If I understand correctly this is executed as a fallback if color could not be detected. Then, it feels wrong to set full transparency, because it makes the text invisible. I think we should rather leave the default as we did before.

Yes, this is a fallback for the case thatfc,ec, andc all havecontinue-ed through, i.e. they are either of the following:

• an empty array,
• 'none' or'None',
• colour with zero alpha value,
• AttributeError raised on the getter function.

Otherwise they would have broken (note thebreak statement) out of the loop beforehand, in which case theelse case of thefor ... else ... construction won't get invoked.

Final example case from thetest_legend_labelcolor_linecolor_plot test:

importnumpyasnpimportmatplotlib.pyplotaspltx=np.arange(5)fig,ax=plt.subplots()p=ax.plot(x,'o',c='none',mec='none',label="invisible circles with invisible label")leg=ax.legend(labelcolor='linecolor')

So yes, the label entry is invisible because the markers and the legend handle are also invisible. In this stand-alone example this seems nonsensical, but something of this sort might come in handy when trying to insert a dummy legend entry in-between other legend entries for spacing.