Doc: we don't guarantee compatibility for backend classes

Similar to QPA, we want to continue to develop the backend APIs between
minor releases. Loading a plugin that uses a different Qt version than
the application is anyway a bad idea (if supported at all), and for Qt
Location specifically we don't want to support this.

Change-Id: Ib8b159e1df391bc5a474ddccb6933ab80529264f
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

6 files changed, 33 insertions, 5 deletions

diff --git a/src/location/doc/src/qt6-changes.qdoc b/src/location/doc/src/qt6-changes.qdoc
index 815edd9d..f5a01d56 100644
--- a/src/location/doc/src/qt6-changes.qdoc
+++ b/src/location/doc/src/qt6-changes.qdoc
@@ -82,9 +82,12 @@
     Functionality that had "labs" status has been removed. This includes the
     experimental framework for turn-by-turn navigation, MapObjects
 
-    \section2 Maps
+    \section2 Backend Provider API
 
-    \section2 Places
+    The backend provider API is no longer subject to binary and source
+    compatibility guarantees.
+
+    \section1 Other API changes
 
     This section contains API improvements that do not break source
     compatibility. However they might have an impact on the application logic,
diff --git a/src/location/maps/qgeocodingmanagerengine.cpp b/src/location/maps/qgeocodingmanagerengine.cpp
index 9d51c31e..6ab62e39 100644
--- a/src/location/maps/qgeocodingmanagerengine.cpp
+++ b/src/location/maps/qgeocodingmanagerengine.cpp
@@ -57,9 +57,14 @@ QT_BEGIN_NAMESPACE
     convenience methods to implementers of QGeoServiceProvider plugins who want
     to provide support for geocoding operations.
 
-    In the default implementation, supportsGeocoding() and supportsReverseGeocoding() returns false while
-    geocode() and reverseGeocode()
-    cause QGeoCodeReply::UnsupportedOptionError to occur.
+    \note There are no source or binary compatibility guarantees for the
+    backend classes. The API is only guaranteed to work with the Qt version it
+    was developed against. API changes will however only be made in minor
+    releases. (6.6, 6.7, and so on.)
+
+    In the default implementation, supportsGeocoding() and
+    supportsReverseGeocoding() returns false while geocode() and
+    reverseGeocode() cause QGeoCodeReply::UnsupportedOptionError to occur.
 
     If the service provider supports geocoding the subclass should provide an
     implementation of geocode() and call setSupportsGeocoding(true) at
diff --git a/src/location/maps/qgeomappingmanagerengine.cpp b/src/location/maps/qgeomappingmanagerengine.cpp
index 5d9f41d1..bb2f9114 100644
--- a/src/location/maps/qgeomappingmanagerengine.cpp
+++ b/src/location/maps/qgeomappingmanagerengine.cpp
@@ -55,6 +55,11 @@ QT_BEGIN_NAMESPACE
 
     \brief Provides support functionality for map display with QGeoServiceProvider.
 
+    \note There are no source or binary compatibility guarantees for the
+    backend classes. The API is only guaranteed to work with the Qt version it
+    was developed against. API changes will however only be made in minor
+    releases. (6.6, 6.7, and so on.)
+
     The QGeoMappingManagerEngine class provides an interface and convenience
     methods to implementors of QGeoServiceProvider plugins who want to
     provide support for displaying and interacting with maps.
diff --git a/src/location/maps/qgeoroutingmanagerengine.cpp b/src/location/maps/qgeoroutingmanagerengine.cpp
index fe7ad322..7226dad1 100644
--- a/src/location/maps/qgeoroutingmanagerengine.cpp
+++ b/src/location/maps/qgeoroutingmanagerengine.cpp
@@ -52,6 +52,11 @@ QT_BEGIN_NAMESPACE
     convenience methods to implementers of QGeoServiceProvider plugins who want
     to provide access to geographic routing information.
 
+    \note There are no source or binary compatibility guarantees for the
+    backend classes. The API is only guaranteed to work with the Qt version it
+    was developed against. API changes will however only be made in minor
+    releases. (6.6, 6.7, and so on.)
+
     Subclasses of QGeoRoutingManagerEngine need to provide an implementation of
     calculateRoute().
 
diff --git a/src/location/maps/qgeoserviceproviderfactory.cpp b/src/location/maps/qgeoserviceproviderfactory.cpp
index 62007bf1..d58773bd 100644
--- a/src/location/maps/qgeoserviceproviderfactory.cpp
+++ b/src/location/maps/qgeoserviceproviderfactory.cpp
@@ -51,6 +51,11 @@ QT_BEGIN_NAMESPACE
     \brief The QGeoServiceProviderFactory class is a factory class used as the
     plugin interface for services related to geographical information.
 
+    \note There are no source or binary compatibility guarantees for the
+    backend classes. The API is only guaranteed to work with the Qt version it
+    was developed against. API changes will however only be made in minor
+    releases. (6.6, 6.7, and so on.)
+
     Implementers must provide a unique combination of providerName() and
     providerVersion() per plugin.
 
diff --git a/src/location/places/qplacemanagerengine.cpp b/src/location/places/qplacemanagerengine.cpp
index cab5603d..971f4621 100644
--- a/src/location/places/qplacemanagerengine.cpp
+++ b/src/location/places/qplacemanagerengine.cpp
@@ -65,6 +65,11 @@ QT_BEGIN_NAMESPACE
     implementers of QGeoServiceProvider plugins who want to provide access to place
     functionality.
 
+    \note There are no source or binary compatibility guarantees for the
+    backend classes. The API is only guaranteed to work with the Qt version it
+    was developed against. API changes will however only be made in minor
+    releases. (6.6, 6.7, and so on.)
+
     Application developers need not concern themselves with the QPlaceManagerEngine.
     Backend implementers however will need to derive from QPlaceManagerEngine and provide
     implementations for the abstract virtual functions.