fix(aqua): skip in-place link when src and dst alias same inode

src/backend/aqua.rs

@@ -2458,6 +2458,13 @@ impl AquaBackend {
             file::create_dir_all(parent)?;
         }
 
+        // On case-insensitive filesystems src and dst can be different
+        // strings but the same on-disk file; without this guard the branches
+        // below would overwrite src with a self-referential link.
+        if link.dst.exists() && same_disk_entry(&link.src, &link.dst) {
+            return Ok(());
+        }
+
         if link.hard || (cfg!(windows) && link.explicit_link) {
             trace!("ln {} {}", link.src.display(), link.dst.display());
             if link.dst.is_dir() {
@@ -2493,6 +2500,24 @@ impl AquaBackend {
     }
 }
 
+fn same_disk_entry(a: &Path, b: &Path) -> bool {
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::MetadataExt;
+        match (fs::metadata(a), fs::metadata(b)) {
+            (Ok(am), Ok(bm)) => am.dev() == bm.dev() && am.ino() == bm.ino(),
+            _ => false,
+        }
+    }
+    #[cfg(not(unix))]
+    {
+        match (fs::canonicalize(a), fs::canonicalize(b)) {
+            (Ok(ac), Ok(bc)) => ac == bc,
+            _ => false,
+        }
+    }
+}
+
 fn relative_path(from: &Path, to: &Path) -> Option<PathBuf> {
     let from_components = from.components().collect_vec();
     let to_components = to.components().collect_vec();
@@ -3047,6 +3072,30 @@ mod tests {
         Ok(())
     }
 
+    #[cfg(unix)]
+    #[test]
+    fn test_create_file_link_skips_when_dst_aliases_src_inode() -> Result<()> {
+        let tmp = tempfile::tempdir()?;
+        let src = tmp.path().join("Godot");
+        fs::write(&src, b"binary contents")?;
+        // hard_link gives portable same-inode src/dst without needing a
+        // case-insensitive filesystem
+        let dst = tmp.path().join("Godot-alias");
+        fs::hard_link(&src, &dst)?;
+
+        AquaBackend::create_file_link(&AquaFileLink {
+            src: src.clone(),
+            dst: dst.clone(),
+            hard: false,
+            explicit_link: false,
+        })?;
+
+        assert!(dst.exists(), "dst must still exist after the early return");
+        assert!(!dst.is_symlink(), "dst must not be replaced with a symlink");
+        assert_eq!(fs::read(&src)?, b"binary contents");
+        Ok(())
+    }
+
     #[test]
     fn test_unescape_regex_literal_no_backslash_is_borrowed() {
         let result = unescape_regex_literal("astral-sh/ruff/.github/workflows/release.yml");