BUG: Mantis-856: allow both internal and external MuParser

CMake/ImportMuParser.cmake

 message(STATUS "Importing MuParser...")
-find_package(MuParser)
 
-if(MUPARSER_FOUND)
-  option(OTB_USE_EXTERNAL_MUPARSER "Use external MuParser library." ON)
+option(OTB_USE_EXTERNAL_MUPARSER "Use external MuParser library." ON)
+mark_as_advanced(OTB_USE_EXTERNAL_MUPARSER)
+
+if(OTB_USE_EXTERNAL_MUPARSER)
+  find_package(MuParser)
 
-  # Starting with muparser 2.0.0,
-  #  intrinsic operators "and", "or", "xor" have been removed
-  #  and intrinsic operators "&&" and "||" have been introduced as replacements
-  set(CMAKE_REQUIRED_INCLUDES ${MUPARSER_INCLUDE_DIR})
-  set(CMAKE_REQUIRED_LIBRARIES ${MUPARSER_LIBRARIES})
-  unset(CMAKE_REQUIRED_FLAGS)
-  unset(CMAKE_REQUIRED_DEFINES)
-  file(READ ${CMAKE_CURRENT_SOURCE_DIR}/CMake/otbTestMuParserHasCxxLogicalOperators.cxx
-       OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS_SOURCEFILE)
-  check_cxx_source_runs(
-    "${OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS_SOURCEFILE}"
-    OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS
-    )
-  unset(CMAKE_REQUIRED_INCLUDES)
-  unset(CMAKE_REQUIRED_LIBRARIES)
-  unset(CMAKE_REQUIRED_FLAGS)
-  unset(CMAKE_REQUIRED_DEFINES)
+  if(MUPARSER_FOUND)
+    # Starting with muparser 2.0.0,
+    #  intrinsic operators "and", "or", "xor" have been removed
+    #  and intrinsic operators "&&" and "||" have been introduced as replacements
+    set(CMAKE_REQUIRED_INCLUDES ${MUPARSER_INCLUDE_DIR})
+    set(CMAKE_REQUIRED_LIBRARIES ${MUPARSER_LIBRARIES})
+    unset(CMAKE_REQUIRED_FLAGS)
+    unset(CMAKE_REQUIRED_DEFINES)
+    file(READ ${CMAKE_CURRENT_SOURCE_DIR}/CMake/otbTestMuParserHasCxxLogicalOperators.cxx
+        OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS_SOURCEFILE)
+    check_cxx_source_runs(
+      "${OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS_SOURCEFILE}"
+      OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS
+      )
+    unset(CMAKE_REQUIRED_INCLUDES)
+    unset(CMAKE_REQUIRED_LIBRARIES)
+    unset(CMAKE_REQUIRED_FLAGS)
+    unset(CMAKE_REQUIRED_DEFINES)
 
-  if(OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS)
-    message(STATUS "  Testing if muParser has '&&' operator -- yes")
+    if(OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS)
+      message(STATUS "  Testing if muParser has '&&' operator -- yes")
+    else()
+      message(STATUS "  Testing if muParser has '&&' operator -- no")
+    endif()
   else()
-    message(STATUS "  Testing if muParser has '&&' operator -- no")
+    message(FATAL_ERROR "Can't build OTB without MuParser. Instal MuParser on your system, or disable the option OTB_USE_EXTERNAL_MUPARSER")
   endif()
 
 else()
-  option(OTB_USE_EXTERNAL_MUPARSER "Use external MuParser library." OFF)
+
   set(MUPARSER_LIBRARIES otbmuparser)
   unset(OTB_MUPARSER_HAS_CXX_LOGICAL_OPERATORS) # internal version is < 2.0.0
-  message(STATUS "  Using MuParser internal version")
+  message(STATUS "  Using MuParser internal version (no '&&' operator)")
 endif()
-mark_as_advanced(OTB_USE_EXTERNAL_MUPARSER)
+