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Implement disabling imports in try/except and * imports, report errors on bad usage of lazy

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This commit is contained in:
Dino Viehland 2025-09-29 09:01:41 -07:00
parent 164423b42b
commit 00e7800e4c
11 changed files with 99 additions and 27 deletions
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2
Include/internal/pycore_magic_number.h
View file

@ -300,7 +300,7 @@ PC/launcher.c must also be updated.
*/
#define PYC_MAGIC_NUMBER 3656
#define PYC_MAGIC_NUMBER 3657
/* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
(little-endian) and then appending b'\r\n'. */
#define PYC_MAGIC_NUMBER_TOKEN \

44
Lib/test/test_import/__init__.py
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@ -2662,6 +2662,50 @@ def test_lazy_value_get(self):
self.assertTrue("test.test_import.data.lazy_imports.basic2" in sys.modules)
def test_lazy_try_except(self):
with self.assertRaises(SyntaxError):
import test.test_import.data.lazy_imports.lazy_try_except
def test_lazy_try_except_from(self):
with self.assertRaises(SyntaxError):
import test.test_import.data.lazy_imports.lazy_try_except_from
def test_lazy_try_except_from_star(self):
with self.assertRaises(SyntaxError):
import test.test_import.data.lazy_imports.lazy_try_except_from_star
def test_try_except_eager(self):
importlib.set_lazy_imports(True)
try:
import test.test_import.data.lazy_imports.try_except_eager
except ImportError as e:
self.fail('lazy import failed')
self.assertTrue("test.test_import.data.lazy_imports.basic2" in sys.modules)
def test_try_except_eager_from(self):
importlib.set_lazy_imports(True)
try:
import test.test_import.data.lazy_imports.try_except_eager_from
except ImportError as e:
self.fail('lazy import failed')
self.assertTrue("test.test_import.data.lazy_imports.basic2" in sys.modules)
def test_lazy_import_func(self):
with self.assertRaises(SyntaxError):
import test.test_import.data.lazy_imports.lazy_import_func
def test_eager_import_func(self):
importlib.set_lazy_imports(True)
try:
import test.test_import.data.lazy_imports.eager_import_func
except ImportError as e:
self.fail('lazy import failed')
f = test.test_import.data.lazy_imports.eager_import_func.f
self.assertEqual(type(f()), type(sys))
class TestSinglePhaseSnapshot(ModuleSnapshot):
"""A representation of a single-phase init module for testing.

2
Lib/test/test_import/data/lazy_imports/lazy_import_func.py Normal file
View file

@ -0,0 +1,2 @@
def f():
lazy import foo

4
Lib/test/test_import/data/lazy_imports/lazy_try_except.py Normal file
View file

@ -0,0 +1,4 @@
try:
lazy import foo
except:
pass

4
Lib/test/test_import/data/lazy_imports/lazy_try_except_from.py Normal file
View file

@ -0,0 +1,4 @@
try:
lazy from foo import bar
except:
pass

1
Lib/test/test_import/data/lazy_imports/lazy_try_except_from_star.py Normal file
View file

@ -0,0 +1 @@
lazy from foo import *

4
Lib/test/test_import/data/lazy_imports/try_except_eager.py Normal file
View file

@ -0,0 +1,4 @@
try:
import test.test_import.data.lazy_imports.basic2
except:
pass

4
Lib/test/test_import/data/lazy_imports/try_except_eager_from.py Normal file
View file

@ -0,0 +1,4 @@
try:
from test.test_import.data.lazy_imports.basic2 import f
except:
pass

11
Python/ceval.c
View file

@ -3049,17 +3049,6 @@ _PyEval_LazyImportName(PyThreadState *tstate, PyObject *builtins, PyObject *glob
break;
}
// Always make star imports eager regardless of lazy setting
if (fromlist && PyTuple_Check(fromlist) && PyTuple_GET_SIZE(fromlist) == 1) {
PyObject *item = PyTuple_GET_ITEM(fromlist, 0);
if (PyUnicode_Check(item)) {
const char *item_str = PyUnicode_AsUTF8(item);
if (item_str && strcmp(item_str, "*") == 0) {
lazy = 0; // Force star imports to be eager
}
}
}
if (!lazy) {
// Not a lazy import or lazy imports are disabled, fallback to the regular import
return _PyEval_ImportName(tstate, builtins, globals, locals, name, fromlist, level);

34
Python/codegen.c
View file

@ -2852,6 +2852,18 @@ codegen_import_as(compiler *c, location loc,
return codegen_nameop(c, loc, asname, Store);
}
static int
codegen_validate_lazy_import(compiler *c, location loc)
{
if (_PyCompile_ScopeType(c) != COMPILE_SCOPE_MODULE) {
return _PyCompile_Error(c, loc, "lazy imports only allowed in module scope");
} else if (_PyCompile_TopFBlock(c)) {
return _PyCompile_Error(c, loc, "cannot lazy import in a nested scope");
}
return SUCCESS;
}
static int
codegen_import(compiler *c, stmt_ty s)
{
@ -2873,12 +2885,16 @@ codegen_import(compiler *c, stmt_ty s)
ADDOP_LOAD_CONST(c, loc, zero);
ADDOP_LOAD_CONST(c, loc, Py_None);
if (s->v.Import.is_lazy) {
// TODO: SyntaxError when not in module scope
RETURN_IF_ERROR(codegen_validate_lazy_import(c, loc));
ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 1);
} else {
// TODO: If in try/except, set 2nd bit
if (_PyCompile_TopFBlock(c) || _PyCompile_ScopeType(c) != COMPILE_SCOPE_MODULE) {
// force eager import in try/except block
ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 2);
} else {
ADDOP_NAME_CUSTOM(c, loc, IMPORT_NAME, alias->name, names, 2, 0);
}
}
if (alias->asname) {
r = codegen_import_as(c, loc, alias->name, alias->asname);
@ -2929,11 +2945,23 @@ codegen_from_import(compiler *c, stmt_ty s)
from = s->v.ImportFrom.module;
}
if (s->v.ImportFrom.is_lazy) {
// TODO: SyntaxError when not in module scope
alias_ty alias = (alias_ty)asdl_seq_GET(s->v.ImportFrom.names, 0);
if (PyUnicode_READ_CHAR(alias->name, 0) == '*') {
return _PyCompile_Error(c, LOC(s), "cannot lazy import *");
}
RETURN_IF_ERROR(codegen_validate_lazy_import(c, LOC(s)));
ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 1);
} else {
alias_ty alias = (alias_ty)asdl_seq_GET(s->v.ImportFrom.names, 0);
if (_PyCompile_TopFBlock(c) || _PyCompile_ScopeType(c) != COMPILE_SCOPE_MODULE ||
PyUnicode_READ_CHAR(alias->name, 0) == '*') {
// forced non-lazy import due to try/except or import *
ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 2);
} else {
ADDOP_NAME_CUSTOM(c, LOC(s), IMPORT_NAME, from, names, 2, 0);
}
}
for (Py_ssize_t i = 0; i < n; i++) {
alias_ty alias = (alias_ty)asdl_seq_GET(s->v.ImportFrom.names, i);
identifier store_name;

12
Python/import.c
View file

@ -4118,16 +4118,8 @@ _PyImport_LazyImportModuleLevelObject(PyThreadState *tstate,
}
PyInterpreterState *interp = tstate->interp;
// Don't return early if we have a fromlist - we need to handle the import properly
// to ensure submodules are loaded
if (fromlist == NULL || fromlist == Py_None) {
PyObject *mod = PyImport_GetModule(abs_name);
if (mod != NULL) {
Py_DECREF(abs_name);
return mod;
}
}
_PyInterpreterFrame *frame = _PyEval_GetFrame();
assert(frame->f_globals == frame->f_locals); // should only be called in global scope
// Check if the filter disables the lazy import
PyObject *filter = LAZY_IMPORTS_FILTER(interp);