diff --git a/gio/gconverter.c b/gio/gconverter.c
index c39700165..88b22c16b 100644
--- a/gio/gconverter.c
+++ b/gio/gconverter.c
@@ -55,7 +55,8 @@ g_converter_default_init (GConverterInterface *iface)
  * @inbuf: (array length=inbuf_size) (element-type guint8): the buffer
  *         containing the data to convert.
  * @inbuf_size: the number of bytes in @inbuf
- * @outbuf: a buffer to write converted data in.
+ * @outbuf: (element-type guint8) (array length=outbuf_size): a buffer to write
+ *    converted data in.
  * @outbuf_size: the number of bytes in @outbuf, must be at least one
  * @flags: a #GConverterFlags controlling the conversion details
  * @bytes_read: (out): will be set to the number of bytes read from @inbuf on success
diff --git a/gio/gcredentials.c b/gio/gcredentials.c
index 6673afddd..6d6b92a77 100644
--- a/gio/gcredentials.c
+++ b/gio/gcredentials.c
@@ -393,7 +393,7 @@ g_credentials_get_native (GCredentials     *credentials,
  * g_credentials_set_native:
  * @credentials: A #GCredentials.
  * @native_type: The type of native credentials to set.
- * @native: A pointer to native credentials.
+ * @native: (not nullable): A pointer to native credentials.
  *
  * Copies the native credentials of type @native_type from @native
  * into @credentials.
diff --git a/gio/gdbusconnection.h b/gio/gdbusconnection.h
index 6876cd420..abc87779e 100644
--- a/gio/gdbusconnection.h
+++ b/gio/gdbusconnection.h
@@ -487,7 +487,7 @@ typedef GDBusInterfaceInfo ** (*GDBusSubtreeIntrospectFunc) (GDBusConnection
  * @object_path: The object path that was registered with g_dbus_connection_register_subtree().
  * @interface_name: The D-Bus interface name that the method call or property access is for.
  * @node: A node that is a child of @object_path (relative to @object_path) or %NULL for the root of the subtree.
- * @out_user_data: Return location for user data to pass to functions in the returned #GDBusInterfaceVTable (never %NULL).
+ * @out_user_data: (nullable) (not optional): Return location for user data to pass to functions in the returned #GDBusInterfaceVTable (never %NULL).
  * @user_data: The @user_data #gpointer passed to g_dbus_connection_register_subtree().
  *
  * The type of the @dispatch function in #GDBusSubtreeVTable.
diff --git a/gio/gfileinfo.c b/gio/gfileinfo.c
index 379850d49..771141686 100644
--- a/gio/gfileinfo.c
+++ b/gio/gfileinfo.c
@@ -711,9 +711,10 @@ g_file_info_remove_attribute (GFileInfo  *info,
  * g_file_info_get_attribute_data:
  * @info: a #GFileInfo
  * @attribute: a file attribute key
- * @type: (out) (allow-none): return location for the attribute type, or %NULL
- * @value_pp: (out) (allow-none): return location for the attribute value, or %NULL
- * @status: (out) (allow-none): return location for the attribute status, or %NULL
+ * @type: (out) (optional): return location for the attribute type, or %NULL
+ * @value_pp: (out) (optional) (not nullable): return location for the
+ *    attribute value, or %NULL; the attribute value will not be %NULL
+ * @status: (out) (optional): return location for the attribute status, or %NULL
  *
  * Gets the attribute type, value and status for an attribute key.
  *
@@ -1108,7 +1109,7 @@ _g_file_info_set_attribute_by_id (GFileInfo                 *info,
  * @info: a #GFileInfo.
  * @attribute: a file attribute key.
  * @type: a #GFileAttributeType
- * @value_p: pointer to the value
+ * @value_p: (not nullable): pointer to the value
  *
  * Sets the @attribute to contain the given value, if possible. To unset the
  * attribute, use %G_ATTRIBUTE_TYPE_INVALID for @type.
diff --git a/gio/gicon.c b/gio/gicon.c
index b5080dae2..6c9a3ec97 100644
--- a/gio/gicon.c
+++ b/gio/gicon.c
@@ -83,7 +83,7 @@ g_icon_default_init (GIconInterface *iface)
 
 /**
  * g_icon_hash:
- * @icon: #gconstpointer to an icon object.
+ * @icon: (not nullable): #gconstpointer to an icon object.
  * 
  * Gets a hash for an icon.
  *
diff --git a/gio/gmemoryoutputstream.c b/gio/gmemoryoutputstream.c
index a89701d60..90b558775 100644
--- a/gio/gmemoryoutputstream.c
+++ b/gio/gmemoryoutputstream.c
@@ -422,7 +422,8 @@ g_memory_output_stream_new_resizable (void)
  * Note that the returned pointer may become invalid on the next
  * write or truncate operation on the stream.
  *
- * Returns: (transfer none): pointer to the stream's data
+ * Returns: (transfer none): pointer to the stream's data, or %NULL if the data
+ *    has been stolen
  **/
 gpointer
 g_memory_output_stream_get_data (GMemoryOutputStream *ostream)
@@ -492,7 +493,8 @@ g_memory_output_stream_get_data_size (GMemoryOutputStream *ostream)
  *
  * @ostream must be closed before calling this function.
  *
- * Returns: (transfer full): the stream's data
+ * Returns: (transfer full): the stream's data, or %NULL if it has previously
+ *    been stolen
  *
  * Since: 2.26
  **/
diff --git a/gio/gsocketaddress.c b/gio/gsocketaddress.c
index cefd9e0fc..6f5c4958b 100644
--- a/gio/gsocketaddress.c
+++ b/gio/gsocketaddress.c
@@ -192,7 +192,7 @@ g_socket_address_to_native (GSocketAddress  *address,
 
 /**
  * g_socket_address_new_from_native:
- * @native: a pointer to a struct sockaddr
+ * @native: (not nullable): a pointer to a struct sockaddr
  * @len: the size of the memory location pointed to by @native
  *
  * Creates a #GSocketAddress subclass corresponding to the native
diff --git a/gio/gsocketcontrolmessage.c b/gio/gsocketcontrolmessage.c
index a526b4f76..c9c4cc634 100644
--- a/gio/gsocketcontrolmessage.c
+++ b/gio/gsocketcontrolmessage.c
@@ -118,7 +118,7 @@ g_socket_control_message_get_msg_type (GSocketControlMessage *message)
 /**
  * g_socket_control_message_serialize:
  * @message: a #GSocketControlMessage
- * @data: A buffer to write data to
+ * @data: (not nullable): A buffer to write data to
  *
  * Converts the data in the message to bytes placed in the
  * message.
diff --git a/glib/garray.c b/glib/garray.c
index 8a94720f7..8c26f8711 100644
--- a/glib/garray.c
+++ b/glib/garray.c
@@ -385,7 +385,7 @@ array_free (GRealArray     *array,
 /**
  * g_array_append_vals:
  * @array: a #GArray
- * @data: a pointer to the elements to append to the end of the array
+ * @data: (not nullable): a pointer to the elements to append to the end of the array
  * @len: the number of elements to append
  *
  * Adds @len elements onto the end of the array.
@@ -430,7 +430,7 @@ g_array_append_vals (GArray       *farray,
 /**
  * g_array_prepend_vals:
  * @array: a #GArray
- * @data: a pointer to the elements to prepend to the start of the array
+ * @data: (not nullable): a pointer to the elements to prepend to the start of the array
  * @len: the number of elements to prepend
  *
  * Adds @len elements onto the start of the array.
@@ -486,7 +486,7 @@ g_array_prepend_vals (GArray        *farray,
  * g_array_insert_vals:
  * @array: a #GArray
  * @index_: the index to place the elements at
- * @data: a pointer to the elements to insert
+ * @data: (not nullable): a pointer to the elements to insert
  * @len: the number of elements to insert
  *
  * Inserts @len elements into a #GArray at the given index.
diff --git a/glib/gatomic.c b/glib/gatomic.c
index 3ca0e403b..e70e8095b 100644
--- a/glib/gatomic.c
+++ b/glib/gatomic.c
@@ -301,7 +301,7 @@ guint
 
 /**
  * g_atomic_pointer_get:
- * @atomic: a pointer to a #gpointer-sized value
+ * @atomic: (not nullable): a pointer to a #gpointer-sized value
  *
  * Gets the current value of @atomic.
  *
@@ -320,7 +320,7 @@ gpointer
 
 /**
  * g_atomic_pointer_set:
- * @atomic: a pointer to a #gpointer-sized value
+ * @atomic: (not nullable): a pointer to a #gpointer-sized value
  * @newval: a new value to store
  *
  * Sets the value of @atomic to @newval.
@@ -339,7 +339,7 @@ void
 
 /**
  * g_atomic_pointer_compare_and_exchange:
- * @atomic: a pointer to a #gpointer-sized value
+ * @atomic: (not nullable): a pointer to a #gpointer-sized value
  * @oldval: the value to compare with
  * @newval: the value to conditionally replace with
  *
@@ -368,7 +368,7 @@ gboolean
 
 /**
  * g_atomic_pointer_add:
- * @atomic: a pointer to a #gpointer-sized value
+ * @atomic: (not nullable): a pointer to a #gpointer-sized value
  * @val: the value to add
  *
  * Atomically adds @val to the value of @atomic.
@@ -391,7 +391,7 @@ gssize
 
 /**
  * g_atomic_pointer_and:
- * @atomic: a pointer to a #gpointer-sized value
+ * @atomic: (not nullable): a pointer to a #gpointer-sized value
  * @val: the value to 'and'
  *
  * Performs an atomic bitwise 'and' of the value of @atomic and @val,
@@ -415,7 +415,7 @@ gsize
 
 /**
  * g_atomic_pointer_or:
- * @atomic: a pointer to a #gpointer-sized value
+ * @atomic: (not nullable): a pointer to a #gpointer-sized value
  * @val: the value to 'or'
  *
  * Performs an atomic bitwise 'or' of the value of @atomic and @val,
@@ -439,7 +439,7 @@ gsize
 
 /**
  * g_atomic_pointer_xor:
- * @atomic: a pointer to a #gpointer-sized value
+ * @atomic: (not nullable): a pointer to a #gpointer-sized value
  * @val: the value to 'xor'
  *
  * Performs an atomic bitwise 'xor' of the value of @atomic and @val,
diff --git a/glib/gbitlock.c b/glib/gbitlock.c
index b0b53504e..d5b4dac62 100644
--- a/glib/gbitlock.c
+++ b/glib/gbitlock.c
@@ -385,7 +385,7 @@ g_futex_int_address (const volatile void *address)
 
 /**
  * g_pointer_bit_lock:
- * @address: a pointer to a #gpointer-sized value
+ * @address: (not nullable): a pointer to a #gpointer-sized value
  * @lock_bit: a bit value between 0 and 31
  *
  * This is equivalent to g_bit_lock, but working on pointers (or other
@@ -454,7 +454,7 @@ void
 
 /**
  * g_pointer_bit_trylock:
- * @address: a pointer to a #gpointer-sized value
+ * @address: (not nullable): a pointer to a #gpointer-sized value
  * @lock_bit: a bit value between 0 and 31
  *
  * This is equivalent to g_bit_trylock, but working on pointers (or
@@ -501,7 +501,7 @@ gboolean
 
 /**
  * g_pointer_bit_unlock:
- * @address: a pointer to a #gpointer-sized value
+ * @address: (not nullable): a pointer to a #gpointer-sized value
  * @lock_bit: a bit value between 0 and 31
  *
  * This is equivalent to g_bit_unlock, but working on pointers (or other
diff --git a/glib/gbytes.c b/glib/gbytes.c
index a106adea5..b9ca4eb04 100644
--- a/glib/gbytes.c
+++ b/glib/gbytes.c
@@ -436,8 +436,9 @@ try_steal_and_unref (GBytes         *bytes,
  * g_bytes_new_take() or g_byte_array_free_to_bytes(). In all other cases the
  * data is copied.
  *
- * Returns: (transfer full) (array length=size) (element-type guint8):
- *          a pointer to the same byte data, which should be freed with g_free()
+ * Returns: (transfer full) (array length=size) (element-type guint8)
+ *          (not nullable): a pointer to the same byte data, which should be
+ *          freed with g_free()
  *
  * Since: 2.32
  */
diff --git a/glib/gconvert.c b/glib/gconvert.c
index 1d55fda13..11841c5cd 100644
--- a/glib/gconvert.c
+++ b/glib/gconvert.c
@@ -872,7 +872,7 @@ strdup_len (const gchar *string,
  *                 nul-terminated (Note that some encodings may allow nul
  *                 bytes to occur inside strings. In that case, using -1
  *                 for the @len parameter is unsafe)
- * @bytes_read:    location to store the number of bytes in the
+ * @bytes_read: (out) (optional): location to store the number of bytes in the
  *                 input string that were successfully converted, or %NULL.
  *                 Even if the conversion was successful, this may be 
  *                 less than @len if there were partial characters
@@ -880,8 +880,8 @@ strdup_len (const gchar *string,
  *                 #G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value
  *                 stored will the byte offset after the last valid
  *                 input sequence.
- * @bytes_written: the number of bytes stored in the output buffer (not 
- *                 including the terminating nul).
+ * @bytes_written: (out) (optional): the number of bytes stored in the output
+ *                 buffer (not including the terminating nul).
  * @error:         location to store the error occurring, or %NULL to ignore
  *                 errors. Any of the errors in #GConvertError may occur.
  * 
@@ -915,7 +915,7 @@ g_locale_to_utf8 (const gchar  *opsysstring,
  *                 nul-terminated (Note that some encodings may allow nul
  *                 bytes to occur inside strings. In that case, using -1
  *                 for the @len parameter is unsafe)
- * @bytes_read:    location to store the number of bytes in the
+ * @bytes_read: (out) (optional): location to store the number of bytes in the
  *                 input string that were successfully converted, or %NULL.
  *                 Even if the conversion was successful, this may be 
  *                 less than @len if there were partial characters
@@ -923,8 +923,8 @@ g_locale_to_utf8 (const gchar  *opsysstring,
  *                 #G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value
  *                 stored will the byte offset after the last valid
  *                 input sequence.
- * @bytes_written: the number of bytes stored in the output buffer (not 
- *                 including the terminating nul).
+ * @bytes_written: (out) (optional): the number of bytes stored in the output
+ *                 buffer (not including the terminating nul).
  * @error:         location to store the error occurring, or %NULL to ignore
  *                 errors. Any of the errors in #GConvertError may occur.
  * 
@@ -1119,7 +1119,7 @@ get_filename_charset (const gchar **filename_charset)
  *                 nul-terminated (Note that some encodings may allow nul
  *                 bytes to occur inside strings. In that case, using -1
  *                 for the @len parameter is unsafe)
- * @bytes_read:    location to store the number of bytes in the
+ * @bytes_read: (out) (optional): location to store the number of bytes in the
  *                 input string that were successfully converted, or %NULL.
  *                 Even if the conversion was successful, this may be 
  *                 less than @len if there were partial characters
@@ -1127,8 +1127,8 @@ get_filename_charset (const gchar **filename_charset)
  *                 #G_CONVERT_ERROR_ILLEGAL_SEQUENCE occurs, the value
  *                 stored will the byte offset after the last valid
  *                 input sequence.
- * @bytes_written: the number of bytes stored in the output buffer (not 
- *                 including the terminating nul).
+ * @bytes_written: (out) (optional): the number of bytes stored in the output
+ *                 buffer (not including the terminating nul).
  * @error:         location to store the error occurring, or %NULL to ignore
  *                 errors. Any of the errors in #GConvertError may occur.
  * 
@@ -1191,7 +1191,7 @@ g_filename_to_utf8 (const gchar *opsysstring,
  * @utf8string:    a UTF-8 encoded string.
  * @len:           the length of the string, or -1 if the string is
  *                 nul-terminated.
- * @bytes_read:    (out) (allow-none): location to store the number of bytes in
+ * @bytes_read:    (out) (optional): location to store the number of bytes in
  *                 the input string that were successfully converted, or %NULL.
  *                 Even if the conversion was successful, this may be 
  *                 less than @len if there were partial characters
@@ -1530,7 +1530,8 @@ hostname_validate (const char *hostname)
 /**
  * g_filename_from_uri:
  * @uri: a uri describing a filename (escaped, encoded in ASCII).
- * @hostname: (out) (allow-none): Location to store hostname for the URI, or %NULL.
+ * @hostname: (out) (optional) (nullable): Location to store hostname for the
+ *            URI.
  *            If there is no hostname in the URI, %NULL will be
  *            stored in this location.
  * @error: location to store the error occurring, or %NULL to ignore
diff --git a/glib/gdataset.c b/glib/gdataset.c
index 71aaa8eae..4f00d990f 100644
--- a/glib/gdataset.c
+++ b/glib/gdataset.c
@@ -318,7 +318,7 @@ g_dataset_destroy_internal (GDataset *dataset)
 
 /**
  * g_dataset_destroy:
- * @dataset_location: the location identifying the dataset.
+ * @dataset_location: (not nullable): the location identifying the dataset.
  *
  * Destroys the dataset, freeing all memory allocated, and calling any
  * destroy functions set for data elements.
@@ -487,7 +487,7 @@ g_data_set_internal (GData	  **datalist,
 
 /**
  * g_dataset_id_set_data_full:
- * @dataset_location: the location identifying the dataset.
+ * @dataset_location: (not nullable): the location identifying the dataset.
  * @key_id: the #GQuark id to identify the data element.
  * @data: the data element.
  * @destroy_func: the function to call when the data element is
@@ -672,7 +672,7 @@ g_datalist_id_set_data_full (GData	  **datalist,
 
 /**
  * g_dataset_id_remove_no_notify:
- * @dataset_location: the location identifying the dataset.
+ * @dataset_location: (not nullable): the location identifying the dataset.
  * @key_id: the #GQuark ID identifying the data element.
  *
  * Removes an element, without calling its destroy notification
@@ -742,7 +742,7 @@ g_datalist_id_remove_no_notify (GData	**datalist,
 
 /**
  * g_dataset_id_get_data:
- * @dataset_location: the location identifying the dataset.
+ * @dataset_location: (not nullable): the location identifying the dataset.
  * @key_id: the #GQuark id to identify the data element.
  *
  * Gets the data element corresponding to a #GQuark.
@@ -1054,7 +1054,7 @@ g_datalist_get_data (GData	 **datalist,
 
 /**
  * g_dataset_foreach:
- * @dataset_location: the location identifying the dataset.
+ * @dataset_location: (not nullable): the location identifying the dataset.
  * @func: the function to call for each data element.
  * @user_data: user data to pass to the function.
  *
diff --git a/glib/gdate.c b/glib/gdate.c
index 2e4d52f1c..4aece02dd 100644
--- a/glib/gdate.c
+++ b/glib/gdate.c
@@ -1938,7 +1938,7 @@ g_date_compare (const GDate *lhs,
 /**
  * g_date_to_struct_tm:
  * @date: a #GDate to set the struct tm from
- * @tm: struct tm to fill
+ * @tm: (not nullable): struct tm to fill
  *
  * Fills in the date-related bits of a struct tm using the @date value.
  * Initializes the non-date parts with something sane but meaningless.
diff --git a/glib/gdatetime.c b/glib/gdatetime.c
index df2dc26ac..ebc4837c7 100644
--- a/glib/gdatetime.c
+++ b/glib/gdatetime.c
@@ -1363,8 +1363,8 @@ g_date_time_add_full (GDateTime *datetime,
 /* Compare, difference, hash, equal {{{1 */
 /**
  * g_date_time_compare:
- * @dt1: first #GDateTime to compare
- * @dt2: second #GDateTime to compare
+ * @dt1: (not nullable): first #GDateTime to compare
+ * @dt2: (not nullable): second #GDateTime to compare
  *
  * A comparison function for #GDateTimes that is suitable
  * as a #GCompareFunc. Both #GDateTimes must be non-%NULL.
@@ -1419,7 +1419,7 @@ g_date_time_difference (GDateTime *end,
 
 /**
  * g_date_time_hash:
- * @datetime: a #GDateTime
+ * @datetime: (not nullable): a #GDateTime
  *
  * Hashes @datetime into a #guint, suitable for use within #GHashTable.
  *
@@ -1435,8 +1435,8 @@ g_date_time_hash (gconstpointer datetime)
 
 /**
  * g_date_time_equal:
- * @dt1: a #GDateTime
- * @dt2: a #GDateTime
+ * @dt1: (not nullable): a #GDateTime
+ * @dt2: (not nullable): a #GDateTime
  *
  * Checks to see if @dt1 and @dt2 are equal.
  *
diff --git a/glib/gerror.c b/glib/gerror.c
index 9263ce939..4d5c60bce 100644
--- a/glib/gerror.c
+++ b/glib/gerror.c
@@ -525,7 +525,7 @@ g_error_copy (const GError *error)
 
 /**
  * g_error_matches:
- * @error: (allow-none): a #GError or %NULL
+ * @error: (nullable): a #GError
  * @domain: an error domain
  * @code: an error code
  *
@@ -558,7 +558,7 @@ g_error_matches (const GError *error,
 
 /**
  * g_set_error:
- * @err: (allow-none): a return location for a #GError, or %NULL
+ * @err: (out callee-allocates) (optional): a return location for a #GError
  * @domain: error domain
  * @code: error code
  * @format: printf()-style format
@@ -596,7 +596,7 @@ g_set_error (GError      **err,
 
 /**
  * g_set_error_literal:
- * @err: (allow-none): a return location for a #GError, or %NULL
+ * @err: (out callee-allocates) (optional): a return location for a #GError
  * @domain: error domain
  * @code: error code
  * @message: error message
@@ -697,7 +697,7 @@ g_error_add_prefix (gchar       **string,
 
 /**
  * g_prefix_error:
- * @err: (allow-none): a return location for a #GError, or %NULL
+ * @err: (inout) (optional) (nullable): a return location for a #GError
  * @format: printf()-style format string
  * @...: arguments to @format
  *
diff --git a/glib/ghash.c b/glib/ghash.c
index 7f8e5dab0..f33fa275a 100644
--- a/glib/ghash.c
+++ b/glib/ghash.c
@@ -767,8 +767,8 @@ g_hash_table_iter_init (GHashTableIter *iter,
 /**
  * g_hash_table_iter_next:
  * @iter: an initialized #GHashTableIter
- * @key: (allow-none): a location to store the key, or %NULL
- * @value: (allow-none): a location to store the value, or %NULL
+ * @key: (out) (optional): a location to store the key
+ * @value: (out) (nullable) (optional): a location to store the value
  *
  * Advances @iter and retrieves the key and/or value that are now
  * pointed to as a result of this advancement. If %FALSE is returned,
@@ -1155,8 +1155,9 @@ g_hash_table_lookup (GHashTable    *hash_table,
  * g_hash_table_lookup_extended:
  * @hash_table: a #GHashTable
  * @lookup_key: the key to look up
- * @orig_key: (allow-none): return location for the original key, or %NULL
- * @value: (allow-none): return location for the value associated with the key, or %NULL
+ * @orig_key: (allow-none): return location for the original key
+ * @value: (out) (optional) (nullable): return location for the value associated
+ * with the key
  *
  * Looks up a key in the #GHashTable, returning the original key and the
  * associated value and a #gboolean which is %TRUE if the key was found. This
@@ -1821,8 +1822,8 @@ g_hash_table_get_values (GHashTable *hash_table)
 
 /**
  * g_str_equal:
- * @v1: a key
- * @v2: a key to compare with @v1
+ * @v1: (not nullable): a key
+ * @v2: (not nullable): a key to compare with @v1
  *
  * Compares two strings for byte-by-byte equality and returns %TRUE
  * if they are equal. It can be passed to g_hash_table_new() as the
@@ -1847,7 +1848,7 @@ g_str_equal (gconstpointer v1,
 
 /**
  * g_str_hash:
- * @v: a string key
+ * @v: (not nullable): a string key
  *
  * Converts a string to a hash value.
  *
@@ -1922,8 +1923,8 @@ g_direct_equal (gconstpointer v1,
 
 /**
  * g_int_equal:
- * @v1: a pointer to a #gint key
- * @v2: a pointer to a #gint key to compare with @v1
+ * @v1: (not nullable): a pointer to a #gint key
+ * @v2: (not nullable): a pointer to a #gint key to compare with @v1
  *
  * Compares the two #gint values being pointed to and returns
  * %TRUE if they are equal.
@@ -1946,7 +1947,7 @@ g_int_equal (gconstpointer v1,
 
 /**
  * g_int_hash:
- * @v: a pointer to a #gint key
+ * @v: (not nullable): a pointer to a #gint key
  *
  * Converts a pointer to a #gint to a hash value.
  * It can be passed to g_hash_table_new() as the @hash_func parameter,
@@ -1966,8 +1967,8 @@ g_int_hash (gconstpointer v)
 
 /**
  * g_int64_equal:
- * @v1: a pointer to a #gint64 key
- * @v2: a pointer to a #gint64 key to compare with @v1
+ * @v1: (not nullable): a pointer to a #gint64 key
+ * @v2: (not nullable): a pointer to a #gint64 key to compare with @v1
  *
  * Compares the two #gint64 values being pointed to and returns
  * %TRUE if they are equal.
@@ -1988,7 +1989,7 @@ g_int64_equal (gconstpointer v1,
 
 /**
  * g_int64_hash:
- * @v: a pointer to a #gint64 key
+ * @v: (not nullable): a pointer to a #gint64 key
  *
  * Converts a pointer to a #gint64 to a hash value.
  *
@@ -2008,8 +2009,8 @@ g_int64_hash (gconstpointer v)
 
 /**
  * g_double_equal:
- * @v1: a pointer to a #gdouble key
- * @v2: a pointer to a #gdouble key to compare with @v1
+ * @v1: (not nullable): a pointer to a #gdouble key
+ * @v2: (not nullable): a pointer to a #gdouble key to compare with @v1
  *
  * Compares the two #gdouble values being pointed to and returns
  * %TRUE if they are equal.
@@ -2030,7 +2031,7 @@ g_double_equal (gconstpointer v1,
 
 /**
  * g_double_hash:
- * @v: a pointer to a #gdouble key
+ * @v: (not nullable): a pointer to a #gdouble key
  *
  * Converts a pointer to a #gdouble to a hash value.
  * It can be passed to g_hash_table_new() as the @hash_func parameter,
diff --git a/glib/ghook.c b/glib/ghook.c
index 44a2665e5..588f45154 100644
--- a/glib/ghook.c
+++ b/glib/ghook.c
@@ -453,7 +453,7 @@ g_hook_prepend (GHookList *hook_list,
 /**
  * g_hook_insert_before:
  * @hook_list: a #GHookList
- * @sibling: the #GHook to insert the new #GHook before
+ * @sibling: (nullable): the #GHook to insert the new #GHook before
  * @hook: the #GHook to insert
  *
  * Inserts a #GHook into a #GHookList, before a given #GHook.
@@ -930,7 +930,7 @@ g_hook_find_func (GHookList *hook_list,
  * @hook_list: a #GHookList
  * @need_valids: %TRUE if #GHook elements which have been destroyed
  *     should be skipped
- * @func: the function to find
+ * @func: (not nullable): the function to find
  * @data: the data to find
  *
  * Finds a #GHook in a #GHookList with the given function and data.
diff --git a/glib/gmain.c b/glib/gmain.c
index f680335cd..29ccee048 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -2361,7 +2361,7 @@ g_source_remove_by_funcs_user_data (GSourceFuncs *funcs,
  *
  * As the name suggests, this function is not available on Windows.
  *
- * Returns: an opaque tag
+ * Returns: (not nullable): an opaque tag
  *
  * Since: 2.36
  **/
@@ -2401,7 +2401,7 @@ g_source_add_unix_fd (GSource      *source,
 /**
  * g_source_modify_unix_fd:
  * @source: a #GSource
- * @tag: the tag from g_source_add_unix_fd()
+ * @tag: (not nullable): the tag from g_source_add_unix_fd()
  * @new_events: the new event mask to watch
  *
  * Updates the event mask to watch for the fd identified by @tag.
@@ -2441,7 +2441,7 @@ g_source_modify_unix_fd (GSource      *source,
 /**
  * g_source_remove_unix_fd:
  * @source: a #GSource
- * @tag: the tag from g_source_add_unix_fd()
+ * @tag: (not nullable): the tag from g_source_add_unix_fd()
  *
  * Reverses the effect of a previous call to g_source_add_unix_fd().
  *
@@ -2488,7 +2488,7 @@ g_source_remove_unix_fd (GSource  *source,
 /**
  * g_source_query_unix_fd:
  * @source: a #GSource
- * @tag: the tag from g_source_add_unix_fd()
+ * @tag: (not nullable): the tag from g_source_add_unix_fd()
  *
  * Queries the events reported for the fd corresponding to @tag on
  * @source during the last poll.
diff --git a/glib/gmem.c b/glib/gmem.c
index 7595ec0b2..e51f0cd13 100644
--- a/glib/gmem.c
+++ b/glib/gmem.c
@@ -192,7 +192,8 @@ g_free (gpointer mem)
 
 /**
  * g_clear_pointer: (skip)
- * @pp: a pointer to a variable, struct member etc. holding a pointer
+ * @pp: (not nullable): a pointer to a variable, struct member etc. holding a
+ *    pointer
  * @destroy: a function to which a gpointer can be passed, to destroy *@pp
  *
  * Clears a reference to a variable.
diff --git a/glib/gmem.h b/glib/gmem.h
index c16e812c4..835624bfb 100644
--- a/glib/gmem.h
+++ b/glib/gmem.h
@@ -129,7 +129,7 @@ gpointer g_try_realloc_n  (gpointer	 mem,
 
 /**
  * g_steal_pointer:
- * @pp: a pointer to a pointer
+ * @pp: (not nullable): a pointer to a pointer
  *
  * Sets @pp to %NULL, returning the value that was there before.
  *
diff --git a/glib/gmessages.c b/glib/gmessages.c
index c2eeb3829..87a7e6579 100644
--- a/glib/gmessages.c
+++ b/glib/gmessages.c
@@ -942,7 +942,8 @@ static GSList *expected_messages = NULL;
 
 /**
  * g_logv:
- * @log_domain: the log domain
+ * @log_domain: (nullable): the log domain, or %NULL for the default ""
+ * application domain
  * @log_level: the log level
  * @format: the message format. See the printf() documentation
  * @args: the parameters to insert into the format string
@@ -1089,7 +1090,8 @@ g_logv (const gchar   *log_domain,
 
 /**
  * g_log:
- * @log_domain: the log domain, usually #G_LOG_DOMAIN
+ * @log_domain: (nullable): the log domain, usually #G_LOG_DOMAIN, or %NULL
+ * for the default
  * @log_level: the log level, either from #GLogLevelFlags
  *     or a user-defined level
  * @format: the message format. See the printf() documentation
@@ -1117,6 +1119,12 @@ g_log (const gchar   *log_domain,
   va_end (args);
 }
 
+/**
+ * g_return_if_fail_warning: (skip)
+ * @log_domain: (nullable):
+ * @pretty_function:
+ * @expression: (nullable):
+ */
 void
 g_return_if_fail_warning (const char *log_domain,
 			  const char *pretty_function,
@@ -1129,6 +1137,14 @@ g_return_if_fail_warning (const char *log_domain,
 	 expression);
 }
 
+/**
+ * g_warn_message: (skip)
+ * @domain: (nullable):
+ * @file:
+ * @line:
+ * @func:
+ * @warnexpr: (nullable):
+ */
 void
 g_warn_message (const char     *domain,
                 const char     *file,
@@ -1379,10 +1395,11 @@ escape_string (GString *string)
 
 /**
  * g_log_default_handler:
- * @log_domain: the log domain of the message
+ * @log_domain: (nullable): the log domain of the message, or %NULL for the
+ * default "" application domain
  * @log_level: the level of the message
- * @message: the message
- * @unused_data: data passed from g_log() which is unused
+ * @message: (nullable): the message
+ * @unused_data: (nullable): data passed from g_log() which is unused
  *
  * The default log handler set up by GLib; g_log_set_default_handler()
  * allows to install an alternate default log handler.
diff --git a/glib/gnode.h b/glib/gnode.h
index 763ac909f..50ad1bdf3 100644
--- a/glib/gnode.h
+++ b/glib/gnode.h
@@ -62,13 +62,13 @@ typedef void		(*GNodeForeachFunc)	(GNode	       *node,
 
 /**
  * GCopyFunc:
- * @src: A pointer to the data which should be copied
+ * @src: (not nullable): A pointer to the data which should be copied
  * @data: Additional data
  *
  * A function of this signature is used to copy the node data 
  * when doing a deep-copy of a tree.
  *
- * Returns: A pointer to the copy
+ * Returns: (not nullable): A pointer to the copy
  *
  * Since: 2.4
  */
diff --git a/glib/gprintf.c b/glib/gprintf.c
index 1c831b04e..71b33225f 100644
--- a/glib/gprintf.c
+++ b/glib/gprintf.c
@@ -58,7 +58,7 @@ g_printf (gchar const *format,
 
 /**
  * g_fprintf:
- * @file: the stream to write to.
+ * @file: (not nullable): the stream to write to.
  * @format: a standard printf() format string, but notice 
  *          [string precision pitfalls][string-precision]
  * @...: the arguments to insert in the output.
@@ -191,7 +191,7 @@ g_vprintf (gchar const *format,
 
 /**
  * g_vfprintf:
- * @file: the stream to write to.
+ * @file: (not nullable): the stream to write to.
  * @format: a standard printf() format string, but notice 
  *          [string precision pitfalls][string-precision]
  * @args: the list of arguments to insert in the output.
diff --git a/glib/gqsort.c b/glib/gqsort.c
index e63264ea4..27347bffe 100644
--- a/glib/gqsort.c
+++ b/glib/gqsort.c
@@ -282,7 +282,7 @@ msort_r (void *b, size_t n, size_t s, GCompareDataFunc cmp, void *arg)
 
 /**
  * g_qsort_with_data:
- * @pbase: start of array to sort
+ * @pbase: (not nullable): start of array to sort
  * @total_elems: elements in the array
  * @size: size of each element
  * @compare_func: function to compare elements
diff --git a/glib/gshell.c b/glib/gshell.c
index a1c7e791f..2c50af8f3 100644
--- a/glib/gshell.c
+++ b/glib/gshell.c
@@ -619,10 +619,10 @@ tokenize_command_line (const gchar *command_line,
 /**
  * g_shell_parse_argv:
  * @command_line: command line to parse
- * @argcp: (out) (optional): return location for number of args, or %NULL
+ * @argcp: (out) (optional): return location for number of args
  * @argvp: (out) (optional) (array length=argcp zero-terminated=1): return
- *   location for array of args, or %NULL
- * @error: (optional): return location for error, or %NULL
+ *   location for array of args
+ * @error: (optional): return location for error
  * 
  * Parses a command line into an argument vector, in much the same way
  * the shell would, but without many of the expansions the shell would
diff --git a/glib/gslice.c b/glib/gslice.c
index 0563d8092..9022062ac 100644
--- a/glib/gslice.c
+++ b/glib/gslice.c
@@ -873,7 +873,11 @@ thread_memory_magazine2_free (ThreadMemory *tmem,
  * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
  * environment variable.
  *
- * Returns: a pointer to the allocated block, cast to a pointer to @type
+ * This can never return %NULL as the minimum allocation size from
+ * `sizeof (@type)` is 1 byte.
+ *
+ * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
+ *    to @type
  *
  * Since: 2.10
  */
@@ -892,13 +896,19 @@ thread_memory_magazine2_free (ThreadMemory *tmem,
  * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
  * environment variable.
  *
+ * This can never return %NULL as the minimum allocation size from
+ * `sizeof (@type)` is 1 byte.
+ *
+ * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
+ *    to @type
+ *
  * Since: 2.10
  */
 
 /**
  * g_slice_dup:
  * @type: the type to duplicate, typically a structure name
- * @mem: the memory to copy into the allocated block
+ * @mem: (not nullable): the memory to copy into the allocated block
  *
  * A convenience macro to duplicate a block of memory using
  * the slice allocator.
@@ -910,7 +920,10 @@ thread_memory_magazine2_free (ThreadMemory *tmem,
  * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
  * environment variable.
  *
- * Returns: a pointer to the allocated block, cast to a pointer to @type
+ * This can never return %NULL.
+ *
+ * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
+ *    to @type
  *
  * Since: 2.14
  */
@@ -929,6 +942,8 @@ thread_memory_magazine2_free (ThreadMemory *tmem,
  * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
  * [`G_SLICE`][G_SLICE] for related debugging options.
  *
+ * If @mem is %NULL, this macro does nothing.
+ *
  * Since: 2.10
  */
 
@@ -947,6 +962,8 @@ thread_memory_magazine2_free (ThreadMemory *tmem,
  * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
  * [`G_SLICE`][G_SLICE] for related debugging options.
  *
+ * If @mem_chain is %NULL, this function does nothing.
+ *
  * Since: 2.10
  */
 
@@ -964,7 +981,8 @@ thread_memory_magazine2_free (ThreadMemory *tmem,
  * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
  * environment variable.
  *
- * Returns: a pointer to the allocated memory block
+ * Returns: a pointer to the allocated memory block, which will be %NULL if and
+ *    only if @mem_size is 0
  *
  * Since: 2.10
  */
@@ -1022,7 +1040,8 @@ g_slice_alloc (gsize mem_size)
  * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
  * environment variable.
  *
- * Returns: a pointer to the allocated block
+ * Returns: a pointer to the allocated block, which will be %NULL if and only
+ *    if @mem_size is 0
  *
  * Since: 2.10
  */
@@ -1043,7 +1062,10 @@ g_slice_alloc0 (gsize mem_size)
  * Allocates a block of memory from the slice allocator
  * and copies @block_size bytes into it from @mem_block.
  *
- * Returns: a pointer to the allocated memory block
+ * @mem_block must be non-%NULL if @block_size is non-zero.
+ *
+ * Returns: a pointer to the allocated memory block, which will be %NULL if and
+ *    only if @mem_size is 0
  *
  * Since: 2.14
  */
@@ -1070,6 +1092,8 @@ g_slice_copy (gsize         mem_size,
  * can be changed with the [`G_DEBUG=gc-friendly`][G_DEBUG] environment
  * variable, also see [`G_SLICE`][G_SLICE] for related debugging options.
  *
+ * If @mem_block is %NULL, this function does nothing.
+ *
  * Since: 2.10
  */
 void
@@ -1130,6 +1154,8 @@ g_slice_free1 (gsize    mem_size,
  * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
  * [`G_SLICE`][G_SLICE] for related debugging options.
  *
+ * If @mem_chain is %NULL, this function does nothing.
+ *
  * Since: 2.10
  */
 void
diff --git a/glib/gstrfuncs.c b/glib/gstrfuncs.c
index 46c5d0608..b5a862b9a 100644
--- a/glib/gstrfuncs.c
+++ b/glib/gstrfuncs.c
@@ -343,7 +343,7 @@ get_C_locale (void)
 
 /**
  * g_strdup:
- * @str: the string to duplicate
+ * @str: (nullable): the string to duplicate
  *
  * Duplicates a string. If @str is %NULL it returns %NULL.
  * The returned string should be freed with g_free()
@@ -2114,7 +2114,7 @@ out:
 /**
  * g_strescape:
  * @source: a string to escape
- * @exceptions: a string of characters not to escape in @source
+ * @exceptions: (nullable): a string of characters not to escape in @source
  *
  * Escapes the special characters '\b', '\f', '\n', '\r', '\t', '\v', '\'
  * and '"' in the string @source by inserting a '\' before
@@ -2467,7 +2467,7 @@ g_strsplit_set (const gchar *string,
 
 /**
  * g_strfreev:
- * @str_array: a %NULL-terminated array of strings to free
+ * @str_array: (nullable): a %NULL-terminated array of strings to free
  *
  * Frees a %NULL-terminated array of strings, as well as each
  * string it contains.
@@ -2490,14 +2490,14 @@ g_strfreev (gchar **str_array)
 
 /**
  * g_strdupv:
- * @str_array: a %NULL-terminated array of strings
+ * @str_array: (nullable): a %NULL-terminated array of strings
  *
  * Copies %NULL-terminated array of strings. The copy is a deep copy;
  * the new array should be freed by first freeing each string, then
  * the array itself. g_strfreev() does this for you. If called
  * on a %NULL value, g_strdupv() simply returns %NULL.
  *
- * Returns: a new %NULL-terminated array of strings.
+ * Returns: (nullable): a new %NULL-terminated array of strings.
  */
 gchar**
 g_strdupv (gchar **str_array)
diff --git a/glib/gstring.c b/glib/gstring.c
index 155b426c7..e0f3ba1f0 100644
--- a/glib/gstring.c
+++ b/glib/gstring.c
@@ -132,8 +132,8 @@ g_string_sized_new (gsize dfl_size)
 
 /**
  * g_string_new:
- * @init: (allow-none): the initial text to copy into the string, or %NULL to
- * start with an empty string.
+ * @init: (nullable): the initial text to copy into the string, or %NULL to
+ * start with an empty string
  *
  * Creates a new #GString, initialized with the given string.
  *
diff --git a/glib/gtestutils.c b/glib/gtestutils.c
index ac4c196e3..79fb68fad 100644
--- a/glib/gtestutils.c
+++ b/glib/gtestutils.c
@@ -1681,7 +1681,7 @@ find_case (gconstpointer l, gconstpointer s)
 
 /**
  * GTestFixtureFunc:
- * @fixture: the test fixture
+ * @fixture: (not nullable): the test fixture
  * @user_data: the data provided when registering the test
  *
  * The type used for functions that operate on test fixtures.  This is
@@ -2429,6 +2429,14 @@ g_assertion_message (const char     *domain,
     abort ();
 }
 
+/**
+ * g_assertion_message_expr: (skip)
+ * @domain: (nullable):
+ * @file:
+ * @line:
+ * @func:
+ * @expr: (nullable):
+ */
 void
 g_assertion_message_expr (const char     *domain,
                           const char     *file,
diff --git a/glib/gthread.c b/glib/gthread.c
index 758182977..b9ae4dfa5 100644
--- a/glib/gthread.c
+++ b/glib/gthread.c
@@ -615,7 +615,8 @@ g_once_impl (GOnce       *once,
 
 /**
  * g_once_init_enter:
- * @location: location of a static initializable variable containing 0
+ * @location: (not nullable): location of a static initializable variable
+ *    containing 0
  *
  * Function to be called when starting a critical initialization
  * section. The argument @location must point to a static
@@ -669,7 +670,8 @@ gboolean
 
 /**
  * g_once_init_leave:
- * @location: location of a static initializable variable containing 0
+ * @location: (not nullable): location of a static initializable variable
+ *    containing 0
  * @result: new non-0 value for *@value_location
  *
  * Counterpart to g_once_init_enter(). Expects a location of a static
diff --git a/glib/gtrashstack.c b/glib/gtrashstack.c
index 896ed6f6d..5c3b317c9 100644
--- a/glib/gtrashstack.c
+++ b/glib/gtrashstack.c
@@ -51,7 +51,7 @@
 /**
  * g_trash_stack_push:
  * @stack_p: a #GTrashStack
- * @data_p: the piece of memory to push on the stack
+ * @data_p: (not nullable): the piece of memory to push on the stack
  *
  * Pushes a piece of memory onto a #GTrashStack.
  */
diff --git a/glib/gtree.c b/glib/gtree.c
index 7fb41c24f..6978d06ed 100644
--- a/glib/gtree.c
+++ b/glib/gtree.c
@@ -853,8 +853,8 @@ g_tree_lookup (GTree         *tree,
  * g_tree_lookup_extended:
  * @tree: a #GTree
  * @lookup_key: the key to look up
- * @orig_key: returns the original key
- * @value: returns the value associated with the key
+ * @orig_key: (optional) (nullable): returns the original key
+ * @value: (optional) (nullable): returns the value associated with the key
  * 
  * Looks up a key in the #GTree, returning the original key and the
  * associated value. This is useful if you need to free the memory
diff --git a/glib/gutf8.c b/glib/gutf8.c
index 4675800a0..e424c1057 100644
--- a/glib/gutf8.c
+++ b/glib/gutf8.c
@@ -153,7 +153,7 @@ g_utf8_find_prev_char (const char *str,
 /**
  * g_utf8_find_next_char:
  * @p: a pointer to a position within a UTF-8 encoded string
- * @end: a pointer to the byte following the end of the string,
+ * @end: (nullable): a pointer to the byte following the end of the string,
  *     or %NULL to indicate that the string is nul-terminated
  *
  * Finds the start of the next UTF-8 character in the string after @p.
@@ -436,9 +436,9 @@ g_utf8_strncpy (gchar       *dest,
 /**
  * g_unichar_to_utf8:
  * @c: a Unicode character code
- * @outbuf: output buffer, must have at least 6 bytes of space.
- *       If %NULL, the length will be computed and returned
- *       and nothing will be written to @outbuf.
+ * @outbuf: (out caller-allocates) (optional): output buffer, must have at
+ *       least 6 bytes of space. If %NULL, the length will be computed and
+ *       returned and nothing will be written to @outbuf.
  * 
  * Converts a single character to UTF-8.
  * 
@@ -684,8 +684,8 @@ g_utf8_get_char_validated (const gchar *p,
  * @str: a UTF-8 encoded string
  * @len: the maximum length of @str to use, in bytes. If @len < 0,
  *     then the string is nul-terminated.
- * @items_written: (allow-none): location to store the number of
- *     characters in the result, or %NULL.
+ * @items_written: (out caller-allocates) (optional): location to store the
+ *     number of characters in the result, or %NULL.
  *
  * Convert a string from UTF-8 to a 32-bit fixed width
  * representation as UCS-4, assuming valid UTF-8 input.
@@ -801,14 +801,15 @@ try_malloc_n (gsize n_blocks, gsize n_block_bytes, GError **error)
  * @str: a UTF-8 encoded string
  * @len: the maximum length of @str to use, in bytes. If @len < 0,
  *     then the string is nul-terminated.
- * @items_read: (allow-none): location to store number of bytes read, or %NULL.
+ * @items_read: (out caller-allocates) (optional): location to store number of
+  *    bytes read, or %NULL.
  *     If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
  *     returned in case @str contains a trailing partial
  *     character. If an error occurs then the index of the
  *     invalid input is stored here.
- * @items_written: (allow-none): location to store number of characters
- *     written or %NULL. The value here stored does not include the
- *     trailing 0 character. 
+ * @items_written: (out caller-allocates) (optional): location to store number
+ *     of characters written or %NULL. The value here stored does not include
+ *     the trailing 0 character.
  * @error: location to store the error occurring, or %NULL to ignore
  *     errors. Any of the errors in #GConvertError other than
  *     %G_CONVERT_ERROR_NO_CONVERSION may occur.
@@ -886,11 +887,11 @@ g_utf8_to_ucs4 (const gchar *str,
  * @str: a UCS-4 encoded string
  * @len: the maximum length (number of characters) of @str to use. 
  *     If @len < 0, then the string is nul-terminated.
- * @items_read: (allow-none): location to store number of characters
- *     read, or %NULL.
- * @items_written: (allow-none): location to store number of bytes
- *     written or %NULL. The value here stored does not include the
- *     trailing 0 byte. 
+ * @items_read: (out caller-allocates) (optional): location to store number of
+ *     characters read, or %NULL.
+ * @items_written: (out caller-allocates) (optioanl): location to store number
+ *     of bytes written or %NULL. The value here stored does not include the
+ *     trailing 0 byte.
  * @error: location to store the error occurring, or %NULL to ignore
  *         errors. Any of the errors in #GConvertError other than
  *         %G_CONVERT_ERROR_NO_CONVERSION may occur.
@@ -960,12 +961,13 @@ g_ucs4_to_utf8 (const gunichar *str,
  * @str: a UTF-16 encoded string
  * @len: the maximum length (number of #gunichar2) of @str to use. 
  *     If @len < 0, then the string is nul-terminated.
- * @items_read: (allow-none): location to store number of words read,
- *     or %NULL. If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
- *     returned in case @str contains a trailing partial character. If
+ * @items_read: (out caller-allocates) (optional): location to store number of
+ *     words read, or %NULL. If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will
+ *     be returned in case @str contains a trailing partial character. If
  *     an error occurs then the index of the invalid input is stored here.
- * @items_written: (allow-none): location to store number of bytes written,
- *     or %NULL. The value stored here does not include the trailing 0 byte.
+ * @items_written: (out caller-allocates) (optional): location to store number
+ *     of bytes written, or %NULL. The value stored here does not include the
+ *     trailing 0 byte.
  * @error: location to store the error occurring, or %NULL to ignore
  *     errors. Any of the errors in #GConvertError other than
  *     %G_CONVERT_ERROR_NO_CONVERSION may occur.
@@ -1114,13 +1116,13 @@ g_utf16_to_utf8 (const gunichar2  *str,
  * @str: a UTF-16 encoded string
  * @len: the maximum length (number of #gunichar2) of @str to use. 
  *     If @len < 0, then the string is nul-terminated.
- * @items_read: (allow-none): location to store number of words read,
- *     or %NULL. If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
- *     returned in case @str contains a trailing partial character. If
+ * @items_read: (out caller-allocates) (optional): location to store number of
+ *     words read, or %NULL. If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will
+ *     be returned in case @str contains a trailing partial character. If
  *     an error occurs then the index of the invalid input is stored here.
- * @items_written: (allow-none): location to store number of characters
- *     written, or %NULL. The value stored here does not include the trailing
- *     0 character.
+ * @items_written: (out caller-allocates) (optional): location to store number
+ *     of characters written, or %NULL. The value stored here does not include
+ *     the trailing 0 character.
  * @error: location to store the error occurring, or %NULL to ignore
  *     errors. Any of the errors in #GConvertError other than
  *     %G_CONVERT_ERROR_NO_CONVERSION may occur.
@@ -1252,13 +1254,13 @@ g_utf16_to_ucs4 (const gunichar2  *str,
  * @str: a UTF-8 encoded string
  * @len: the maximum length (number of bytes) of @str to use.
  *     If @len < 0, then the string is nul-terminated.
- * @items_read: (allow-none): location to store number of bytes read,
- *     or %NULL. If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will be
- *     returned in case @str contains a trailing partial character. If
+ * @items_read: (out caller-allocates) (optional): location to store number of
+ *     bytes read, or %NULL. If %NULL, then %G_CONVERT_ERROR_PARTIAL_INPUT will
+ *     be returned in case @str contains a trailing partial character. If
  *     an error occurs then the index of the invalid input is stored here.
- * @items_written: (allow-none): location to store number of #gunichar2
- *     written, or %NULL. The value stored here does not include the
- *     trailing 0.
+ * @items_written: (out caller-allocates) (optional): location to store number
+ *     of #gunichar2 written, or %NULL. The value stored here does not include
+ *     the trailing 0.
  * @error: location to store the error occurring, or %NULL to ignore
  *     errors. Any of the errors in #GConvertError other than
  *     %G_CONVERT_ERROR_NO_CONVERSION may occur.
@@ -1369,12 +1371,12 @@ g_utf8_to_utf16 (const gchar *str,
  * @str: a UCS-4 encoded string
  * @len: the maximum length (number of characters) of @str to use. 
  *     If @len < 0, then the string is nul-terminated.
- * @items_read: (allow-none): location to store number of bytes read,
- *     or %NULL. If an error occurs then the index of the invalid input
- *     is stored here.
- * @items_written: (allow-none): location to store number of #gunichar2 
- *     written, or %NULL. The value stored here does not include the
- *     trailing 0.
+ * @items_read: (out caller-allocates) (optional): location to store number of
+ *     bytes read, or %NULL. If an error occurs then the index of the invalid
+ *     input is stored here.
+ * @items_written: (out caller-allocates) (optional): location to store number
+ *     of #gunichar2  written, or %NULL. The value stored here does not include
+ *     the trailing 0.
  * @error: location to store the error occurring, or %NULL to ignore
  *     errors. Any of the errors in #GConvertError other than
  *     %G_CONVERT_ERROR_NO_CONVERSION may occur.
diff --git a/glib/gutils.c b/glib/gutils.c
index 360a4d5c8..d0711e3d2 100644
--- a/glib/gutils.c
+++ b/glib/gutils.c
@@ -2018,7 +2018,7 @@ g_get_system_config_dirs (void)
 
 /**
  * g_nullify_pointer:
- * @nullify_location: the memory address of the pointer.
+ * @nullify_location: (not nullable): the memory address of the pointer.
  *
  * Set the pointer at the specified location to %NULL.
  **/
diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
index a9f5d9423..8301250dd 100644
--- a/glib/gvariant-core.c
+++ b/glib/gvariant-core.c
@@ -1023,7 +1023,7 @@ g_variant_get_child_value (GVariant *value,
 /**
  * g_variant_store:
  * @value: the #GVariant to store
- * @data: the location to store the serialised data at
+ * @data: (not nullable): the location to store the serialised data at
  *
  * Stores the serialised form of @value at @data.  @data should be
  * large enough.  See g_variant_get_size().
diff --git a/gobject/gboxed.c b/gobject/gboxed.c
index 54f658ed3..40723f53b 100644
--- a/gobject/gboxed.c
+++ b/gobject/gboxed.c
@@ -322,11 +322,12 @@ g_boxed_type_register_static (const gchar   *name,
 /**
  * g_boxed_copy:
  * @boxed_type: The type of @src_boxed.
- * @src_boxed: The boxed structure to be copied.
+ * @src_boxed: (not nullable): The boxed structure to be copied.
  * 
  * Provide a copy of a boxed structure @src_boxed which is of type @boxed_type.
  * 
- * Returns: (transfer full): The newly created copy of the boxed structure.
+ * Returns: (transfer full) (not nullable): The newly created copy of the boxed
+ *    structure.
  */
 gpointer
 g_boxed_copy (GType         boxed_type,
@@ -383,7 +384,7 @@ g_boxed_copy (GType         boxed_type,
 /**
  * g_boxed_free:
  * @boxed_type: The type of @boxed.
- * @boxed: The boxed structure to be freed.
+ * @boxed: (not nullable): The boxed structure to be freed.
  *
  * Free the boxed structure @boxed which is of type @boxed_type.
  */
diff --git a/gobject/gboxed.h b/gobject/gboxed.h
index d398da572..d169d03c6 100644
--- a/gobject/gboxed.h
+++ b/gobject/gboxed.h
@@ -46,18 +46,18 @@ G_BEGIN_DECLS
 /* --- typedefs --- */
 /**
  * GBoxedCopyFunc:
- * @boxed: The boxed structure to be copied.
+ * @boxed: (not nullable): The boxed structure to be copied.
  *
  * This function is provided by the user and should produce a copy
  * of the passed in boxed structure.
  *
- * Returns: The newly created copy of the boxed structure.
+ * Returns: (not nullable): The newly created copy of the boxed structure.
  */
 typedef gpointer (*GBoxedCopyFunc) (gpointer boxed);
 
 /**
  * GBoxedFreeFunc:
- * @boxed: The boxed structure to be freed.
+ * @boxed: (not nullable): The boxed structure to be freed.
  *
  * This function is provided by the user and should free the boxed
  * structure passed.
diff --git a/gobject/gclosure.c b/gobject/gclosure.c
index 3c6894a7c..8daf5f9b4 100644
--- a/gobject/gclosure.c
+++ b/gobject/gclosure.c
@@ -319,7 +319,8 @@ g_closure_set_meta_va_marshal (GClosure       *closure,
 /**
  * g_closure_set_meta_marshal: (skip)
  * @closure: a #GClosure
- * @marshal_data: context-dependent data to pass to @meta_marshal
+ * @marshal_data: (closure meta_marshal): context-dependent data to pass
+ *  to @meta_marshal
  * @meta_marshal: a #GClosureMarshal function
  *
  * Sets the meta marshaller of @closure.  A meta marshaller wraps
@@ -360,9 +361,11 @@ g_closure_set_meta_marshal (GClosure       *closure,
 /**
  * g_closure_add_marshal_guards: (skip)
  * @closure: a #GClosure
- * @pre_marshal_data: data to pass to @pre_marshal_notify
+ * @pre_marshal_data: (closure pre_marshal_notify): data to pass
+ *  to @pre_marshal_notify
  * @pre_marshal_notify: a function to call before the closure callback
- * @post_marshal_data: data to pass to @post_marshal_notify
+ * @post_marshal_data: (closure post_marshal_notify): data to pass
+ *  to @post_marshal_notify
  * @post_marshal_notify: a function to call after the closure callback
  *
  * Adds a pair of notifiers which get invoked before and after the
@@ -417,7 +420,7 @@ g_closure_add_marshal_guards (GClosure      *closure,
 /**
  * g_closure_add_finalize_notifier: (skip)
  * @closure: a #GClosure
- * @notify_data: data to pass to @notify_func
+ * @notify_data: (closure notify_func): data to pass to @notify_func
  * @notify_func: the callback function to register
  *
  * Registers a finalization notifier which will be called when the
@@ -453,7 +456,7 @@ g_closure_add_finalize_notifier (GClosure      *closure,
 /**
  * g_closure_add_invalidate_notifier: (skip)
  * @closure: a #GClosure
- * @notify_data: data to pass to @notify_func
+ * @notify_data: (closure notify_func): data to pass to @notify_func
  * @notify_func: the callback function to register
  *
  * Registers an invalidation notifier which will be called when the
@@ -921,7 +924,7 @@ _g_closure_set_va_marshal (GClosure       *closure,
 /**
  * g_cclosure_new: (skip)
  * @callback_func: the function to invoke
- * @user_data: user data to pass to @callback_func
+ * @user_data: (closure callback_func): user data to pass to @callback_func
  * @destroy_data: destroy notify to be called when @user_data is no longer used
  *
  * Creates a new closure which invokes @callback_func with @user_data as
@@ -949,7 +952,7 @@ g_cclosure_new (GCallback      callback_func,
 /**
  * g_cclosure_new_swap: (skip)
  * @callback_func: the function to invoke
- * @user_data: user data to pass to @callback_func
+ * @user_data: (closure callback_func): user data to pass to @callback_func
  * @destroy_data: destroy notify to be called when @user_data is no longer used
  *
  * Creates a new closure which invokes @callback_func with @user_data as
@@ -1496,7 +1499,8 @@ g_cclosure_marshal_generic (GClosure     *closure,
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is
+ *  invoked.
  * @args_list: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
diff --git a/gobject/gclosure.h b/gobject/gclosure.h
index 41f0799c7..3195809c3 100644
--- a/gobject/gclosure.h
+++ b/gobject/gclosure.h
@@ -125,7 +125,8 @@ typedef void  (*GClosureMarshal)	(GClosure	*closure,
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is
+ *  invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
diff --git a/gobject/gmarshal.c b/gobject/gmarshal.c
index 122f73f47..f270f2e66 100644
--- a/gobject/gmarshal.c
+++ b/gobject/gmarshal.c
@@ -426,7 +426,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -444,7 +444,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -461,7 +461,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -478,7 +478,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -495,7 +495,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -512,7 +512,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -529,7 +529,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -546,7 +546,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -563,7 +563,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -580,7 +580,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -597,7 +597,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -614,7 +614,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -631,7 +631,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -648,7 +648,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -665,7 +665,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -682,7 +682,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -699,7 +699,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -716,7 +716,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -733,7 +733,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -750,7 +750,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -767,7 +767,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
@@ -784,7 +784,7 @@
  * @return_value: (allow-none): a #GValue to store the return
  *  value. May be %NULL if the callback of @closure doesn't return a
  *  value.
- * @instance: the instance on which the closure is invoked.
+ * @instance: (type GObject.TypeInstance): the instance on which the closure is invoked.
  * @args: va_list of arguments to be passed to the closure.
  * @marshal_data: (allow-none): additional data specified when
  *  registering the marshaller, see g_closure_set_marshal() and
diff --git a/gobject/gobject.c b/gobject/gobject.c
index a3c0875e9..8163d3de6 100644
--- a/gobject/gobject.c
+++ b/gobject/gobject.c
@@ -702,7 +702,8 @@ g_object_class_install_properties (GObjectClass  *oclass,
 
 /**
  * g_object_interface_install_property:
- * @g_iface: any interface vtable for the interface, or the default
+ * @g_iface: (type GObject.TypeInterface): any interface vtable for the
+ *    interface, or the default
  *  vtable for the interface.
  * @pspec: the #GParamSpec for the new property
  *
@@ -781,8 +782,8 @@ g_object_class_find_property (GObjectClass *class,
 
 /**
  * g_object_interface_find_property:
- * @g_iface: any interface vtable for the interface, or the default
- *  vtable for the interface
+ * @g_iface: (type GObject.TypeInterface): any interface vtable for the
+ *  interface, or the default vtable for the interface
  * @property_name: name of a property to lookup.
  *
  * Find the #GParamSpec with the given name for an
@@ -919,8 +920,8 @@ g_object_class_list_properties (GObjectClass *class,
 
 /**
  * g_object_interface_list_properties:
- * @g_iface: any interface vtable for the interface, or the default
- *  vtable for the interface
+ * @g_iface: (type GObject.TypeInterface): any interface vtable for the
+ *  interface, or the default vtable for the interface
  * @n_properties_p: (out): location to store number of properties returned.
  *
  * Lists the properties of an interface.Generally, the interface
@@ -1602,7 +1603,8 @@ g_object_get_type (void)
  * Construction parameters (see #G_PARAM_CONSTRUCT, #G_PARAM_CONSTRUCT_ONLY)
  * which are not explicitly specified are set to their default values.
  *
- * Returns: (transfer full): a new instance of @object_type
+ * Returns: (transfer full) (type GObject.Object) : a new instance of
+ *   @object_type
  */
 gpointer
 g_object_new (GType	   object_type,
@@ -2248,7 +2250,7 @@ g_object_get_valist (GObject	 *object,
 
 /**
  * g_object_set: (skip)
- * @object: a #GObject
+ * @object: (type GObject.Object): a #GObject
  * @first_property_name: name of the first property to set
  * @...: value for the first property, followed optionally by more
  *  name/value pairs, followed by %NULL
@@ -2276,7 +2278,7 @@ g_object_set (gpointer     _object,
 
 /**
  * g_object_get: (skip)
- * @object: a #GObject
+ * @object: (type GObject.Object): a #GObject
  * @first_property_name: name of the first property to get
  * @...: return location for the first property, followed optionally by more
  *  name/return location pairs, followed by %NULL
@@ -2452,7 +2454,7 @@ g_object_get_property (GObject	   *object,
 
 /**
  * g_object_connect: (skip)
- * @object: a #GObject
+ * @object: (type GObject.Object): a #GObject
  * @signal_spec: the spec for the first signal
  * @...: #GCallback for the first signal, followed by data for the
  *       first signal, followed optionally by more signal
@@ -2482,7 +2484,7 @@ g_object_get_property (GObject	   *object,
  * 				     NULL);
  * ]|
  *
- * Returns: (transfer none): @object
+ * Returns: (transfer none) (type GObject.Object): @object
  */
 gpointer
 g_object_connect (gpointer     _object,
@@ -2554,7 +2556,7 @@ g_object_connect (gpointer     _object,
 
 /**
  * g_object_disconnect: (skip)
- * @object: a #GObject
+ * @object: (type GObject.Object): a #GObject
  * @signal_spec: the spec for the first signal
  * @...: #GCallback for the first signal, followed by data for the first signal,
  *  followed optionally by more signal spec/callback/data triples,
@@ -2729,7 +2731,8 @@ g_object_weak_unref (GObject    *object,
 /**
  * g_object_add_weak_pointer: (skip)
  * @object: The object that should be weak referenced.
- * @weak_pointer_location: (inout): The memory address of a pointer.
+ * @weak_pointer_location: (inout) (not optional) (nullable): The memory address
+ *    of a pointer.
  *
  * Adds a weak reference from weak_pointer to @object to indicate that
  * the pointer located at @weak_pointer_location is only valid during
@@ -2756,7 +2759,8 @@ g_object_add_weak_pointer (GObject  *object,
 /**
  * g_object_remove_weak_pointer: (skip)
  * @object: The object that is weak referenced.
- * @weak_pointer_location: (inout): The memory address of a pointer.
+ * @weak_pointer_location: (inout) (not optional) (nullable): The memory address
+ *    of a pointer.
  *
  * Removes a weak reference from @object that was previously added
  * using g_object_add_weak_pointer(). The @weak_pointer_location has
@@ -3830,10 +3834,11 @@ g_value_dup_object (const GValue *value)
 
 /**
  * g_signal_connect_object: (skip)
- * @instance: the instance to connect to.
+ * @instance: (type GObject.TypeInstance): the instance to connect to.
  * @detailed_signal: a string of the form "signal-name::detail".
  * @c_handler: the #GCallback to connect.
- * @gobject: the object to pass as data to @c_handler.
+ * @gobject: (type GObject.Object) (nullable): the object to pass as data
+ *    to @c_handler.
  * @connect_flags: a combination of #GConnectFlags.
  *
  * This is similar to g_signal_connect_data(), but uses a closure which
@@ -4140,7 +4145,7 @@ g_initially_unowned_class_init (GInitiallyUnownedClass *klass)
  * g_weak_ref_init: (skip)
  * @weak_ref: (inout): uninitialized or empty location for a weak
  *    reference
- * @object: (allow-none): a #GObject or %NULL
+ * @object: (type GObject.Object) (nullable): a #GObject or %NULL
  *
  * Initialise a non-statically-allocated #GWeakRef.
  *
@@ -4226,7 +4231,7 @@ g_weak_ref_get (GWeakRef *weak_ref)
 /**
  * g_weak_ref_set: (skip)
  * @weak_ref: location for a weak reference
- * @object: (allow-none): a #GObject or %NULL
+ * @object: (type GObject.Object) (nullable): a #GObject or %NULL
  *
  * Change the object to which @weak_ref points, or set it to
  * %NULL.
diff --git a/gobject/gparam.c b/gobject/gparam.c
index e26482c3e..46c359ba2 100644
--- a/gobject/gparam.c
+++ b/gobject/gparam.c
@@ -417,7 +417,7 @@ is_canonical (const gchar *key)
  * @blurb, which should be a somewhat longer description, suitable for
  * e.g. a tooltip. The @nick and @blurb should ideally be localized.
  *
- * Returns: a newly allocated #GParamSpec instance
+ * Returns: (type GObject.ParamSpec): a newly allocated #GParamSpec instance
  */
 gpointer
 g_param_spec_internal (GType        param_type,
diff --git a/gobject/gsignal.c b/gobject/gsignal.c
index 91d748ae0..9229f44a6 100644
--- a/gobject/gsignal.c
+++ b/gobject/gsignal.c
@@ -2112,7 +2112,8 @@ g_signal_chain_from_overridden (const GValue *instance_and_params,
 
 /**
  * g_signal_chain_from_overridden_handler: (skip)
- * @instance: the instance the signal is being emitted on.
+ * @instance: (type GObject.TypeInstance): the instance the signal is being
+ *    emitted on.
  * @...: parameters to be passed to the parent class closure, followed by a
  *  location for the return value. If the return type of the signal
  *  is #G_TYPE_NONE, the return value location can be omitted.
@@ -3141,7 +3142,8 @@ accumulate (GSignalInvocationHint *ihint,
 
 /**
  * g_signal_emit_valist: (skip)
- * @instance: the instance the signal is being emitted on.
+ * @instance: (type GObject.TypeInstance): the instance the signal is being
+ *    emitted on.
  * @signal_id: the signal id
  * @detail: the detail
  * @var_args: a list of parameters to be passed to the signal, followed by a
diff --git a/gobject/gtype.c b/gobject/gtype.c
index 754507999..eb416aba9 100644
--- a/gobject/gtype.c
+++ b/gobject/gtype.c
@@ -4502,7 +4502,8 @@ gobject_init_ctor (void)
 
 /**
  * g_type_class_add_private:
- * @g_class: class structure for an instantiatable type
+ * @g_class: (type GObject.TypeClass): class structure for an instantiatable
+ *    type
  * @private_size: size of private structure
  *
  * Registers a private structure for an instantiatable type.
@@ -4734,7 +4735,7 @@ g_type_instance_get_private (GTypeInstance *instance,
 
 /**
  * g_type_class_get_instance_private_offset: (skip)
- * @g_class: a #GTypeClass
+ * @g_class: (type GObject.TypeClass): a #GTypeClass
  *
  * Gets the offset of the private data for instances of @g_class.
  *
diff --git a/gobject/gtype.h b/gobject/gtype.h
index f4cbf2f99..25f5bc12d 100644
--- a/gobject/gtype.h
+++ b/gobject/gtype.h
@@ -629,7 +629,7 @@ struct _GTypeQuery
  * This macro should only be used in type implementations.
  * 
  * Since: 2.4
- * Returns: a pointer to the private data structure
+ * Returns: (not nullable): a pointer to the private data structure
  */
 #define G_TYPE_INSTANCE_GET_PRIVATE(instance, g_type, c_type)   ((c_type*) g_type_instance_get_private ((GTypeInstance*) (instance), (g_type)))
 
@@ -646,7 +646,7 @@ struct _GTypeQuery
  * This macro should only be used in type implementations.
  * 
  * Since: 2.24
- * Returns: a pointer to the private data structure
+ * Returns: (not nullable): a pointer to the private data structure
  */
 #define G_TYPE_CLASS_GET_PRIVATE(klass, g_type, c_type)   ((c_type*) g_type_class_get_private ((GTypeClass*) (klass), (g_type)))
 
@@ -746,7 +746,7 @@ int                   g_type_get_instance_count      (GType            type);
 /* --- type registration --- */
 /**
  * GBaseInitFunc:
- * @g_class: The #GTypeClass structure to initialize
+ * @g_class: (type GObject.TypeClass): The #GTypeClass structure to initialize
  * 
  * A callback function used by the type system to do base initialization
  * of the class structures of derived types. It is called as part of the
@@ -755,23 +755,23 @@ int                   g_type_get_instance_count      (GType            type);
  * For example, class members (such as strings) that are not sufficiently
  * handled by a plain memory copy of the parent class into the derived class
  * have to be altered. See GClassInitFunc() for a discussion of the class
- * intialization process.
+ * initialization process.
  */
 typedef void   (*GBaseInitFunc)              (gpointer         g_class);
 /**
  * GBaseFinalizeFunc:
- * @g_class: The #GTypeClass structure to finalize
+ * @g_class: (type GObject.TypeClass): The #GTypeClass structure to finalize
  * 
  * A callback function used by the type system to finalize those portions
  * of a derived types class structure that were setup from the corresponding
  * GBaseInitFunc() function. Class finalization basically works the inverse
- * way in which class intialization is performed.
- * See GClassInitFunc() for a discussion of the class intialization process.
+ * way in which class initialization is performed.
+ * See GClassInitFunc() for a discussion of the class initialization process.
  */
 typedef void   (*GBaseFinalizeFunc)          (gpointer         g_class);
 /**
  * GClassInitFunc:
- * @g_class: The #GTypeClass structure to initialize.
+ * @g_class: (type GObject.TypeClass): The #GTypeClass structure to initialize.
  * @class_data: The @class_data member supplied via the #GTypeInfo structure.
  * 
  * A callback function used by the type system to initialize the class
@@ -874,7 +874,7 @@ typedef void   (*GClassInitFunc)             (gpointer         g_class,
 					      gpointer         class_data);
 /**
  * GClassFinalizeFunc:
- * @g_class: The #GTypeClass structure to finalize
+ * @g_class: (type GObject.TypeClass): The #GTypeClass structure to finalize
  * @class_data: The @class_data member supplied via the #GTypeInfo structure
  * 
  * A callback function used by the type system to finalize a class.
@@ -890,7 +890,8 @@ typedef void   (*GClassFinalizeFunc)         (gpointer         g_class,
 /**
  * GInstanceInitFunc:
  * @instance: The instance to initialize
- * @g_class: The class of the type the instance is created for
+ * @g_class: (type GObject.TypeClass): The class of the type the instance is
+ *    created for
  * 
  * A callback function used by the type system to initialize a new
  * instance of a type. This function initializes all instance members and
@@ -908,7 +909,7 @@ typedef void   (*GInstanceInitFunc)          (GTypeInstance   *instance,
 					      gpointer         g_class);
 /**
  * GInterfaceInitFunc:
- * @g_iface: The interface structure to initialize
+ * @g_iface: (type GObject.TypeInterface): The interface structure to initialize
  * @iface_data: The @interface_data supplied via the #GInterfaceInfo structure
  * 
  * A callback function used by the type system to initialize a new
@@ -922,7 +923,7 @@ typedef void   (*GInterfaceInitFunc)         (gpointer         g_iface,
 					      gpointer         iface_data);
 /**
  * GInterfaceFinalizeFunc:
- * @g_iface: The interface structure to finalize
+ * @g_iface: (type GObject.TypeInterface): The interface structure to finalize
  * @iface_data: The @interface_data supplied via the #GInterfaceInfo structure
  * 
  * A callback function used by the type system to finalize an interface.
@@ -934,7 +935,8 @@ typedef void   (*GInterfaceFinalizeFunc)     (gpointer         g_iface,
 /**
  * GTypeClassCacheFunc:
  * @cache_data: data that was given to the g_type_add_class_cache_func() call
- * @g_class: The #GTypeClass structure which is unreferenced
+ * @g_class: (type GObject.TypeClass): The #GTypeClass structure which is
+ *    unreferenced
  * 
  * A callback function which is called when the reference count of a class 
  * drops to zero. It may use g_type_class_ref() to prevent the class from
@@ -954,7 +956,8 @@ typedef gboolean (*GTypeClassCacheFunc)	     (gpointer	       cache_data,
 /**
  * GTypeInterfaceCheckFunc:
  * @check_data: data passed to g_type_add_interface_check()
- * @g_iface: the interface that has been initialized
+ * @g_iface: (type GObject.TypeInterface): the interface that has been
+ *    initialized
  * 
  * A callback called after an interface vtable is initialized.
  * See g_type_add_interface_check().
diff --git a/gobject/gvalue.c b/gobject/gvalue.c
index a3709b4ec..7276cc102 100644
--- a/gobject/gvalue.c
+++ b/gobject/gvalue.c
@@ -379,7 +379,7 @@ g_value_set_instance (GValue  *value,
 /**
  * g_value_init_from_instance:
  * @value: An uninitialized #GValue structure.
- * @instance: the instance
+ * @instance: (type GObject.TypeInstance): the instance
  *
  * Initializes and sets @value from an instantiatable type via the
  * value_table's collect_value() function.