From 85204e9847a85ec24d5f8f91c76a9abca3847b6f Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Wed, 17 Dec 2025 21:02:30 -0500
Subject: [PATCH] xo-alloc2: bugfix for DX1CollectorIterator

---
 include/xo/alloc2/cmpresult.hpp     | 13 ++++++++++-
 src/alloc2/CMakeLists.txt           |  1 +
 src/alloc2/DArenaIterator.cpp       |  6 +++++
 src/alloc2/DX1Collector.cpp         | 14 +++++++++--
 src/alloc2/DX1CollectorIterator.cpp |  8 +++++--
 src/alloc2/cmpresult.cpp            | 36 +++++++++++++++++++++++++++++
 6 files changed, 73 insertions(+), 5 deletions(-)
 create mode 100644 src/alloc2/cmpresult.cpp

diff --git a/include/xo/alloc2/cmpresult.hpp b/include/xo/alloc2/cmpresult.hpp
index 9fab433..2b67d0a 100644
--- a/include/xo/alloc2/cmpresult.hpp
+++ b/include/xo/alloc2/cmpresult.hpp
@@ -16,6 +16,14 @@ namespace xo {
             incomparable = 1,
         };
 
+        extern const char * comparison2str(comparison x);
+
+        inline std::ostream &
+        operator<<(std::ostream & os, comparison x) {
+            os << comparison2str(x);
+            return os;
+        }
+
         struct cmpresult {
             cmpresult() : err_{comparison::invalid}, cmp_{0} {}
             cmpresult(comparison err, std::int16_t cmp) : err_{err}, cmp_{cmp} {}
@@ -35,6 +43,8 @@ namespace xo {
                     return cmpresult::greater();
             }
 
+            /** print to stream **/
+            void display(std::ostream & os) const;
 
             bool is_equal() const { return (err_ == comparison::comparable) && (cmp_ == 0); }
 
@@ -50,7 +60,8 @@ namespace xo {
         inline std::ostream & operator<<(std::ostream & os,
                                          const cmpresult & x)
         {
-            os << "<cmpresult " << xtag("err", x.err_) << xtag("cmp", x.cmp_) << ">";
+            x.display(os);
+            return os;
         }
 
     } /*namespace mm*/
diff --git a/src/alloc2/CMakeLists.txt b/src/alloc2/CMakeLists.txt
index 7dde13f..8732713 100644
--- a/src/alloc2/CMakeLists.txt
+++ b/src/alloc2/CMakeLists.txt
@@ -4,6 +4,7 @@ set(SELF_LIB xo_alloc2)
 set(SELF_SRCS
 
     AllocInfo.cpp
+    cmpresult.cpp
 
     AAllocator.cpp
     DArena.cpp
diff --git a/src/alloc2/DArenaIterator.cpp b/src/alloc2/DArenaIterator.cpp
index 2a3e852..4704746 100644
--- a/src/alloc2/DArenaIterator.cpp
+++ b/src/alloc2/DArenaIterator.cpp
@@ -87,6 +87,12 @@ namespace xo {
         cmpresult
         DArenaIterator::compare(const DArenaIterator & other_ix) const noexcept
         {
+            scope log(XO_DEBUG(false),
+                      xtag("arena", arena_),
+                      xtag("pos", pos_),
+                      xtag("other.arena", other_ix.arena_),
+                      xtag("other.pos", other_ix.pos_));
+
             if (is_invalid() || (arena_ != other_ix.arena_))
                 return cmpresult::incomparable();
 
diff --git a/src/alloc2/DX1Collector.cpp b/src/alloc2/DX1Collector.cpp
index 1ac6cdf..8b033a7 100644
--- a/src/alloc2/DX1Collector.cpp
+++ b/src/alloc2/DX1Collector.cpp
@@ -238,11 +238,21 @@ namespace xo {
         DX1Collector::end() const noexcept {
             generation gen_hi = generation{config_.n_generation_};
 
+            /** valid iterator for end points to end of last DArena.
+             *  otherwise will interfere with working compare
+             *  (since invalid iterators are incomparable)
+             **/
+
+            const DArena * arena
+                = get_space(role::to_space(),
+                            generation(config_.n_generation_ - 1));
+            DArenaIterator arena_end = arena->end();
+
             return DX1CollectorIterator(this,
                                         gen_hi,
                                         gen_hi,
-                                        DArenaIterator(),
-                                        DArenaIterator());
+                                        arena_end,
+                                        arena_end);
         }
 
         void
diff --git a/src/alloc2/DX1CollectorIterator.cpp b/src/alloc2/DX1CollectorIterator.cpp
index c8377ca..799b38a 100644
--- a/src/alloc2/DX1CollectorIterator.cpp
+++ b/src/alloc2/DX1CollectorIterator.cpp
@@ -51,7 +51,7 @@ namespace xo {
         cmpresult
         DX1CollectorIterator::compare(const DX1CollectorIterator & other_ix) const noexcept
         {
-            scope log(XO_DEBUG(true),
+            scope log(XO_DEBUG(false),
                       xtag("is_valid", is_valid()),
                       xtag("other_ix.is_valid", other_ix.is_valid()) );
 
@@ -71,7 +71,11 @@ namespace xo {
             /* both iterators refer to the same arena,
              * so can compare their arena iterators directly
              */
-            return arena_ix_.compare(other_ix.arena_ix_);
+            cmpresult retval = arena_ix_.compare(other_ix.arena_ix_);
+
+            log && log(xtag("retval", retval));
+
+            return retval;
         }
 
         void
diff --git a/src/alloc2/cmpresult.cpp b/src/alloc2/cmpresult.cpp
new file mode 100644
index 0000000..d9f4713
--- /dev/null
+++ b/src/alloc2/cmpresult.cpp
@@ -0,0 +1,36 @@
+/** @file cmpresult.cpp
+ *
+ *  @author Roland Conybeare, Dec 2025
+ **/
+
+#include "cmpresult.hpp"
+#include <xo/indentlog/print/tag.hpp>
+#include <iostream>
+
+namespace xo {
+    namespace mm {
+        const char *
+        comparison2str(comparison x)
+        {
+            switch (x) {
+            case comparison::invalid:
+                return "?comparison";
+            case comparison::comparable:
+                return "cmp";
+            case comparison::incomparable:
+                return "!cmp";
+            }
+        }
+
+        void
+        cmpresult::display(std::ostream & os) const
+        {
+            os << "<cmpresult "
+               << xtag("err", err_)
+               << xtag("cmp", cmp_)
+               << ">";
+        }
+    } /*namespace mm*/
+} /*namespace xo*/
+
+/* end cmpresult.cpp */