From 607ea25ea1c0397749db39a15bd52c5e0d3cf552 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Tue, 4 Apr 2023 10:52:13 -0600
Subject: containers: IntervalTree: Add a sanity check that intervals aren't
 backward

---
 lib/containers/intervaltree.go | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/containers/intervaltree.go b/lib/containers/intervaltree.go
index d2e2732..16a9fdd 100644
--- a/lib/containers/intervaltree.go
+++ b/lib/containers/intervaltree.go
@@ -4,6 +4,10 @@
 
 package containers
 
+import (
+	"fmt"
+)
+
 type interval[K Ordered[K]] struct {
 	Min, Max K
 }
@@ -71,11 +75,17 @@ func (t *IntervalTree[K, V]) Equal(u *IntervalTree[K, V]) bool {
 
 func (t *IntervalTree[K, V]) Insert(val V) {
 	t.init()
+	min := t.MinFn(val)
+	max := t.MaxFn(val)
+	if max.Compare(min) < 0 {
+		panic(fmt.Errorf("containers.IntervalTree.Insert: max < min: [%v, %v]: %v",
+			min, max, val))
+	}
 	t.inner.Insert(intervalValue[K, V]{
 		Val: val,
 		ValSpan: interval[K]{
-			Min: t.MinFn(val),
-			Max: t.MaxFn(val),
+			Min: min,
+			Max: max,
 		},
 	})
 }
-- 
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