration directory
+            // inside {git_dir}/worktrees/{last_path_component}. Look at this:
+            //
+            // ```
+            // $ git worktree add 1/2/3 -b 1/2/3
+            // $ ls .git/worktrees
+            // 3
+            // ```
+            //
+            // Interesting: When adding a worktree with a different name but the
+            // same final path component, git starts adding a counter suffix to
+            // the worktree directories:
+            //
+            // ```
+            // $ git worktree add 1/3/3 -b 1/3/3
+            // $ git worktree add 1/4/3 -b 1/4/3
+            // $ ls .git/worktrees
+            // 3
+            // 31
+            // 32
+            // ```
+            //
+            // I *guess* that the mapping back from the worktree directory under .git to the actual
+            // worktree directory is done via the `gitdir` file inside `.git/worktrees/{worktree}.
+            // This means that the actual directory would not matter. You can verify this by
+            // just renaming it:
+            //
+            // ```
+            // $ mv .git/worktrees/3 .git/worktrees/foobar
+            // $ git worktree list
+            // /tmp/       fcc8a2a7 [master]
+            // /tmp/1/2/3  fcc8a2a7 [1/2/3]
+            // /tmp/1/3/3  fcc8a2a7 [1/3/3]
+            // /tmp/1/4/3  fcc8a2a7 [1/4/3]
+            // ```
+            //
+            // => Still works
+            //
+            // Anyway, libgit2 does not do this: It tries to create the worktree
+            // directory inside .git with the exact name of the worktree, including
+            // any slashes. It should be this code:
+            //
+            // https://github.com/libgit2/libgit2/blob/f98dd5438f8d7bfd557b612fdf1605b1c3fb8eaf/src/libgit2/worktree.c#L346
+            //
+            // As a workaround, we can create the base directory manually for now.
+            //
+            // Tracking upstream issue: https://github.com/libgit2/libgit2/issues/6327
+            std::fs::create_dir_all(
+                directory
+                    .join(GIT_MAIN_WORKTREE_DIRECTORY)
+                    .join("worktrees")
+                    .join(base),
+            )
+            .map_err(|error| error.to_string())?;
+            std::fs::create_dir_all(base).map_err(|error| error.to_string())?;
+        }
     }
-    repo.new_worktree(name, &path, &target_branch)?;
+
+    repo.new_worktree(name, &directory.join(&name), &target_branch)?;
 
     Ok(())
 }