chore: add structurally typed GenericPythonConfiguration (pypa#1458)

* Add structually typed GenericPythonConfiguration

Use structural typing for the return value of get_python_configurations
so that we don't have to specify a union of all possible PythonConfiguration
types

* address henryiii's comments

* Use Set in more places

cibuildwheel/__main__.py

@@ -7,6 +7,7 @@
 import tarfile
 import textwrap
 import typing
+from collections.abc import Sequence, Set
 from pathlib import Path
 from tempfile import mkdtemp
 
@@ -18,7 +19,12 @@
 from cibuildwheel.architecture import Architecture, allowed_architectures_check
 from cibuildwheel.logger import log
 from cibuildwheel.options import CommandLineArguments, Options, compute_options
-from cibuildwheel.typing import PLATFORMS, PlatformName, assert_never
+from cibuildwheel.typing import (
+    PLATFORMS,
+    GenericPythonConfiguration,
+    PlatformName,
+    assert_never,
+)
 from cibuildwheel.util import (
     CIBW_CACHE_PATH,
     BuildSelector,
@@ -339,13 +345,9 @@ def print_preamble(platform: str, options: Options, identifiers: list[str]) -> N
 
 
 def get_build_identifiers(
-    platform: PlatformName, build_selector: BuildSelector, architectures: set[Architecture]
+    platform: PlatformName, build_selector: BuildSelector, architectures: Set[Architecture]
 ) -> list[str]:
-    python_configurations: (
-        list[cibuildwheel.linux.PythonConfiguration]
-        | list[cibuildwheel.windows.PythonConfiguration]
-        | list[cibuildwheel.macos.PythonConfiguration]
-    )
+    python_configurations: Sequence[GenericPythonConfiguration]
 
     if platform == "linux":
         python_configurations = cibuildwheel.linux.get_python_configurations(

cibuildwheel/linux.py

@@ -3,6 +3,7 @@
 import subprocess
 import sys
 import textwrap
+from collections.abc import Set
 from dataclasses import dataclass
 from pathlib import Path, PurePath, PurePosixPath
 from typing import Iterator, Tuple
@@ -46,7 +47,7 @@ class BuildStep:
 
 def get_python_configurations(
     build_selector: BuildSelector,
-    architectures: set[Architecture],
+    architectures: Set[Architecture],
 ) -> list[PythonConfiguration]:
     full_python_configs = read_python_configs("linux")
 

cibuildwheel/macos.py

@@ -8,6 +8,7 @@
 import shutil
 import subprocess
 import sys
+from collections.abc import Set
 from dataclasses import dataclass
 from pathlib import Path
 from typing import Sequence, Tuple, cast
@@ -69,7 +70,7 @@ class PythonConfiguration:
 
 
 def get_python_configurations(
-    build_selector: BuildSelector, architectures: set[Architecture]
+    build_selector: BuildSelector, architectures: Set[Architecture]
 ) -> list[PythonConfiguration]:
     full_python_configs = read_python_configs("macos")
 

cibuildwheel/typing.py

@@ -42,3 +42,9 @@
 
 PlatformName = Literal["linux", "macos", "windows"]
 PLATFORMS: Final[set[PlatformName]] = {"linux", "macos", "windows"}
+
+
+class GenericPythonConfiguration(Protocol):
+    @property
+    def identifier(self) -> str:
+        ...

cibuildwheel/windows.py

@@ -6,6 +6,7 @@
 import subprocess
 import sys
 import textwrap
+from collections.abc import Set
 from dataclasses import dataclass
 from functools import lru_cache
 from pathlib import Path
@@ -71,7 +72,7 @@ class PythonConfiguration:
 
 def get_python_configurations(
     build_selector: BuildSelector,
-    architectures: set[Architecture],
+    architectures: Set[Architecture],
 ) -> list[PythonConfiguration]:
     full_python_configs = read_python_configs("windows")