Implement __eq__ for remaining standard-library gates except mcx (#13327)

Most standard-library gates had a specialised `__eq__` added in
gh-11370, but a small number were left over.  This adds specialisation
to almost all the stragglers, which were mostly old soft-deperecated
gates.  Despite not appearing in most circuits, these gates have an
outsized effect on equality comparisons if they ever _do_ appear,
because they involve construction of entire `definition` fields.

Author: jakelishman

qiskit/circuit/library/standard_gates/p.py

@@ -431,3 +431,11 @@ def control(
     def inverse(self, annotated: bool = False):
         r"""Return inverted MCPhase gate (:math:`MCPhase(\lambda)^{\dagger} = MCPhase(-\lambda)`)"""
         return MCPhaseGate(-self.params[0], self.num_ctrl_qubits)
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, MCPhaseGate)
+            and self.num_ctrl_qubits == other.num_ctrl_qubits
+            and self.ctrl_state == other.ctrl_state
+            and self._compare_parameters(other)
+        )

qiskit/circuit/library/standard_gates/u.py

@@ -393,3 +393,10 @@ def __deepcopy__(self, memo=None):
         out = super().__deepcopy__(memo)
         out._params = _copy.deepcopy(out._params, memo)
         return out
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, CUGate)
+            and self.ctrl_state == other.ctrl_state
+            and self._compare_parameters(other)
+        )

qiskit/circuit/library/standard_gates/u1.py

@@ -170,6 +170,9 @@ def __array__(self, dtype=None, copy=None):
         lam = float(self.params[0])
         return numpy.array([[1, 0], [0, numpy.exp(1j * lam)]], dtype=dtype)
 
+    def __eq__(self, other):
+        return isinstance(other, U1Gate) and self._compare_parameters(other)
+
 
 class CU1Gate(ControlledGate):
     r"""Controlled-U1 gate.
@@ -341,6 +344,13 @@ def __array__(self, dtype=None, copy=None):
                 [[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, eith, 0], [0, 0, 0, 1]], dtype=dtype
             )
 
+    def __eq__(self, other):
+        return (
+            isinstance(other, CU1Gate)
+            and self.ctrl_state == other.ctrl_state
+            and self._compare_parameters(other)
+        )
+
 
 class MCU1Gate(ControlledGate):
     r"""Multi-controlled-U1 gate.
@@ -481,3 +491,11 @@ def inverse(self, annotated: bool = False):
             MCU1Gate: inverse gate.
         """
         return MCU1Gate(-self.params[0], self.num_ctrl_qubits)
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, MCU1Gate)
+            and self.num_ctrl_qubits == other.num_ctrl_qubits
+            and self.ctrl_state == other.ctrl_state
+            and self._compare_parameters(other)
+        )

qiskit/circuit/library/standard_gates/u2.py

@@ -144,3 +144,6 @@ def __array__(self, dtype=None, copy=None):
             ],
             dtype=dtype or complex,
         )
+
+    def __eq__(self, other):
+        return isinstance(other, U2Gate) and self._compare_parameters(other)

qiskit/circuit/library/standard_gates/u3.py

@@ -178,6 +178,9 @@ def __array__(self, dtype=None, copy=None):
             dtype=dtype or complex,
         )
 
+    def __eq__(self, other):
+        return isinstance(other, U3Gate) and self._compare_parameters(other)
+
 
 class CU3Gate(ControlledGate):
     r"""Controlled-U3 gate (3-parameter two-qubit gate).
@@ -368,6 +371,13 @@ def __array__(self, dtype=None, copy=None):
                 dtype=dtype or complex,
             )
 
+    def __eq__(self, other):
+        return (
+            isinstance(other, CU3Gate)
+            and self.ctrl_state == other.ctrl_state
+            and self._compare_parameters(other)
+        )
+
 
 def _generate_gray_code(num_bits):
     """Generate the gray code for ``num_bits`` bits."""

releasenotes/notes/circuit-library-missing-eq-568e7a72008c0ab2.yaml

@@ -0,0 +1,6 @@
+---
+features_circuits:
+  - |
+    Specialized implementations of :meth:`~object.__eq__` have been added for all standard-library circuit gates.
+    Most of the standard gates already specialized this method, but a few did not, and could cause significant
+    slowdowns in unexpected places.