Backport PR matplotlib#27504: DOC: correct return type for axline

Author: timhoffm

lib/matplotlib/axes/_axes.py

@@ -893,7 +893,7 @@ def axline(self, xy1, xy2=None, *, slope=None, **kwargs):
 
         Returns
         -------
-        `.Line2D`
+        `.AxLine`
 
         Other Parameters
         ----------------

lib/matplotlib/axes/_axes.pyi

@@ -18,7 +18,7 @@ from matplotlib.contour import ContourSet, QuadContourSet
 from matplotlib.image import AxesImage, PcolorImage
 from matplotlib.legend import Legend
 from matplotlib.legend_handler import HandlerBase
-from matplotlib.lines import Line2D
+from matplotlib.lines import Line2D, AxLine
 from matplotlib.mlab import GaussianKDE
 from matplotlib.patches import Rectangle, FancyArrow, Polygon, StepPatch, Wedge
 from matplotlib.quiver import Quiver, QuiverKey, Barbs
@@ -151,7 +151,7 @@ class Axes(_AxesBase):
         *,
         slope: float | None = ...,
         **kwargs
-    ) -> Line2D: ...
+    ) -> AxLine: ...
     def axhspan(
         self, ymin: float, ymax: float, xmin: float = ..., xmax: float = ..., **kwargs
     ) -> Polygon: ...

lib/matplotlib/pyplot.py

@@ -130,7 +130,7 @@
 
 # We may not need the following imports here:
 from matplotlib.colors import Normalize
-from matplotlib.lines import Line2D
+from matplotlib.lines import Line2D, AxLine
 from matplotlib.text import Text, Annotation
 from matplotlib.patches import Polygon, Rectangle, Circle, Arrow
 from matplotlib.widgets import Button, Slider, Widget
@@ -2721,7 +2721,7 @@ def axline(
     *,
     slope: float | None = None,
     **kwargs,
-) -> Line2D:
+) -> AxLine:
     return gca().axline(xy1, xy2=xy2, slope=slope, **kwargs)