KConfig: stop exporting and installing KConfigBackend.

Summary:
It can't possibly have been used anywhere, because it's not in the KConfig
API anywhere. The intended way to use this API was by providing a plugin
that would derive from KConfigBackend but the plugin loading code
in KConfigBackend::create has been disabled since before KF 5.0.

The reason I want to stop exporting this class is to be able to
optimize it (e.g. the QDateTime in it is completely unused but leads
to data races due to tzset)

Test Plan: Note, I'll rename it to _p.h if we agree, it would just have made this diff too big.

Reviewers: mdawson

Reviewed By: mdawson

Subscribers: #frameworks

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D4604

cmake/rules_PyKF5.py

@@ -52,7 +52,6 @@ def discard_base(container, sip, matcher):
 
 def local_container_rules():
     return [
-        [".*", "KConfigBackend", ".*", ".*", ".*", mark_and_discard_QSharedData],
         [".*", "KConfigBase", ".*", ".*", ".*", rules_engine.container_mark_abstract],
 
         [".*KCoreConfigSkeleton.*", ".*ItemString", ".*", ".*", ".*", set_skeleton_item_base],
@@ -107,11 +106,6 @@ def local_function_rules():
         ["KEntryMap", "setEntryOption", ".*", ".*", ".*", rules_engine.function_discard],
         ["KEntryMap", "findEntry", ".*", ".*", ".*", rules_engine.function_discard],
         ["KEntryMap", "findExactEntry", ".*", ".*", ".*", rules_engine.function_discard],
-
-        ["KConfigBackend", "registerMappings", ".*", ".*", ".*", rules_engine.function_discard],
-        ["KConfigBackend", "parseConfig", ".*", ".*", ".*", rules_engine.function_discard],
-        ["KConfigBackend", "writeConfig", ".*", ".*", ".*", rules_engine.function_discard],
-
     ]
 
 def local_typedef_rules():

src/core/CMakeLists.txt

@@ -40,7 +40,6 @@ ecm_generate_headers(KConfigCore_HEADERS
   HEADER_NAMES
   KAuthorized
   KConfig
-  KConfigBackend
   KConfigBase
   KConfigGroup
   KDesktopFile
@@ -66,7 +65,6 @@ if (PythonModuleGeneration_FOUND)
     HEADERS
       kauthorized.h
       kconfig.h
-      kconfigbackend.h
       kconfigbase.h
       kconfiggroup.h
       kdesktopfile.h

src/core/kconfigbackend.h

@@ -41,11 +41,13 @@ class QDateTime;
  *
  * Provides the implementation for accessing configuration sources.
  *
- * KDELibs only provides an INI backend, but this class can be used
+ * KConfig only provides an INI backend, but this class can be used
  * to create plugins that allow access to other file formats and
  * configuration systems.
+ *
+ * \internal
  */
-class KCONFIGCORE_EXPORT KConfigBackend : public QObject, public QSharedData
+class KConfigBackend : public QObject, public QSharedData
 {
     Q_OBJECT
 
@@ -201,10 +203,12 @@ private:
 Q_DECLARE_OPERATORS_FOR_FLAGS(KConfigBackend::ParseOptions)
 Q_DECLARE_OPERATORS_FOR_FLAGS(KConfigBackend::WriteOptions)
 
+#if 0 // TODO re-enable if the plugin loading code is re-enabled
 /**
  * Register a KConfig backend when it is contained in a loadable module
  */
 #define K_EXPORT_KCONFIGBACKEND(libname, classname) \
     K_PLUGIN_FACTORY(factory, registerPlugin<classname>();)
+#endif
 
 #endif // KCONFIGBACKEND_H