Correct lint issues exposed with update to pylint-3 (#1652)

Fixes #1440 

Re-enables the following pylint issues which were disabled when bumping
to pylint-3.

- [x] abstract-class-instantiated
- [X] deprecated-class
- [x] possibly-used-before-assignment
- [x] used-before-assignment

---------

Co-authored-by: Matthew Harrigan <mpharrigan@google.com>

Author: micpap25

dev_tools/conf/.pylintrc

@@ -7,10 +7,6 @@ score=no
 reports=no
 py-version=3.9
 disable=
-    abstract-class-instantiated,        # TODO: #1440 - enable and fix
-    deprecated-class,                   # TODO: #1440 - enable and fix
-    possibly-used-before-assignment,    # TODO: #1440 - enable and fix
-    used-before-assignment,             # TODO: #1440 - enable and fix
     C,
     R,
     missing-raises-doc,
@@ -19,15 +15,16 @@ disable=
     unused-argument,
     fixme,
     unspecified-encoding,
-    not-an-iterable,         # buggy with attrs
-    unsubscriptable-object,  # buggy with attrs
-    not-callable,            # buggy with attrs
-    no-member,               # buggy with attrs
-    reimported,              # often relevant for 'autodoc' functionality
-    import-self,             # often relevant for 'autodoc' functionality
-    redefined-outer-name,    # tiggered by re-importing
-    abstract-method,         # cirq's @value.alternative not respected
-    protected-access,        # a lot of usages in tests
+    abstract-class-instantiated,    # buggy with attrs
+    not-an-iterable,                # buggy with attrs
+    unsubscriptable-object,         # buggy with attrs
+    not-callable,                   # buggy with attrs
+    no-member,                      # buggy with attrs
+    reimported,                     # often relevant for 'autodoc' functionality
+    import-self,                    # often relevant for 'autodoc' functionality
+    redefined-outer-name,           # triggered by re-importing
+    abstract-method,                # cirq's @value.alternative not respected
+    protected-access,               # a lot of usages in tests
     redundant-returns-doc
 enable=
     wrong-or-nonexistent-copyright-notice

qualtran/_infra/composite_bloq.py

@@ -13,13 +13,13 @@
 #  limitations under the License.
 
 """Classes for building and manipulating `CompositeBloq`."""
+from collections.abc import Hashable
 from functools import cached_property
 from typing import (
     Callable,
     cast,
     Dict,
     FrozenSet,
-    Hashable,
     Iterable,
     Iterator,
     List,

qualtran/bloqs/block_encoding/product.py

@@ -227,6 +227,9 @@ def build_composite_bloq(
             # set corresponding flag if ancillas are all zero
             if u.ancilla_bitsize > 0 and n - 1 > 0 and i != n - 1:
                 controls = bb.split(cast(Soquet, anc_soq))
+                # flag_bits_soq will always be assigned based on the following assertion
+                assert self.ancilla_bitsize > 0
+                # pylint: disable=used-before-assignment
                 controls[: u.ancilla_bitsize], flag_bits_soq[i] = bb.add_t(
                     MultiControlX(tuple([0] * u.ancilla_bitsize)),
                     controls=controls[: u.ancilla_bitsize],

qualtran/bloqs/block_encoding/tensor_product.py

@@ -148,9 +148,11 @@ def build_composite_bloq(
         for u in self.block_encodings:
             u_soqs = dict()
             u_soqs["system"] = sys_out_regs[sys_i]
-            if "ancilla" in u.signature._lefts:
+            # restatement of nonzero anc / res lengths prevent a
+            # "possibly-used-before-assignment" warning from pylint
+            if "ancilla" in u.signature._lefts and len(anc_regs) > 0:
                 u_soqs["ancilla"] = anc_out_regs[anc_i]
-            if "resource" in u.signature._lefts:
+            if "resource" in u.signature._lefts and len(res_regs) > 0:
                 u_soqs["resource"] = res_out_regs[res_i]
             u_soqs_out = bb.add_d(u, **u_soqs)
             sys_out_regs[sys_i] = u_soqs_out["system"]

qualtran/bloqs/reflections/reflection_using_prepare_test.py

@@ -135,6 +135,10 @@ def test_reflection_using_prepare(num_ones, eps, global_phase):
         signs = '-' * num_ones + '+' * (9 - num_ones)
     elif np.sign(global_phase) == -1:
         signs = '+' * num_ones + '-' * (9 - num_ones)
+    else:
+        raise ValueError(
+            "sign function has failed to return 1 or -1. This may be due to nan or complex input."
+        )
     assert cirq.dirac_notation(prepared_state) == get_3q_uniform_dirac_notation(signs, global_phase)
 
 

qualtran/symbolics/types.py

@@ -11,7 +11,8 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-from typing import overload, Sized, TypeVar, Union
+from collections.abc import Sized
+from typing import overload, TypeVar, Union
 
 import numpy as np
 import sympy