From c04128fa0d2b4d9022e322b3bdba768641069639 Mon Sep 17 00:00:00 2001
From: Nils Wentzell <nwentzell@flatironinstitute.org>
Date: Wed, 8 Jul 2020 11:25:57 -0400
Subject: [PATCH] [cmake] Protect against flags -I/usr/include in
 extract_flags.cmake

---
 share/cmake/extract_flags.cmake | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/share/cmake/extract_flags.cmake b/share/cmake/extract_flags.cmake
index dfcf67b0..6bce43c2 100644
--- a/share/cmake/extract_flags.cmake
+++ b/share/cmake/extract_flags.cmake
@@ -76,10 +76,14 @@ macro(extract_flags)
     list(REMOVE_ITEM sys_inc_dirs ${inc_dirs})
   endif()
   foreach(dir ${inc_dirs})
-    set(${target}_CXXFLAGS "${${target}_CXXFLAGS} -I${dir}")
+    if(NOT dir STREQUAL "/usr/include")
+      set(${target}_CXXFLAGS "${${target}_CXXFLAGS} -I${dir}")
+    endif()
   endforeach()
   foreach(dir ${sys_inc_dirs})
-    set(${target}_CXXFLAGS "${${target}_CXXFLAGS} -isystem${dir}")
+    if(NOT dir STREQUAL "/usr/include")
+      set(${target}_CXXFLAGS "${${target}_CXXFLAGS} -isystem${dir}")
+    endif()
   endforeach()
 
   get_property_recursive(libs TARGET ${target} PROPERTY INTERFACE_LINK_LIBRARIES)