refactor tags._generic_api to use EXT_SUFFIX (#607)

Co-authored-by: Brett Cannon <brett@python.org>

src/packaging/tags.py

@@ -225,10 +225,45 @@ def cpython_tags(
                 yield Tag(interpreter, "abi3", platform_)
 
 
-def _generic_abi() -> Iterator[str]:
-    abi = sysconfig.get_config_var("SOABI")
-    if abi:
-        yield _normalize_string(abi)
+def _generic_abi() -> List[str]:
+    """
+    Return the ABI tag based on EXT_SUFFIX.
+    """
+    # The following are examples of `EXT_SUFFIX`.
+    # We want to keep the parts which are related to the ABI and remove the
+    # parts which are related to the platform:
+    # - linux:   '.cpython-310-x86_64-linux-gnu.so' => cp310
+    # - mac:     '.cpython-310-darwin.so'           => cp310
+    # - win:     '.cp310-win_amd64.pyd'             => cp310
+    # - win:     '.pyd'                             => cp37 (uses _cpython_abis())
+    # - pypy:    '.pypy38-pp73-x86_64-linux-gnu.so' => pypy38_pp73
+    # - graalpy: '.graalpy-38-native-x86_64-darwin.dylib'
+    #                                               => graalpy_38_native
+
+    ext_suffix = _get_config_var("EXT_SUFFIX", warn=True)
+    if not isinstance(ext_suffix, str) or ext_suffix[0] != ".":
+        raise SystemError("invalid sysconfig.get_config_var('EXT_SUFFIX')")
+    parts = ext_suffix.split(".")
+    if len(parts) < 3:
+        # CPython3.7 and earlier uses ".pyd" on Windows.
+        return _cpython_abis(sys.version_info[:2])
+    soabi = parts[1]
+    if soabi.startswith("cpython"):
+        # non-windows
+        abi = "cp" + soabi.split("-")[1]
+    elif soabi.startswith("cp"):
+        # windows
+        abi = soabi.split("-")[0]
+    elif soabi.startswith("pypy"):
+        abi = "-".join(soabi.split("-")[:2])
+    elif soabi.startswith("graalpy"):
+        abi = "-".join(soabi.split("-")[:3])
+    elif soabi:
+        # pyston, ironpython, others?
+        abi = soabi
+    else:
+        return []
+    return [_normalize_string(abi)]
 
 
 def generic_tags(
@@ -252,8 +287,9 @@ def generic_tags(
         interpreter = "".join([interp_name, interp_version])
     if abis is None:
         abis = _generic_abi()
+    else:
+        abis = list(abis)
     platforms = list(platforms or platform_tags())
-    abis = list(abis)
     if "none" not in abis:
         abis.append("none")
     for abi in abis:
@@ -463,6 +499,9 @@ def platform_tags() -> Iterator[str]:
 def interpreter_name() -> str:
     """
     Returns the name of the running interpreter.
+
+    Some implementations have a reserved, two-letter abbreviation which will
+    be returned when appropriate.
     """
     name = sys.implementation.name
     return INTERPRETER_SHORT_NAMES.get(name) or name

tests/test_tags.py

@@ -823,22 +823,78 @@ def test_no_abi3_python27(self):
 
 
 class TestGenericTags:
-    @pytest.mark.skipif(
-        not sysconfig.get_config_var("SOABI"), reason="SOABI not defined"
-    )
-    def test__generic_abi_soabi_provided(self):
-        abi = sysconfig.get_config_var("SOABI").replace(".", "_").replace("-", "_")
-        assert [abi] == list(tags._generic_abi())
-
-    def test__generic_abi(self, monkeypatch):
+    def test__generic_abi_macos(self, monkeypatch):
         monkeypatch.setattr(
-            sysconfig, "get_config_var", lambda key: "cpython-37m-darwin"
+            sysconfig, "get_config_var", lambda key: ".cpython-37m-darwin.so"
         )
-        assert list(tags._generic_abi()) == ["cpython_37m_darwin"]
+        monkeypatch.setattr(tags, "interpreter_name", lambda: "cp")
+        assert tags._generic_abi() == ["cp37m"]
+
+    def test__generic_abi_linux_cpython(self, monkeypatch):
+        config = {
+            "Py_DEBUG": False,
+            "WITH_PYMALLOC": True,
+            "EXT_SUFFIX": ".cpython-37m-x86_64-linux-gnu.so",
+        }
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        monkeypatch.setattr(tags, "interpreter_name", lambda: "cp")
+        # They are identical
+        assert tags._cpython_abis((3, 7)) == ["cp37m"]
+        assert tags._generic_abi() == ["cp37m"]
+
+    def test__generic_abi_jp(self, monkeypatch):
+        config = {"EXT_SUFFIX": ".return exactly this.so"}
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        assert tags._generic_abi() == ["return exactly this"]
+
+    def test__generic_abi_graal(self, monkeypatch):
+        config = {"EXT_SUFFIX": ".graalpy-38-native-x86_64-darwin.so"}
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        assert tags._generic_abi() == ["graalpy_38_native"]
+
+    def test__generic_abi_none(self, monkeypatch):
+        config = {"EXT_SUFFIX": "..so"}
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        assert tags._generic_abi() == []
+
+    @pytest.mark.parametrize("ext_suffix", ["invalid", None])
+    def test__generic_abi_error(self, ext_suffix, monkeypatch):
+        config = {"EXT_SUFFIX": ext_suffix}
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        with pytest.raises(SystemError) as e:
+            tags._generic_abi()
+        assert "EXT_SUFFIX" in str(e.value)
+
+    def test__generic_abi_linux_pypy(self, monkeypatch):
+        # issue gh-606
+        config = {
+            "Py_DEBUG": False,
+            "EXT_SUFFIX": ".pypy39-pp73-x86_64-linux-gnu.so",
+        }
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        monkeypatch.setattr(tags, "interpreter_name", lambda: "pp")
+        assert tags._generic_abi() == ["pypy39_pp73"]
+
+    def test__generic_abi_old_windows(self, monkeypatch):
+        config = {
+            "EXT_SUFFIX": ".pyd",
+            "Py_DEBUG": 0,
+            "WITH_PYMALLOC": 0,
+        }
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        assert tags._generic_abi() == tags._cpython_abis(sys.version_info[:2])
+
+    def test__generic_abi_windows(self, monkeypatch):
+        config = {
+            "EXT_SUFFIX": ".cp310-win_amd64.pyd",
+        }
+        monkeypatch.setattr(sysconfig, "get_config_var", config.__getitem__)
+        assert tags._generic_abi() == ["cp310"]
 
-    def test__generic_abi_no_soabi(self, monkeypatch):
-        monkeypatch.setattr(sysconfig, "get_config_var", lambda key: None)
-        assert not list(tags._generic_abi())
+    @pytest.mark.skipif(sys.implementation.name != "cpython", reason="CPython-only")
+    def test__generic_abi_agree(self):
+        """Test that the two methods of finding the abi tag agree"""
+        assert tags._generic_abi() == tags._cpython_abis(sys.version_info[:2])
 
     def test_generic_platforms(self):
         platform = sysconfig.get_platform().replace("-", "_")
@@ -874,7 +930,7 @@ def test_interpreter_default(self, monkeypatch):
         assert result == [tags.Tag("sillywalkNN", "none", "any")]
 
     def test_abis_default(self, monkeypatch):
-        monkeypatch.setattr(tags, "_generic_abi", lambda: iter(["abi"]))
+        monkeypatch.setattr(tags, "_generic_abi", lambda: ["abi"])
         result = list(tags.generic_tags(interpreter="sillywalk", platforms=["any"]))
         assert result == [
             tags.Tag("sillywalk", "abi", "any"),