Tolerate qiskit.circuit.Gate.to_matrix() failures

Co-authored-by: Timon Gehr <timon.gehr@gmx.ch>
Reported-by: Timon Gehr <timon.gehr@gmx.ch>

Author: hvenev-insait

python/qblaze/qiskit.py

@@ -426,11 +426,16 @@ def handle_generic_uncontrolled(self, sim: Simulator, ctl: list[tuple[int, bool]
             self.sv.append((op, sv))
             return
 
-        match op:
-            case qiskit.circuit.Gate() if op.num_qubits == 1:
-                assert not clbits
-                [q] = qubits
-                (theta, phi, lam) = _zyz_decomposer.angles(op.to_matrix())
+        if isinstance(op, qiskit.circuit.Gate) and op.num_qubits == 1:
+            assert not clbits
+            [q] = qubits
+            try:
+                m = op.to_matrix()
+            except qiskit.circuit.exceptions.CircuitError:
+                # Qiskit...
+                pass
+            else:
+                (theta, phi, lam) = _zyz_decomposer.angles(m)
                 return sim.u3(q, theta, phi, lam)
 
         if (sub := op.definition) is not None:
@@ -439,13 +444,18 @@ def handle_generic_uncontrolled(self, sim: Simulator, ctl: list[tuple[int, bool]
 
     @_CONTROLLED.register(qiskit.circuit.Instruction)
     def handle_generic_controlled(self, sim: Simulator, ctl: list[tuple[int, bool]], op: qiskit.circuit.Instruction, clbits: list[qiskit.circuit.Clbit], qubits: list[int], /) -> None:
-        match op:
-            case qiskit.circuit.Gate() if op.num_qubits == 1:
-                assert not clbits
-                [q] = qubits
-                subctl = [*ctl, (q, True)]
-                # rz(lam); h; rz(theta); h; rz(phi)
-                (theta, phi, lam, corr) = _zxz_decomposer.angles_and_phase(op.to_matrix())
+        if isinstance(op, qiskit.circuit.Gate) and op.num_qubits == 1:
+            assert not clbits
+            [q] = qubits
+            subctl = [*ctl, (q, True)]
+            # rz(lam); h; rz(theta); h; rz(phi)
+            try:
+                m = op.to_matrix()
+            except qiskit.circuit.exceptions.CircuitError:
+                # Qiskit...
+                pass
+            else:
+                (theta, phi, lam, corr) = _zxz_decomposer.angles_and_phase(m)
                 corr -= (theta + phi + lam) / 2
                 if abs(theta) < 1e-8:
                     sim.mcphase(subctl, lam + phi)

tests/circuits/qasm3-gate.qasm3

@@ -0,0 +1,9 @@
+OPENQASM 3.0;
+include "stdgates.inc";
+gate phxz(a,x,z) q0 {
+  rz(-a*pi) q0;
+  rx(x*pi) q0;
+  rz((a+z)*pi) q0;
+}
+qreg q[1];
+phxz(0.7070988294,0.1093253464,0.07720078801) q[0];

tests/test_qasm.py

@@ -0,0 +1,28 @@
+import os
+import sys
+
+from qiskit import qasm3
+import qblaze.qiskit
+
+import pytest
+
+
+circ_path = os.path.dirname(__file__) + '/circuits'
+qasm3_circuits = []
+
+for name in os.listdir(circ_path):
+    if name.startswith('.'):
+        continue
+    if name.endswith('.qasm3'):
+        with open(f'{circ_path}/{name}', 'r') as f:
+            qasm3_circuits.append(f.read())
+        continue
+    raise RuntimeError(f'Bad file {name!r}')
+
+
+@pytest.mark.parametrize('circ', qasm3_circuits)
+def test_qasm3(circ: str) -> None:
+    circ = qasm3.loads(circ)
+    backend = qblaze.qiskit.Backend()
+    result = backend.run(circ, shots=128).result()
+    result.get_counts()