matplotlib · ksunden · Nov 3, 2022 · Nov 2, 2022
diff --git a/lib/matplotlib/_tight_layout.py b/lib/matplotlib/_tight_layout.py
@@ -226,7 +226,10 @@ def get_tight_layout_figure(fig, axes_list, subplotspec_list, renderer,
     ss_to_subplots = {ss: [] for ss in subplotspec_list}
     for ax, ss in zip(axes_list, subplotspec_list):
         ss_to_subplots[ss].append(ax)
-    ss_to_subplots.pop(None, None)  # Skip subplotspec == None.
+    if ss_to_subplots.pop(None, None):
+        _api.warn_external(
+            "This figure includes Axes that are not compatible with "
+            "tight_layout, so results might be incorrect.")
     if not ss_to_subplots:
         return {}
     subplot_list = list(ss_to_subplots.values())

diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -3424,12 +3424,6 @@ def tight_layout(self, *, pad=1.08, h_pad=None, w_pad=None, rect=None):
         .Figure.set_layout_engine
         .pyplot.tight_layout
         """
-        from ._tight_layout import get_subplotspec_list
-        subplotspec_list = get_subplotspec_list(self.axes)
-        if None in subplotspec_list:
-            _api.warn_external("This figure includes Axes that are not "
-                               "compatible with tight_layout, so results "
-                               "might be incorrect.")
         # note that here we do not permanently set the figures engine to
         # tight_layout but rather just perform the layout in place and remove
         # any previous engines.

diff --git a/lib/matplotlib/gridspec.py b/lib/matplotlib/gridspec.py
@@ -467,20 +467,12 @@ def tight_layout(self, figure, renderer=None,
             coordinates that the whole subplots area (including labels) will
             fit into. Default (None) is the whole figure.
         """
-
-        subplotspec_list = _tight_layout.get_subplotspec_list(
-            figure.axes, grid_spec=self)
-        if None in subplotspec_list:
-            _api.warn_external("This figure includes Axes that are not "
-                               "compatible with tight_layout, so results "
-                               "might be incorrect.")
-
         if renderer is None:
             renderer = figure._get_renderer()
-
         kwargs = _tight_layout.get_tight_layout_figure(
-            figure, figure.axes, subplotspec_list, renderer,
-            pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
+            figure, figure.axes,
+            _tight_layout.get_subplotspec_list(figure.axes, grid_spec=self),
+            renderer, pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
         if kwargs:
             self.update(**kwargs)
 

diff --git a/lib/matplotlib/layout_engine.py b/lib/matplotlib/layout_engine.py
@@ -17,7 +17,6 @@
 from contextlib import nullcontext
 
 import matplotlib as mpl
-import matplotlib._api as _api
 
 from matplotlib._constrained_layout import do_constrained_layout
 from matplotlib._tight_layout import (get_subplotspec_list,
@@ -170,15 +169,10 @@ def execute(self, fig):
         See also: `.figure.Figure.tight_layout` and `.pyplot.tight_layout`.
         """
         info = self._params
-        subplotspec_list = get_subplotspec_list(fig.axes)
-        if None in subplotspec_list:
-            _api.warn_external("This figure includes Axes that are not "
-                               "compatible with tight_layout, so results "
-                               "might be incorrect.")
         renderer = fig._get_renderer()
         with getattr(renderer, "_draw_disabled", nullcontext)():
             kwargs = get_tight_layout_figure(
-                fig, fig.axes, subplotspec_list, renderer,
+                fig, fig.axes, get_subplotspec_list(fig.axes), renderer,
                 pad=info['pad'], h_pad=info['h_pad'], w_pad=info['w_pad'],
                 rect=info['rect'])
         if kwargs: