32-bit Linux running on 64-bit ARM arch should have platform "linux_armv7l"

CHANGELOG.rst

@@ -4,7 +4,8 @@ Changelog
 *unreleased*
 ~~~~~~~~~~~~
 
-No changes yet.
+* Fix a bug that caused a 32-bit OS that runs on a 64-bit ARM CPU (e.g. ARM-v8,
+  aarch64), to report the wrong bitness.
 
 20.1 - 2020-01-24
 ~~~~~~~~~~~~~~~~~~~

packaging/tags.py

@@ -636,8 +636,11 @@ def _have_compatible_manylinux_abi(arch):
 def _linux_platforms(is_32bit=_32_BIT_INTERPRETER):
     # type: (bool) -> Iterator[str]
     linux = _normalize_string(distutils.util.get_platform())
-    if linux == "linux_x86_64" and is_32bit:
-        linux = "linux_i686"
+    if is_32bit:
+        if linux == "linux_x86_64":
+            linux = "linux_i686"
+        elif linux == "linux_aarch64":
+            linux = "linux_armv7l"
     manylinux_support = []
     _, arch = linux.split("_", 1)
     if _have_compatible_manylinux_abi(arch):

tests/test_tags.py

@@ -37,11 +37,6 @@ def is_x86():
     return re.match(r"(i\d86|x86_64)", platform.machine()) is not None
 
 
-@pytest.fixture
-def is_64bit_os():
-    return platform.architecture()[0] == "64bit"
-
-
 @pytest.fixture
 def manylinux_module(monkeypatch):
     monkeypatch.setattr(tags, "_have_compatible_glibc", lambda *args: False)
@@ -415,19 +410,22 @@ def test_glibc_version_string_none(self, monkeypatch):
         monkeypatch.setattr(tags, "_glibc_version_string", lambda: None)
         assert not tags._have_compatible_glibc(2, 4)
 
-    def test_linux_platforms_64bit_on_64bit_os(self, is_64bit_os, is_x86, monkeypatch):
-        if platform.system() != "Linux" or not is_64bit_os or not is_x86:
-            monkeypatch.setattr(distutils.util, "get_platform", lambda: "linux_x86_64")
-            monkeypatch.setattr(tags, "_is_manylinux_compatible", lambda *args: False)
-        linux_platform = list(tags._linux_platforms(is_32bit=False))[-1]
-        assert linux_platform == "linux_x86_64"
-
-    def test_linux_platforms_32bit_on_64bit_os(self, is_64bit_os, is_x86, monkeypatch):
-        if platform.system() != "Linux" or not is_64bit_os or not is_x86:
-            monkeypatch.setattr(distutils.util, "get_platform", lambda: "linux_x86_64")
-            monkeypatch.setattr(tags, "_is_manylinux_compatible", lambda *args: False)
-        linux_platform = list(tags._linux_platforms(is_32bit=True))[-1]
-        assert linux_platform == "linux_i686"
+    @pytest.mark.parametrize(
+        "arch,is_32bit,expected",
+        [
+            ("linux-x86_64", False, "linux_x86_64"),
+            ("linux-x86_64", True, "linux_i686"),
+            ("linux-aarch64", False, "linux_aarch64"),
+            ("linux-aarch64", True, "linux_armv7l"),
+        ],
+    )
+    def test_linux_platforms_32_64bit_on_64bit_os(
+        self, arch, is_32bit, expected, monkeypatch
+    ):
+        monkeypatch.setattr(distutils.util, "get_platform", lambda: arch)
+        monkeypatch.setattr(tags, "_is_manylinux_compatible", lambda *args: False)
+        linux_platform = list(tags._linux_platforms(is_32bit=is_32bit))[-1]
+        assert linux_platform == expected
 
     def test_linux_platforms_manylinux_unsupported(self, monkeypatch):
         monkeypatch.setattr(distutils.util, "get_platform", lambda: "linux_x86_64")