gentoo-overlay/dev-util/mdds/files/mdds-1.7.0-rtree_test.patch

From 7ab81002fe127d16602b85b391c1d1b0422a9afd Mon Sep 17 00:00:00 2001
From: Kohei Yoshida <kohei.yoshida@gmail.com>
Date: Mon, 14 Jun 2021 22:52:14 -0400
Subject: [PATCH] std::deque::erase invalidates all elements if the erased
 element ...

... is not the first or the last element. My previous assumption (
that only the elements that occur after the erased element become
invalid) was in fact wrong.

This should resolve #66.
---
 include/mdds/rtree_def.inl | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/include/mdds/rtree_def.inl b/include/mdds/rtree_def.inl
index ed0e9be..84f0673 100644
--- a/include/mdds/rtree_def.inl
+++ b/include/mdds/rtree_def.inl
@@ -836,17 +836,20 @@ bool rtree<_Key,_Value,_Trait>::directory_node::erase(const node_store* ns)
     if (it == children.end())
         return false;
 
-    it = children.erase(it);
+    // NB: std::deque::erase invalidates all elements when the erased element
+    // is somwhere in the middle. But if the erased element is either the
+    // first or the last element, only the erased element becomes invalidated.
 
-    // All nodes that occur after the erased node have their memory addresses
-    // shifted.
+    std::size_t pos = std::distance(children.begin(), it);
+    bool all_valid = pos == 0 || pos == children.size() - 1;
 
-    std::for_each(it, children.end(),
-        [](node_store& this_ns)
-        {
-            this_ns.valid_pointer = false;
-        }
-    );
+    it = children.erase(it);
+
+    if (!all_valid)
+    {
+        for (node_store& ns : children)
+            ns.valid_pointer = false;
+    }
 
     return true;
 }
-- 
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