From 52e8811d97afcda72fae42310b4e5b6a98155f73 Mon Sep 17 00:00:00 2001
From: Luciano Bello <bel@zurich.ibm.com>
Date: Mon, 24 Feb 2025 17:10:30 +0100
Subject: [PATCH 1/4] rename module

---
 qiskit/circuit/{add_control.py => _add_control.py} | 0
 qiskit/circuit/gate.py                             | 2 +-
 test/python/circuit/test_controlled_gate.py        | 2 +-
 3 files changed, 2 insertions(+), 2 deletions(-)
 rename qiskit/circuit/{add_control.py => _add_control.py} (100%)

diff --git a/qiskit/circuit/add_control.py b/qiskit/circuit/_add_control.py
similarity index 100%
rename from qiskit/circuit/add_control.py
rename to qiskit/circuit/_add_control.py
diff --git a/qiskit/circuit/gate.py b/qiskit/circuit/gate.py
index 122db0973124..f087c02f2844 100644
--- a/qiskit/circuit/gate.py
+++ b/qiskit/circuit/gate.py
@@ -137,7 +137,7 @@ def control(
         """
         if not annotated:  # captures both None and False
             # pylint: disable=cyclic-import
-            from .add_control import add_control
+            from ._add_control import add_control
 
             return add_control(self, num_ctrl_qubits, label, ctrl_state)
 
diff --git a/test/python/circuit/test_controlled_gate.py b/test/python/circuit/test_controlled_gate.py
index 02190e07f882..a00f680dc388 100644
--- a/test/python/circuit/test_controlled_gate.py
+++ b/test/python/circuit/test_controlled_gate.py
@@ -27,7 +27,7 @@
 from qiskit.quantum_info.operators.predicates import matrix_equal, is_unitary_matrix
 from qiskit.quantum_info.random import random_unitary
 from qiskit.quantum_info.states import Statevector
-import qiskit.circuit.add_control as ac
+import qiskit.circuit._add_control as ac
 from qiskit.transpiler.passes import UnrollCustomDefinitions, BasisTranslator
 from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager
 from qiskit.converters.circuit_to_dag import circuit_to_dag

From 63c7bb3fdec1d3feef04f7f8e2241d7e78a197b7 Mon Sep 17 00:00:00 2001
From: Luciano Bello <bel@zurich.ibm.com>
Date: Mon, 24 Feb 2025 17:29:22 +0100
Subject: [PATCH 2/4] simplify tests

---
 test/python/circuit/test_controlled_gate.py | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/test/python/circuit/test_controlled_gate.py b/test/python/circuit/test_controlled_gate.py
index a00f680dc388..980c670194de 100644
--- a/test/python/circuit/test_controlled_gate.py
+++ b/test/python/circuit/test_controlled_gate.py
@@ -27,7 +27,6 @@
 from qiskit.quantum_info.operators.predicates import matrix_equal, is_unitary_matrix
 from qiskit.quantum_info.random import random_unitary
 from qiskit.quantum_info.states import Statevector
-import qiskit.circuit._add_control as ac
 from qiskit.transpiler.passes import UnrollCustomDefinitions, BasisTranslator
 from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager
 from qiskit.converters.circuit_to_dag import circuit_to_dag
@@ -1584,10 +1583,10 @@ class TestSingleControlledRotationGates(QiskitTestCase):
     gry = ry.RYGate(theta)
     grz = rz.RZGate(theta)
 
-    ugu1 = ac._unroll_gate(gu1, ["p", "u", "cx"])
-    ugrx = ac._unroll_gate(grx, ["p", "u", "cx"])
-    ugry = ac._unroll_gate(gry, ["p", "u", "cx"])
-    ugrz = ac._unroll_gate(grz, ["p", "u", "cx"])
+    ugu1 = u1.U1Gate(theta).definition
+    ugrx = rx.RXGate(theta).definition
+    ugry = ry.RYGate(theta).definition
+    ugrz = rz.RZGate(theta).definition
     ugrz.params = grz.params
 
     cgu1 = ugu1.control(num_ctrl)

From ec86e8ffe4c67db2d0a101bcbde6d7c6ae6b9a8a Mon Sep 17 00:00:00 2001
From: Luciano Bello <bel@zurich.ibm.com>
Date: Mon, 24 Feb 2025 17:31:39 +0100
Subject: [PATCH 3/4] reno

---
 .../notes/private-add_control-2367872c0f7136c4.yaml         | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 releasenotes/notes/private-add_control-2367872c0f7136c4.yaml

diff --git a/releasenotes/notes/private-add_control-2367872c0f7136c4.yaml b/releasenotes/notes/private-add_control-2367872c0f7136c4.yaml
new file mode 100644
index 000000000000..862ccaa3af7b
--- /dev/null
+++ b/releasenotes/notes/private-add_control-2367872c0f7136c4.yaml
@@ -0,0 +1,6 @@
+---
+upgrade_circuits:
+  - |
+    The internal function ``qiskit.circuit.add_control.add_control`` was removed and inlined, as it is not part of the
+    public API. User that had been wrongly using it as ``add_control(SomeGate(...), ...)`` should change their code to
+    ``SomeGate(...).control(...)`` instead.

From d9b744ab13a8a6f4c0f3b50c87bc0c537600537f Mon Sep 17 00:00:00 2001
From: Jake Lishman <jake@binhbar.com>
Date: Thu, 6 Mar 2025 09:53:27 +0100
Subject: [PATCH 4/4] Reword release note

---
 .../notes/private-add_control-2367872c0f7136c4.yaml         | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/releasenotes/notes/private-add_control-2367872c0f7136c4.yaml b/releasenotes/notes/private-add_control-2367872c0f7136c4.yaml
index 862ccaa3af7b..17fe70ef8d6d 100644
--- a/releasenotes/notes/private-add_control-2367872c0f7136c4.yaml
+++ b/releasenotes/notes/private-add_control-2367872c0f7136c4.yaml
@@ -1,6 +1,6 @@
 ---
 upgrade_circuits:
   - |
-    The internal function ``qiskit.circuit.add_control.add_control`` was removed and inlined, as it is not part of the
-    public API. User that had been wrongly using it as ``add_control(SomeGate(...), ...)`` should change their code to
-    ``SomeGate(...).control(...)`` instead.
+    The internal function ``qiskit.circuit.add_control.add_control`` was removed, as it is not part of the
+    public API. It had fragile preconditions to uphold and was a common source of bugs. Uses of ``add_control(SomeGate(...), ...)``
+    should change to ``SomeGate(...).control(...)`` using :meth:`.Gate.control` instead, which is far safer.