http://isvolatileusefulwiththreads.in/c/
It’s possible that the variables here are only marked as volatile
because they’re arguments to `g_once_*()`. Those arguments will be
modified in a subsequent commit.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #600
This commit is the unmodified results of running
```
black $(git ls-files '*.py')
```
with black version 19.10b0. See #2046.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Add a test for a signal returning interface types, using
the generic marshaller. This will hopefully exercise newly
added code in value_from_ffi_type().
This tests the new functionality that
g_type_interface_instantiable_prerequisite
was added for.
Before the changes, this fails with
GObject-WARNING **: Unable to convert a value of type \
GObject to a value of type Foo
We do the same test with g_object_bind_property_with_closures
as well, to exercise g_cclosure_marshal_generic.
Use the new g_type_interface_instantiable_prerequisite() to check
compatibility for transform functions.
In particular, this allows interfaces (in my case GDK_TYPE_PAINTABLE) to
be transformed to/from any GObject type (in my case G_TYPE_OBJECT) using
the transform function registered to transform between any 2 objects
(g_value_object_transform_value() does a type check and uses NULL if the
types don't match).
And this in turn allows be to g_object_bind_property() a gobject-typed
generic property (GtkListItem::item) to a GtkImage::paintable.
Tests for the new functionality are included.
This function returns the most specific instantiatable type
that is a prerequisite for a given interface.
This type is necessary in particular when dealing with GValues
because a GValue contains an instance of a type.
This commit includes tests for the new API.
It may be defined by the environment (we document that as being allowed)
— if so, individual files should not try to redefine it, as that causes
a preprocessor warning.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
The G_VALUE_NOCOPY_CONTENTS for strings can only be used when collecting them
and not when copying them.
Instead only avoid copies for strings that are interned.
Fixes#2141
This was mostly machine generated with the following command:
```
codespell \
--builtin clear,rare,usage \
--skip './po/*' --skip './.git/*' --skip './NEWS*' \
--write-changes .
```
using the latest git version of `codespell` as per [these
instructions](https://github.com/codespell-project/codespell#user-content-updating).
Then I manually checked each change using `git add -p`, made a few
manual fixups and dropped a load of incorrect changes.
There are still some outdated or loaded terms used in GLib, mostly to do
with git branch terminology. They will need to be changed later as part
of a wider migration of git terminology.
If I’ve missed anything, please file an issue!
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This adds support to be able to explicitely stored interned strings into
G_TYPE_STRING GValue.
This is useful for cases where the user:
* *knows* the string to be stored in the GValue is canonical
* Wants to know whther the string stored is canonical
This allows:
* zero-cost GValue copy (the content is guaranteed to be unique and exist
throughout the process life)
* zero-cost string equality checks (if both string GValue are interned, you just
need to check the pointers for equality or not, instead of doing a strcmp).
Fixes#2109
The glib-mkenums program allows generating code to handle enums/flags
with very different purposes. One of its purposes could be generating
per-enum/flag methods to be exposed in a library API, and while doing
that, it would be nice to have a way to specify in which API version
the enum/flag was introduced, so that the same version could be shown
in the generated API methods.
E.g. From the following code:
/**
* QmiWmsMessageProtocol:
* @QMI_WMS_MESSAGE_PROTOCOL_CDMA: CDMA.
* @QMI_WMS_MESSAGE_PROTOCOL_WCDMA: WCDMA.
*
* Type of message protocol.
*
* Since: 1.0
*/
typedef enum { /*< since=1.0 >*/
QMI_WMS_MESSAGE_PROTOCOL_CDMA = 0x00,
QMI_WMS_MESSAGE_PROTOCOL_WCDMA = 0x01
} QmiWmsMessageProtocol;
The template would allow us to generate a method documented like this,
including the Since tag with the value given in the mkenums 'since' tag.
/**
* qmi_wms_message_protocol_get_string:
* @val: a QmiWmsMessageProtocol.
*
* Gets the nickname string for the #QmiWmsMessageProtocol specified at @val.
*
* Returns: (transfer none): a string with the nickname, or %NULL if not found. Do not free the returned value.
* Since: 1.0
*/
const gchar *qmi_wms_message_protocol_get_string (QmiWmsMessageProtocol val);
Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Making this validation code public allows projects to validate a
GParamSpec name before creating it. While hard-coded GParamSpec don't
need this, we can't afford crashing the main program for dynamically
generated GParamSpec from user-created data.
In such case, we will need to validate the param names and return errors
instead of trying to create a GParamSpec with invalid names.
Includes modifications from Philip Withnall and Emmanuele Bassi to
rearrange the new function addition and split it into one function for
GParamSpecs and one for GSignals.
When calling `g_set_object()` for a type derived from `GObject`, GCC 9.2
was giving the following strict aliasing warning:
```
../../source/malcontent/libmalcontent-ui/user-controls.c:1001:21: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
1001 | if (g_set_object (&self->user, user))
/opt/gnome/install/include/glib-2.0/gobject/gobject.h:744:33: note: in definition of macro ‘g_set_object’
744 | (g_set_object) ((GObject **) (object_ptr), (GObject *) (new_object)) \
| ^~~~~~~~~~
```
This was due to the `(GObject **)` cast.
Pass the pointer through a union to squash this warning. We already do
some size and type checks of the dereferenced type, which should catch
casual errors. The `g_object_ref()` and `g_object_unref()` calls which
subsequently happen inside the `g_set_object()` function also do some
dynamic type checks.
Add a test.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
While we automatically define cleanup functions for the module, we don't
do it for the module class.
This will allow to manage the ownership of the class when reffing it
without having to cast it to GTypeClass.
It provides more useful output on failure, and isn’t compiled out when
building with `G_DISABLE_ASSERT`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
It provides more useful output on failure, and isn’t compiled out when
building with `G_DISABLE_ASSERT`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This will allow subsequent testing of property name canonicalisation.
This test introduces no functional changes.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #358
Rather than adding a canonicalised and non-canonicalised version of the
signal to `g_signal_key_bsa`, just add the canonicalised version. Signal
lookups always use the canonicalised key (since the previous commit).
This saves space in `g_signal_key_bsa`, which should speed up lookups;
and it saves significant space in the global `GQuark` table (a 9.6%
reduction in entries in that table, by a rough test using
gnome-software).
We have to be a little more relaxed on the signal name validation than
we are for property name validation, as GTK installs a
`-gtk-private-changed` signal which violates the signal naming rules.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Rather than interning a property name string which isn’t canonicalised,
canonicalise it first, and enforce stricter validation on inputs.
The previous code was not incorrect (since the property machinery would
have canonicalised the property names itself, internally), but would
have resulted in non-canonical property names getting into the GQuark
table unnecessarily. With the new code, the interned property names from
property installation time should be consistently reused.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #358
Inline with the stricter version of the property naming rules from the
documentation, tighten up the validation of property names at
installation time.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
It provides more useful output on failure, and isn’t compiled out when
building with `G_DISABLE_ASSERT`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
The documentation says that parameter names must be alphanumeric (plus
`-` or `_`) and that canonicalisation turns `_` into `-`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #358
The static analyser can’t yet work out how `g_autofree` works, so
disable those tests.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #1767
The Python runtime is not amenable to Valgrind, and leak checking is a
lot less relevant in Python compared to C.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #487
The two test scripts actually assumed some *NIX paradigms, so we need
to adapt them so that they can work on Windows as well, the changes are
namely:
-Call the glib-mkenums and glib-genmarshal Python scripts with the
Python interpreter, not just relying on shebang lines, on Windows.
This is because the native Windows console (cmd.exe) does not support
shebang lines, for subprocess.run().
-Use NamedTemporaryFile with delete=False, otherwise Windows cannot find
the temp files we need when running the tests.
-Use universal_newlines=True for subprocess.run() so that we do not need
to worry out line ending differences on different systems.
-Make sure we are not in the temp directories we create, where the tests
are being run, upon cleanup. Windows does not like deleting
directories that we are currently in.
On Windows and possibly other platforms the '%p' printf modifier does
not prefix printed values with '0x', so do not expect the warning
message to contain the '0x' prefix for the handler pointer value.
When building a valist marshaller, we can avoid reffing a GParamSpec
if the argument is known to always be static. The marshaller we ship in
`gmarshal.c` got this right, but marshallers generated by
glib-genmarshal were missing the optimisation. Fix that, and add a unit
test.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1792
When building a valist marshaller, we can avoid a string copy if the
argument is known to always be static. The marshaller we ship in
`gmarshal.c` got this right, but marshallers generated by
glib-genmarshal were missing the optimisation. Fix that, and add a unit
test.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1792
The old (Perl) implementation of glib-genmarshal used
g_variant_ref_sink() to correctly handle floating inputs; the Python
version should do the same.
Includes a unit test.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1793
This is a basic test suite for the `glib-genmarshal` utility, lifted
mostly directly from the tests for `glib-mkenums`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This makes the Meson build code for it a little more generic, and adds
support for installed tests.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
While this was useful for local testing while developing the test, it’s
not widely applicable. Look the binary up in the current `${PATH}` if
it’s not specified using `G_TEST_BUILDDIR`.
This is needed to get the `mkenums.py` test working as an
installed-test.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
We already have the GType with which the GValue should be initialized,
so requiring an initialized GValue is not really necessary, and it
actually complicates code that wraps GObject, by requiring the retrieval
of the GParamSpec in order to get the property type. Additionally, it
introduces a mostly unnecessary g_value_reset().
We already changed g_object_getv() to allow passing uninitialized
GValues, but this fell through the cracks.
Closes: #737
These have all been documented as deprecated for a long time, but we’ve
never had a way to programmatically mark them as deprecated. Do that
now.
This is based on the list of deprecations from the reverted commit
80fcb1bc2.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #638
In order to allow GLib itself to be built with G_DISABLE_ASSERT defined,
we need to explicitly undefine it when building the tests, otherwise
g_test_init() turns into an abort.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1708
The threads used to iterate at least 10000 times before setting the
"seen thread" flag to true. After porting they inadvertently did that
in the first iteration.
Previously, the test assumed that thread1 and thread2 would be scheduled
enough to set seen_thread{1,2} by the fact that the test runs for a high
number of iterations. On some platforms/schedulers, that’s not true,
which causes the test to spuriously fail.
Fix that by forcing the test to continue iterating until both threads
are seen. If this takes too long, the Meson test runner timeout will be
hit and the test will be terminated.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Previously, all three threads would access several global variables
without locking.
Fix that by using atomic accesses to data stored within the
test_closure_refcount() function, which also eliminates the global state
(which would confuse further tests if they were added to this file).
Signed-off-by: Philip Withnall <withnall@endlessm.com>
g_assert() can be compiled out if G_DISABLE_ASSERT is defined; and
g_assert_*() provide more specific error messages on failure.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
These functions are not run more than once, so the variables don’t need
to be static to save state between runs.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
It's necessary sometimes for installed tests to be able to run with a
custom environment. For example, the gsocketclient-slow test requires an
LD_PRELOADed library to provide a slow connect() (this is to be added in
a followup commit).
Introduce a variable `@env@` into the installed test template, which we
can override as necessary when generating `.test` files, to run tests
prefixed with `/usr/bin/env <LIST OF VARIABLES>`.
As the only test that requires this currently lives in `gio/tests/`, we
are only hooking this up for that directory right now. If other tests in
future require this treatment, then the support can be extended at that
point.
So long, and thanks for everything. We’re a Meson-only shop now.
glib-2-58 will remain the last stable GLib release series which is
buildable using autotools.
We continue to install autoconf macros for autotools-using projects
which depend on GLib; they are stable API.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Add tests using an object declared with G_DECLARE_FINAL_TYPE, that is derived
from another, declared using G_DECLARE_DERIVABLE_TYPE, and that
thus uses _GLIB_DEFINE_AUTOPTR_CHAINUP to define cleanup functions.
And verify that both g_autoptr(Type) and g_auto(s)list(Type) work
This makes it easier to debug test failures, by ensuring that g_debug()
and g_test_message() are printed as TAP diagnostics.
Fixes: https://gitlab.gnome.org/GNOME/glib/issues/1528
Signed-off-by: Simon McVittie <smcv@collabora.com>
g_object_bind_property() (transfer none) returns a GBinding with an existing internal
reference which is active as long as the "binding" is. This allows to optionally use
the binding without any memory management, as it will remove itself when it is no longer
needed.
There are currently three ways to remove the "binding" and as a result the reference:
1) Either the source or target dies and we get notified by a weakref callback
2) The user unrefs the binding until it is destroyed (which is semi-legal,
but worked and is used in the test suite)
3) The user calls g_binding_unbind()
In case (3) the problem was that it always calls unref even if the "binding" is already
gone, leading to crashes when called from bindings multiple times.
In #1373 and !197 it was noticed that a function always unrefs which would be a
"transfer full" annotation, but the problem here is that it should only remove the
ref when removing the "binding" and the annotation should stay "transfer none".
As a side effect of this fix it is now also possible to call g_binding_unbind() multiple
times where every call after the first is a no-op.
This also adds explicit tests for case (1) and (3) - only case (3) is affected by this change.
Part of runMkenumsWithHeader() was duplicated in test_reproducible(),
and would otherwise need to be duplicated again in upcoming tests. Many
places duplicated decoding stdout/stderr and checking the exit code.
Introduce a named tuple for the returned fields; and factor out writing
a template file to pass with --template.
The new python module, added with 0.46, works with Python 2 and 3 and
allows to pass a path for the interpreter to use, if the need arises.
Previously the meson build set PYTHON, used in the shebang line of
the scripts installed by glib, to the full path of the interpreter.
The new meson module doesn't expose that atm, but we should set it to
a executable name anyway, and not a full path.
The implementation is silently discarding this anyway, and
g_object_unref() is using atomic operations. So this should be safe.
Having this here triggers -Wdiscarded-qualifiers when g_clear_pointer()
is fixed to use __typeof__().
The implementation is silently discarding this anyway, and
g_object_unref() is using atomic operations. So this should be safe.
Having this here triggers -Wdiscarded-qualifiers when g_clear_pointer()
is fixed to use __typeof__().
Switch the check which tests whether the object has been finalised from
being a use-after-free, to using a weak pointer which is nullified on
finalisation.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
It's been 4 years and 8 development cycles since we introduced
G_ADD_PRIVATE and offset-based private data access. It is now
time to finally deprecate the old mechanism.
Closes: #699
Meson has the ability to classify tests according to "suites", a list of
tags. This is especially useful when we want to run specific sets of
tests — e.g. only GLib's tests — instead of the whole test suite. It
also allows us to classify special tests, like "slow" ones, so that we
can only run them when needed.
The timer tests expect that a small value for sleep does not result in
no sleep at all. Round up to the next millisecond to bring it more in line
with other platforms.
This fixes the glib/timer tests.
This makes the 'threadtests' time out since that uses small usleeps a lot and
until now didn't wait at all, but now always waits a msec. Reduce the amount
of tests done on Windows to get the runtime down to something reasonable again.
https://bugzilla.gnome.org/show_bug.cgi?id=795569
Weak-pointers are currently lacking g_set_object() & g_clear_object()
helpers equivalent. New functions (and macros, both are provided) are
convenient in many case, especially for the property's notify-on-set
pattern:
if (g_set_weak_pointer (...))
g_object_notify (...)
Inspired by Christian Hergert's original implementation for
gnome-builder.
https://bugzilla.gnome.org/show_bug.cgi?id=749527
The Meson build has fallen a bit behind the Autotools one, when it comes
to the internally built tools like glib-mkenums and glib-genmarshals.
We don't need to generate gmarshal.strings any more, and since the
glib-genmarshal tool is now written in Python it can also be used when
cross-compiling, and without indirection, just like we use glib-mkenums.
We can also coalesce various rules into a simple array iteration, with
minimal changes to glib-mkenums, thus making the build a bit more
resilient and without unnecessary duplication.
Disable gio tests on Windows, fix .gitignore to not ignore
config.h.meson, and add more things to it.
Rename the library file naming and versioning to match what Autotools
outputs, e.g., libglib-2.0.so.0.5000.2 on Linux, libglib-2.0-0.dll and
glib-2.0-0.dll on Windows with MSVC.
Several more tiny fixes, more executables built and installed, install
pkg-config and m4 files, fix building of gobject tests.
Changes to gdbus-codegen to support out-of-tree builds without
environment variables set (which you can't in Meson). We now add the
build directory to the Python module search path.
It's unnecessary, and only adds visual noise; we have been fairly
inconsistent in the past, but the semi-colon-less version clearly
dominates in the code base.
https://bugzilla.gnome.org/show_bug.cgi?id=669355
This will not catch the case where we fail in libffi and always use 0.
In fact, be a real annoying person and use (1 << 31) as a flags value to
test signedness, too.
Also update the testcase to actually use flags everywhere and ot uint.
https://bugzilla.gnome.org/show_bug.cgi?id=754882
We don't need to run binaries we just built in order to successfully
build GLib and friends any more.
Since commit b74e2a7, we don't need to run glib-genmarshal when building
GIO; since commit f9eb9eed, all our tests (including the ones that do
need to run binaries we just built) are only built when running "make
check", instead of unconditionally at every build.
This means that we don't need to check for existing, native binaries
when cross-compiling, and fail the configuration step if they are not
found — which also means that you don't need to natively build GLib for
your toolchain, in order to cross-compile GLib.
We can also use the cross-compilation conditional, and skip those tests
that require a binary we just built in order to build.
https://bugzilla.gnome.org/show_bug.cgi?id=753745
This test checks the performance of connecting, disconnecting and
blocking many handlers. Various cases are checked: disconnect in
the same order, in the inverse order, at random. Connect to one
signal on a single object, to two signals on the same object, or
to the same signal on two different objects.
https://bugzilla.gnome.org/show_bug.cgi?id=737009
I searched all files that mention g_test_run, and replaced most
g_print() calls. This avoids interfering with TAP. Exceptions:
* gio/tests/network-monitor: a manual mode that is run by
"./network-monitor --watch" is unaffected
* glib/gtester.c: not a test
* glib/gtestutils.c: not a test
* glib/tests/logging.c: specifically exercising g_print()
* glib/tests/markup-parse.c: a manual mode that is run by
"./markup-parse --cdata-as-text" is unaffected
* glib/tests/testing.c: specifically exercising capture of stdout
in subprocesses
* glib/tests/utils.c: captures a subprocess's stdout
* glib/tests/testglib.c: exercises an assertion failure in g_print()
Bug: https://bugzilla.gnome.org/show_bug.cgi?id=725981
Reviewed-by: Colin Walters <walters@verbum.org>
Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Along the same lines as g_clear_object(), g_set_object() is a
convenience function to update a GObject pointer, handling reference
counting transparently and correctly.
Specifically, it handles the case where a pointer is set to its current
value. If handled naïvely, that could result in the object instance
being finalised. In the following code, that happens when
(my_obj == new_value) and the object has a single reference:
g_clear_object (&my_obj);
my_obj = g_object_ref (new_value);
It also simplifies boilerplate code such as set_property()
implementations, which are otherwise long and boring.
Test cases included.
https://bugzilla.gnome.org/show_bug.cgi?id=741589
Although returning NULL from constructor is strongly discouraged, some
old libraries need to keep doing it for ABI-compatibility reasons.
Given this, it's rude to forbid finalization from within
constructor(), since it would otherwise work correctly now anyway (and
the critical when returning NULL should discourage any new uses of
returning NULL from constructor()).
https://bugzilla.gnome.org/show_bug.cgi?id=661576
Take this test out of 'make check'. It's causing problems for a lot of people
due to fact that it's essentially a forkbomb. It's causing failures for Debian
on ARM and it's DoSing coredumps to system crash collectors.
The conditional only covers registration of the master, not the
subprocess parts. This is because g_test_slow() always return FALSE in
the subprocesses, so they would fail to run if we didn't register them
unconditionally.
This is the sole piece of code in GLib where we make use of the
stack growing direction. And this test proves that we have been
getting the direction wrong all these years...
If a constructor() implementation created an object but then unreffed
it rather than returning it, that object would get left on the
construction_objects list, which would cause problems later when that
memory location got reused by another object.
"Fix" this by making it fail intentionally, and add a test for it (and
for the normal, working singleton case).
https://bugzilla.gnome.org/show_bug.cgi?id=661576
GBindingTransformFunc called its arguments "source_value" and
"target_value", but in the transform_from function of a bidirectional
binding, "source_value" comes from the target object, and
"target_value" comes from the source object, which quickly gets
confusing if you need to use g_binding_get_source(), etc, in the
function.
Of course developers can call their transform function arguments
whatever they want, but many will copy from the headers/docs to start
out, so use less confusing names here ("from_value" and "to_value").
Also, fix the documentation to describe the bidirectional case
correctly.
https://bugzilla.gnome.org/show_bug.cgi?id=709440
Convert {glib,gobject,gio}/tests to use the automake TAP driver
and test harness instead of gtester. To do so, we add a glib-tap.mk
that provides the same interface as glib.mk, except for the
reporting and coverage testing functionality. Eventually, we may
want to replace glib.mk with it. I've not yet converted the
toplevel tests/ directory, since it mixes gtestutils tests with
other binaries.
https://bugzilla.gnome.org/show_bug.cgi?id=692125
Just like g_object_notify, check for a zero ref_count in
g_object_notify_by_pspec and leave if it is 0.
This allows using functions in ->finalize() that possibly also
notify a property change on the object. Previously,
this resulted in an error from g_object_ref.
https://bugzilla.gnome.org/show_bug.cgi?id=705570
Otherwise in e.g. the gnome-ostree integrationtest system, we
end up sending SIGUSR1 to the *entire session*, which triggers
various badness in untested debugging paths from gnome-session.
This test worked when compiled without optimization, but fails with
-O2. Presumably we just happened to find the GMainLoop off the stack
somewhere.
https://bugzilla.gnome.org/show_bug.cgi?id=704267
As it turns out, we have examples of internal functions called
type_name_get_private() in the wild (especially among older libraries),
so we need to use a name for the per-instance private data getter
function that hopefully won't conflict with anything.
For static types, it should be possible to register a private data
structure right when we are registering the type, i.e. from the
get_type() implementation. By allowing this, we can take advantage of
the existing type definition macros to cut down the amount of code
necessary (as well as the knowledge baggage) when creating a new type.
The main issue with this new feature is that it cannot be mixed with the
old idiomatic way of adding private instance data by calling a function
in the middle of the class_init() implementation, as that imposes the
additional constraint of initializing the whole type hierarchy in order
to retrieve the offset of the private data in the GTypeInstance
allocation.
For this reason we are going to follow a two-step process; in the first
step, we are going to introduce the new (semi-private) API to register
the intent to add private instance data from within the get_type()
implementation, and hide it behind a macro; at the same time, the
G_DEFINE_TYPE_EXTENDED macro is going to be modified so that it will
register the private instance data if the macro was used, using a new
(semi-private) function as well. Once we have migrated all our code, we
will make the first new function perform the actual private data
registration, and turn the second new function into a no-op. This should
guarantee a transparent migration of existing code to the new idiomatic
form.
https://bugzilla.gnome.org/show_bug.cgi?id=700035
