Error out when x/y are passed as kwargs.

anntzer · anntzer · commit 434a6a59a9f5 · 2018-11-08T11:00:58.000+01:00
We only support passing them positionally; right now passing them as
kwargs silently does nothing.  The error message is the standard one for
unknown kwargs.
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -172,6 +172,11 @@ def __call__(self, *args, **kwargs):
             if yunits != self.axes.yaxis.units:
                 self.axes.yaxis.set_units(yunits)
 
+        for pos_only in "xy":
+            if pos_only in kwargs:
+                raise TypeError("{} got an unexpected keyword argument {!r}"
+                                .format(self.command, pos_only))
+
         if not args:
             return
 
