From 232feec0b1e9c115bbb30da2293dc5bed3fd97b7 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Thu, 4 Sep 2025 00:17:12 -0400
Subject: [PATCH] cmCMakePath: support constructing `.end()` iterators

Dereferencing the iterator must be avoided once it becomes the `.end()`
value. Check for iterator validity before updating the `PathElement`
member.
---
 Source/cmCMakePath.h | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/Source/cmCMakePath.h b/Source/cmCMakePath.h
index da92424d18..e681c81a16 100644
--- a/Source/cmCMakePath.h
+++ b/Source/cmCMakePath.h
@@ -664,12 +664,7 @@ public:
 
   iterator() = default;
 
-  iterator(iterator const& other)
-    : Iterator(other.Iterator)
-    , Path(other.Path)
-    , PathElement(*this->Iterator)
-  {
-  }
+  iterator(iterator const& other) = default;
 
   ~iterator() = default;
 
@@ -678,7 +673,7 @@ public:
     if (this != &other) {
       this->Iterator = other.Iterator;
       this->Path = other.Path;
-      this->PathElement = *this->Iterator;
+      this->PathElement = other.PathElement;
     }
 
     return *this;
@@ -691,7 +686,9 @@ public:
   iterator& operator++()
   {
     ++this->Iterator;
-    this->PathElement = *this->Iterator;
+    if (this->Path && this->Iterator != this->Path->Path.end()) {
+      this->PathElement = *this->Iterator;
+    }
 
     return *this;
   }
@@ -706,7 +703,9 @@ public:
   iterator& operator--()
   {
     --this->Iterator;
-    this->PathElement = *this->Iterator;
+    if (this->Path && this->Iterator != this->Path->Path.end()) {
+      this->PathElement = *this->Iterator;
+    }
 
     return *this;
   }
@@ -725,8 +724,10 @@ private:
   iterator(cmCMakePath const* path, cm::filesystem::path::iterator const& it)
     : Iterator(it)
     , Path(path)
-    , PathElement(*this->Iterator)
   {
+    if (this->Path && this->Iterator != this->Path->Path.end()) {
+      this->PathElement = *this->Iterator;
+    }
   }
 
   cm::filesystem::path::iterator Iterator;