From 33704ea61f6a3fa60612cbe4463894d2859fe9ec Mon Sep 17 00:00:00 2001
From: Diego Emilio Serrano <65074936+diemilio@users.noreply.github.com>
Date: Wed, 19 Apr 2023 20:48:44 -0400
Subject: [PATCH] Fix circuit drawer for instructions with circuit parameters
 (#9942)

* fix: modify get_param_str to prevent circuit drawer from displaying params of type QuantumCircuit

* fix lint errors

* test: add circuit drawer test for instructions with parameters of type QuantumCircuit

* test: add circuit drawer tests for no parameters and params of type ndarray

* fix lint errors

* remove variable to fix lint error

* add reno

* update releasenotes/notes/fix-circuit-drawer-for-qc-params
---
 qiskit/visualization/circuit/_utils.py        | 12 ++---
 ...drawer-for-qc-params-e78c67310ae43ccf.yaml |  5 ++
 .../visualization/test_circuit_text_drawer.py | 50 ++++++++++++++++++-
 3 files changed, 60 insertions(+), 7 deletions(-)
 create mode 100644 releasenotes/notes/fix-circuit-drawer-for-qc-params-e78c67310ae43ccf.yaml

diff --git a/qiskit/visualization/circuit/_utils.py b/qiskit/visualization/circuit/_utils.py
index 5242e0c48d46..4117b0e76177 100644
--- a/qiskit/visualization/circuit/_utils.py
+++ b/qiskit/visualization/circuit/_utils.py
@@ -25,10 +25,9 @@
     Gate,
     Instruction,
     Measure,
-    ControlFlowOp,
 )
 from qiskit.circuit.library import PauliEvolutionGate
-from qiskit.circuit import ClassicalRegister
+from qiskit.circuit import ClassicalRegister, QuantumCircuit
 from qiskit.circuit.tools import pi_check
 from qiskit.converters import circuit_to_dag
 from qiskit.utils import optionals as _optionals
@@ -119,10 +118,11 @@ def get_gate_ctrl_text(op, drawer, style=None, calibrations=None):
 
 def get_param_str(op, drawer, ndigits=3):
     """Get the params as a string to add to the gate text display"""
-    if not hasattr(op, "params") or any(isinstance(param, np.ndarray) for param in op.params):
-        return ""
-
-    if isinstance(op, ControlFlowOp):
+    if (
+        not hasattr(op, "params")
+        or any(isinstance(param, np.ndarray) for param in op.params)
+        or any(isinstance(param, QuantumCircuit) for param in op.params)
+    ):
         return ""
 
     if isinstance(op, Delay):
diff --git a/releasenotes/notes/fix-circuit-drawer-for-qc-params-e78c67310ae43ccf.yaml b/releasenotes/notes/fix-circuit-drawer-for-qc-params-e78c67310ae43ccf.yaml
new file mode 100644
index 000000000000..778c42041643
--- /dev/null
+++ b/releasenotes/notes/fix-circuit-drawer-for-qc-params-e78c67310ae43ccf.yaml
@@ -0,0 +1,5 @@
+fixes:
+  - |
+    Fixes the circuit drawer from displaying parameters when they are of type :class:`.QuantumCircuit`
+    since this resulted in an illegible drawing.
+    
\ No newline at end of file
diff --git a/test/python/visualization/test_circuit_text_drawer.py b/test/python/visualization/test_circuit_text_drawer.py
index 9a44a7ed2cd6..e5d4f543734e 100644
--- a/test/python/visualization/test_circuit_text_drawer.py
+++ b/test/python/visualization/test_circuit_text_drawer.py
@@ -22,7 +22,7 @@
 import numpy
 
 from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister, transpile
-from qiskit.circuit import Gate, Parameter, Qubit, Clbit
+from qiskit.circuit import Gate, Parameter, Qubit, Clbit, Instruction
 from qiskit.quantum_info.operators import SuperOp
 from qiskit.quantum_info.random import random_unitary
 from qiskit.test import QiskitTestCase
@@ -1839,6 +1839,21 @@ def test_control_gate_label_with_cond_2_low_cregbundle(self):
 class TestTextDrawerParams(QiskitTestCase):
     """Test drawing parameters."""
 
+    def test_text_no_parameters(self):
+        """Test drawing with no parameters"""
+        expected = "\n".join(
+            [
+                "      ┌───┐",
+                "q: |0>┤ X ├",
+                "      └───┘",
+            ]
+        )
+
+        qr = QuantumRegister(1, "q")
+        circuit = QuantumCircuit(qr)
+        circuit.x(0)
+        self.assertEqual(str(_text_circuit_drawer(circuit)), expected)
+
     def test_text_parameters_mix(self):
         """cu3 drawing with parameters"""
         expected = "\n".join(
@@ -1904,6 +1919,39 @@ def test_text_utf8(self):
         circuit.u(0, phi, lam, 0)
         self.assertEqual(circuit.draw(output="text").single_string(), expected)
 
+    def test_text_ndarray_parameters(self):
+        """Test that if params are type ndarray, params are not displayed."""
+        # fmt: off
+        expected = "\n".join(["      ┌─────────┐",
+                              "q: |0>┤ Unitary ├",
+                              "      └─────────┘"])
+        # fmt: on
+        qr = QuantumRegister(1, "q")
+        circuit = QuantumCircuit(qr)
+        circuit.unitary(numpy.array([[0, 1], [1, 0]]), 0)
+        self.assertEqual(str(_text_circuit_drawer(circuit)), expected)
+
+    def test_text_qc_parameters(self):
+        """Test that if params are type QuantumCircuit, params are not displayed."""
+        expected = "\n".join(
+            [
+                "        ┌───────┐",
+                "q_0: |0>┤0      ├",
+                "        │  name │",
+                "q_1: |0>┤1      ├",
+                "        └───────┘",
+            ]
+        )
+
+        my_qc_param = QuantumCircuit(2)
+        my_qc_param.h(0)
+        my_qc_param.cx(0, 1)
+        inst = Instruction("name", 2, 0, [my_qc_param])
+        qr = QuantumRegister(2, "q")
+        circuit = QuantumCircuit(qr)
+        circuit.append(inst, [0, 1])
+        self.assertEqual(str(_text_circuit_drawer(circuit)), expected)
+
 
 class TestTextDrawerVerticalCompressionLow(QiskitTestCase):
     """Test vertical_compression='low'"""