From 27bf044ca282abf9814e5519f0ed15b84dcc32eb Mon Sep 17 00:00:00 2001
From: Yury Delendik <ydelendik@mozilla.com>
Date: Thu, 26 Mar 2020 12:25:26 -0500
Subject: [PATCH] Fix debug asserts for dwarf transform (#1413)

* Fix debug asserts for dwarf transform

* feedback
---
 crates/debug/src/transform/address_transform.rs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/crates/debug/src/transform/address_transform.rs b/crates/debug/src/transform/address_transform.rs
index bd49358eeb..c89c9ea92b 100644
--- a/crates/debug/src/transform/address_transform.rs
+++ b/crates/debug/src/transform/address_transform.rs
@@ -357,6 +357,7 @@ pub struct TransformRangeIter<'a> {
     end_it: TransformRangeEndIter<'a>,
     last_start: Option<(GeneratedAddress, RangeIndex)>,
     last_end: Option<(GeneratedAddress, RangeIndex)>,
+    last_item: Option<(GeneratedAddress, GeneratedAddress)>,
 }
 
 impl<'a> TransformRangeIter<'a> {
@@ -371,6 +372,7 @@ impl<'a> TransformRangeIter<'a> {
             end_it,
             last_start,
             last_end,
+            last_item: None,
         }
     }
 }
@@ -409,9 +411,6 @@ impl<'a> Iterator for TransformRangeIter<'a> {
                 Some(range_start) => {
                     // Consume start iterator.
                     self.last_start = self.start_it.next();
-                    debug_assert!(
-                        self.last_start.is_none() || range_start < self.last_start.unwrap().0
-                    );
                     range_start
                 }
                 None => {
@@ -423,7 +422,6 @@ impl<'a> Iterator for TransformRangeIter<'a> {
                 Some(range_end) => {
                     // Consume end iterator.
                     self.last_end = self.end_it.next();
-                    debug_assert!(self.last_end.is_none() || range_end < self.last_end.unwrap().0);
                     range_end
                 }
                 None => {
@@ -432,6 +430,13 @@ impl<'a> Iterator for TransformRangeIter<'a> {
                 }
             };
 
+            if cfg!(debug_assertions) {
+                match self.last_item.replace((range_start, range_end)) {
+                    Some((_, last_end)) => debug_assert!(last_end <= range_start),
+                    None => (),
+                }
+            }
+
             if range_start < range_end {
                 return Some((range_start, range_end));
             }