Drop support for Python 3.8.

This also adds the recently released Python 3.13 to CI.

Author: whitequark

.github/workflows/main.yaml

@@ -11,18 +11,17 @@ jobs:
     strategy:
       matrix:
         python-version:
-        - '3.8'
         - '3.9'
         - '3.10'
         - '3.11'
         - '3.12'
-        - 'pypy-3.8'
+        - '3.13'
         - 'pypy-3.9'
         - 'pypy-3.10'
         allow-failure:
         - false
         include:
-        - python-version: '3.13-dev'
+        - python-version: '3.14-dev'
           allow-failure: true
     continue-on-error: ${{ matrix.allow-failure }}
     name: 'test (${{ matrix.python-version }})'

amaranth/_toolchain/yosys.py

@@ -4,15 +4,8 @@
 import subprocess
 import warnings
 import pathlib
-from importlib import metadata as importlib_metadata
-try:
-    from importlib import resources as importlib_resources
-    try:
-        importlib_resources.files # py3.9+ stdlib
-    except AttributeError:
-        import importlib_resources # py3.8- shim
-except ImportError:
-    importlib_resources = None
+import importlib.metadata
+import importlib.resources
 
 from . import has_tool, require_tool
 
@@ -109,23 +102,21 @@ class _BuiltinYosys(YosysBinary):
 
     @classmethod
     def available(cls):
-        if importlib_metadata is None or importlib_resources is None:
-            return False
         try:
-            importlib_metadata.version(cls.YOSYS_PACKAGE)
+            importlib.metadata.version(cls.YOSYS_PACKAGE)
             return True
-        except importlib_metadata.PackageNotFoundError:
+        except importlib.metadata.PackageNotFoundError:
             return False
 
     @classmethod
     def version(cls):
-        version = importlib_metadata.version(cls.YOSYS_PACKAGE)
+        version = importlib.metadata.version(cls.YOSYS_PACKAGE)
         match = re.match(r"^(\d+)\.(\d+)\.(?:\d+)(?:\.(\d+))?(?:\.post(\d+))?", version)
         return (int(match[1]), int(match[2]), int(match[3] or 0), int(match[4] or 0))
 
     @classmethod
     def data_dir(cls):
-        return importlib_resources.files(cls.YOSYS_PACKAGE) / "share"
+        return importlib.resources.files(cls.YOSYS_PACKAGE) / "share"
 
     @classmethod
     def run(cls, args, stdin="", *, ignore_warnings=False, src_loc_at=0):

amaranth/back/rtlil.py

@@ -1,4 +1,4 @@
-from typing import Iterable
+from collections.abc import Iterable
 from contextlib import contextmanager
 import io
 

amaranth/build/res.py

@@ -311,9 +311,7 @@ def add_clock_constraint(self, clock, period=None, frequency=None):
             clocks[clock] = frequency
 
     def iter_signal_clock_constraints(self):
-        for signal, frequency in self._clocks.items():
-            yield signal, frequency
+        yield from self._clocks.items()
 
     def iter_port_clock_constraints(self):
-        for port, frequency in self._io_clocks.items():
-            yield port, frequency
+        yield from self._io_clocks.items()

amaranth/hdl/_ir.py

@@ -706,7 +706,7 @@ def __init__(self, netlist: _nir.Netlist, design: Design, *, all_undef_to_ff=Fal
         # SignalDict from Signal to dict from (module index, ClockDomain | None) to NetlistDriver
         self.drivers = _ast.SignalDict()
         self.io_ports: dict[_ast.IOPort, int] = {}
-        self.rhs_cache: dict[int, Tuple[_nir.Value, bool, _ast.Value]] = {}
+        self.rhs_cache: dict[int, tuple[_nir.Value, bool, _ast.Value]] = {}
         self.matches_cache = {}
         self.priority_match_cache = {}
         self.fragment_module_idx: dict[Fragment, int] = {}
@@ -817,7 +817,7 @@ def unify_shapes_bitwise(self,
         operand_b = self.extend(operand_b, signed_b, shape.width)
         return (operand_a, operand_b, shape.signed)
 
-    def emit_rhs(self, module_idx: int, value: _ast.Value) -> Tuple[_nir.Value, bool]:
+    def emit_rhs(self, module_idx: int, value: _ast.Value) -> tuple[_nir.Value, bool]:
         """Emits a RHS value, returns a tuple of (value, is_signed)"""
         try:
             result, signed, value = self.rhs_cache[id(value)]

amaranth/hdl/_nir.py

@@ -1,4 +1,5 @@
-from typing import Iterable, Any
+from typing import Any
+from collections.abc import Iterable
 import enum
 
 from ._ast import SignalDict

amaranth/lib/enum.py

@@ -29,11 +29,6 @@ class EnumType(ShapeCastable, py_enum.EnumMeta):
     can be specified by passing the ``view_class=`` keyword argument when creating the enum class.
     """
 
-    # TODO: remove this shim once py3.8 support is dropped
-    @classmethod
-    def __prepare__(metacls, name, bases, shape=None, view_class=None, **kwargs):
-        return super().__prepare__(name, bases, **kwargs)
-
     def __new__(metacls, name, bases, namespace, shape=None, view_class=None, **kwargs):
         if shape is not None:
             shape = Shape.cast(shape)

amaranth/lib/meta.py

@@ -141,6 +141,6 @@ def _extract_schemas(package, *, base_uri, path="schema/"):
             f"Schema $id {schema['$id']} must be {base_uri}/{relative_path}"
 
         schema_filename.parent.mkdir(parents=True, exist_ok=True)
-        with open(pathlib.Path(path) / relative_path, "wt") as schema_file:
+        with open(pathlib.Path(path) / relative_path, "w") as schema_file:
             json.dump(schema, schema_file, indent=2)
         print(f"Extracted {schema['$id']} to {schema_filename}")

docs/install.rst

@@ -23,7 +23,7 @@ System requirements
 
 .. |yosys-version| replace:: 0.40 (or newer)
 
-Amaranth HDL requires Python 3.8; it works on CPython_ 3.8 (or newer), and works faster on PyPy3.8_ 7.3.7 (or newer). Installation requires pip_ 23.0 (or newer).
+Amaranth HDL requires Python 3.9; it works on CPython_ 3.9 (or newer), and works faster on PyPy3.9_ 7.3.7 (or newer). Installation requires pip_ 23.0 (or newer).
 
 For most workflows, Amaranth requires Yosys_ |yosys-version|. A `compatible version of Yosys <amaranth-yosys_>`_ is distributed via PyPI_ for most popular platforms, so it is usually not necessary to install Yosys separately.
 
@@ -34,7 +34,7 @@ Synthesizing, placing and routing an Amaranth design for an FPGA requires the FP
 .. TODO: Link to FPGA family docs here
 
 .. _CPython: https://www.python.org/
-.. _PyPy3.8: https://www.pypy.org/
+.. _PyPy3.9: https://www.pypy.org/
 .. _pip: https://pip.pypa.io/en/stable/
 .. _Yosys: https://yosyshq.net/yosys/
 .. _amaranth-yosys: https://pypi.org/project/amaranth-yosys/

pyproject.toml

@@ -13,9 +13,8 @@ readme = "README.md"
 authors = [{name = "Amaranth HDL contributors"}]
 license = { text = "BSD-2-clause" }
 
-requires-python = "~=3.8"
+requires-python = "~=3.9"
 dependencies = [
-  "importlib_resources; python_version<'3.9'", # for amaranth._toolchain.yosys
   "jschon~=0.11.1", # for amaranth.lib.meta
   "pyvcd>=0.2.2,<0.5", # for amaranth.sim.pysim
   "Jinja2~=3.0", # for amaranth.build
@@ -47,10 +46,6 @@ amaranth-rpc = "amaranth.rpc:main"
 requires = ["pdm-backend~=2.3.0"]
 build-backend = "pdm.backend"
 
-[tool.pdm]
-# Remove this once we no longer support Python 3.8.
-ignore_package_warnings = ["sphinx*", "alabaster"]
-
 [tool.pdm.build]
 # If amaranth 0.3 is checked out with git (e.g. as a part of a persistent editable install or
 # a git worktree cached by tools like poetry), it can have an empty `nmigen` directory left over,