common/rust: add Path::parents helper method

common/rust/src/lib.rs

@@ -2,7 +2,7 @@
 
 mod section_range;
 
-use std::mem;
+use std::{mem, path::Path};
 
 pub use section_range::{EmptyRange, InvalidSectionString, SectionRange};
 
@@ -61,3 +61,18 @@ impl<T> Iterator for UpToTwoIter<T> {
         ret
     }
 }
+
+pub trait PathExt {
+    type Iter<'a>: Iterator<Item = &'a Path>
+    where
+        Self: 'a;
+    fn parents(&self) -> Self::Iter<'_>;
+}
+
+impl PathExt for Path {
+    type Iter<'a> = std::iter::Successors<&'a Path, for<'p> fn(&&'p Path) -> Option<&'p Path>>;
+
+    fn parents(&self) -> Self::Iter<'_> {
+        std::iter::successors(Some(self), |dir| dir.parent())
+    }
+}