From 93689f40ddad1f4597611c7c40ee8a33a0ba671c Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Fri, 30 Dec 2022 00:39:23 -0500
Subject: [PATCH] fix compiler flags issue on Ubuntu18.04

---
 unittest/CMakeLists.txt | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/unittest/CMakeLists.txt b/unittest/CMakeLists.txt
index 9819a53e10..45501d92ae 100644
--- a/unittest/CMakeLists.txt
+++ b/unittest/CMakeLists.txt
@@ -34,6 +34,14 @@ foreach(_FLAG ${CMAKE_TUNE_FLAGS})
   add_compile_options(${_FLAG})
 endforeach()
 
+# must repeat handling coverage for older CMake
+if((CMAKE_CXX_COMPILER_ID STREQUAL "GNU") AND ENABLE_COVERAGE)
+  if(CMAKE_VERSION VERSION_LESS 3.13)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --coverage")
+  else()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_${CMAKE_BUILD_TYPE}_FLAGS} --coverage")
+  endif()
+endif()
 
 ########################################
 # General tests using the LAMMPS executable itself