added example code which demonstrates the problem introduced in 4.5.0 and fixed in 4.5.1

4 files changed, 31 insertions, 16 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 6721d4544..997d9d6cb 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -10,9 +10,15 @@ NOTE: 4.3.0 now requires Python 3.6.0 and above. Python 3.5.x is no longer suppo
 RELEASE 4.5.1
 
   From Mats Wichmann
-    - Fix a problem in 4.5.0 where in some circumstances a Clone environment
-      could share the CPPDEFINES data structure with the original, causing
-      leakage when they should be completely independent after the Clone.
+    - Fix a problem in 4.5.0 where using something like the following code
+      will cause a Clone()'d environment to share the CPPDEFINES with the
+      original Environment() which was cloned. Causing leakage of changes
+      to CPPDEFINES when they should be completely independent after the Clone.
+          env=Environment(CPPDEFINES=['a'])
+          env.Append(CPPDEFINES=['b']) (or AppendUnique,Prepend,PrependUnique)
+          env1=env.Clone()
+          env1.Append(CPPDEFINES=['c']) (or any other modification, but not overwriting CPPDEFINES
+      Now env['CPPDEFINES'] will contain 'c' when it should not.
 
 
 RELEASE 4.5.0 -  Sun, 05 Mar 2023 14:08:29 -0700
diff --git a/RELEASE.txt b/RELEASE.txt
index 0726607a3..42e4465b9 100644
--- a/RELEASE.txt
+++ b/RELEASE.txt
@@ -6,7 +6,7 @@ Past official release announcements appear at:
 
 ==================================================================
 
-A new SCons release, 4.4.1, is now available on the SCons download page:
+A new SCons release, 4.5.1, is now available on the SCons download page:
 
     https://scons.org/pages/download.html
 
@@ -32,9 +32,17 @@ CHANGED/ENHANCED EXISTING FUNCTIONALITY
 FIXES
 -----
 
-- Fix a problem in 4.5.0 where in some circumstances a Clone environment
-  could share the CPPDEFINES data structure with the original, causing
-  leakage when they should be completely independent after the Clone.
+- Fix a problem in 4.5.0 where using something like the following code
+  will cause a Clone()'d environment to share the CPPDEFINES with the
+  original Environment() which was cloned. Causing leakage of changes
+  to CPPDEFINES when they should be completely independent after the Clone.
+      env=Environment(CPPDEFINES=['a'])
+      env.Append(CPPDEFINES=['b']) (or AppendUnique,Prepend,PrependUnique)
+      env1=env.Clone()
+      env1.Append(CPPDEFINES=['c']) (or any other modification, but not overwriting CPPDEFINES)
+  Now env['CPPDEFINES'] will contain 'c' when it should not.
+
+
 
 IMPROVEMENTS
 ------------
diff --git a/SCons/EnvironmentTests.py b/SCons/EnvironmentTests.py
index 0f429b492..fb089b1a5 100644
--- a/SCons/EnvironmentTests.py
+++ b/SCons/EnvironmentTests.py
@@ -1869,15 +1869,15 @@ def exists(env):
                 ZZZ=UD({1: 2, 3: 4}),
             )
             env2 = env1.Clone()
-            env2.Dictionary('XXX').append(4)
-            env2.Dictionary('YYY').append(4)
-            env2.Dictionary('ZZZ')[5] = 6
-            self.assertIn(4, env2.Dictionary('XXX'))
-            self.assertNotIn(4, env1.Dictionary('XXX'))
-            self.assertIn(4, env2.Dictionary('YYY'))
-            self.assertNotIn(4, env1.Dictionary('YYY'))
-            self.assertIn(5, env2.Dictionary('ZZZ'))
-            self.assertNotIn(5, env1.Dictionary('ZZZ'))
+            env2['XXX'].append(4)
+            env2['YYY'].append(4)
+            env2['ZZZ'][5] = 6
+            self.assertIn(4, env2['XXX'])
+            self.assertNotIn(4, env1['XXX'])
+            self.assertIn(4, env2['YYY'])
+            self.assertNotIn(4, env1['YYY'])
+            self.assertIn(5, env2['ZZZ'])
+            self.assertNotIn(5, env1['ZZZ'])
 
         # BUILDERS is special...
         with self.subTest():
diff --git a/SCons/Util/__init__.py b/SCons/Util/__init__.py
index ffc636414..2760298b5 100644
--- a/SCons/Util/__init__.py
+++ b/SCons/Util/__init__.py
@@ -516,6 +516,7 @@ _semi_deepcopy_dispatch = {
     tuple: _semi_deepcopy_tuple,
 }
 
+
 def semi_deepcopy(obj):
     copier = _semi_deepcopy_dispatch.get(type(obj))
     if copier: