From 9fde9124927789ca2399f99c1be9b101ed1e8550 Mon Sep 17 00:00:00 2001
From: Silvio Traversaro <silvio.traversaro@iit.it>
Date: Thu, 3 Sep 2020 17:28:01 +0200
Subject: [PATCH] CMake: Add DART_SKIP_<dep> advanced option

Add DART_SKIP_<dep> option to permit to specify that
a dependecy should not used even if it is found in the system.
---
 cmake/DARTMacros.cmake | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/cmake/DARTMacros.cmake b/cmake/DARTMacros.cmake
index 8b1a89292ee..409b02bd742 100644
--- a/cmake/DARTMacros.cmake
+++ b/cmake/DARTMacros.cmake
@@ -127,7 +127,9 @@ endfunction()
 
 #===============================================================================
 macro(dart_check_optional_package variable component dependency)
-  if(${${variable}_FOUND})
+  option(DART_SKIP_${variable} "If ON, do not use ${variable} even if it is found." OFF)
+  mark_as_advanced(DART_SKIP_${variable})
+  if(${${variable}_FOUND} AND NOT ${DART_SKIP_${variable}})
     set(HAVE_${variable} TRUE CACHE BOOL "Check if ${variable} found." FORCE)
     if(DART_VERBOSE)
       message(STATUS "Looking for ${dependency} - version ${${variable}_VERSION}"
@@ -135,12 +137,17 @@ macro(dart_check_optional_package variable component dependency)
     endif()
   else()
     set(HAVE_${variable} FALSE CACHE BOOL "Check if ${variable} found." FORCE)
-    if(ARGV3) # version
-      message(STATUS "Looking for ${dependency} - NOT found, to use"
-                      " ${component}, please install ${dependency} (>= ${ARGV3})")
-    else()
-      message(STATUS "Looking for ${dependency} - NOT found, to use"
-                      " ${component}, please install ${dependency}")
+    if(NOT ${${variable}_FOUND})
+      if(ARGV3) # version
+        message(STATUS "Looking for ${dependency} - NOT found, to use"
+                        " ${component}, please install ${dependency} (>= ${ARGV3})")
+      else()
+        message(STATUS "Looking for ${dependency} - NOT found, to use"
+                        " ${component}, please install ${dependency}")
+      endif()
+    elseif(${DART_SKIP_${variable}} AND DART_VERBOSE)
+      message(STATUS "Not using ${dependency} - version ${${variable}_VERSION}"
+                     " even if found because DART_SKIP_${variable} is ON.")
     endif()
     return()
   endif()