"Un-cache" Feature Lists in CMake

Fixes OpenDDS#4328

The equivalent to many MPC features in CMake are built up using a
function called `_opendds_feature` that adds features to lists to use.
The issue is these lists are set as cache variables, which are
persistent across CMake runs. This resulted in the features being
appended each time, so they are listed multiple times in output and
`default.features` if building ACE.

These don't really have to be cache variables, so just set them as
normal variables in the parent scope.

Also fixed some typos in the same file and added a note about removing
an include in the future.

cmake/init.cmake

@@ -9,6 +9,8 @@ if(_OPENDDS_INIT_CMAKE)
 endif()
 set(_OPENDDS_INIT_CMAKE TRUE)
 
+# This is required for CMake <=3.4 for cmake_parse_arguments. Remove this when
+# we no longer need to support those versions.
 include(CMakeParseArguments)
 
 include("${CMAKE_CURRENT_LIST_DIR}/opendds_version.cmake")
@@ -108,9 +110,9 @@ function(_opendds_feature name default_value)
     list(APPEND _OPENDDS_MPC_FEATURES "${mpc_feature}")
   endif()
 
-  set(_OPENDDS_ALL_FEATURES "${_OPENDDS_ALL_FEATURES}" CACHE INTERNAL "" FORCE)
-  set(_OPENDDS_FEATURE_VARS "${_OPENDDS_FEATURE_VARS}" CACHE INTERNAL "" FORCE)
-  set(_OPENDDS_MPC_FEATURES "${_OPENDDS_MPC_FEATURES}" CACHE INTERNAL "" FORCE)
+  set(_OPENDDS_ALL_FEATURES "${_OPENDDS_ALL_FEATURES}" PARENT_SCOPE)
+  set(_OPENDDS_FEATURE_VARS "${_OPENDDS_FEATURE_VARS}" PARENT_SCOPE)
+  set(_OPENDDS_MPC_FEATURES "${_OPENDDS_MPC_FEATURES}" PARENT_SCOPE)
 endfunction()
 
 # OpenDDS Features
@@ -119,7 +121,7 @@ _opendds_feature(OBJECT_MODEL_PROFILE ON DOC "Allows using presentation group Qo
 _opendds_feature(PERSISTENCE_PROFILE ON
   DOC "Allows using the durability and durability service QoS")
 _opendds_feature(OWNERSHIP_PROFILE ON
-  DOC "Allows history depth QoS adn implies OPENDDS_OWNERSHIP_KIND_EXCLUSIVE")
+  DOC "Allows history depth QoS and implies OPENDDS_OWNERSHIP_KIND_EXCLUSIVE")
 _opendds_feature(OWNERSHIP_KIND_EXCLUSIVE ${OPENDDS_OWNERSHIP_PROFILE}
   DOC "Allows the EXCLUSIVE ownership QoS")
 _opendds_feature(CONTENT_SUBSCRIPTION ON
@@ -147,7 +149,7 @@ else()
   _opendds_feature(STATIC ON MPC DOC "(Not for CMake-built OpenDDS)")
 endif()
 _opendds_feature(XERCES3 "${OPENDDS_SECURITY}" MPC TYPE PATH
-  DOC "Build with Xerces XML parser, needed for secuirty and QoS XML Handler")
+  DOC "Build with Xerces XML parser, needed for security and QoS XML Handler")
 _opendds_feature(IPV6 OFF MPC DOC "Build with IPv6 support")
 
 # TAO Features

docs/news.d/cmake-features.rst

@@ -0,0 +1,7 @@
+.. news-prs: 4329
+
+.. news-start-section: Fixes
+.. news-start-section: Building with CMake
+- Fixed :ghissue:`4328`, where each run of CMake effectively always appended the MPC features to ``default.features`` in ACE.
+.. news-end-section
+.. news-end-section