From 7c88951845263a5540dafd2466a5c07db213d6f7 Mon Sep 17 00:00:00 2001
From: OpenSauce04 <opensauce04@gmail.com>
Date: Sat, 22 Mar 2025 21:10:46 +0000
Subject: [PATCH] cmake: Correctly handle `_FORTIFY_SOURCE` being pre-defined
 in `CXXFLAGS`

---
 src/CMakeLists.txt | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 6d41f42d6..a60053cf0 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -115,7 +115,10 @@ else()
         -fstack-clash-protection
     )
 
-    if (NOT CMAKE_BUILD_TYPE STREQUAL Debug)
+    # If we define _FORTIFY_SOURCE when it is already defined, compilation will fail
+    string(FIND "-D_FORTIFY_SOURCE" ${CMAKE_CXX_FLAGS} FORTIFY_SOURCE_DEFINED)
+
+    if (NOT CMAKE_BUILD_TYPE STREQUAL Debug AND NOT FORTIFY_SOURCE_DEFINED)
         # _FORTIFY_SOURCE can't be used without optimizations.
         add_compile_options(-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2)
     endif()