Merge pull request matplotlib#22931 from larsoner/ls

BUG: Fix regression with ls=(0, ())

Author: timhoffm

lib/matplotlib/backend_bases.py

@@ -924,7 +924,7 @@ def set_dashes(self, dash_offset, dash_list):
             if np.any(dl < 0.0):
                 raise ValueError(
                     "All values in the dash list must be non-negative")
-            if not np.any(dl > 0.0):
+            if dl.size and not np.any(dl > 0.0):
                 raise ValueError(
                     'At least one value in the dash list must be positive')
         self._dashes = dash_offset, dash_list

lib/matplotlib/tests/test_lines.py

@@ -108,7 +108,9 @@ def test_valid_colors():
 def test_linestyle_variants():
     fig, ax = plt.subplots()
     for ls in ["-", "solid", "--", "dashed",
-               "-.", "dashdot", ":", "dotted"]:
+               "-.", "dashdot", ":", "dotted",
+               (0, None), (0, ()), (0, []),  # gh-22930
+               ]:
         ax.plot(range(10), linestyle=ls)
     fig.canvas.draw()