Dec 7, 2022 · Nov 21, 2022
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
        engine = TightLayoutEngine(pad=pad, h_pad=h_pad, w_pad=w_pad,
                                   rect=rect)
        try:
            previous_engine = self.get_layout_engine()
            self.set_layout_engine(engine)
            engine.execute(self)
            if not isinstance(previous_engine, TightLayoutEngine) \
                    and previous_engine is not None:
                _api.warn_external('The figure layout has changed to tight')
        finally:
            self.set_layout_engine(None)

diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
        fig.set_layout_engine("constrained")


 @pytest.mark.parametrize('layout', ['constrained', 'compressed'])
 def test_layout_change_warning(layout):
    """
    Raise a warning when a previously assigned layout changes to tight using
    plt.tight_layout().
    """
    fig, ax = plt.subplots(layout=layout)
    with pytest.warns(UserWarning, match='The figure layout has changed to'):
        plt.tight_layout()


 @check_figures_equal(extensions=["png", "pdf"])
 def test_add_artist(fig_test, fig_ref):
    fig_test.dpi = 100
Original file line number	Diff line number	Diff line change
Expand Up		@@ -3430,8 +3430,12 @@ def tight_layout(self, *, pad=1.08, h_pad=None, w_pad=None, rect=None):
		engine = TightLayoutEngine(pad=pad, h_pad=h_pad, w_pad=w_pad,
		rect=rect)
		try:
		previous_engine = self.get_layout_engine()
		self.set_layout_engine(engine)
		engine.execute(self)
		if not isinstance(previous_engine, TightLayoutEngine) \
		and previous_engine is not None:
		_api.warn_external('The figure layout has changed to tight')
		finally:
		self.set_layout_engine(None)

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -598,6 +598,17 @@ def test_invalid_layouts():
		fig.set_layout_engine("constrained")


		@pytest.mark.parametrize('layout', ['constrained', 'compressed'])
		def test_layout_change_warning(layout):
		"""
		Raise a warning when a previously assigned layout changes to tight using
		plt.tight_layout().
		"""
		fig, ax = plt.subplots(layout=layout)
		with pytest.warns(UserWarning, match='The figure layout has changed to'):
		plt.tight_layout()


		@check_figures_equal(extensions=["png", "pdf"])
		def test_add_artist(fig_test, fig_ref):
		fig_test.dpi = 100
Expand Down