From 8d63f70b7a2c30242b059534042c1b00a548f770 Mon Sep 17 00:00:00 2001
From: Pieter Pas <pieter.pas@outlook.com>
Date: Sun, 11 Feb 2024 14:44:08 +0100
Subject: [PATCH] [CMake] Do not set CMAKE_CXX_EXTENSIONS if already defined

---
 CMakeLists.txt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 16e97f835f..a19249bee0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -107,8 +107,12 @@ add_warnings_target(warnings ${ALPAQA_WARNINGS_AS_ERRORS})
 add_library(alpaqa::warnings ALIAS warnings)
 
 # Compiler options
-set(CMAKE_CXX_EXTENSIONS ${ALPAQA_WITH_QUAD_PRECISION})
-set(CMAKE_C_EXTENSIONS ${ALPAQA_WITH_QUAD_PRECISION})
+if (NOT DEFINED CMAKE_CXX_EXTENSIONS)
+    set(CMAKE_CXX_EXTENSIONS ${ALPAQA_WITH_QUAD_PRECISION})
+endif()
+if (NOT DEFINED CMAKE_C_EXTENSIONS)
+    set(CMAKE_C_EXTENSIONS ${ALPAQA_WITH_QUAD_PRECISION})
+endif()
 if (ALPAQA_WITH_PYTHON OR ALPAQA_WITH_MATLAB)
     set(CMAKE_POSITION_INDEPENDENT_CODE On)
 endif()