Use the correct edition when formatting path deps

Author: Jonas Schievink

Diff for: crates/rust-analyzer/src/handlers.rs

@@ -1788,14 +1788,15 @@ fn run_rustfmt(
     let file_id = from_proto::file_id(snap, &text_document.uri)?;
     let file = snap.analysis.file_text(file_id)?;
 
-    // find the edition of the package the file belongs to
-    // (if it belongs to multiple we'll just pick the first one and pray)
-    let edition = snap
+    // Determine the edition of the crate the file belongs to (if there's multiple, we pick the
+    // highest edition).
+    let editions = snap
         .analysis
         .relevant_crates_for(file_id)?
         .into_iter()
-        .find_map(|crate_id| snap.cargo_target_for_crate_root(crate_id))
-        .map(|(ws, target)| ws[ws[target].package].edition);
+        .map(|crate_id| snap.analysis.crate_edition(crate_id))
+        .collect::<Result<Vec<_>, _>>()?;
+    let edition = editions.iter().copied().max();
 
     let line_index = snap.file_line_index(file_id)?;