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bpo-43693: Add the MAKE_CELL opcode and interleave fast locals offset…
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…s. (gh-26396)

This moves logic out of the frame initialization code and into the compiler and eval loop.  Doing so simplifies the runtime code and allows us to optimize it better.

https://bugs.python.org/issue43693
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@ericsnowcurrently
ericsnowcurrently authored Jun 7, 2021
1 parent e915db3 commit 631f993
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Showing 16 changed files with 4,466 additions and 4,231 deletions.
8 changes: 8 additions & 0 deletions Doc/library/dis.rst
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Expand Up @@ -1056,6 +1056,14 @@ All of the following opcodes use their arguments.
Deletes local ``co_varnames[var_num]``.


.. opcode:: MAKE_CELL (i)

Creates a new cell in slot ``i``. If that slot is empty then
that value is stored into the new cell.

.. versionadded:: 3.11


.. opcode:: LOAD_CLOSURE (i)

Pushes a reference to the cell contained in slot ``i`` of the "fast locals"
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11 changes: 9 additions & 2 deletions Include/cpython/code.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,16 @@
# error "this header file must not be included directly"
#endif

/* Each instruction in a code object is a fixed-width value,
* currently 2 bytes: 1-byte opcode + 1-byte oparg. The EXTENDED_ARG
* opcode allows for larger values but the current limit is 3 uses
* of EXTENDED_ARG (see Python/wordcode_helpers.h), for a maximum
* 32-bit value. This aligns with the note in Python/compile.c
* (compiler_addop_i_line) indicating that the max oparg value is
* 2**32 - 1, rather than INT_MAX.
*/

typedef uint16_t _Py_CODEUNIT;
// Each oparg must fit in the second half of _Py_CODEUNIT, hence 8 bits.
#define _Py_MAX_OPARG 255

#ifdef WORDS_BIGENDIAN
# define _Py_OPCODE(word) ((word) >> 8)
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2 changes: 2 additions & 0 deletions Include/internal/pycore_frame.h
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Expand Up @@ -32,6 +32,8 @@ _PyFrame_GetBuiltins(PyFrameObject *f)

int _PyFrame_TakeLocals(PyFrameObject *f);

PyAPI_FUNC(int) _PyFrame_OpAlreadyRan(PyFrameObject *f, int opcode, int oparg);

#ifdef __cplusplus
}
#endif
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9 changes: 5 additions & 4 deletions Include/opcode.h
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3 changes: 2 additions & 1 deletion Lib/importlib/_bootstrap_external.py
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Expand Up @@ -357,6 +357,7 @@ def _write_atomic(path, data, mode=0o666):
# Python 3.11a1 3452 (drop nlocals from marshaled code objects)
# Python 3.11a1 3453 (add co_fastlocalnames and co_fastlocalkinds)
# Python 3.11a1 3454 (compute cell offsets relative to locals bpo-43693)
# Python 3.11a1 3455 (add MAKE_CELL bpo-43693)

#
# MAGIC must change whenever the bytecode emitted by the compiler may no
Expand All @@ -366,7 +367,7 @@ def _write_atomic(path, data, mode=0o666):
# Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
# in PC/launcher.c must also be updated.

MAGIC_NUMBER = (3454).to_bytes(2, 'little') + b'\r\n'
MAGIC_NUMBER = (3455).to_bytes(2, 'little') + b'\r\n'
_RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little') # For import.c

_PYCACHE = '__pycache__'
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10 changes: 6 additions & 4 deletions Lib/opcode.py
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Expand Up @@ -181,14 +181,16 @@ def jabs_op(name, op):
def_op('MAKE_FUNCTION', 132) # Flags
def_op('BUILD_SLICE', 133) # Number of items

def_op('LOAD_CLOSURE', 135)
def_op('MAKE_CELL', 135)
hasfree.append(135)
def_op('LOAD_DEREF', 136)
def_op('LOAD_CLOSURE', 136)
hasfree.append(136)
def_op('STORE_DEREF', 137)
def_op('LOAD_DEREF', 137)
hasfree.append(137)
def_op('DELETE_DEREF', 138)
def_op('STORE_DEREF', 138)
hasfree.append(138)
def_op('DELETE_DEREF', 139)
hasfree.append(139)

def_op('CALL_FUNCTION_KW', 141) # #args + #kwargs
def_op('CALL_FUNCTION_EX', 142) # Flags
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131 changes: 70 additions & 61 deletions Lib/test/test_dis.py
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Expand Up @@ -427,15 +427,17 @@ def foo(x):
return foo

dis_nested_0 = """\
%3d 0 LOAD_CLOSURE 2 (y)
2 BUILD_TUPLE 1
4 LOAD_CONST 1 (<code object foo at 0x..., file "%s", line %d>)
6 LOAD_CONST 2 ('_h.<locals>.foo')
8 MAKE_FUNCTION 8 (closure)
10 STORE_FAST 1 (foo)
%3d 12 LOAD_FAST 1 (foo)
14 RETURN_VALUE
0 MAKE_CELL 2 (y)
%3d 2 LOAD_CLOSURE 2 (y)
4 BUILD_TUPLE 1
6 LOAD_CONST 1 (<code object foo at 0x..., file "%s", line %d>)
8 LOAD_CONST 2 ('_h.<locals>.foo')
10 MAKE_FUNCTION 8 (closure)
12 STORE_FAST 1 (foo)
%3d 14 LOAD_FAST 1 (foo)
16 RETURN_VALUE
""" % (_h.__code__.co_firstlineno + 1,
__file__,
_h.__code__.co_firstlineno + 1,
Expand All @@ -444,15 +446,17 @@ def foo(x):

dis_nested_1 = """%s
Disassembly of <code object foo at 0x..., file "%s", line %d>:
%3d 0 LOAD_CLOSURE 1 (x)
2 BUILD_TUPLE 1
4 LOAD_CONST 1 (<code object <listcomp> at 0x..., file "%s", line %d>)
6 LOAD_CONST 2 ('_h.<locals>.foo.<locals>.<listcomp>')
8 MAKE_FUNCTION 8 (closure)
10 LOAD_DEREF 2 (y)
12 GET_ITER
14 CALL_FUNCTION 1
16 RETURN_VALUE
0 MAKE_CELL 1 (x)
%3d 2 LOAD_CLOSURE 1 (x)
4 BUILD_TUPLE 1
6 LOAD_CONST 1 (<code object <listcomp> at 0x..., file "%s", line %d>)
8 LOAD_CONST 2 ('_h.<locals>.foo.<locals>.<listcomp>')
10 MAKE_FUNCTION 8 (closure)
12 LOAD_DEREF 2 (y)
14 GET_ITER
16 CALL_FUNCTION 1
18 RETURN_VALUE
""" % (dis_nested_0,
__file__,
_h.__code__.co_firstlineno + 1,
Expand Down Expand Up @@ -958,59 +962,64 @@ def jumpy():
#print('expected_opinfo_jumpy = [\n ',
#',\n '.join(map(str, _instructions)), ',\n]', sep='')

#dis.dis(outer)

Instruction = dis.Instruction
expected_opinfo_outer = [
Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval=(3, 4), argrepr='(3, 4)', offset=0, starts_line=2, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=135, arg=3, argval='a', argrepr='a', offset=2, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=135, arg=4, argval='b', argrepr='b', offset=4, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_TUPLE', opcode=102, arg=2, argval=2, argrepr='', offset=6, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_f, argrepr=repr(code_object_f), offset=8, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f', argrepr="'outer.<locals>.f'", offset=10, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_FUNCTION', opcode=132, arg=9, argval=9, argrepr='defaults, closure', offset=12, starts_line=None, is_jump_target=False),
Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='f', argrepr='f', offset=14, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=16, starts_line=7, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=3, argval='a', argrepr='a', offset=18, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=4, argval='b', argrepr='b', offset=20, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval='', argrepr="''", offset=22, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval=1, argrepr='1', offset=24, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_LIST', opcode=103, arg=0, argval=0, argrepr='', offset=26, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_MAP', opcode=105, arg=0, argval=0, argrepr='', offset=28, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval='Hello world!', argrepr="'Hello world!'", offset=30, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=7, argval=7, argrepr='', offset=32, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=34, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='f', argrepr='f', offset=36, starts_line=8, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=38, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_CELL', opcode=135, arg=3, argval='a', argrepr='a', offset=0, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_CELL', opcode=135, arg=4, argval='b', argrepr='b', offset=2, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval=(3, 4), argrepr='(3, 4)', offset=4, starts_line=2, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=136, arg=3, argval='a', argrepr='a', offset=6, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=136, arg=4, argval='b', argrepr='b', offset=8, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_TUPLE', opcode=102, arg=2, argval=2, argrepr='', offset=10, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_f, argrepr=repr(code_object_f), offset=12, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f', argrepr="'outer.<locals>.f'", offset=14, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_FUNCTION', opcode=132, arg=9, argval=9, argrepr='defaults, closure', offset=16, starts_line=None, is_jump_target=False),
Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='f', argrepr='f', offset=18, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=20, starts_line=7, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=3, argval='a', argrepr='a', offset=22, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=4, argval='b', argrepr='b', offset=24, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval='', argrepr="''", offset=26, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval=1, argrepr='1', offset=28, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_LIST', opcode=103, arg=0, argval=0, argrepr='', offset=30, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_MAP', opcode=105, arg=0, argval=0, argrepr='', offset=32, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval='Hello world!', argrepr="'Hello world!'", offset=34, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=7, argval=7, argrepr='', offset=36, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=38, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='f', argrepr='f', offset=40, starts_line=8, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=42, starts_line=None, is_jump_target=False),
]

expected_opinfo_f = [
Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=(5, 6), argrepr='(5, 6)', offset=0, starts_line=3, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=135, arg=5, argval='a', argrepr='a', offset=2, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=135, arg=6, argval='b', argrepr='b', offset=4, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=135, arg=3, argval='c', argrepr='c', offset=6, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=135, arg=4, argval='d', argrepr='d', offset=8, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_TUPLE', opcode=102, arg=4, argval=4, argrepr='', offset=10, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_inner, argrepr=repr(code_object_inner), offset=12, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f.<locals>.inner', argrepr="'outer.<locals>.f.<locals>.inner'", offset=14, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_FUNCTION', opcode=132, arg=9, argval=9, argrepr='defaults, closure', offset=16, starts_line=None, is_jump_target=False),
Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='inner', argrepr='inner', offset=18, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=20, starts_line=5, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=5, argval='a', argrepr='a', offset=22, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=6, argval='b', argrepr='b', offset=24, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=3, argval='c', argrepr='c', offset=26, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=4, argval='d', argrepr='d', offset=28, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=4, argval=4, argrepr='', offset=30, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=32, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='inner', argrepr='inner', offset=34, starts_line=6, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=36, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_CELL', opcode=135, arg=3, argval='c', argrepr='c', offset=0, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_CELL', opcode=135, arg=4, argval='d', argrepr='d', offset=2, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=(5, 6), argrepr='(5, 6)', offset=4, starts_line=3, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=136, arg=5, argval='a', argrepr='a', offset=6, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=136, arg=6, argval='b', argrepr='b', offset=8, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=136, arg=3, argval='c', argrepr='c', offset=10, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CLOSURE', opcode=136, arg=4, argval='d', argrepr='d', offset=12, starts_line=None, is_jump_target=False),
Instruction(opname='BUILD_TUPLE', opcode=102, arg=4, argval=4, argrepr='', offset=14, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_inner, argrepr=repr(code_object_inner), offset=16, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f.<locals>.inner', argrepr="'outer.<locals>.f.<locals>.inner'", offset=18, starts_line=None, is_jump_target=False),
Instruction(opname='MAKE_FUNCTION', opcode=132, arg=9, argval=9, argrepr='defaults, closure', offset=20, starts_line=None, is_jump_target=False),
Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='inner', argrepr='inner', offset=22, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=24, starts_line=5, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=5, argval='a', argrepr='a', offset=26, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=6, argval='b', argrepr='b', offset=28, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=3, argval='c', argrepr='c', offset=30, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=4, argval='d', argrepr='d', offset=32, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=4, argval=4, argrepr='', offset=34, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=36, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='inner', argrepr='inner', offset=38, starts_line=6, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=40, starts_line=None, is_jump_target=False),
]

expected_opinfo_inner = [
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=0, starts_line=4, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=2, argval='a', argrepr='a', offset=2, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=3, argval='b', argrepr='b', offset=4, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=4, argval='c', argrepr='c', offset=6, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=136, arg=5, argval='d', argrepr='d', offset=8, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=2, argval='a', argrepr='a', offset=2, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=3, argval='b', argrepr='b', offset=4, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=4, argval='c', argrepr='c', offset=6, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_DEREF', opcode=137, arg=5, argval='d', argrepr='d', offset=8, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='e', argrepr='e', offset=10, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_FAST', opcode=124, arg=1, argval='f', argrepr='f', offset=12, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=6, argval=6, argrepr='', offset=14, starts_line=None, is_jump_target=False),
Expand Down
51 changes: 51 additions & 0 deletions Lib/test/test_scope.py
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Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,57 @@ def bar():
self.assertEqual(foo(a=42), 50)
self.assertEqual(foo(), 25)

def testCellIsArgAndEscapes(self):
# We need to be sure that a cell passed in as an arg still
# gets wrapped in a new cell if the arg escapes into an
# inner function (closure).

def external():
value = 42
def inner():
return value
cell, = inner.__closure__
return cell
cell_ext = external()

def spam(arg):
def eggs():
return arg
return eggs

eggs = spam(cell_ext)
cell_closure, = eggs.__closure__
cell_eggs = eggs()

self.assertIs(cell_eggs, cell_ext)
self.assertIsNot(cell_eggs, cell_closure)

def testCellIsLocalAndEscapes(self):
# We need to be sure that a cell bound to a local still
# gets wrapped in a new cell if the local escapes into an
# inner function (closure).

def external():
value = 42
def inner():
return value
cell, = inner.__closure__
return cell
cell_ext = external()

def spam(arg):
cell = arg
def eggs():
return cell
return eggs

eggs = spam(cell_ext)
cell_closure, = eggs.__closure__
cell_eggs = eggs()

self.assertIs(cell_eggs, cell_ext)
self.assertIsNot(cell_eggs, cell_closure)

def testRecursion(self):

def f(x):
Expand Down
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