Minor fixes for new adder and multiplier gates classes

qiskit/circuit/library/arithmetic/adders/adder.py

@@ -231,4 +231,5 @@ def _define(self):
         """Populates self.definition with a decomposition of this gate."""
         from qiskit.synthesis.arithmetic import adder_ripple_c04
 
+        # In the case of a full adder, this method does not use any ancilla qubits
         self.definition = adder_ripple_c04(self.num_state_qubits, kind="full")

qiskit/transpiler/passes/synthesis/hls_plugins.py

@@ -1357,7 +1357,9 @@ def run(self, high_level_object, coupling_map=None, target=None, qubits=None, **
             return decomposition
 
         # The QFT-based adder does not require ancilla qubits and should always succeed
-        return HalfAdderSynthesisD00.run(high_level_object, coupling_map, target, qubits, **options)
+        return HalfAdderSynthesisD00().run(
+            high_level_object, coupling_map, target, qubits, **options
+        )
 
 
 class HalfAdderSynthesisC04(HighLevelSynthesisPlugin):

releasenotes/notes/fix-adder-gates-39cf3d5f683e8880.yaml

@@ -1,20 +1,19 @@
 ---
-features_transpiler:
-  - |
-    Added :class:`.FullAdderSynthesisDefault` plugin that chooses the best decomposition
-    for :class:`.FullAdderGate` based on the number of clean ancilla qubits 
-    available. 
-  - |
-    Improved :class:`.HalfAdderSynthesisDefault` and :class:`.ModularAdderSynthesisDefault`
-    plugins for :class:`.HalfAdderGate` and :class:`.ModularAdderGate` respectively,
-    choosing the best decomposition based on the number of clean ancilla qubits available.
 fixes:
   - |
-    Adding default definitions for :class:`.FullAdderGate`, :class:`.HalfAdderGate`,
+    Added default definitions for :class:`.FullAdderGate`, :class:`.HalfAdderGate`,
     :class:`.ModularAdderGate` and :class:`.MultiplierGate` gates, allowing to 
     contruct :class:`qiskit.quantum_info.Operator`\s from quantum circuits 
     containing these gates.
   - |
     Fixed the number of clean ancilla qubits required by
     :class:`.FullAdderSynthesisV95`, :class:`.HalfAdderSynthesisV95`, and
     :class:`.ModularAdderSynthesisV95` plugins.
+  - |
+    Added missing :class:`.FullAdderSynthesisDefault` plugin that chooses the best
+    decomposition for :class:`.FullAdderGate` based on the number of clean ancilla qubits
+    available.
+  - |
+    Fixed :class:`.HalfAdderSynthesisDefault` and :class:`.ModularAdderSynthesisDefault`
+    plugins, for :class:`.HalfAdderGate` and :class:`.ModularAdderGate` respectively,
+    to choose the best decomposition based on the number of clean ancilla qubits available.

test/python/circuit/library/test_adders.py

@@ -233,6 +233,57 @@ def test_plugins_when_do_not_apply(self):
             synth = hls(circuit)
             self.assertEqual(synth.count_ops(), {"ModularAdder": 1})
 
+    def test_default_plugins(self):
+        """Tests covering different branches in the default synthesis plugins.."""
+        with self.subTest(name="HalfAdderTest1"):
+            adder = HalfAdderGate(3)
+            circuit = QuantumCircuit(9)
+            circuit.append(adder, range(7))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+        with self.subTest(name="HalfAdderTest2"):
+            adder = HalfAdderGate(4)
+            circuit = QuantumCircuit(12)
+            circuit.append(adder, range(9))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+        with self.subTest(name="HalfAdderTest3"):
+            adder = HalfAdderGate(4)
+            circuit = QuantumCircuit(9)
+            circuit.append(adder, range(9))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+        with self.subTest(name="FullAdderTest1"):
+            adder = FullAdderGate(4)
+            circuit = QuantumCircuit(10)
+            circuit.append(adder, range(10))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+        with self.subTest(name="FullAdderTest2"):
+            adder = FullAdderGate(1)
+            circuit = QuantumCircuit(10)
+            circuit.append(adder, range(4))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+        with self.subTest(name="ModularAdderTest1"):
+            adder = ModularAdderGate(4)
+            circuit = QuantumCircuit(8)
+            circuit.append(adder, range(8))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+        with self.subTest(name="ModularAdderTest2"):
+            adder = ModularAdderGate(6)
+            circuit = QuantumCircuit(12)
+            circuit.append(adder, range(12))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+        with self.subTest(name="ModularAdderTest3"):
+            adder = ModularAdderGate(6)
+            circuit = QuantumCircuit(16)
+            circuit.append(adder, range(12))
+            hls = HighLevelSynthesis()
+            _ = hls(circuit)
+
 
 if __name__ == "__main__":
     unittest.main()