[3.15] gh-149321: Remove lazy_imports=none startup mode (GH-149389)

(cherry picked from commit 1f3c267)

Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>

Author: pablogsal

Doc/c-api/import.rst

@@ -393,11 +393,6 @@ Importing Modules
 
       Make all imports lazy by default.
 
-   .. c:enumerator:: PyImport_LAZY_NONE
-
-      Disable lazy imports entirely. Even explicit ``lazy`` statements become
-      eager imports.
-
    .. versionadded:: 3.15
 
 .. c:function:: PyObject* PyImport_CreateModuleFromInitfunc(PyObject *spec, PyObject* (*initfunc)(void))

Doc/library/sys.rst

@@ -919,8 +919,6 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    * ``"normal"``: Only imports explicitly marked with the ``lazy`` keyword
      are lazy
    * ``"all"``: All top-level imports are potentially lazy
-   * ``"none"``: All lazy imports are suppressed (even explicitly marked
-     ones)
 
    See also :func:`set_lazy_imports` and :pep:`810`.
 
@@ -1772,8 +1770,6 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    * ``"normal"``: Only imports explicitly marked with the ``lazy`` keyword
      are lazy
    * ``"all"``: All top-level imports become potentially lazy
-   * ``"none"``: All lazy imports are suppressed (even explicitly marked
-     ones)
 
    This function is intended for advanced users who need to control lazy
    imports across their entire application. Library developers should

Doc/reference/simple_stmts.rst

@@ -965,10 +965,6 @@ Imports inside functions, class bodies, or
 :keyword:`try`/:keyword:`except`/:keyword:`finally` blocks are always eager,
 regardless of :attr:`!__lazy_modules__`.
 
-Setting ``-X lazy_imports=none`` (or the :envvar:`PYTHON_LAZY_IMPORTS`
-environment variable to ``none``) overrides :attr:`!__lazy_modules__` and
-forces all imports to be eager.
-
 .. versionadded:: 3.15
 
 .. _future:

Doc/using/cmdline.rst

@@ -705,10 +705,9 @@ Miscellaneous options
 
      .. versionadded:: 3.14
 
-   * :samp:`-X lazy_imports={all,none,normal}` controls lazy import behavior.
-     ``all`` makes all imports lazy by default, ``none`` disables lazy imports
-     entirely (even explicit ``lazy`` statements become eager), and ``normal``
-     (the default) respects the ``lazy`` keyword in source code.
+   * :samp:`-X lazy_imports={all,normal}` controls lazy import behavior.
+     ``all`` makes all imports lazy by default, and ``normal`` (the default)
+     respects the ``lazy`` keyword in source code.
      See also :envvar:`PYTHON_LAZY_IMPORTS`.
 
      .. versionadded:: 3.15
@@ -1416,10 +1415,9 @@ conflict.
 
 .. envvar:: PYTHON_LAZY_IMPORTS
 
-   Controls lazy import behavior. Accepts three values: ``all`` makes all
-   imports lazy by default, ``none`` disables lazy imports entirely (even
-   explicit ``lazy`` statements become eager), and ``normal`` (the default)
-   respects the ``lazy`` keyword in source code.
+   Controls lazy import behavior. Accepts two values: ``all`` makes all
+   imports lazy by default, and ``normal`` (the default) respects the
+   ``lazy`` keyword in source code.
 
    See also the :option:`-X lazy_imports <-X>` command-line option.
 

Doc/whatsnew/3.15.rst

@@ -157,11 +157,10 @@ making it straightforward to diagnose and debug the failure.
 For cases where you want to enable lazy loading globally without modifying
 source code, Python provides the :option:`-X lazy_imports <-X>` command-line
 option and the :envvar:`PYTHON_LAZY_IMPORTS` environment variable. Both
-accept three values: ``all`` makes all imports lazy by default, ``none``
-disables lazy imports entirely (even explicit ``lazy`` statements become
-eager), and ``normal`` (the default) respects the ``lazy`` keyword in source
-code. The :func:`sys.set_lazy_imports` and :func:`sys.get_lazy_imports`
-functions allow changing and querying this mode at runtime.
+accept two values: ``all`` makes all imports lazy by default, and ``normal``
+(the default) respects the ``lazy`` keyword in source code. The
+:func:`sys.set_lazy_imports` and :func:`sys.get_lazy_imports` functions allow
+changing and querying this mode at runtime.
 
 For more selective control, :func:`sys.set_lazy_imports_filter` accepts a
 callable that determines whether a specific module should be loaded lazily.

Include/import.h

@@ -90,8 +90,7 @@ PyAPI_FUNC(int) PyImport_AppendInittab(
 
 typedef enum {
     PyImport_LAZY_NORMAL,
-    PyImport_LAZY_ALL,
-    PyImport_LAZY_NONE
+    PyImport_LAZY_ALL
 } PyImport_LazyImportsMode;
 
 #ifndef Py_LIMITED_API

Lib/test/test_lazy_import/__init__.py

@@ -171,10 +171,18 @@ def test_from_import_with_imported_module_getattr(self):
 class GlobalLazyImportModeTests(LazyImportTestCase):
     """Tests for sys.set_lazy_imports() global mode control."""
 
-    def test_global_off(self):
-        """Mode 'none' should disable lazy imports entirely."""
-        import test.test_lazy_import.data.global_off
-        self.assertIn("test.test_lazy_import.data.basic2", sys.modules)
+    def tearDown(self):
+        for key in list(sys.modules.keys()):
+            if key.startswith('test.test_lazy_import.data'):
+                del sys.modules[key]
+
+        sys.set_lazy_imports_filter(None)
+        sys.set_lazy_imports("normal")
+
+    def test_global_off_rejected(self):
+        """Mode 'none' is not supported."""
+        with self.assertRaises(ValueError):
+            sys.set_lazy_imports("none")
 
     def test_global_on(self):
         """Mode 'all' should make regular imports lazy."""
@@ -612,9 +620,6 @@ def test_get_lazy_imports_returns_string(self):
         sys.set_lazy_imports("all")
         self.assertEqual(sys.get_lazy_imports(), "all")
 
-        sys.set_lazy_imports("none")
-        self.assertEqual(sys.get_lazy_imports(), "none")
-
     def test_get_lazy_imports_filter_default(self):
         """get_lazy_imports_filter should return None by default."""
         sys.set_lazy_imports_filter(None)
@@ -1111,68 +1116,16 @@ def test_cli_lazy_imports_all_makes_regular_imports_lazy(self):
         self.assertEqual(result.returncode, 0, f"stderr: {result.stderr}")
         self.assertIn("LAZY", result.stdout)
 
-    def test_cli_lazy_imports_none_forces_all_imports_eager(self):
-        """-X lazy_imports=none should force all imports to be eager."""
-        code = textwrap.dedent("""
-            import sys
-            # Even explicit lazy imports should be eager in 'none' mode
-            lazy import json
-            if 'json' in sys.modules:
-                print("EAGER")
-            else:
-                print("LAZY")
-        """)
+    def test_cli_lazy_imports_none_is_rejected(self):
+        """-X lazy_imports=none should be rejected."""
         result = subprocess.run(
-            [sys.executable, "-X", "lazy_imports=none", "-c", code],
+            [sys.executable, "-X", "lazy_imports=none", "-c", "pass"],
             capture_output=True,
             text=True
         )
-        self.assertEqual(result.returncode, 0, f"stderr: {result.stderr}")
-        self.assertIn("EAGER", result.stdout)
-
-    @support.requires_resource("cpu")
-    def test_cli_lazy_imports_modes_import_stdlib_modules(self):
-        """-X lazy_imports modes should import available stdlib modules."""
-        # Do not smoke-test modules with intentional import-time effects.
-        import_side_effect_modules = {"antigravity", "this"}
-        importable = []
-
-        for module in sorted(sys.stdlib_module_names):
-            if module in import_side_effect_modules:
-                continue
-
-            with self.subTest(module=module):
-                code = f"import {module}; print({module})"
-                baseline = subprocess.run(
-                    [sys.executable, "-I", "-c", code],
-                    capture_output=True,
-                    text=True,
-                    timeout=60,
-                )
-                if baseline.returncode:
-                    # sys.stdlib_module_names includes modules for other
-                    # platforms and optional extension modules not built here.
-                    continue
-                importable.append(module)
-
-                for mode in ("normal", "none"):
-                    with self.subTest(module=module, mode=mode):
-                        result = subprocess.run(
-                            [
-                                sys.executable,
-                                "-I",
-                                "-X",
-                                f"lazy_imports={mode}",
-                                "-c",
-                                code,
-                            ],
-                            capture_output=True,
-                            text=True,
-                            timeout=60,
-                        )
-                        self.assertEqual(result.returncode, 0, result.stderr)
-
-        self.assertGreater(len(importable), 100)
+        self.assertNotEqual(result.returncode, 0)
+        self.assertIn("-X lazy_imports: invalid value", result.stderr)
+        self.assertIn("expected 'all' or 'normal'", result.stderr)
 
     def test_cli_lazy_imports_normal_respects_lazy_keyword_only(self):
         """-X lazy_imports=normal should respect lazy keyword only."""
@@ -1221,101 +1174,51 @@ def test_env_var_lazy_imports_all_enables_global_lazy(self):
         self.assertEqual(result.returncode, 0, f"stderr: {result.stderr}")
         self.assertIn("LAZY", result.stdout)
 
-    def test_env_var_lazy_imports_none_disables_all_lazy(self):
-        """PYTHON_LAZY_IMPORTS=none should disable all lazy imports."""
-        code = textwrap.dedent("""
-            import sys
-            lazy import json
-            if 'json' in sys.modules:
-                print("EAGER")
-            else:
-                print("LAZY")
-        """)
+    def test_env_var_lazy_imports_none_is_rejected(self):
+        """PYTHON_LAZY_IMPORTS=none should be rejected."""
         import os
         env = os.environ.copy()
         env["PYTHON_LAZY_IMPORTS"] = "none"
         result = subprocess.run(
-            [sys.executable, "-c", code],
+            [sys.executable, "-c", "pass"],
             capture_output=True,
             text=True,
             env=env
         )
-        self.assertEqual(result.returncode, 0, f"stderr: {result.stderr}")
-        self.assertIn("EAGER", result.stdout)
-
-    def test_cli_lazy_imports_none_disables_dunder_lazy_modules(self):
-        """-X lazy_imports=none should override __lazy_modules__."""
-        code = textwrap.dedent("""
-            import sys
-            __lazy_modules__ = ["json"]
-            import json
-            if 'json' in sys.modules:
-                print("EAGER")
-            else:
-                print("LAZY")
-        """)
-        result = subprocess.run(
-            [sys.executable, "-X", "lazy_imports=none", "-c", code],
-            capture_output=True,
-            text=True,
-        )
-        self.assertEqual(result.returncode, 0, f"stderr: {result.stderr}")
-        self.assertIn("EAGER", result.stdout)
-
-    def test_env_var_lazy_imports_none_disables_dunder_lazy_modules(self):
-        """PYTHON_LAZY_IMPORTS=none should override __lazy_modules__."""
-        code = textwrap.dedent("""
-            import sys
-            __lazy_modules__ = ["json"]
-            import json
-            if 'json' in sys.modules:
-                print("EAGER")
-            else:
-                print("LAZY")
-        """)
-        import os
-
-        env = os.environ.copy()
-        env["PYTHON_LAZY_IMPORTS"] = "none"
-        result = subprocess.run(
-            [sys.executable, "-c", code],
-            capture_output=True,
-            text=True,
-            env=env,
-        )
-        self.assertEqual(result.returncode, 0, f"stderr: {result.stderr}")
-        self.assertIn("EAGER", result.stdout)
+        self.assertNotEqual(result.returncode, 0)
+        self.assertIn("PYTHON_LAZY_IMPORTS: invalid value", result.stderr)
+        self.assertIn("expected 'all' or 'normal'", result.stderr)
 
     def test_cli_overrides_env_var(self):
         """Command-line option should take precedence over environment variable."""
         # PEP 810: -X lazy_imports takes precedence over PYTHON_LAZY_IMPORTS
         code = textwrap.dedent("""
             import sys
-            lazy import json
+            import json
             if 'json' in sys.modules:
                 print("EAGER")
             else:
                 print("LAZY")
         """)
         import os
         env = os.environ.copy()
-        env["PYTHON_LAZY_IMPORTS"] = "all"  # env says all
+        env["PYTHON_LAZY_IMPORTS"] = "all"  # env says all imports are lazy
         result = subprocess.run(
-            [sys.executable, "-X", "lazy_imports=none", "-c", code],  # CLI says none
+            [sys.executable, "-X", "lazy_imports=normal", "-c", code],
             capture_output=True,
             text=True,
             env=env
         )
         self.assertEqual(result.returncode, 0, f"stderr: {result.stderr}")
-        # CLI should win - imports should be eager
+        # CLI should win, so a regular import should stay eager.
         self.assertIn("EAGER", result.stdout)
 
     def test_sys_set_lazy_imports_overrides_cli(self):
         """sys.set_lazy_imports() should take precedence over CLI option."""
         code = textwrap.dedent("""
             import sys
-            sys.set_lazy_imports("none")  # Override CLI
-            lazy import json
+            sys.set_lazy_imports("normal")  # Override CLI
+            import json
             if 'json' in sys.modules:
                 print("EAGER")
             else:
@@ -2037,9 +1940,10 @@ def test_normal_import_dis(self):
 class LazyCApiTests(LazyImportTestCase):
     def test_set_matches_sys(self):
         self.assertEqual(_testcapi.PyImport_GetLazyImportsMode(), sys.get_lazy_imports())
-        for mode in ("normal", "all", "none"):
+        for mode in ("normal", "all"):
             _testcapi.PyImport_SetLazyImportsMode(mode)
             self.assertEqual(_testcapi.PyImport_GetLazyImportsMode(), sys.get_lazy_imports())
+        self.assertRaises(ValueError, _testcapi.PyImport_SetLazyImportsMode, "none")
 
     def test_filter_matches_sys(self):
         self.assertEqual(_testcapi.PyImport_GetLazyImportsFilter(), sys.get_lazy_imports_filter())

Lib/test/test_lazy_import/data/global_off.py

@@ -180,16 +180,6 @@ dealing with contradictions in ``make_bottom``.
 
 ..
 
-.. date: 2026-03-24-13-06-52
-.. gh-issue: 146369
-.. nonce: 6wDI6S
-.. section: Core and Builtins
-
-Ensure ``-X lazy_imports=none`` and ``PYTHON_LAZY_IMPORTS=none`` override
-:attr:`~module.__lazy_modules__`. Patch by Hugo van Kemenade.
-
-..
-
 .. date: 2026-03-22-19-30-00
 .. gh-issue: 146308
 .. nonce: AxnRVA

Misc/NEWS.d/3.15.0a8.rst

@@ -0,0 +1 @@
+Do not support ``none`` as a lazy imports mode.