From db0ae34d6da183bce93c3f044abb727b0474c8c2 Mon Sep 17 00:00:00 2001
From: William Deegan <bill@baddogconsulting.com>
Date: Thu, 2 Feb 2023 20:43:57 -0800
Subject: Alter append logic to keep existing append of tuple value yielding
 -Dkey=value

---
 SCons/Environment.py | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/SCons/Environment.py b/SCons/Environment.py
index e10bec1bb..26f7036fb 100644
--- a/SCons/Environment.py
+++ b/SCons/Environment.py
@@ -269,7 +269,6 @@ def _add_cppdefines(
 
         return False
 
-
     key = 'CPPDEFINES'
     try:
         defines = env_dict[key]
@@ -330,6 +329,19 @@ def _add_cppdefines(
         else:
             _add_define(val, defines, prepend)
 
+    # A tuple appended to anything should yield -Dkey=value
+    elif is_Tuple(val):
+        item = (val[0], val[1])
+        if unique:
+            match = _is_in(item, defines)
+            if match and delete_existing:
+                defines.remove(match)
+                _add_define(item, defines, prepend)
+            elif not match:
+                _add_define(item, defines, prepend)
+        else:
+            _add_define(item, defines, prepend)
+
     elif is_Sequence(val):
         tmp = []
         for item in val:
-- 
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