From 2769039d2b71028430867627c98906a157c942db Mon Sep 17 00:00:00 2001
From: ptr25 <tr.pranathi@gmail.com>
Date: Mon, 28 Sep 2026 19:01:22 +0530
Subject: [PATCH 1/9] Validate that control and target qubits are disjoint

Raises ValueError when a command is initialized or when control qubits are added that overlap with target qubits, or when target qubits are not distinct. This prevents obscure IndexError exceptions during optimization passes (fixes #343).
---
 projectq/meta/_control_test.py | 16 +++++++++++++---
 projectq/ops/_command.py       | 26 ++++++++++++++++++++++++++
 projectq/ops/_command_test.py  | 28 ++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/projectq/meta/_control_test.py b/projectq/meta/_control_test.py
index 73810b95..e7d53260 100755
--- a/projectq/meta/_control_test.py
+++ b/projectq/meta/_control_test.py
@@ -61,9 +61,9 @@ def test_canonical_representation():
 
 def test_has_negative_control():
     qubit0 = WeakQubitRef(None, 0)
-    qubit1 = WeakQubitRef(None, 0)
-    qubit2 = WeakQubitRef(None, 0)
-    qubit3 = WeakQubitRef(None, 0)
+    qubit1 = WeakQubitRef(None, 1)
+    qubit2 = WeakQubitRef(None, 2)
+    qubit3 = WeakQubitRef(None, 3)
     assert not _control.has_negative_control(Command(None, H, ([qubit0],)))
     assert not _control.has_negative_control(Command(None, H, ([qubit0],), [qubit1]))
     assert not _control.has_negative_control(Command(None, H, ([qubit0],), [qubit1], control_state=CtrlAll.One))
@@ -175,3 +175,13 @@ def test_control_state_contradiction():
             with _control.Control(eng, qureg[0], '1'):
                 H | qubit
     eng.flush()
+
+
+def test_control_overlapping_target_raises():
+    backend = DummyEngine(save_commands=True)
+    eng = MainEngine(backend=backend, engine_list=[DummyEngine()])
+    q0 = eng.allocate_qubit()
+    with pytest.raises(ValueError, match="Control and target qubits must be disjoint"):
+        with _control.Control(eng, q0):
+            H | q0
+    eng.flush()
diff --git a/projectq/ops/_command.py b/projectq/ops/_command.py
index 481efcc1..5fcd59ce 100755
--- a/projectq/ops/_command.py
+++ b/projectq/ops/_command.py
@@ -126,6 +126,8 @@ def qubits(self):
     def qubits(self, qubits):
         """Set the qubits stored in a Command object."""
         self._qubits = self._order_qubits(qubits)
+        if hasattr(self, '_control_qubits'):
+            self._check_disjoint_qubits()
 
     def __deepcopy__(self, memo):
         """Deepcopy implementation. Engine should stay a reference."""
@@ -230,6 +232,7 @@ def control_qubits(self, qubits):
         """
         self._control_qubits = [WeakQubitRef(qubit.engine, qubit.id) for qubit in qubits]
         self._control_qubits = sorted(self._control_qubits, key=lambda x: x.id)
+        self._check_disjoint_qubits()
 
     @property
     def control_state(self):
@@ -251,6 +254,20 @@ def control_state(self, state):
 
         self._control_state = canonical_ctrl_state(state, len(self._control_qubits))
 
+    def _check_disjoint_qubits(self):
+        """Check that control qubits and target qubits are disjoint, and target qubits are distinct."""
+        if hasattr(self, '_qubits') and self._qubits:
+            target_ids = [q.id for qreg in self._qubits for q in qreg]
+            if len(target_ids) != len(set(target_ids)):
+                raise ValueError('Target qubits for a gate must be distinct.')
+            if hasattr(self, '_control_qubits') and self._control_qubits:
+                ctrl_ids = {q.id for q in self._control_qubits}
+                overlap = ctrl_ids.intersection(target_ids)
+                if overlap:
+                    raise ValueError(
+                        f'Control and target qubits must be disjoint. Overlapping qubit ID(s): {sorted(overlap)}'
+                    )
+
     def add_control_qubits(self, qubits, state=CtrlAll.One):
         """
         Add (additional) control qubits to this command object.
@@ -271,6 +288,13 @@ def add_control_qubits(self, qubits, state=CtrlAll.One):
 
         if not isinstance(qubits, list):
             raise ValueError('Control qubits must be a list of qubits!')
+
+        new_ctrl_ids = {q.id for q in qubits}
+        target_ids = {q.id for qreg in self._qubits for q in qreg}
+        overlap = new_ctrl_ids.intersection(target_ids)
+        if overlap:
+            raise ValueError(f'Control and target qubits must be disjoint. Overlapping qubit ID(s): {sorted(overlap)}')
+
         self._control_qubits.extend([WeakQubitRef(qubit.engine, qubit.id) for qubit in qubits])
         self._control_state += canonical_ctrl_state(state, len(qubits))
 
@@ -286,6 +310,8 @@ def add_control_qubits(self, qubits, state=CtrlAll.One):
                     f'Control qubits {list(qubits)} cannot have conflicting control states: {states}'
                 )
 
+        self._check_disjoint_qubits()
+
     @property
     def all_qubits(self):
         """
diff --git a/projectq/ops/_command_test.py b/projectq/ops/_command_test.py
index 19db3644..1cbf2c24 100755
--- a/projectq/ops/_command_test.py
+++ b/projectq/ops/_command_test.py
@@ -311,3 +311,31 @@ def test_command_to_string(main_engine):
     else:
         assert cmd.to_string(symbols=False) == "CRx(1.5707963268) | ( Qureg[1], Qureg[0] )"
         assert cmd2.to_string(symbols=False) == "Rx(1.5707963268) | Qureg[0]"
+
+
+def test_command_disjoint_control_target(main_engine):
+    qubit0 = Qubit(main_engine, 0)
+    qubit1 = Qubit(main_engine, 1)
+    gate = BasicGate()
+
+    # Overlapping control and target at initialization
+    with pytest.raises(ValueError, match="Control and target qubits must be disjoint"):
+        _command.Command(main_engine, gate, ([qubit0],), controls=[qubit0])
+
+    # Adding an overlapping control qubit
+    cmd = _command.Command(main_engine, gate, ([qubit0],))
+    with pytest.raises(ValueError, match="Control and target qubits must be disjoint"):
+        cmd.add_control_qubits([qubit0])
+
+    # Valid disjoint qubits succeed
+    cmd.add_control_qubits([qubit1])
+    assert len(cmd.control_qubits) == 1
+
+
+def test_command_distinct_target_qubits(main_engine):
+    qubit0 = Qubit(main_engine, 0)
+    gate = BasicGate()
+
+    # Duplicate target qubits for a gate
+    with pytest.raises(ValueError, match="Target qubits for a gate must be distinct"):
+        _command.Command(main_engine, gate, ([qubit0], [qubit0]))

From 9069565c68a065cebeb570ff0533e74f00f6715a Mon Sep 17 00:00:00 2001
From: ptr25 <tr.pranathi@gmail.com>
Date: Mon, 28 Sep 2026 19:11:57 +0530
Subject: [PATCH 2/9] Update CHANGELOG and fix compiler dry_run check for
 modern setuptools

- Add CHANGELOG.md entry for #343 and #485
- Handle missing compiler.dry_run attribute in setup.py under setuptools >= 81.0.0
- Use dict.fromkeys in _plot.py to satisfy flake8 comprehension rule
---
 CHANGELOG.md                         |  2 ++
 projectq/backends/_circuits/_plot.py |  2 +-
 setup.py                             | 11 ++++++++---
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e58e1202..6dd80666 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 -   Fixed some typos (thanks to @eltociear, @Darkdragon84)
 -   Fixed support for Python 3.12
+-   Fixed obscure IndexError in optimizer when control and target qubits overlap or are not distinct (#343)
+-   Fixed installation failure with setuptools >= 81.0.0 due to compiler dry_run attribute (#485)
 
 ### Removed
 
diff --git a/projectq/backends/_circuits/_plot.py b/projectq/backends/_circuits/_plot.py
index b450309f..c86363b4 100644
--- a/projectq/backends/_circuits/_plot.py
+++ b/projectq/backends/_circuits/_plot.py
@@ -98,7 +98,7 @@ def to_draw(qubit_lines, qubit_labels=None, drawing_order=None, **kwargs):
             wires (roughly in inches)
     """
     if qubit_labels is None:
-        qubit_labels = {qubit_id: r'$|0\rangle$' for qubit_id in qubit_lines}
+        qubit_labels = dict.fromkeys(qubit_lines, r'$|0\rangle$')
     else:
         if list(qubit_labels) != list(qubit_lines):
             raise RuntimeError('Qubit IDs in qubit_labels do not match qubit IDs in qubit_lines!')
diff --git a/setup.py b/setup.py
index 24a647bd..1bc10c79 100755
--- a/setup.py
+++ b/setup.py
@@ -429,8 +429,11 @@ def _get_compilation_commands(self, ext):
 
     def _configure_compiler(self):
         # Force dry_run = False to allow for compiler feature testing
-        dry_run_old = self.compiler.dry_run
-        self.compiler.dry_run = False
+        dry_run_old = getattr(self.compiler, 'dry_run', getattr(self, 'dry_run', False))
+        if hasattr(self.compiler, 'dry_run'):
+            self.compiler.dry_run = False
+        dry_run_cmd_old = getattr(self, 'dry_run', False)
+        self.dry_run = False
 
         if (
             int(os.environ.get('PROJECTQ_CLEANUP_COMPILER_FLAGS', 0))
@@ -472,7 +475,9 @@ def _configure_compiler(self):
         if compiler_type == 'unix' and compiler_test(self.compiler, '-fvisibility=hidden'):
             self.opts.append('-fvisibility=hidden')
 
-        self.compiler.dry_run = dry_run_old
+        if hasattr(self.compiler, 'dry_run'):
+            self.compiler.dry_run = dry_run_old
+        self.dry_run = dry_run_cmd_old
         status_msgs('Finished configuring compiler!')
 
     def _configure_openmp(self):

From 4a9e89317285eb8bc1eec3e417312a130abe11ea Mon Sep 17 00:00:00 2001
From: ptr25 <tr.pranathi@gmail.com>
Date: Mon, 28 Sep 2026 19:19:31 +0530
Subject: [PATCH 3/9] Fix NumPy 2.0 deprecations in tests and refine control
 disjointness check

- Fix np.complex_ and np.array copy=False for NumPy 2.0 compatibility in tests
- Keep command disjointness check focused strictly on control vs target qubits
---
 projectq/backends/_sim/_simulator_test.py    |  4 ++--
 projectq/ops/_command.py                     | 21 +++++++++-----------
 projectq/ops/_command_test.py                |  9 ---------
 projectq/setups/decompositions/rz2rx_test.py |  4 ++--
 4 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/projectq/backends/_sim/_simulator_test.py b/projectq/backends/_sim/_simulator_test.py
index 1b4b6b7b..0eaa6a23 100755
--- a/projectq/backends/_sim/_simulator_test.py
+++ b/projectq/backends/_sim/_simulator_test.py
@@ -559,8 +559,8 @@ def build_matrix(list_single_matrices):
         res_matrix += build_matrix(matrix) * c
     res_matrix *= -1j * time_to_evolve
 
-    init_wavefunction = numpy.array(init_wavefunction, copy=False)
-    final_wavefunction = numpy.array(final_wavefunction, copy=False)
+    init_wavefunction = numpy.asarray(init_wavefunction)
+    final_wavefunction = numpy.asarray(final_wavefunction)
     res = scipy.sparse.linalg.expm_multiply(res_matrix, init_wavefunction)
 
     half = int(len(final_wavefunction) / 2)
diff --git a/projectq/ops/_command.py b/projectq/ops/_command.py
index 5fcd59ce..3eb69219 100755
--- a/projectq/ops/_command.py
+++ b/projectq/ops/_command.py
@@ -255,18 +255,15 @@ def control_state(self, state):
         self._control_state = canonical_ctrl_state(state, len(self._control_qubits))
 
     def _check_disjoint_qubits(self):
-        """Check that control qubits and target qubits are disjoint, and target qubits are distinct."""
-        if hasattr(self, '_qubits') and self._qubits:
-            target_ids = [q.id for qreg in self._qubits for q in qreg]
-            if len(target_ids) != len(set(target_ids)):
-                raise ValueError('Target qubits for a gate must be distinct.')
-            if hasattr(self, '_control_qubits') and self._control_qubits:
-                ctrl_ids = {q.id for q in self._control_qubits}
-                overlap = ctrl_ids.intersection(target_ids)
-                if overlap:
-                    raise ValueError(
-                        f'Control and target qubits must be disjoint. Overlapping qubit ID(s): {sorted(overlap)}'
-                    )
+        """Check that control qubits and target qubits are disjoint."""
+        if hasattr(self, '_qubits') and self._qubits and hasattr(self, '_control_qubits') and self._control_qubits:
+            ctrl_ids = {q.id for q in self._control_qubits}
+            target_ids = {q.id for qreg in self._qubits for q in qreg}
+            overlap = ctrl_ids.intersection(target_ids)
+            if overlap:
+                raise ValueError(
+                    f'Control and target qubits must be disjoint. Overlapping qubit ID(s): {sorted(overlap)}'
+                )
 
     def add_control_qubits(self, qubits, state=CtrlAll.One):
         """
diff --git a/projectq/ops/_command_test.py b/projectq/ops/_command_test.py
index 1cbf2c24..08348f03 100755
--- a/projectq/ops/_command_test.py
+++ b/projectq/ops/_command_test.py
@@ -330,12 +330,3 @@ def test_command_disjoint_control_target(main_engine):
     # Valid disjoint qubits succeed
     cmd.add_control_qubits([qubit1])
     assert len(cmd.control_qubits) == 1
-
-
-def test_command_distinct_target_qubits(main_engine):
-    qubit0 = Qubit(main_engine, 0)
-    gate = BasicGate()
-
-    # Duplicate target qubits for a gate
-    with pytest.raises(ValueError, match="Target qubits for a gate must be distinct"):
-        _command.Command(main_engine, gate, ([qubit0], [qubit0]))
diff --git a/projectq/setups/decompositions/rz2rx_test.py b/projectq/setups/decompositions/rz2rx_test.py
index 7418c5a1..41322647 100644
--- a/projectq/setups/decompositions/rz2rx_test.py
+++ b/projectq/setups/decompositions/rz2rx_test.py
@@ -107,8 +107,8 @@ def test_decomposition(angle):
 
             # Create empty vectors for the wave vectors for the correct and
             # test qubits
-            correct_vector = np.zeros((2, 1), dtype=np.complex_)
-            test_vector = np.zeros((2, 1), dtype=np.complex_)
+            correct_vector = np.zeros((2, 1), dtype=complex)
+            test_vector = np.zeros((2, 1), dtype=complex)
 
             i = 0
             for fstate in ['0', '1']:

From f059f75af676aa27bd39acb6e7320d26348a75f3 Mon Sep 17 00:00:00 2001
From: ptr25 <tr.pranathi@gmail.com>
Date: Mon, 28 Sep 2026 19:32:09 +0530
Subject: [PATCH 4/9] Fix Python 3.8 compatibility with azure-quantum
 dependency

---
 projectq/backends/_azure/__init__.py                   | 2 +-
 projectq/backends/_azure/_azure_quantum.py             | 2 +-
 projectq/backends/_azure/_azure_quantum_client_test.py | 2 +-
 projectq/backends/_azure/_azure_quantum_test.py        | 2 +-
 projectq/backends/_azure/_utils_test.py                | 2 +-
 pyproject.toml                                         | 3 ++-
 6 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/projectq/backends/_azure/__init__.py b/projectq/backends/_azure/__init__.py
index 23d2cb3c..b56cff51 100644
--- a/projectq/backends/_azure/__init__.py
+++ b/projectq/backends/_azure/__init__.py
@@ -16,7 +16,7 @@
 
 try:
     from ._azure_quantum import AzureQuantumBackend
-except ImportError:  # pragma: no cover
+except (ImportError, TypeError):  # pragma: no cover
 
     class AzureQuantumBackend:
         """Dummy class."""
diff --git a/projectq/backends/_azure/_azure_quantum.py b/projectq/backends/_azure/_azure_quantum.py
index 682caa69..f9e17fa4 100644
--- a/projectq/backends/_azure/_azure_quantum.py
+++ b/projectq/backends/_azure/_azure_quantum.py
@@ -39,7 +39,7 @@
     from azure.quantum import Workspace
     from azure.quantum.target import IonQ, Quantinuum, Target
     from azure.quantum.target.target_factory import TargetFactory
-except ImportError:  # pragma: no cover
+except (ImportError, TypeError):  # pragma: no cover
     raise ImportError(  # pylint: disable=raise-missing-from
         "Missing optional 'azure-quantum' dependencies. To install run: pip install projectq[azure-quantum]"
     )
diff --git a/projectq/backends/_azure/_azure_quantum_client_test.py b/projectq/backends/_azure/_azure_quantum_client_test.py
index 5ce1a6d8..bb69a317 100644
--- a/projectq/backends/_azure/_azure_quantum_client_test.py
+++ b/projectq/backends/_azure/_azure_quantum_client_test.py
@@ -25,7 +25,7 @@
     import azure.quantum  # noqa: F401
 
     from projectq.backends._azure._azure_quantum_client import retrieve, send
-except ImportError:
+except (ImportError, TypeError):
     _has_azure_quantum = False
 
 has_azure_quantum = pytest.mark.skipif(not _has_azure_quantum, reason="azure quantum package is not installed")
diff --git a/projectq/backends/_azure/_azure_quantum_test.py b/projectq/backends/_azure/_azure_quantum_test.py
index f6d2193d..1f1df1df 100644
--- a/projectq/backends/_azure/_azure_quantum_test.py
+++ b/projectq/backends/_azure/_azure_quantum_test.py
@@ -30,7 +30,7 @@
     import projectq.backends._azure._azure_quantum
     from projectq.backends import AzureQuantumBackend
     from projectq.backends._azure._exceptions import AzureQuantumTargetNotFoundError
-except ImportError:
+except (ImportError, TypeError):
     _has_azure_quantum = False
 
 has_azure_quantum = pytest.mark.skipif(not _has_azure_quantum, reason="azure quantum package is not installed")
diff --git a/projectq/backends/_azure/_utils_test.py b/projectq/backends/_azure/_utils_test.py
index 8fdf70b4..312fce38 100644
--- a/projectq/backends/_azure/_utils_test.py
+++ b/projectq/backends/_azure/_utils_test.py
@@ -64,7 +64,7 @@
         to_json,
         to_qasm,
     )
-except ImportError:
+except (ImportError, TypeError):
     _has_azure_quantum = False
 
 has_azure_quantum = pytest.mark.skipif(not _has_azure_quantum, reason="azure quantum package is not installed")
diff --git a/pyproject.toml b/pyproject.toml
index 6e4686e2..4b38f7c2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,7 +44,8 @@ dependencies = [
 [project.optional-dependencies]
 
 azure-quantum = [
-      'azure-quantum'
+      'azure-quantum <= 3.5.0; python_version <= "3.8"',
+      'azure-quantum; python_version > "3.8"'
 ]
 
 braket = [

From 8ff49a4951b0373f0546717ff1ccb4353a641714 Mon Sep 17 00:00:00 2001
From: ptr25 <62867142+ptr25@users.noreply.github.com>
Date: Wed, 30 Sep 2026 12:42:15 +0530
Subject: [PATCH 5/9] Preserve dependency marker quotes in fallback
 requirements parser

---
 projectq/_setup_test.py | 44 +++++++++++++++++++++++++++++++++++++++++
 setup.py                |  3 ++-
 2 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 projectq/_setup_test.py

diff --git a/projectq/_setup_test.py b/projectq/_setup_test.py
new file mode 100644
index 00000000..70dfc908
--- /dev/null
+++ b/projectq/_setup_test.py
@@ -0,0 +1,44 @@
+#   Copyright 2017, 2021 ProjectQ-Framework (www.projectq.ch)
+#
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   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.
+"""Regression tests for source-tree packaging commands."""
+
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+
+def test_requirements_fallback_preserves_marker_quotes(tmp_path):
+    """Requirement generation must work without an optional TOML parser."""
+    setup_path = Path(__file__).resolve().parents[1] / 'setup.py'
+    if not setup_path.is_file():
+        pytest.skip('Requires a source checkout')
+    script = """
+import runpy
+import sys
+import setuptools
+
+sys.modules['tomllib'] = None
+sys.modules['toml'] = None
+sys.argv = [sys.argv[1], 'gen_reqfile', '--include-extras=azure-quantum']
+runpy.run_path(sys.argv[0], run_name='__main__')
+"""
+    result = subprocess.run(
+        [sys.executable, '-c', script, str(setup_path)], cwd=tmp_path, capture_output=True, text=True, check=False
+    )
+    assert result.returncode == 0, result.stdout + result.stderr
+    requirements = (tmp_path / 'requirements.txt').read_text().splitlines()
+    assert 'azure-quantum <= 3.5.0; python_version <= "3.8"' in requirements
+    assert 'azure-quantum; python_version > "3.8"' in requirements
diff --git a/setup.py b/setup.py
index 1bc10c79..ac79a272 100755
--- a/setup.py
+++ b/setup.py
@@ -116,7 +116,8 @@ def _parse_list(lines):
                     continue
                 if line.startswith("]"):
                     return (name, elements, idx + 1)
-                elements.append(line.rstrip(',').strip("'").strip('"'))
+                # Remove only the TOML string delimiters, preserving quotes in dependency markers.
+                elements.append(line.rstrip(',')[1:-1])
 
             raise RuntimeError(f'Failed to locate closing "]" for {name}')
 

From d39b9b681b51299ec1f994e816140ff1311aed74 Mon Sep 17 00:00:00 2001
From: ptr25 <62867142+ptr25@users.noreply.github.com>
Date: Wed, 30 Sep 2026 12:42:15 +0530
Subject: [PATCH 6/9] Repair CI dependency builds and legacy runner setup

---
 .github/scripts/ci-centos.sh |  40 ++++++++++++
 .github/workflows/ci.yml     | 123 +++++++++++------------------------
 .github/workflows/format.yml |   7 ++
 3 files changed, 85 insertions(+), 85 deletions(-)
 create mode 100644 .github/scripts/ci-centos.sh

diff --git a/.github/scripts/ci-centos.sh b/.github/scripts/ci-centos.sh
new file mode 100644
index 00000000..06f9dc45
--- /dev/null
+++ b/.github/scripts/ci-centos.sh
@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+# Run inside the CentOS container; checkout and other Node actions run on the host.
+set -euo pipefail
+
+if [[ "$CENTOS_VERSION" == 7 ]]; then
+    vault_version=7.9.2009
+else
+    vault_version=8.5.2111
+fi
+
+# Both CentOS releases have moved from the live mirrors to the vault.
+sed -i \
+    -e 's|^mirrorlist=|#mirrorlist=|' \
+    -e "s|^#baseurl=http://mirror.centos.org/centos/\$releasever|baseurl=https://vault.centos.org/$vault_version|" \
+    -e 's|^#baseurl=http://mirror.centos.org/$contentdir/$releasever|baseurl=https://vault.centos.org/'"$vault_version"'|' \
+    /etc/yum.repos.d/CentOS-*.repo
+yum update -y
+
+if [[ "$CENTOS_VERSION" == 7 ]]; then
+    yum install -y centos-release-scl-rh
+    sed -i \
+        -e 's|^mirrorlist=|#mirrorlist=|' \
+        -e 's|^#baseurl=http://mirror.centos.org/centos/7|baseurl=https://vault.centos.org/7.9.2009|' \
+        /etc/yum.repos.d/CentOS-SCLo-scl-rh.repo
+    yum install -y https://packages.endpointdev.com/rhel/7/os/x86_64/endpoint-repo.x86_64.rpm
+    yum install -y --enablerepo=centos-sclo-rh rh-python38-python-pip rh-python38-python-devel
+    export PATH="/opt/rh/rh-python38/root/usr/bin:$PATH"
+    export LD_LIBRARY_PATH="/opt/rh/rh-python38/root/usr/lib64:${LD_LIBRARY_PATH:-}"
+else
+    yum install -y python38-devel
+fi
+
+yum install -y git gcc-c++ make
+git config --global --add safe.directory /src
+python3 -m pip install -U pip setuptools wheel
+python3 setup.py gen_reqfile --include-extras=test,azure-quantum,braket
+python3 -m pip install -r requirements.txt --prefer-binary
+python3 -m pip install -ve '.[azure-quantum,braket,test]'
+echo 'backend: Agg' > matplotlibrc
+python3 -m pytest -p no:warnings
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bb242ba8..5a456b3d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,7 +21,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        runs-on: [ubuntu-latest, windows-latest, macos-latest]
+        runs-on: [ubuntu-latest, windows-latest, macos-15-intel]
         python:
           - 3.8
           - 3.9
@@ -41,6 +41,10 @@ jobs:
           git fetch --prune --unshallow
           git fetch --depth=1 origin +refs/tags/*:refs/tags/*
 
+      - name: Install Python runtime library (macOS)
+        if: runner.os == 'macOS'
+        run: brew install gettext
+
       - name: Setup Python ${{ matrix.python }}
         uses: actions/setup-python@v4
         with:
@@ -65,9 +69,17 @@ jobs:
         run: |
           python setup.py gen_reqfile --include-extras=test,azure-quantum,braket
 
-      - name: Prepare env
+      - name: Install build tools
         run: |
           python -m pip install -U pip setuptools wheel pybind11
+
+      # RevKit's legacy build imports pybind11 without declaring it as a build dependency.
+      - name: Build RevKit with preinstalled pybind11 (Unix)
+        if: runner.os != 'Windows'
+        run: python -m pip install --no-build-isolation 'revkit==3.0a2.dev2'
+
+      - name: Install dependencies
+        run: |
           cat requirements.txt
           python -m pip install -r requirements.txt --prefer-binary
           python -m pip install coveralls
@@ -123,9 +135,16 @@ jobs:
       PROJECTQ_CLEANUP_COMPILER_FLAGS: ${{ (matrix.clang <= 10) && 1 || 0 }}
 
     name: "Python 3 • Clang ${{ matrix.clang }} • x64"
-    container: "silkeh/clang:${{ matrix.clang }}"
+    container: "silkeh/clang:${{ matrix.clang == 11 && '11-bullseye' || matrix.clang }}"
 
     steps:
+      # Use HTTPS and the security archive origin to avoid stale HTTP mirror indexes.
+      - name: Refresh Debian repository URLs
+        run: |
+          find /etc/apt -name '*.list' -exec sed -i \
+            -e 's|http://deb.debian.org/debian-security|https://security.debian.org/debian-security|g' \
+            -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
+
       - name: Install Git
         run: |
           apt-get update && apt-get install -y git --no-install-recommends
@@ -182,6 +201,13 @@ jobs:
     container: "gcc:${{ matrix.gcc }}"
 
     steps:
+      # Use HTTPS and the security archive origin to avoid stale HTTP mirror indexes.
+      - name: Refresh Debian repository URLs
+        run: |
+          find /etc/apt -name '*.list' -exec sed -i \
+            -e 's|http://deb.debian.org/debian-security|https://security.debian.org/debian-security|g' \
+            -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
+
       - uses: actions/checkout@v3
 
       # Work-around for https://github.com/actions/runner-images/issues/6775
@@ -221,99 +247,26 @@ jobs:
           ./venv/bin/python3 -m pytest -p no:warnings
 
 
-  # Testing on CentOS (manylinux uses a centos base, and this is an easy way
-  # to get GCC 4.8, which is the manylinux1 compiler).
+  # Keep JavaScript actions on the host: Node 24 cannot run on CentOS 7's glibc.
+  # Build and test in the original containers to retain the older compiler coverage.
   centos:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
-        centos:
-          - 7  # GCC 4.8
-          - 8
-        include:
-          - centos: 7
-            python_pkg: rh-python38-python-pip rh-python38-python-devel
-            enable_repo: --enablerepo=centos-sclo-rh
-          - centos: 8
-            python_pkg: python38-devel
-
-
+        centos: [7, 8]
     name: "Python 3 • CentOS ${{ matrix.centos }} • x64"
-    container: "centos:${{ matrix.centos }}"
-
     steps:
-      - name: Enable cache for yum
-        run: echo 'keepcache=1' >> /etc/yum.conf
-
-      - name: Setup yum cache
-        uses: actions/cache@v3
-        with:
-          path: |
-            /var/cache/yum/
-            /var/cache/dnf/
-          key: ${{ runner.os }}-centos${{ matrix.centos }}-yum-${{ secrets.yum_cache }}
-
-      - name: Fix repository URLs (CentOS 8 only)
-        if: matrix.centos == 8
-        run: |
-          sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
-          sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*
-
-      - name: Update YUM/DNF
-        run: yum update -y
-
-      - name: Enable extra repositories && modify PATH (CentOS 7)
-        if: matrix.centos == 7
-        run: |
-          yum install -y centos-release-scl-rh
-          yum -y install https://packages.endpointdev.com/rhel/7/os/x86_64/endpoint-repo.x86_64.rpm
-          echo '/opt/rh/rh-python38/root/usr/bin' >> $GITHUB_PATH
-
-      - name: Add Python 3 and other dependencies
-        run: yum install -y ${{ matrix.enable_repo }} ${{ matrix.python_pkg }} gcc-c++ make
-
-      - name: Install Git > 2.18
-        run: |
-          yum install -y git
-          git config --global --add safe.directory /__w/ProjectQ/ProjectQ
-
-      # Work-around for https://github.com/actions/runner-images/issues/6775
-      - name: Change Owner of Container Working Directory
-        run: chown root:root .
-
       - uses: actions/checkout@v3
-
-      - name: Get history and tags for SCM versioning to work
-        if: ${{ !env.ACT }}
-        run: |
-          git fetch --prune --unshallow
-          git fetch --depth=1 origin +refs/tags/*:refs/tags/*
-
-      - name: Create pip cache dir
-        run: mkdir -p ~/.cache/pip
-
-      - name: Cache wheels
-        uses: actions/cache@v3
         with:
-          path: ~/.cache/pip
-          key: ${{ runner.os }}-centos${{ matrix.centos }}-pip-${{ hashFiles('**/setup.cfg', '**/pyproject.toml') }}
-          restore-keys: ${{ runner.os }}-centos-pip-
+          fetch-depth: 0
 
-      - name: Install dependencies
+      - name: Build and test in CentOS
         run: |
-          python3 -m pip install -U pip setuptools wheel
-          python3 setup.py gen_reqfile --include-extras=test,azure-quantum,braket
-          cat requirements.txt
-          python3 -m pip install -r requirements.txt --prefer-binary
-
-      - name: Build and install package
-        run: python3 -m pip install -ve .[azure-quantum,braket,test]
-
-      - name: Pytest
-        run: |
-          echo 'backend: Agg' > matplotlibrc
-          python3 -m pytest -p no:warnings
+          docker run --rm \
+            -v "$GITHUB_WORKSPACE:/src" -w /src \
+            -e CENTOS_VERSION=${{ matrix.centos }} \
+            centos:${{ matrix.centos }} bash .github/scripts/ci-centos.sh
 
 
   documentation:
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index 18a5a10c..a65b8644 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -27,6 +27,13 @@ jobs:
       CXX: clang++
 
     steps:
+      # Use HTTPS and the security archive origin to avoid stale HTTP mirror indexes.
+      - name: Refresh Debian repository URLs
+        run: |
+          find /etc/apt -name '*.list' -exec sed -i \
+            -e 's|http://deb.debian.org/debian-security|https://security.debian.org/debian-security|g' \
+            -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
+
       - uses: actions/checkout@v3
 
       - name: Prepare env

From 4c473bfccb7af946fd422eabaa372b66d7c387a4 Mon Sep 17 00:00:00 2001
From: ptr25 <62867142+ptr25@users.noreply.github.com>
Date: Wed, 30 Sep 2026 12:45:41 +0530
Subject: [PATCH 7/9] Pin archived Debian packages and GCC 4.8 build
 dependencies

---
 .github/scripts/ci-centos.sh | 8 +++++++-
 .github/workflows/ci.yml     | 8 ++++----
 .github/workflows/format.yml | 4 ++--
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/.github/scripts/ci-centos.sh b/.github/scripts/ci-centos.sh
index 06f9dc45..acde1a8b 100644
--- a/.github/scripts/ci-centos.sh
+++ b/.github/scripts/ci-centos.sh
@@ -35,6 +35,12 @@ git config --global --add safe.directory /src
 python3 -m pip install -U pip setuptools wheel
 python3 setup.py gen_reqfile --include-extras=test,azure-quantum,braket
 python3 -m pip install -r requirements.txt --prefer-binary
-python3 -m pip install -ve '.[azure-quantum,braket,test]'
+if [[ "$CENTOS_VERSION" == 7 ]]; then
+    # Retain GCC 4.8 coverage with the last compatible pybind11 series.
+    python3 -m pip install 'pybind11<2.11' 'setuptools_scm[toml]>6'
+    python3 -m pip install --no-build-isolation -ve '.[azure-quantum,braket,test]'
+else
+    python3 -m pip install -ve '.[azure-quantum,braket,test]'
+fi
 echo 'backend: Agg' > matplotlibrc
 python3 -m pytest -p no:warnings
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5a456b3d..5c55828b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -138,11 +138,11 @@ jobs:
     container: "silkeh/clang:${{ matrix.clang == 11 && '11-bullseye' || matrix.clang }}"
 
     steps:
-      # Use HTTPS and the security archive origin to avoid stale HTTP mirror indexes.
+      # Bullseye security packages have left the live mirrors; keep this legacy toolchain reproducible.
       - name: Refresh Debian repository URLs
         run: |
           find /etc/apt -name '*.list' -exec sed -i \
-            -e 's|http://deb.debian.org/debian-security|https://security.debian.org/debian-security|g' \
+            -e 's|^deb http://deb.debian.org/debian-security bullseye-security|deb [check-valid-until=no] https://snapshot.debian.org/archive/debian-security/20260801T000000Z bullseye-security|' \
             -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
 
       - name: Install Git
@@ -201,11 +201,11 @@ jobs:
     container: "gcc:${{ matrix.gcc }}"
 
     steps:
-      # Use HTTPS and the security archive origin to avoid stale HTTP mirror indexes.
+      # Bullseye security packages have left the live mirrors; keep this legacy toolchain reproducible.
       - name: Refresh Debian repository URLs
         run: |
           find /etc/apt -name '*.list' -exec sed -i \
-            -e 's|http://deb.debian.org/debian-security|https://security.debian.org/debian-security|g' \
+            -e 's|^deb http://deb.debian.org/debian-security bullseye-security|deb [check-valid-until=no] https://snapshot.debian.org/archive/debian-security/20260801T000000Z bullseye-security|' \
             -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
 
       - uses: actions/checkout@v3
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index a65b8644..50f13fe1 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -27,11 +27,11 @@ jobs:
       CXX: clang++
 
     steps:
-      # Use HTTPS and the security archive origin to avoid stale HTTP mirror indexes.
+      # Bullseye security packages have left the live mirrors; keep this legacy toolchain reproducible.
       - name: Refresh Debian repository URLs
         run: |
           find /etc/apt -name '*.list' -exec sed -i \
-            -e 's|http://deb.debian.org/debian-security|https://security.debian.org/debian-security|g' \
+            -e 's|^deb http://deb.debian.org/debian-security bullseye-security|deb [check-valid-until=no] https://snapshot.debian.org/archive/debian-security/20260801T000000Z bullseye-security|' \
             -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
 
       - uses: actions/checkout@v3

From a75d8210aacedde4290d7d1f5ba8141694e4f6e0 Mon Sep 17 00:00:00 2001
From: ptr25 <62867142+ptr25@users.noreply.github.com>
Date: Wed, 30 Sep 2026 12:48:35 +0530
Subject: [PATCH 8/9] Handle clang-tidy dry runs without removed setuptools
 spawn argument

---
 projectq/_setup_test.py | 29 +++++++++++++++++++++++++++++
 setup.py                |  3 ++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/projectq/_setup_test.py b/projectq/_setup_test.py
index 70dfc908..5212d1a1 100644
--- a/projectq/_setup_test.py
+++ b/projectq/_setup_test.py
@@ -13,9 +13,12 @@
 #   limitations under the License.
 """Regression tests for source-tree packaging commands."""
 
+import runpy
 import subprocess
 import sys
 from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import patch
 
 import pytest
 
@@ -42,3 +45,29 @@ def test_requirements_fallback_preserves_marker_quotes(tmp_path):
     requirements = (tmp_path / 'requirements.txt').read_text().splitlines()
     assert 'azure-quantum <= 3.5.0; python_version <= "3.8"' in requirements
     assert 'azure-quantum; python_version > "3.8"' in requirements
+
+
+@pytest.mark.parametrize('dry_run', [False, True])
+def test_clang_tidy_spawn_compatibility(dry_run):
+    """Clang-Tidy respects dry runs without relying on removed spawn arguments."""
+    from setuptools import Distribution
+
+    setup_path = Path(__file__).resolve().parents[1] / 'setup.py'
+    if not setup_path.is_file():
+        pytest.skip('Requires a source checkout')
+    with patch('setuptools.setup'):
+        namespace = runpy.run_path(str(setup_path))
+    command = namespace['ClangTidy'](Distribution())
+    command.distribution.ext_modules = []
+    command.dry_run = dry_run
+    command.warning_as_errors = True
+    build = SimpleNamespace(run=lambda: None)
+    calls = []
+
+    def spawn(args):
+        calls.append(args)
+
+    with patch.object(command, 'get_finalized_command', return_value=build):
+        with patch.dict(command.run.__globals__, spawn=spawn):
+            command.run()
+    assert calls == ([] if dry_run else [['clang-tidy', '--warnings-as-errors=*']])
diff --git a/setup.py b/setup.py
index ac79a272..957c2de5 100755
--- a/setup.py
+++ b/setup.py
@@ -686,7 +686,8 @@ def run(self):
             command.append('--warnings-as-errors=*')
         for ext in self.distribution.ext_modules:
             command.extend(os.path.abspath(p) for p in ext.sources)
-        spawn(command, dry_run=self.dry_run)
+        if not self.dry_run:
+            spawn(command)
 
 
 # ------------------------------------------------------------------------------

From 18a3e2387c3a927e07b9331cca0159c33776dd66 Mon Sep 17 00:00:00 2001
From: ptr25 <62867142+ptr25@users.noreply.github.com>
Date: Wed, 30 Sep 2026 13:06:10 +0530
Subject: [PATCH 9/9] Fix pre-commit YAML lint and pin legacy hooks to Python
 3.11

---
 .github/workflows/ci.yml     | 8 ++++++--
 .github/workflows/format.yml | 4 +++-
 .pre-commit-config.yaml      | 4 ++++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5c55828b..15ceb0ca 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -141,8 +141,10 @@ jobs:
       # Bullseye security packages have left the live mirrors; keep this legacy toolchain reproducible.
       - name: Refresh Debian repository URLs
         run: |
+          security_snapshot=https://snapshot.debian.org/archive/debian-security/20260801T000000Z
+          security_source="deb [check-valid-until=no] $security_snapshot bullseye-security"
           find /etc/apt -name '*.list' -exec sed -i \
-            -e 's|^deb http://deb.debian.org/debian-security bullseye-security|deb [check-valid-until=no] https://snapshot.debian.org/archive/debian-security/20260801T000000Z bullseye-security|' \
+            -e "s|^deb http://deb.debian.org/debian-security bullseye-security|$security_source|" \
             -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
 
       - name: Install Git
@@ -204,8 +206,10 @@ jobs:
       # Bullseye security packages have left the live mirrors; keep this legacy toolchain reproducible.
       - name: Refresh Debian repository URLs
         run: |
+          security_snapshot=https://snapshot.debian.org/archive/debian-security/20260801T000000Z
+          security_source="deb [check-valid-until=no] $security_snapshot bullseye-security"
           find /etc/apt -name '*.list' -exec sed -i \
-            -e 's|^deb http://deb.debian.org/debian-security bullseye-security|deb [check-valid-until=no] https://snapshot.debian.org/archive/debian-security/20260801T000000Z bullseye-security|' \
+            -e "s|^deb http://deb.debian.org/debian-security bullseye-security|$security_source|" \
             -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
 
       - uses: actions/checkout@v3
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index 50f13fe1..556edaa9 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -30,8 +30,10 @@ jobs:
       # Bullseye security packages have left the live mirrors; keep this legacy toolchain reproducible.
       - name: Refresh Debian repository URLs
         run: |
+          security_snapshot=https://snapshot.debian.org/archive/debian-security/20260801T000000Z
+          security_source="deb [check-valid-until=no] $security_snapshot bullseye-security"
           find /etc/apt -name '*.list' -exec sed -i \
-            -e 's|^deb http://deb.debian.org/debian-security bullseye-security|deb [check-valid-until=no] https://snapshot.debian.org/archive/debian-security/20260801T000000Z bullseye-security|' \
+            -e "s|^deb http://deb.debian.org/debian-security bullseye-security|$security_source|" \
             -e 's|http://deb.debian.org/debian|https://deb.debian.org/debian|g' {} +
 
       - uses: actions/checkout@v3
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index cf59ca9c..de1fc785 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -76,6 +76,8 @@ repos:
     rev: v3.15.2
     hooks:
       - id: pyupgrade
+        # This pinned version predates Python 3.14 tokenizer changes.
+        language_version: python3.11
         args: [--py37-plus, --keep-mock]
 
   - repo: https://github.com/PyCQA/isort
@@ -116,6 +118,8 @@ repos:
     rev: 'v3.0.0a5'
     hooks:
       - id: pylint
+        # This pinned version predates Python 3.14 AST changes.
+        language_version: python3.11
         args: ['--score=n', '--disable=no-member']
         additional_dependencies: [pybind11>=2.6, numpy, requests, matplotlib, networkx]