From d081364685181dd2f5ed32232e745fb92b362a4e Mon Sep 17 00:00:00 2001
From: Roberto Di Remigio <roberto.diremigio@gmail.com>
Date: Thu, 6 Apr 2017 14:52:58 +0200
Subject: [PATCH] Add EXTRA_<LANG>FLAGS to CMAKE_<LANG>_FLAGS if the former are
 not an empty string

---
 modules/cc.cmake          | 2 ++
 modules/cxx.cmake         | 2 ++
 modules/fc.cmake          | 2 ++
 modules/fc_optional.cmake | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/modules/cc.cmake b/modules/cc.cmake
index 2975024..e624ca7 100644
--- a/modules/cc.cmake
+++ b/modules/cc.cmake
@@ -36,7 +36,9 @@ if(NOT CMAKE_C_COMPILER_WORKS)
 endif()
 
 if(DEFINED EXTRA_CFLAGS)
+  if(NOT EXTRA_CFLAGS STREQUAL "")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_CFLAGS}")
+  endif()
 endif()
 
 if(DEFINED ENV{CFLAGS})
diff --git a/modules/cxx.cmake b/modules/cxx.cmake
index 5ec6bf2..c44209c 100644
--- a/modules/cxx.cmake
+++ b/modules/cxx.cmake
@@ -36,7 +36,9 @@ if(NOT CMAKE_C_COMPILER_WORKS)
 endif()
 
 if(DEFINED EXTRA_CXXFLAGS)
+  if(NOT EXTRA_CXXFLAGS STREQUAL "")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_CXXFLAGS}")
+  endif()
 endif()
 
 if(DEFINED ENV{CXXFLAGS})
diff --git a/modules/fc.cmake b/modules/fc.cmake
index 5832571..d798ddb 100644
--- a/modules/fc.cmake
+++ b/modules/fc.cmake
@@ -43,7 +43,9 @@ if(NOT CMAKE_Fortran_COMPILER_WORKS)
 endif()
 
 if(DEFINED EXTRA_FCFLAGS)
+  if(NOT EXTRA_FCFLAGS STREQUAL "")
     set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} ${EXTRA_FCFLAGS}")
+  endif()
 endif()
 
 if(DEFINED ENV{FCFLAGS})
diff --git a/modules/fc_optional.cmake b/modules/fc_optional.cmake
index c7cf6c6..2095cc4 100644
--- a/modules/fc_optional.cmake
+++ b/modules/fc_optional.cmake
@@ -54,7 +54,9 @@ if(ENABLE_FC_SUPPORT)
     endif()
 
     if(DEFINED EXTRA_FCFLAGS)
+      if(NOT EXTRA_FCFLAGS STREQUAL "")
         set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} ${EXTRA_FCFLAGS}")
+      endif()
     endif()
 
     if(DEFINED ENV{FCFLAGS})