Fix compatibility with Matplotlib 3.5

azure-pipelines.yml

@@ -778,7 +778,7 @@ stages:
             python -m pip install --upgrade pip
             pip install -U -r requirements.txt -r requirements-dev.txt -c constraints.txt
             pip install -c constraints.txt -e .
-            pip install "qiskit-ibmq-provider" "qiskit-aer" "z3-solver" "qiskit-ignis" "matplotlib>=3.3.0,<3.5" sphinx nbsphinx sphinx_rtd_theme cvxpy -c constraints.txt
+            pip install "qiskit-ibmq-provider" "qiskit-aer" "z3-solver" "qiskit-ignis" "matplotlib>=3.3.0" sphinx nbsphinx sphinx_rtd_theme cvxpy -c constraints.txt
             python setup.py build_ext --inplace
             sudo apt install -y graphviz pandoc
             pip check

qiskit/visualization/bloch.py

@@ -54,19 +54,36 @@
 import matplotlib.pyplot as plt
 from matplotlib.patches import FancyArrowPatch
 from mpl_toolkits.mplot3d import Axes3D, proj3d
+from mpl_toolkits.mplot3d.art3d import Patch3D
 
 from .utils import matplotlib_close_if_inline
 
 
-class Arrow3D(FancyArrowPatch):
+class Arrow3D(Patch3D, FancyArrowPatch):
     """Makes a fancy arrow"""
 
-    def __init__(self, xs, ys, zs, *args, **kwargs):
-        FancyArrowPatch.__init__(self, (0, 0), (0, 0), *args, **kwargs)
-        self._verts3d = xs, ys, zs
+    # Nasty hack around a poorly implemented deprecation warning in Matplotlib 3.5 that issues two
+    # deprecation warnings if an artist's module does not claim to be part of the below module.
+    # This revolves around the method `Patch3D.do_3d_projection(self, renderer=None)`.  The
+    # `renderer` argument has been deprecated since Matplotlib 3.4, but in 3.5 some internal calls
+    # during `Axes3D` display started calling the method.  If an artist does not have this module,
+    # then it issues a deprecation warning, and calls it by passing the `renderer` parameter as
+    # well, which consequently triggers another deprecation warning.  We should be able to remove
+    # this once 3.6 is the minimum supported version, because the deprecation period ends then.
+    __module__ = "mpl_toolkits.mplot3d.art3d"
+
+    def __init__(self, xs, ys, zs, zdir="z", **kwargs):
+        # The Patch3D.__init__() method just calls its own super() method and then
+        # self.set_3d_properties, but it its __init__ signature is actually pretty incompatible with
+        # how it goes on to call set_3d_properties, so we just have to do things ourselves.  The
+        # parent of Patch3D is Patch, which is also a parent of FancyArrowPatch, so its __init__ is
+        # still getting suitably called.
+        # pylint: disable=super-init-not-called
+        FancyArrowPatch.__init__(self, (0, 0), (0, 0), **kwargs)
+        self.set_3d_properties(tuple(zip(xs, ys)), zs, zdir)
 
     def draw(self, renderer):
-        xs3d, ys3d, zs3d = self._verts3d
+        xs3d, ys3d, zs3d = zip(*self._segment3d)
         x_s, y_s, _ = proj3d.proj_transform(xs3d, ys3d, zs3d, self.axes.M)
         self.set_positions((x_s[0], y_s[0]), (x_s[1], y_s[1]))
         FancyArrowPatch.draw(self, renderer)

releasenotes/notes/fix-matplotlib-3.5-40f6d1a109ae06fe.yaml

@@ -0,0 +1,4 @@
+fixes:
+  - |
+    Fixed a compatibility issue with Matplotlib 3.5, where the Bloch sphere would fail to render if it had any vectors attached, such as by using :obj:`~qiskit.visualization.plot_bloch_vector`.
+    See `#7272 <https://github.com/Qiskit/qiskit-terra/issues/7272>`__ for more detail.

requirements-dev.txt

@@ -4,7 +4,7 @@ ipython<7.22.0
 ipykernel<5.5.2
 ipywidgets>=7.3.0
 jupyter
-matplotlib>=3.3,<3.5
+matplotlib>=3.3
 pillow>=4.2.1
 black==21.4b2
 pydot

setup.py

@@ -79,7 +79,7 @@
 
 
 visualization_extras = [
-    "matplotlib>=3.3,<3.5",
+    "matplotlib>=3.3",
     "ipywidgets>=7.3.0",
     "pydot",
     "pillow>=4.2.1",