This goes undiagnosed under normal circumstances, but is a critical
warning (which is fatal by default) under G_ENABLE_DIAGNOSTIC. This is a
programming error, so we should only exercise it under
g_test_undefined(), and only in a test that is intentionally doing this
(as in the previous commit).
Signed-off-by: Simon McVittie <smcv@collabora.com>
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.
There is (at most) a single GType that is instantiable and a
prerequisite for an interface. This function returns that type.
This type is necessary in particular when dealing with GValues because a
GValue contains an instance of a type.
