fix: default to creating file-symlinks if it is dangling on Windows (#1354)

This behaviour is the same as in Git.

Author: Byron

gix-fs/src/symlink.rs

@@ -31,10 +31,20 @@ pub fn remove(path: &Path) -> io::Result<()> {
 
 #[cfg(windows)]
 /// Create a new symlink at `link` which points to `original`.
+///
+/// Note that if a symlink target (the `original`) isn't present on disk, it's assumed to be a
+/// file, creating a dangling file symlink. This is similar to a dangling symlink on Unix,
+/// which doesn't have to care about the target type though.
 pub fn create(original: &Path, link: &Path) -> io::Result<()> {
     use std::os::windows::fs::{symlink_dir, symlink_file};
     // TODO: figure out if links to links count as files or whatever they point at
-    if std::fs::metadata(link.parent().expect("dir for link").join(original))?.is_dir() {
+    let orig_abs = link.parent().expect("dir for link").join(original);
+    let is_dir = match std::fs::metadata(orig_abs) {
+        Ok(m) => m.is_dir(),
+        Err(err) if err.kind() == io::ErrorKind::NotFound => false,
+        Err(err) => return Err(err),
+    };
+    if is_dir {
         symlink_dir(original, link)
     } else {
         symlink_file(original, link)

gix-worktree-state/tests/fixtures/generated-archives/make_dangling_symlink.tar.xz

@@ -0,0 +1,11 @@
+#!/bin/bash
+set -eu -o pipefail
+
+git init -q
+
+target_oid=$(echo -n "non-existing-target" | git hash-object -w --stdin)
+  git update-index --index-info <<-EOF
+120000 $target_oid	dangling
+EOF
+
+git commit -m "dangling symlink in index"

gix-worktree-state/tests/fixtures/make_dangling_symlink.sh

@@ -42,6 +42,11 @@ fn driver_exe() -> String {
     exe
 }
 
+fn assure_is_empty(dir: impl AsRef<Path>) -> std::io::Result<()> {
+    assert_eq!(std::fs::read_dir(dir)?.count(), 0);
+    Ok(())
+}
+
 #[test]
 fn submodules_are_instantiated_as_directories() -> crate::Result {
     let mut opts = opts_from_probe();
@@ -57,11 +62,6 @@ fn submodules_are_instantiated_as_directories() -> crate::Result {
     Ok(())
 }
 
-fn assure_is_empty(dir: impl AsRef<Path>) -> std::io::Result<()> {
-    assert_eq!(std::fs::read_dir(dir)?.count(), 0);
-    Ok(())
-}
-
 #[test]
 fn accidental_writes_through_symlinks_are_prevented_if_overwriting_is_forbidden() {
     let mut opts = opts_from_probe();
@@ -257,6 +257,30 @@ fn symlinks_become_files_if_disabled() -> crate::Result {
     Ok(())
 }
 
+#[test]
+fn dangling_symlinks_can_be_created() -> crate::Result {
+    let opts = opts_from_probe();
+    if !opts.fs.symlink {
+        eprintln!("Skipping dangling symlink test on filesystem that doesn't support it");
+        return Ok(());
+    }
+
+    let (_source_tree, destination, _index, outcome) =
+        checkout_index_in_tmp_dir(opts.clone(), "make_dangling_symlink")?;
+    let worktree_files = dir_structure(&destination);
+    let worktree_files_stripped = stripped_prefix(&destination, &worktree_files);
+
+    assert_eq!(worktree_files_stripped, paths(["dangling"]));
+    let symlink_path = &worktree_files[0];
+    assert!(symlink_path
+        .symlink_metadata()
+        .expect("dangling symlink is on disk")
+        .is_symlink());
+    assert_eq!(std::fs::read_link(symlink_path)?, Path::new("non-existing-target"));
+    assert!(outcome.collisions.is_empty());
+    Ok(())
+}
+
 #[test]
 fn allow_or_disallow_symlinks() -> crate::Result {
     let mut opts = opts_from_probe();