Ensure version inference falls back to PKG-INFO when building wheel from sdist

Author: abravalheri

setup.py

@@ -36,8 +36,12 @@ def _get_version() -> str:
         version = subprocess.check_output(cmd, encoding="utf-8")
         return _normalization.best_effort_version(version, "{safe}.dev+{sanitized}")
     except subprocess.CalledProcessError:  # e.g.: git not installed or history missing
+        if os.path.exists("PKG-INFO"):  # building wheel from sdist
+            with open("PKG-INFO", encoding="utf-8") as fp:
+                if match := re.search(r"^Version: (\d+\.\d+\.\d+.*)$", fp.read(), re.M):
+                    return match[1]
         with open("NEWS.rst", encoding="utf-8") as fp:
-            match = re.search(r"v\d+\.\d+.\d+", fp.read())  # latest version
+            match = re.search(r"v\d+\.\d+\.\d+", fp.read())  # latest version
             return f"{match[0] if match else '0.0.0'}.dev+{time.strftime('%Y%m%d')}"
 
 

setuptools/tests/test_setuptools.py

@@ -265,6 +265,15 @@ def test_findall_missing_symlink(tmpdir):
         assert found == []
 
 
+def test_setuptools_own_dists_infers_version(setuptools_sdist, setuptools_wheel):
+    # Sanity check
+    # Validates that `setup.py:_get_version` works as expected
+    assert "0.0.0" not in setuptools_sdist.name
+    # Validates that `setup.py:_get_version` guarantees the fallback
+    # code path is finding something in PKG-INFO:
+    assert "0.0.0" not in setuptools_wheel.name
+
+
 @pytest.mark.xfail(reason="unable to exclude tests; #4475 #3260")
 def test_its_own_wheel_does_not_contain_tests(setuptools_wheel):
     with ZipFile(setuptools_wheel) as zipfile: