Soften warnings about unsupported Expr nodes

Author: jakelishman

qiskit/circuit/quantumcircuit.py

@@ -1794,6 +1794,13 @@ def draw(
 
         **latex_source**: raw uncompiled latex output.
 
+        .. warning::
+
+            Support for :class:`~.expr.Expr` nodes in conditions and :attr:`.SwitchCaseOp.target`
+            fields is preliminary and incomplete.  The ``text`` and ``mpl`` drawers will make a
+            best-effort attempt to show data dependencies, but the LaTeX-based drawers will skip
+            these completely.
+
         Args:
             output (str): select the output method to use for drawing the circuit.
                 Valid choices are ``text``, ``mpl``, ``latex``, ``latex_source``.

qiskit/visualization/circuit/circuit_visualization.py

@@ -73,6 +73,12 @@ def circuit_drawer(
 
     **latex_source**: raw uncompiled latex output.
 
+    .. warning::
+
+        Support for :class:`~.expr.Expr` nodes in conditions and :attr:`.SwitchCaseOp.target` fields
+        is preliminary and incomplete.  The ``text`` and ``mpl`` drawers will make a best-effort
+        attempt to show data dependencies, but the LaTeX-based drawers will skip these completely.
+
     Args:
         circuit (QuantumCircuit): the quantum circuit to draw
         scale (float): scale of image to draw (shrink if < 1.0). Only used by

qiskit/visualization/circuit/matplotlib.py

@@ -1107,7 +1107,8 @@ def _condition(self, node, node_data, wire_map, cond_xy, glob_data):
         cond_pos = []
 
         if isinstance(condition, expr.Expr):
-            warn("runtime-expression conditions are not properly supported yet")
+            # If fixing this, please update the docstrings of `QuantumCircuit.draw` and
+            # `visualization.circuit_drawer` to remove warnings.
             condition_bits = condition_resources(condition).clbits
             label = "[expression]"
             override_fc = True

qiskit/visualization/circuit/text.py

@@ -1348,7 +1348,8 @@ def set_cl_multibox(self, condition, top_connect="┴"):
             List: list of tuples of connections between clbits for multi-bit conditions
         """
         if isinstance(condition, expr.Expr):
-            warn("runtime-expression conditions are not properly supported yet")
+            # If fixing this, please update the docstrings of `QuantumCircuit.draw` and
+            # `visualization.circuit_drawer` to remove warnings.
             label = "<expression>"
             out = []
             condition_bits = node_resources(condition).clbits