Update to Pylint 4.0.0 (#2121)

**Context:**
Update to Pylint 4.0.0.
This needs to be coordinated cross the ecosystem, to determine the
target pylint version we're going to.
For now, I'm saving the work I have done so far on trying to update
catalyst to pylint 4.0.0. I am handing this off to @rniczh

**Description of the Change:**

**Benefits:**

**Possible Drawbacks:**

**Related GitHub Issues:**

---------

Co-authored-by: Hong-Sheng Zheng <[email protected]>
Co-authored-by: Alex Preciado <[email protected]>

Author: 3 people

.github/workflows/check-formatting.yaml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Install dependencies
-        run: pip install black isort pylint==3.3.9
+        run: pip install black==25.9.0 isort~=7.0.0 pylint~=4.0.0
 
       - name: Checkout code
         uses: actions/checkout@v4

frontend/test/lit/test_autograph.py

@@ -240,7 +240,7 @@ def if_assign_partial(x: float):
         if x < 3:
             y = 4
 
-        return y
+        return y  # pylint: disable=possibly-used-before-assignment
 
 except AutoGraphError as e:
     # CHECK:   Some branches did not define a value for variable 'y'

frontend/test/lit/test_from_plxpr.py

@@ -71,7 +71,7 @@ def captured_circuit():
         def loop_fn(_):
             qml.Hadamard(0)
 
-        loop_fn()
+        loop_fn()  # pylint: disable=no-value-for-parameter
 
         return qml.state()
 

frontend/test/lit/test_function_attributes.py

@@ -33,7 +33,7 @@ def qnode(x):
 # The entry point has no internal linkage.
 # CHECK-DAG: func.func public @jit_workload(%arg0: tensor<f64>) -> tensor<4xcomplex<f64>> attributes {llvm.emit_c_interface} {
 def workload(x: float):
-    y = x * qml.numpy.pi
+    y = x * qml.numpy.pi  # pylint: disable=no-member
     return qnode(y)
 
 

frontend/test/lit/test_measurements.py

@@ -370,10 +370,10 @@ def expval5(x: float, y: float):
 print(expval5.mlir)
 
 
-# CHECK-LABEL: public @expval5(
+# CHECK-LABEL: public @expval6(
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=3))
-def expval5(x: float, y: float):
+def expval6(x: float, y: float):
     # CHECK: [[q0:%.+]] = quantum.custom "RX"
     qml.RX(x, wires=0)
     # CHECK: [[q1:%.+]] = quantum.custom "RY"
@@ -395,13 +395,13 @@ def expval5(x: float, y: float):
     return qml.expval(qml.Hamiltonian(coeffs, obs))
 
 
-print(expval5.mlir)
+print(expval6.mlir)
 
 
-# CHECK-LABEL: public @expval6(
+# CHECK-LABEL: public @expval7(
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=2))
-def expval6(x: float):
+def expval7(x: float):
     # CHECK: [[q0:%.+]] = quantum.custom "RX"
     qml.RX(x, wires=0)
 
@@ -424,27 +424,27 @@ def expval6(x: float):
     return qml.expval(qml.Hamiltonian(coeff, [obs, qml.PauliX(0)]))
 
 
-print(expval6.mlir)
+print(expval7.mlir)
 
 
-# CHECK-LABEL: public @expval7(
+# CHECK-LABEL: public @expval8(
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=2))
-def expval7():
+def expval8():
     A = np.array([[complex(1.0, 0.0), complex(2.0, 0.0)], [complex(2.0, 0.0), complex(1.0, 0.0)]])
 
     # CHECK: [[obs:%.+]] = quantum.hermitian
     # CHECK: quantum.expval [[obs]] : f64
     return qml.expval(qml.Hermitian(A, wires=0))
 
 
-print(expval7.mlir)
+print(expval8.mlir)
 
 
-# CHECK-LABEL: public @expval8(
+# CHECK-LABEL: public @expval9(
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=2))
-def expval8():
+def expval9():
     B = np.array(
         [
             [complex(1.0, 0.0), complex(2.0, 0.0), complex(1.0, 0.0), complex(2.0, 0.0)],
@@ -459,13 +459,13 @@ def expval8():
     return qml.expval(qml.Hermitian(B, wires=[0, 1]))
 
 
-print(expval8.mlir)
+print(expval9.mlir)
 
 
-# CHECK-LABEL: public @expval9(
+# CHECK-LABEL: public @expval10(
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=3))
-def expval9(x: float, y: float):
+def expval10(x: float, y: float):
     # CHECK: [[q0:%.+]] = quantum.custom "RX"
     qml.RX(x, wires=0)
     # CHECK: [[q1:%.+]] = quantum.custom "RY"
@@ -481,13 +481,13 @@ def expval9(x: float, y: float):
     return qml.expval(qml.PauliX(0) @ qml.PauliZ(1) @ qml.Hadamard(2))
 
 
-print(expval9.mlir)
+print(expval10.mlir)
 
 
-# CHECK-LABEL: public @expval10(
+# CHECK-LABEL: public @expval11(
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=3))
-def expval10(x: float, y: float):
+def expval11(x: float, y: float):
     # CHECK: [[q0:%.+]] = quantum.custom "RX"
     qml.RX(x, wires=0)
     # CHECK: [[q1:%.+]] = quantum.custom "RY"
@@ -511,12 +511,12 @@ def expval10(x: float, y: float):
     return qml.expval(qml.PauliX(1) @ qml.Hermitian(B, wires=[0, 2]))
 
 
-print(expval10.mlir)
+print(expval11.mlir)
 
 
-# CHECK-LABEL: @expval11
+# CHECK-LABEL: @expval12
 @qjit(target="mlir")
-def expval11(num_qubits):
+def expval12(num_qubits):
     # CHECK: func.func public @circ(%arg0: tensor<i64>) -> tensor<f64>
     @qml.qnode(qml.device("lightning.qubit", wires=num_qubits))
     def circ():
@@ -542,8 +542,8 @@ def circ():
     return circ()
 
 
-_ = expval11(10)
-print(expval11.mlir)
+_ = expval12(10)
+print(expval12.mlir)
 
 
 # CHECK-LABEL: public @var1(

frontend/test/lit/test_multi_qubit_gates.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""Tests for multi-qubit gate compilation in Catalyst."""
+
 # RUN: %PYTHON %s | FileCheck %s
 
 import os
@@ -34,6 +36,7 @@
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=5))
 def circuit(x: float):
+    """Test circuit with various multi-qubit gates."""
     # CHECK: {{%.+}} = quantum.custom "Identity"() {{.+}} : !quantum.bit
     qml.Identity(0)
     # CHECK: {{%.+}} = quantum.custom "CNOT"() {{.+}} : !quantum.bit, !quantum.bit
@@ -53,10 +56,11 @@ def circuit(x: float):
 print(circuit.mlir)
 
 
-# CHECK-LABEL: public @jit_circuit
+# CHECK-LABEL: public @jit_circuit_unitary
 @qjit(target="mlir")
 @qml.qnode(qml.device("lightning.qubit", wires=3))
-def circuit():
+def circuit_unitary():
+    """Test circuit with unitary gates."""
     U1 = 1 / np.sqrt(2) * np.array([[1.0, 1.0], [1.0, -1.0]], dtype=complex)
     # CHECK: {{%.+}} = quantum.unitary({{%.+}} : tensor<2x2xcomplex<f64>>) {{%.+}} : !quantum.bit
     qml.QubitUnitary(U1, wires=0)
@@ -69,13 +73,14 @@ def circuit():
             [0.0 + 0.0j, 0.0 + 0.0j, 0.0 + 0.0j, 0.99500417 - 0.09983342j],
         ]
     )
+    # pylint: disable=line-too-long
     # CHECK: {{%.+}} = quantum.unitary({{%.+}} : tensor<4x4xcomplex<f64>>) {{%.+}}, {{%.+}} : !quantum.bit, !quantum.bit
     qml.QubitUnitary(U2, wires=[0, 2])
 
     return measure(wires=0), measure(wires=1)
 
 
-print(circuit.mlir)
+print(circuit_unitary.mlir)
 
 
 def get_custom_qjit_device(num_wires, discards, additions):
@@ -114,20 +119,21 @@ def execute(self, circuits, execution_config):
     return CustomDevice(wires=num_wires)
 
 
-# CHECK-LABEL: public @jit_circuit
+# CHECK-LABEL: public @jit_circuit_iswap_pswap
 @qjit(target="mlir")
 @qml.qnode(
     get_custom_qjit_device(2, (), {"ISWAP": OperatorProperties(), "PSWAP": OperatorProperties()})
 )
-def circuit(x: float):
+def circuit_iswap_pswap(x: float):
+    """Test circuit with ISWAP and PSWAP gates."""
     # CHECK: {{%.+}} = quantum.custom "ISWAP"() {{.+}} : !quantum.bit, !quantum.bit
     qml.ISWAP(wires=[0, 1])
     # CHECK: {{%.+}} = quantum.custom "PSWAP"({{%.+}}) {{.+}} : !quantum.bit, !quantum.bit
     qml.PSWAP(x, wires=[0, 1])
     return qml.probs()
 
 
-print(circuit.mlir)
+print(circuit_iswap_pswap.mlir)
 
 
 # CHECK-LABEL: public @jit_isingZZ_circuit

frontend/test/lit/test_snapshot_mlir.py

@@ -47,7 +47,7 @@ def single_qubit_circuit():
     # CHECK: [[snapshot2:%.+]] = quantum.state [[compbasis]] : tensor<2xcomplex<f64>>
     qml.Snapshot()  # |->
 
-    qml.PhaseShift(np.pi / 2, wires=0)
+    qml.PhaseShift(np.pi / 2, wires=0)  # pylint: disable=no-member
 
     # CHECK: [[compbasis:%.+]] = quantum.compbasis qreg {{%.+}} : !quantum.obs
     # CHECK: [[snapshot3:%.+]] = quantum.state [[compbasis]] : tensor<2xcomplex<f64>>
@@ -59,7 +59,7 @@ def single_qubit_circuit():
     # CHECK: [[snapshot4:%.+]] = quantum.state [[compbasis]] : tensor<2xcomplex<f64>>
     qml.Snapshot()  # |+i>
 
-    qml.PhaseShift(-np.pi / 2, wires=0)
+    qml.PhaseShift(-np.pi / 2, wires=0)  # pylint: disable=no-member
 
     # CHECK: [[compbasis:%.+]] = quantum.compbasis qreg {{%.+}} : !quantum.obs
     # CHECK: [[snapshot5:%.+]] = quantum.state [[compbasis]] : tensor<2xcomplex<f64>>

frontend/test/pytest/from_plxpr/test_capture_integration.py

@@ -420,7 +420,7 @@ def loop(i):
                 qml.CNOT(wires=[0, i])
                 qml.RX(x, wires=i)
 
-            loop()
+            loop()  # pylint: disable=no-value-for-parameter
 
             return qml.expval(qml.Z(2))
 
@@ -458,7 +458,7 @@ def loop_rx(_, x):
                 return jnp.sin(x)
 
             # apply the for loop
-            loop_rx(x)
+            loop_rx(x)  # pylint: disable=no-value-for-parameter
 
             return qml.expval(qml.Z(0))
 
@@ -478,7 +478,7 @@ def loop_rx(_, x):
                 return jnp.sin(x)
 
             # apply the for loop
-            loop_rx(x)
+            loop_rx(x)  # pylint: disable=no-value-for-parameter
 
             return qml.expval(qml.Z(0))
 
@@ -508,10 +508,10 @@ def qft(i):
                 def inner(j):
                     qml.ControlledPhaseShift(jnp.pi / 2 ** (n - j + 1), [i, j])
 
-                inner()
+                inner()  # pylint: disable=no-value-for-parameter
 
-            init()
-            qft()
+            init()  # pylint: disable=no-value-for-parameter
+            qft()  # pylint: disable=no-value-for-parameter
 
             # Expected output: |100...>
             return qml.state()
@@ -539,10 +539,10 @@ def qft(i):
                 def inner(j):
                     qml.ControlledPhaseShift(jnp.pi / 2 ** (n - j + 1), [i, j])
 
-                inner()
+                inner()  # pylint: disable=no-value-for-parameter
 
-            init()
-            qft()
+            init()  # pylint: disable=no-value-for-parameter
+            qft()  # pylint: disable=no-value-for-parameter
 
             # Expected output: |100...>
             return qml.state()
@@ -1544,7 +1544,7 @@ def captured_circuit():
                 def loop_0(i):
                     qml.RX(0, wires=i)
 
-                loop_0()
+                loop_0()  # pylint: disable=no-value-for-parameter
 
                 qml.RX(0, wires=0)
                 return qml.sample()
@@ -1562,7 +1562,7 @@ def circuit():
             def loop_0(i):
                 qml.RX(0, wires=i)
 
-            loop_0()
+            loop_0()  # pylint: disable=no-value-for-parameter
 
             qml.RX(0, wires=0)
             return qml.sample()
@@ -1648,7 +1648,7 @@ def f(i0):
             def g(i, x):
                 return c(i) + x
 
-            return g(i0)
+            return g(i0)  # pylint: disable=no-value-for-parameter
 
         out = f(3.0)
         assert qml.math.allclose(out, 3 + jnp.cos(2) + jnp.cos(4) + jnp.cos(6))
@@ -1695,9 +1695,9 @@ def outer(i):
                 def inner(j):
                     qml.RY(x, wires=j)
 
-                inner()
+                inner()  # pylint: disable=no-value-for-parameter
 
-            outer()
+            outer()  # pylint: disable=no-value-for-parameter
 
             # Expected output: |100...>
             return [qml.expval(qml.PauliZ(i)) for i in range(3)]
@@ -1723,9 +1723,9 @@ def outer(i, a):
                 def inner(j, b):
                     return b + x
 
-                return inner(a)
+                return inner(a)  # pylint: disable=no-value-for-parameter
 
-            return outer(0.0)
+            return outer(0.0)  # pylint: disable=no-value-for-parameter
 
         res = f(0.2, 2)
         assert qml.math.allclose(res, 0.2 * 2 * 3)

frontend/test/pytest/from_plxpr/test_from_plxpr.py

@@ -844,7 +844,7 @@ def f(i0):
             def g(i, x):
                 return i + x
 
-            return g(i0)
+            return g(i0)  # pylint: disable=no-value-for-parameter
 
         jaxpr = jax.make_jaxpr(f)(2)
         catalyst_jaxpr = from_plxpr(jaxpr)(2)