From 5004cb928b2c430a6d7fba59d89f7829982d8baa Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Sun, 9 Dec 2018 14:21:54 +0300
Subject: verbose assertions in SourceFileItems

---
 crates/ra_hir/src/lib.rs | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 578fde259..760524f6b 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -139,12 +139,21 @@ impl SourceFileItems {
         self.id_of_unchecked(item)
     }
     fn id_of_unchecked(&self, item: SyntaxNodeRef) -> SourceFileItemId {
-        let (id, _item) = self
-            .arena
-            .iter()
-            .find(|(_id, i)| i.borrowed() == item)
-            .unwrap();
-        id
+        if let Some((id, _)) = self.arena.iter().find(|(_id, i)| i.borrowed() == item) {
+            return id;
+        }
+        // This should not happen. Let's try to give a sensible diagnostics.
+        if let Some((_, i)) = self.arena.iter().find(|(_id, i)| i.range() == item.range()) {
+            panic!(
+                "unequal syntax nodes with the same range:\n{:?}\n{:?}",
+                item, i
+            )
+        }
+        panic!(
+            "Can't find {:?} in SourceFileItems:\n{:?}",
+            item,
+            self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
+        );
     }
     pub fn id_of_source_file(&self) -> SourceFileItemId {
         let (id, _syntax) = self.arena.iter().next().unwrap();
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