1 files changed, 16 insertions, 1 deletions
diff --git a/src/tools/rust-analyzer/crates/vfs/src/vfs_path.rs b/src/tools/rust-analyzer/crates/vfs/src/vfs_path.rs
index b23c9f196..38501a8ba 100644
--- a/src/tools/rust-analyzer/crates/vfs/src/vfs_path.rs
+++ b/src/tools/rust-analyzer/crates/vfs/src/vfs_path.rs
@@ -1,7 +1,7 @@
 //! Abstract-ish representation of paths for VFS.
 use std::fmt;
 
-use paths::{AbsPath, AbsPathBuf};
+use paths::{AbsPath, AbsPathBuf, RelPath};
 
 /// Path in [`Vfs`].
 ///
@@ -84,6 +84,14 @@ impl VfsPath {
         }
     }
 
+    pub fn strip_prefix(&self, other: &VfsPath) -> Option<&RelPath> {
+        match (&self.0, &other.0) {
+            (VfsPathRepr::PathBuf(lhs), VfsPathRepr::PathBuf(rhs)) => lhs.strip_prefix(rhs),
+            (VfsPathRepr::VirtualPath(lhs), VfsPathRepr::VirtualPath(rhs)) => lhs.strip_prefix(rhs),
+            (VfsPathRepr::PathBuf(_) | VfsPathRepr::VirtualPath(_), _) => None,
+        }
+    }
+
     /// Returns the `VfsPath` without its final component, if there is one.
     ///
     /// Returns [`None`] if the path is a root or prefix.
@@ -320,6 +328,13 @@ impl VirtualPath {
         self.0.starts_with(&other.0)
     }
 
+    fn strip_prefix(&self, base: &VirtualPath) -> Option<&RelPath> {
+        <_ as AsRef<std::path::Path>>::as_ref(&self.0)
+            .strip_prefix(&base.0)
+            .ok()
+            .map(RelPath::new_unchecked)
+    }
+
     /// Remove the last component of `self`.
     ///
     /// This will find the last `'/'` in `self`, and remove everything after it,