Raise minimum python version to 3.9 (#12910)

* Raise minimum python version to 3.9

Qiskit 1.2.0 was the final minor version release of qiskit with Python
3.8 support. As Python 3.8 is going EoL before the next Qiskit minor
release 1.3.0 we can drop support for running with 3.8 on the main
branch now. This commit makes that change and updates everything using
python 3.8 currently to use our new minimum instead.

* Pin dependency versions when installing historical versions

Now that we're running Python 3.9 as the base version we are
encountering compatibility issues with some of our dependencies because
3.9 supports newer versions of things like numpy than older Qiskit
releases were compatible with. The only way to work around this is to
pin the versions when installing historical versions. To start this sets
a single constraints version since we can get away with using the same
version for everything. In the future though it is possible that we'll
need separate files for different historical releases.

* Update reference images

* Drop 3.8 support in asv too

* Remove deprecation warning for 3.8

.github/workflows/coverage.yml

@@ -22,7 +22,7 @@ jobs:
       - uses: actions/setup-python@v5
         name: Install Python
         with:
-          python-version: '3.8'
+          python-version: '3.11'
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable

.github/workflows/randomized_tests.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/setup-python@v5
         name: Install Python
         with:
-          python-version: '3.8'
+          python-version: '3.11'
       - name: Install dependencies
         run: |
           python -m pip install -U pip setuptools wheel

.github/workflows/tests.yml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        # Normally we test min and max version but we can't run python 3.8 or
+        # Normally we test min and max version but we can't run python
         # 3.9 on arm64 until actions/setup-python#808 is resolved
         python-version: ["3.10", "3.12"]
     steps:

.github/workflows/wheels.yml

@@ -41,35 +41,6 @@ jobs:
         with:
           path: ./wheelhouse/*.whl
           name: wheels-${{ matrix.os }}
-  build_wheels_macos_arm_py38:
-    name: Build wheels on macOS arm
-    runs-on: ${{ matrix.os }}
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [macos-12]
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
-        name: Install Python
-        with:
-          python-version: '3.10'
-      - uses: dtolnay/rust-toolchain@stable
-        with:
-          components: llvm-tools-preview
-      - name: Build wheels
-        uses: pypa/cibuildwheel@v2.19.2
-        env:
-          CIBW_BEFORE_ALL: rustup target add aarch64-apple-darwin
-          CIBW_BUILD: cp38-macosx_universal2 cp38-macosx_arm64
-          CIBW_ARCHS_MACOS: arm64 universal2
-          CIBW_ENVIRONMENT: >-
-            CARGO_BUILD_TARGET="aarch64-apple-darwin"
-            PYO3_CROSS_LIB_DIR="/Library/Frameworks/Python.framework/Versions/$(python -c 'import sys; print(str(sys.version_info[0])+"."+str(sys.version_info[1]))')/lib/python$(python -c 'import sys; print(str(sys.version_info[0])+"."+str(sys.version_info[1]))')"
-      - uses: actions/upload-artifact@v4
-        with:
-          path: ./wheelhouse/*.whl
-          name: wheels-${{ matrix.os }}-arm
   build_wheels_32bit:
     name: Build wheels 32bit
     runs-on: ${{ matrix.os }}
@@ -100,7 +71,7 @@ jobs:
     environment: release
     permissions:
       id-token: write
-    needs: ["build_wheels", "build_wheels_32bit", "build_wheels_macos_arm_py38"]
+    needs: ["build_wheels", "build_wheels_32bit"]
     steps:
       - uses: actions/download-artifact@v4
         with:

Cargo.toml

@@ -34,7 +34,7 @@ rayon = "1.10"
 # distributions).  We only activate that feature when building the C extension module; we still need
 # it disabled for Rust-only tests to avoid linker errors with it not being loaded.  See
 # https://pyo3.rs/main/features#extension-module for more.
-pyo3 = { version = "0.21.2", features = ["abi3-py38"] }
+pyo3 = { version = "0.21.2", features = ["abi3-py39"] }
 
 # These are our own crates.
 qiskit-accelerate = { path = "crates/accelerate" }

asv.conf.json

@@ -17,7 +17,7 @@
     "dvcs": "git",
     "environment_type": "virtualenv",
     "show_commit_url": "http://github.com/Qiskit/qiskit/commit/",
-    "pythons": ["3.8", "3.9", "3.10", "3.11", "3.12"],
+    "pythons": ["3.9", "3.10", "3.11", "3.12"],
     "benchmark_dir": "test/benchmarks",
     "env_dir": ".asv/env",
     "results_dir": ".asv/results"

azure-pipelines.yml

@@ -37,12 +37,12 @@ parameters:
   - name: "supportedPythonVersions"
     displayName: "All supported versions of Python"
     type: object
-    default: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+    default: ["3.9", "3.10", "3.11", "3.12"]
 
   - name: "minimumPythonVersion"
     displayName: "Minimum supported version of Python"
     type: string
-    default: "3.8"
+    default: "3.9"
 
   - name: "maximumPythonVersion"
     displayName: "Maximum supported version of Python"

pyproject.toml

@@ -5,7 +5,7 @@ build-backend = "setuptools.build_meta"
 [project]
 name = "qiskit"
 description = "An open-source SDK for working with quantum computers at the level of extended quantum circuits, operators, and primitives."
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 license = {text = "Apache 2.0"}
 authors = [
     { name = "Qiskit Development Team", email = "qiskit@us.ibm.com" },
@@ -27,7 +27,6 @@ classifiers = [
     "Operating System :: Microsoft :: Windows",
     "Operating System :: POSIX :: Linux",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
@@ -140,12 +139,12 @@ include = ["qiskit", "qiskit.*"]
 
 [tool.black]
 line-length = 100
-target-version = ['py38', 'py39', 'py310', 'py311']
+target-version = ['py39', 'py310', 'py311']
 
 [tool.cibuildwheel]
 manylinux-x86_64-image = "manylinux2014"
 manylinux-i686-image = "manylinux2014"
-skip = "pp* cp36-* cp37-* *musllinux* *win32 *i686 cp38-macosx_arm64"
+skip = "pp* cp36-* cp37-* cp38-* *musllinux* *win32 *i686 cp38-macosx_arm64"
 test-skip = "*win32 *linux_i686"
 test-command = "python {project}/examples/python/stochastic_swap.py"
 # We need to use pre-built versions of Numpy and Scipy in the tests; they have a
@@ -197,7 +196,7 @@ extension-pkg-allow-list = [
     "tweedledum",
 ]
 load-plugins = ["pylint.extensions.docparams", "pylint.extensions.docstyle"]
-py-version = "3.8"  # update it when bumping minimum supported python version
+py-version = "3.9"  # update it when bumping minimum supported python version
 
 [tool.pylint.basic]
 good-names = ["a", "b", "i", "j", "k", "d", "n", "m", "ex", "v", "w", "x", "y", "z", "Run", "_", "logger", "q", "c", "r", "qr", "cr", "qc", "nd", "pi", "op", "b", "ar", "br", "p", "cp", "ax", "dt", "__unittest", "iSwapGate", "mu"]

qiskit/__init__.py

@@ -43,14 +43,6 @@
             " Qiskit unfortunately cannot enforce this requirement during environment resolution."
             " See https://qisk.it/packaging-1-0 for more detail."
         )
-if sys.version_info < (3, 9):
-    warnings.warn(
-        "Using Qiskit with Python 3.8 is deprecated as of the 1.1.0 release. "
-        "Support for running Qiskit with Python 3.8 will be removed in the "
-        "1.3.0 release, which coincides with when Python 3.8 goes end of life.",
-        DeprecationWarning,
-    )
-
 
 from . import _accelerate
 import qiskit._numpy_compat

releasenotes/notes/py3.9-min-now-c9781484a0eb288e.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    The minimum supported version of Python is now 3.9, this has been raised
+    from the previous minimum support version of 3.8. This change was necessary
+    because the upstream cPython project no longer supports Python 3.8.

test/python/circuit/test_circuit_load_from_qpy.py

@@ -1948,8 +1948,11 @@ def test_pre_v12_rejects_standalone_var(self, version):
         """Test that dumping to older QPY versions rejects standalone vars."""
         a = expr.Var.new("a", types.Bool())
         qc = QuantumCircuit(inputs=[a])
-        with io.BytesIO() as fptr, self.assertRaisesRegex(
-            UnsupportedFeatureForVersion, "version 12 is required.*realtime variables"
+        with (
+            io.BytesIO() as fptr,
+            self.assertRaisesRegex(
+                UnsupportedFeatureForVersion, "version 12 is required.*realtime variables"
+            ),
         ):
             dump(qc, fptr, version=version)
 
@@ -1959,8 +1962,9 @@ def test_pre_v12_rejects_index(self, version):
         # Be sure to use a register, since standalone vars would be rejected for other reasons.
         qc = QuantumCircuit(ClassicalRegister(2, "cr"))
         qc.store(expr.index(qc.cregs[0], 0), False)
-        with io.BytesIO() as fptr, self.assertRaisesRegex(
-            UnsupportedFeatureForVersion, "version 12 is required.*Index"
+        with (
+            io.BytesIO() as fptr,
+            self.assertRaisesRegex(UnsupportedFeatureForVersion, "version 12 is required.*Index"),
         ):
             dump(qc, fptr, version=version)
 

test/python/circuit/test_control_flow_builders.py

@@ -3464,9 +3464,12 @@ def test_switch_rejects_entering_case_after_close(self):
     def test_switch_rejects_reentering_case(self):
         """It shouldn't be possible to enter a case within another case."""
         circuit = QuantumCircuit(1, 1)
-        with circuit.switch(0) as case, case(0), self.assertRaisesRegex(
-            CircuitError, r"Cannot enter more than one case at once"
-        ), case(1):
+        with (
+            circuit.switch(0) as case,
+            case(0),
+            self.assertRaisesRegex(CircuitError, r"Cannot enter more than one case at once"),
+            case(1),
+        ):
             pass
 
     @ddt.data("1", 1.0, None, (1, 2))

test/qpy_compat/process_version.sh

@@ -45,9 +45,9 @@ if [[ ! -d qpy_$version ]] ; then
     echo "Building venv for qiskit-terra $version"
     python -m venv $version
     if [[ ${parts[0]} -eq 0 ]] ; then
-        ./$version/bin/pip install "qiskit-terra==$version"
+        ./$version/bin/pip install -c qpy_test_constraints.txt "qiskit-terra==$version"
     else
-        ./$version/bin/pip install "qiskit==$version"
+        ./$version/bin/pip install -c qpy_test_constraints.txt "qiskit==$version"
     fi
     mkdir qpy_$version
     pushd qpy_$version

test/qpy_compat/qpy_test_constraints.txt

@@ -0,0 +1,2 @@
+numpy===1.24.4
+scipy===1.10.1

test/qpy_compat/run_tests.sh

@@ -20,7 +20,7 @@ export PYTHONHASHSEED=$(python -S -c "import random; print(random.randint(1, 429
 echo "PYTHONHASHSEED=$PYTHONHASHSEED"
 
 python -m venv qiskit_venv
-qiskit_venv/bin/pip install ../..
+qiskit_venv/bin/pip install -c ../../constraints.txt ../..
 
 parallel bash ./process_version.sh ::: `git tag --sort=-creatordate`
 

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 4.0
-envlist = py38, py39, py310, py311, py312, lint-incr
+envlist = py39, py310, py311, py312, lint-incr
 isolated_build = true
 
 [testenv]
@@ -15,7 +15,7 @@ setenv =
   QISKIT_SUPRESS_PACKAGING_WARNINGS=Y
   QISKIT_TEST_CAPTURE_STREAMS=1
   QISKIT_PARALLEL=FALSE
-passenv = 
+passenv =
   RUSTUP_TOOLCHAIN
   RAYON_NUM_THREADS
   OMP_NUM_THREADS