Bug report

Consider you have a figure with multiple subplots sharing the X axis (fig.subplots(2, 2, sharex="all")). When using axhspan() in an Ax without data, the rest of Axes will change the X axis potentially leaving data outside the range.

Code for reproduction

import matplotlib.pyplot as plt

fig = plt.figure()
ax1, ax2 = fig.subplots(2, 1, sharex="all")
ax1.set_title("ax1")
ax2.set_title("ax2")

ax1.scatter([1, 2, 3, 4], [2, 3, 2, 3])
ax2.axhspan(-5, 5, alpha=0.2)

fig.show()

Actual outcome

Expected outcome

I expected both Axes to use a shared X axis in the range 1 to 4, because the data covers that interval

Matplotlib version

• Operating system: Debian 10
• Matplotlib version: 3.2.2
• Matplotlib backend (print(matplotlib.get_backend())): nbAgg
• Python version: 3.7.3
• Jupyter version (if applicable): Happens outside of Jupyter as well

Installed via pip. Running inside a python3 -m venv

Thank you!