From f9af3a7269c2b8ec8c7b8238c73b871ce8b3d2dd Mon Sep 17 00:00:00 2001
From: Dennis Klein <d.klein@gsi.de>
Date: Mon, 22 Mar 2021 06:07:26 +0100
Subject: [PATCH] CMake: Do not unconditionally override settings without good
 reason

relates FairRootGroup/FairMQ#342
---
 cmake/FairLoggerLib.cmake | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/cmake/FairLoggerLib.cmake b/cmake/FairLoggerLib.cmake
index 11edab9..5b57d83 100644
--- a/cmake/FairLoggerLib.cmake
+++ b/cmake/FairLoggerLib.cmake
@@ -100,14 +100,16 @@ macro(set_fairlogger_defaults)
   endif()
 
   # Generate compile_commands.json file (https://clang.llvm.org/docs/JSONCompilationDatabase.html)
-  set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+  if(NOT DEFINED CMAKE_EXPORT_COMPILE_COMMANDS)
+    set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+  endif()
 
-  if(NOT BUILD_SHARED_LIBS)
+  if(NOT DEFINED BUILD_SHARED_LIBS)
     set(BUILD_SHARED_LIBS ON CACHE BOOL "Whether to build shared libraries or static archives")
   endif()
 
   # Set -fPIC as default for all library types
-  if(NOT CMAKE_POSITION_INDEPENDENT_CODE)
+  if(NOT DEFINED CMAKE_POSITION_INDEPENDENT_CODE)
     set(CMAKE_POSITION_INDEPENDENT_CODE ON)
   endif()
 
@@ -126,13 +128,13 @@ macro(set_fairlogger_defaults)
   list(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES "${CMAKE_INSTALL_PREFIX}/${PROJECT_INSTALL_LIBDIR}" isSystemDir)
   if("${isSystemDir}" STREQUAL "-1")
     if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
-      set(CMAKE_EXE_LINKER_FLAGS ${CMAKE_EXE_LINKER_FLAGS} "-Wl,--enable-new-dtags")
-      set(CMAKE_SHARED_LINKER_FLAGS ${CMAKE_SHARED_LINKER_FLAGS} "-Wl,--enable-new-dtags")
-      set(CMAKE_INSTALL_RPATH "$ORIGIN/../${PROJECT_INSTALL_LIBDIR}")
+      list(APPEND CMAKE_EXE_LINKER_FLAGS "-Wl,--enable-new-dtags")
+      list(APPEND CMAKE_SHARED_LINKER_FLAGS "-Wl,--enable-new-dtags")
+      list(APPEND CMAKE_INSTALL_RPATH "$ORIGIN/../${PROJECT_INSTALL_LIBDIR}")
     elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
-      set(CMAKE_INSTALL_RPATH "@loader_path/../${PROJECT_INSTALL_LIBDIR}")
+      list(APPEND CMAKE_INSTALL_RPATH "@loader_path/../${PROJECT_INSTALL_LIBDIR}")
     else()
-      set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/${PROJECT_INSTALL_LIBDIR}")
+      list(APPEND CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/${PROJECT_INSTALL_LIBDIR}")
     endif()
   endif()