Attempt to avoid error with _read_utf8_with_fallback by moving code…

… in `pkg_resources` (#4422)

newsfragments/4422.misc.rst

@@ -0,0 +1 @@
+Reorder code in ``pkg_resources/__init__.py`` to avoid definitions after ``@_call_aside``.

pkg_resources/__init__.py

@@ -3426,6 +3426,38 @@ class PkgResourcesDeprecationWarning(Warning):
     """
 
 
+# Ported from ``setuptools`` to avoid introducing an import inter-dependency:
+_LOCALE_ENCODING = "locale" if sys.version_info >= (3, 10) else None
+
+
+def _read_utf8_with_fallback(file: str, fallback_encoding=_LOCALE_ENCODING) -> str:
+    """See setuptools.unicode_utils._read_utf8_with_fallback"""
+    try:
+        with open(file, "r", encoding="utf-8") as f:
+            return f.read()
+    except UnicodeDecodeError:  # pragma: no cover
+        msg = f"""\
+        ********************************************************************************
+        `encoding="utf-8"` fails with {file!r}, trying `encoding={fallback_encoding!r}`.
+
+        This fallback behaviour is considered **deprecated** and future versions of
+        `setuptools/pkg_resources` may not implement it.
+
+        Please encode {file!r} with "utf-8" to ensure future builds will succeed.
+
+        If this file was produced by `setuptools` itself, cleaning up the cached files
+        and re-building/re-installing the package with a newer version of `setuptools`
+        (e.g. by updating `build-system.requires` in its `pyproject.toml`)
+        might solve the problem.
+        ********************************************************************************
+        """
+        # TODO: Add a deadline?
+        #       See comment in setuptools.unicode_utils._Utf8EncodingNeeded
+        warnings.warn(msg, PkgResourcesDeprecationWarning, stacklevel=2)
+        with open(file, "r", encoding=fallback_encoding) as f:
+            return f.read()
+
+
 # from jaraco.functools 1.3
 def _call_aside(f, *args, **kwargs):
     f(*args, **kwargs)
@@ -3498,35 +3530,3 @@ def _initialize_master_working_set():
     add_activation_listener = working_set.subscribe
     run_script = working_set.run_script
     run_main = run_script
-
-
-#  ---- Ported from ``setuptools`` to avoid introducing an import inter-dependency ----
-LOCALE_ENCODING = "locale" if sys.version_info >= (3, 10) else None
-
-
-def _read_utf8_with_fallback(file: str, fallback_encoding=LOCALE_ENCODING) -> str:
-    """See setuptools.unicode_utils._read_utf8_with_fallback"""
-    try:
-        with open(file, "r", encoding="utf-8") as f:
-            return f.read()
-    except UnicodeDecodeError:  # pragma: no cover
-        msg = f"""\
-        ********************************************************************************
-        `encoding="utf-8"` fails with {file!r}, trying `encoding={fallback_encoding!r}`.
-
-        This fallback behaviour is considered **deprecated** and future versions of
-        `setuptools/pkg_resources` may not implement it.
-
-        Please encode {file!r} with "utf-8" to ensure future builds will succeed.
-
-        If this file was produced by `setuptools` itself, cleaning up the cached files
-        and re-building/re-installing the package with a newer version of `setuptools`
-        (e.g. by updating `build-system.requires` in its `pyproject.toml`)
-        might solve the problem.
-        ********************************************************************************
-        """
-        # TODO: Add a deadline?
-        #       See comment in setuptools.unicode_utils._Utf8EncodingNeeded
-        warnings.warn(msg, PkgResourcesDeprecationWarning, stacklevel=2)
-        with open(file, "r", encoding=fallback_encoding) as f:
-            return f.read()

pkg_resources/tests/test_integration_zope_interface.py

@@ -0,0 +1,54 @@
+import platform
+from inspect import cleandoc
+
+import jaraco.path
+import pytest
+
+pytestmark = pytest.mark.integration
+
+
+# For the sake of simplicity this test uses fixtures defined in
+# `setuptools.test.fixtures`,
+# and it also exercise conditions considered deprecated...
+# So if needed this test can be deleted.
+@pytest.mark.skipif(
+    platform.system() != "Linux",
+    reason="only demonstrated to fail on Linux in #4399",
+)
+def test_interop_pkg_resources_iter_entry_points(tmp_path, venv):
+    """
+    Importing pkg_resources.iter_entry_points on console_scripts
+    seems to cause trouble with zope-interface, when deprecates installation method
+    is used. See #4399.
+    """
+    project = {
+        "pkg": {
+            "foo.py": cleandoc(
+                """
+                from pkg_resources import iter_entry_points
+
+                def bar():
+                    print("Print me if you can")
+                """
+            ),
+            "setup.py": cleandoc(
+                """
+                from setuptools import setup, find_packages
+
+                setup(
+                    install_requires=["zope-interface==6.4.post2"],
+                    entry_points={
+                        "console_scripts": [
+                            "foo=foo:bar",
+                        ],
+                    },
+                )
+                """
+            ),
+        }
+    }
+    jaraco.path.build(project, prefix=tmp_path)
+    cmd = ["pip", "install", "-e", ".", "--no-use-pep517"]
+    venv.run(cmd, cwd=tmp_path / "pkg")  # Needs this version of pkg_resources installed
+    out = venv.run(["foo"])
+    assert "Print me if you can" in out