fix(pypi): include platform-specific packages in unified hub

news/unified-platform-packages.fixed.md

@@ -0,0 +1,3 @@
+(pypi) Include platform-specific packages in the unified
+`@pypi` hub so that their aliases resolve on supported target
+platforms. ([#4171](https://github.com/bazel-contrib/rules_python/issues/4171))

python/private/pypi/extension.bzl

@@ -505,7 +505,7 @@ def _create_unified_hub_repo(mods):
     extra_aliases = {}
 
     for hub_name in hubs:
-        for pkg_name in mods.exposed_packages.get(hub_name, []):
+        for pkg_name in mods.hub_whl_map[hub_name]:
             norm_pkg = normalize_name(pkg_name)
             if norm_pkg not in packages:
                 packages[norm_pkg] = []

tests/integration/unified_pypi/BUILD.bazel

@@ -59,3 +59,19 @@ py_binary(
     main = "bin_declared_only.py",
     deps = ["@pypi//declared_only_pkg:declared-only-alias"],
 )
+
+platform(
+    name = "linux_x86_64",
+    constraint_values = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+)
+
+platform(
+    name = "windows_x86_64",
+    constraint_values = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:windows",
+    ],
+)

tests/integration/unified_pypi/MODULE.bazel

@@ -1,5 +1,6 @@
 module(name = "unified_pypi")
 
+bazel_dep(name = "platforms", version = "0.0.11")
 bazel_dep(name = "rules_python", version = "0.0.0")
 local_path_override(
     module_name = "rules_python",
@@ -36,11 +37,19 @@ pip.parse(
 )
 use_repo(pip, "pypi_a")
 
-# pypi_b has colorama and six, and acts as designated fallback
+# `pypi_b` supplies `six` only on Linux and is the fallback hub.
 pip.parse(
     hub_name = "pypi_b",
     python_version = "3.11",
-    requirements_lock = "//:requirements_b.txt",
+    requirements_by_platform = {
+        "//:requirements_b.txt": "linux_*",
+        "//:requirements_b_without_six.txt": "osx_*,windows_*",
+    },
+    target_platforms = [
+        "{os}_{arch}",
+        "linux_x86_64",
+        "windows_x86_64",
+    ],
 )
 use_repo(pip, "pypi_b")
 

tests/integration/unified_pypi/requirements_b_without_six.txt

@@ -0,0 +1,3 @@
+colorama==0.4.5 \
+    --hash=sha256:854bf444933e37f5824ae7bfc1e98d5bce2ebe4160d46b5edf346a89358e99da \
+    --hash=sha256:e6c6b4334fc50988a639d9b98ae42f5c90ec94cb1495b4fe76c5f72cf7f79435

tests/integration/unified_pypi_test.py

@@ -20,6 +20,27 @@ def test_cli_override(self):
             "//:test_cli",
         )
 
+    def test_platform_specific_package(self):
+        for hub in ("auto", "pypi_b"):
+            with self.subTest(hub=hub):
+                self.run_bazel(
+                    "build",
+                    "--platforms=//:linux_x86_64",
+                    f"--@rules_python//python/config_settings:venv={hub}",
+                    "@pypi//six",
+                    "@pypi//six:whl",
+                )
+
+    def test_platform_specific_package_rejects_unsupported_platform(self):
+        result = self.run_bazel(
+            "cquery",
+            "--platforms=//:windows_x86_64",
+            "@pypi//six",
+            check=False,
+        )
+        self.assertNotEqual(result.exit_code, 0)
+        self.assert_result_matches(result, "No matching wheel")
+
     def test_disjoint_package_cquery_succeeds_but_build_fails(self):
         self.run_bazel("cquery", "//:bin_six_a")
         result = self.run_bazel("build", "//:bin_six_a", check=False)