gh-126072: do not add None to co_consts if there is no docstring (GH-126101)

Doc/library/inspect.rst

@@ -1700,6 +1700,14 @@ which is a bitmap of the following flags:
 
    .. versionadded:: 3.6
 
+.. data:: CO_HAS_DOCSTRING
+
+   The flag is set when there is a docstring for the code object in
+   the source code. If set, it will be the first item in
+   :attr:`~codeobject.co_consts`.
+
+   .. versionadded:: 3.14
+
 .. note::
    The flags are specific to CPython, and may not be defined in other
    Python implementations.  Furthermore, the flags are an implementation

Doc/reference/datamodel.rst

@@ -1536,9 +1536,9 @@ Other bits in :attr:`~codeobject.co_flags` are reserved for internal use.
 
 .. index:: single: documentation string
 
-If a code object represents a function, the first item in
-:attr:`~codeobject.co_consts` is
-the documentation string of the function, or ``None`` if undefined.
+If a code object represents a function and has a docstring,
+the first item in :attr:`~codeobject.co_consts` is
+the docstring of the function.
 
 Methods on code objects
 ~~~~~~~~~~~~~~~~~~~~~~~

Include/cpython/code.h

@@ -174,6 +174,11 @@ struct PyCodeObject _PyCode_DEF(1);
 
 #define CO_NO_MONITORING_EVENTS 0x2000000
 
+/* Whether the code object has a docstring,
+   If so, it will be the first item in co_consts
+*/
+#define CO_HAS_DOCSTRING 0x4000000
+
 /* This should be defined if a future statement modifies the syntax.
    For example, when a keyword is added.
 */

Include/internal/pycore_symtable.h

@@ -123,6 +123,7 @@ typedef struct _symtable_entry {
     unsigned ste_comp_iter_target : 1; /* true if visiting comprehension target */
     unsigned ste_can_see_class_scope : 1; /* true if this block can see names bound in an
                                              enclosing class scope */
+    unsigned ste_has_docstring : 1; /* true if docstring present */
     int ste_comp_iter_expr; /* non-zero if visiting a comprehension range expression */
     _Py_SourceLocation ste_loc; /* source location of block */
     struct _symtable_entry *ste_annotation_block; /* symbol table entry for this entry's annotations */

Lib/dis.py

@@ -151,16 +151,17 @@ def distb(tb=None, *, file=None, show_caches=False, adaptive=False, show_offsets
 # list of CO_* constants. It is also used by pretty_flags to
 # turn the co_flags field into a human readable list.
 COMPILER_FLAG_NAMES = {
-     1: "OPTIMIZED",
-     2: "NEWLOCALS",
-     4: "VARARGS",
-     8: "VARKEYWORDS",
-    16: "NESTED",
-    32: "GENERATOR",
-    64: "NOFREE",
-   128: "COROUTINE",
-   256: "ITERABLE_COROUTINE",
-   512: "ASYNC_GENERATOR",
+            1: "OPTIMIZED",
+            2: "NEWLOCALS",
+            4: "VARARGS",
+            8: "VARKEYWORDS",
+           16: "NESTED",
+           32: "GENERATOR",
+           64: "NOFREE",
+          128: "COROUTINE",
+          256: "ITERABLE_COROUTINE",
+          512: "ASYNC_GENERATOR",
+    0x4000000: "HAS_DOCSTRING",
 }
 
 def pretty_flags(flags):

Lib/inspect.py

@@ -56,6 +56,7 @@ __all__ = [
     "CO_OPTIMIZED",
     "CO_VARARGS",
     "CO_VARKEYWORDS",
+    "CO_HAS_DOCSTRING",
     "ClassFoundException",
     "ClosureVars",
     "EndOfBlock",
@@ -409,6 +410,7 @@ def iscode(object):
         co_flags            bitmap: 1=optimized | 2=newlocals | 4=*arg | 8=**arg
                             | 16=nested | 32=generator | 64=nofree | 128=coroutine
                             | 256=iterable_coroutine | 512=async_generator
+                            | 0x4000000=has_docstring
         co_freevars         tuple of names of free variables
         co_posonlyargcount  number of positional only arguments
         co_kwonlyargcount   number of keyword only arguments (not including ** arg)

Lib/test/test_code.py

@@ -17,7 +17,7 @@ cellvars: ('x',)
 freevars: ()
 nlocals: 2
 flags: 3
-consts: ('None', '<code object g>')
+consts: ('<code object g>',)
 
 >>> dump(f(4).__code__)
 name: g
@@ -86,7 +86,7 @@ varnames: ()
 cellvars: ()
 freevars: ()
 nlocals: 0
-flags: 3
+flags: 67108867
 consts: ("'doc string'", 'None')
 
 >>> def keywordonly_args(a,b,*,k1):
@@ -123,6 +123,61 @@ nlocals: 3
 flags: 3
 consts: ('None',)
 
+>>> def has_docstring(x: str):
+...     'This is a one-line doc string'
+...     x += x
+...     x += "hello world"
+...     # co_flags should be 0x4000003 = 67108867
+...     return x
+
+>>> dump(has_docstring.__code__)
+name: has_docstring
+argcount: 1
+posonlyargcount: 0
+kwonlyargcount: 0
+names: ()
+varnames: ('x',)
+cellvars: ()
+freevars: ()
+nlocals: 1
+flags: 67108867
+consts: ("'This is a one-line doc string'", "'hello world'")
+
+>>> async def async_func_docstring(x: str, y: str):
+...     "This is a docstring from async function"
+...     import asyncio
+...     await asyncio.sleep(1)
+...     # co_flags should be 0x4000083 = 67108995
+...     return x + y
+
+>>> dump(async_func_docstring.__code__)
+name: async_func_docstring
+argcount: 2
+posonlyargcount: 0
+kwonlyargcount: 0
+names: ('asyncio', 'sleep')
+varnames: ('x', 'y', 'asyncio')
+cellvars: ()
+freevars: ()
+nlocals: 3
+flags: 67108995
+consts: ("'This is a docstring from async function'", 'None')
+
+>>> def no_docstring(x, y, z):
+...     return x + "hello" + y + z + "world"
+
+>>> dump(no_docstring.__code__)
+name: no_docstring
+argcount: 3
+posonlyargcount: 0
+kwonlyargcount: 0
+names: ()
+varnames: ('x', 'y', 'z')
+cellvars: ()
+freevars: ()
+nlocals: 3
+flags: 3
+consts: ("'hello'", "'world'")
 """
 
 import copy

Lib/test/test_compile.py

@@ -834,7 +834,7 @@ class TestSpecifics(unittest.TestCase):
                 return "unused"
 
         self.assertEqual(f.__code__.co_consts,
-                         (None, "used"))
+                         (True, "used"))
 
     @support.cpython_only
     def test_remove_unused_consts_extended_args(self):
@@ -852,9 +852,9 @@ class TestSpecifics(unittest.TestCase):
         eval(compile(code, "file.py", "exec"), g)
         exec(code, g)
         f = g['f']
-        expected = tuple([None, ''] + [f't{i}' for i in range(N)])
+        expected = tuple([''] + [f't{i}' for i in range(N)])
         self.assertEqual(f.__code__.co_consts, expected)
-        expected = "".join(expected[2:])
+        expected = "".join(expected[1:])
         self.assertEqual(expected, f())
 
     # Stripping unused constants is not a strict requirement for the
@@ -1244,7 +1244,7 @@ class TestSpecifics(unittest.TestCase):
                     y)
         genexp_lines = [0, 4, 2, 0, 4]
 
-        genexp_code = return_genexp.__code__.co_consts[1]
+        genexp_code = return_genexp.__code__.co_consts[0]
         code_lines = self.get_code_lines(genexp_code)
         self.assertEqual(genexp_lines, code_lines)
 

Lib/test/test_compiler_assemble.py

@@ -84,7 +84,7 @@ class IsolatedAssembleTests(AssemblerTestCase):
                 return x
             return inner() % 2
 
-        inner_code = mod_two.__code__.co_consts[1]
+        inner_code = mod_two.__code__.co_consts[0]
         assert isinstance(inner_code, types.CodeType)
 
         metadata = {

Lib/test/test_dis.py

@@ -197,7 +197,7 @@ dis_bug1333982 = """\
 %3d           RESUME                   0
 
 %3d           LOAD_COMMON_CONSTANT     0 (AssertionError)
-              LOAD_CONST               1 (<code object <genexpr> at 0x..., file "%s", line %d>)
+              LOAD_CONST               0 (<code object <genexpr> at 0x..., file "%s", line %d>)
               MAKE_FUNCTION
               LOAD_FAST                0 (x)
               GET_ITER
@@ -276,10 +276,10 @@ dis_kw_names = """\
               LOAD_SMALL_INT           1
               LOAD_SMALL_INT           2
               LOAD_SMALL_INT           5
-              LOAD_CONST               1 (('c',))
+              LOAD_CONST               0 (('c',))
               CALL_KW                  3
               POP_TOP
-              LOAD_CONST               0 (None)
+              LOAD_CONST               1 (None)
               RETURN_VALUE
 """ % (wrap_func_w_kwargs.__code__.co_firstlineno,
        wrap_func_w_kwargs.__code__.co_firstlineno + 1)
@@ -500,18 +500,18 @@ dis_fstring = """\
 
 %3d           LOAD_FAST                0 (a)
               FORMAT_SIMPLE
-              LOAD_CONST               1 (' ')
+              LOAD_CONST               0 (' ')
               LOAD_FAST                1 (b)
-              LOAD_CONST               2 ('4')
+              LOAD_CONST               1 ('4')
               FORMAT_WITH_SPEC
-              LOAD_CONST               1 (' ')
+              LOAD_CONST               0 (' ')
               LOAD_FAST                2 (c)
               CONVERT_VALUE            2 (repr)
               FORMAT_SIMPLE
-              LOAD_CONST               1 (' ')
+              LOAD_CONST               0 (' ')
               LOAD_FAST                3 (d)
               CONVERT_VALUE            2 (repr)
-              LOAD_CONST               2 ('4')
+              LOAD_CONST               1 ('4')
               FORMAT_WITH_SPEC
               BUILD_STRING             7
               RETURN_VALUE
@@ -785,7 +785,7 @@ dis_nested_0 = """\
 
 %4d           LOAD_FAST                0 (y)
                BUILD_TUPLE              1
-               LOAD_CONST               1 (<code object foo at 0x..., file "%s", line %d>)
+               LOAD_CONST               0 (<code object foo at 0x..., file "%s", line %d>)
                MAKE_FUNCTION
                SET_FUNCTION_ATTRIBUTE   8 (closure)
                STORE_FAST               1 (foo)
@@ -884,7 +884,7 @@ dis_loop_test_quickened_code = """\
 %3d           RESUME_CHECK             0
 
 %3d           BUILD_LIST               0
-              LOAD_CONST               1 ((1, 2, 3))
+              LOAD_CONST               0 ((1, 2, 3))
               LIST_EXTEND              1
               LOAD_SMALL_INT           3
               BINARY_OP                5 (*)
@@ -900,7 +900,7 @@ dis_loop_test_quickened_code = """\
 
 %3d   L2:     END_FOR
               POP_TOP
-              LOAD_CONST_IMMORTAL      0 (None)
+              LOAD_CONST_IMMORTAL      1 (None)
               RETURN_VALUE
 """ % (loop_test.__code__.co_firstlineno,
        loop_test.__code__.co_firstlineno + 1,
@@ -913,12 +913,12 @@ def extended_arg_quick():
 dis_extended_arg_quick_code = """\
 %3d           RESUME                   0
 
-%3d           LOAD_CONST               1 (Ellipsis)
+%3d           LOAD_CONST               0 (Ellipsis)
               EXTENDED_ARG             1
               UNPACK_EX              256
               POP_TOP
               STORE_FAST               0 (_)
-              LOAD_CONST               0 (None)
+              LOAD_CONST               1 (None)
               RETURN_VALUE
 """% (extended_arg_quick.__code__.co_firstlineno,
       extended_arg_quick.__code__.co_firstlineno + 1,)
@@ -1465,7 +1465,7 @@ Positional-only arguments: 0
 Kw-only arguments: 0
 Number of locals:  1
 Stack size:        \\d+
-Flags:             OPTIMIZED, NEWLOCALS
+Flags:             OPTIMIZED, NEWLOCALS, HAS_DOCSTRING
 Constants:
    {code_info_consts}
 Names:
@@ -1491,8 +1491,8 @@ Number of locals:  10
 Stack size:        \\d+
 Flags:             OPTIMIZED, NEWLOCALS, VARARGS, VARKEYWORDS, GENERATOR
 Constants:
-   0: None
-   1: <code object f at (.*), file "(.*)", line (.*)>
+   0: <code object f at (.*), file "(.*)", line (.*)>
+   1: None
 Variable names:
    0: a
    1: b
@@ -1510,10 +1510,12 @@ Cell variables:
    2: [abedfxyz]
    3: [abedfxyz]
    4: [abedfxyz]
-   5: [abedfxyz]"""
+   5: [abedfxyz]
+   6: [abedfxyz]
+   7: [abedfxyz]"""
 # NOTE: the order of the cell variables above depends on dictionary order!
 
-co_tricky_nested_f = tricky.__func__.__code__.co_consts[1]
+co_tricky_nested_f = tricky.__func__.__code__.co_consts[0]
 
 code_info_tricky_nested_f = """\
 Filename:          (.*)
@@ -1677,9 +1679,9 @@ def jumpy():
 # End fodder for opinfo generation tests
 expected_outer_line = 1
 _line_offset = outer.__code__.co_firstlineno - 1
-code_object_f = outer.__code__.co_consts[1]
+code_object_f = outer.__code__.co_consts[0]
 expected_f_line = code_object_f.co_firstlineno - _line_offset
-code_object_inner = code_object_f.co_consts[1]
+code_object_inner = code_object_f.co_consts[0]
 expected_inner_line = code_object_inner.co_firstlineno - _line_offset
 expected_jumpy_line = 1
 
@@ -1735,11 +1737,11 @@ expected_opinfo_outer = [
   Instruction(opname='MAKE_CELL', opcode=92, arg=0, argval='a', argrepr='a', offset=0, start_offset=0, starts_line=True, line_number=None, label=None, positions=None, cache_info=None),
   Instruction(opname='MAKE_CELL', opcode=92, arg=1, argval='b', argrepr='b', offset=2, start_offset=2, starts_line=False, line_number=None, label=None, positions=None, cache_info=None),
   Instruction(opname='RESUME', opcode=149, arg=0, argval=0, argrepr='', offset=4, start_offset=4, starts_line=True, line_number=1, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=4, argval=(3, 4), argrepr='(3, 4)', offset=6, start_offset=6, starts_line=True, line_number=2, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=3, argval=(3, 4), argrepr='(3, 4)', offset=6, start_offset=6, starts_line=True, line_number=2, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=81, arg=0, argval='a', argrepr='a', offset=8, start_offset=8, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=81, arg=1, argval='b', argrepr='b', offset=10, start_offset=10, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
   Instruction(opname='BUILD_TUPLE', opcode=48, arg=2, argval=2, argrepr='', offset=12, start_offset=12, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=1, argval=code_object_f, argrepr=repr(code_object_f), offset=14, start_offset=14, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=0, argval=code_object_f, argrepr=repr(code_object_f), offset=14, start_offset=14, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
   Instruction(opname='MAKE_FUNCTION', opcode=23, arg=None, argval=None, argrepr='', offset=16, start_offset=16, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
   Instruction(opname='SET_FUNCTION_ATTRIBUTE', opcode=103, arg=8, argval=8, argrepr='closure', offset=18, start_offset=18, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
   Instruction(opname='SET_FUNCTION_ATTRIBUTE', opcode=103, arg=1, argval=1, argrepr='defaults', offset=20, start_offset=20, starts_line=False, line_number=2, label=None, positions=None, cache_info=None),
@@ -1747,11 +1749,11 @@ expected_opinfo_outer = [
   Instruction(opname='LOAD_GLOBAL', opcode=87, arg=1, argval='print', argrepr='print + NULL', offset=24, start_offset=24, starts_line=True, line_number=7, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('index', 1, b'\x00\x00'), ('module_keys_version', 1, b'\x00\x00'), ('builtin_keys_version', 1, b'\x00\x00')]),
   Instruction(opname='LOAD_DEREF', opcode=80, arg=0, argval='a', argrepr='a', offset=34, start_offset=34, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_DEREF', opcode=80, arg=1, argval='b', argrepr='b', offset=36, start_offset=36, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=2, argval='', argrepr="''", offset=38, start_offset=38, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=1, argval='', argrepr="''", offset=38, start_offset=38, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_SMALL_INT', opcode=89, arg=1, argval=1, argrepr='', offset=40, start_offset=40, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
   Instruction(opname='BUILD_LIST', opcode=43, arg=0, argval=0, argrepr='', offset=42, start_offset=42, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
   Instruction(opname='BUILD_MAP', opcode=44, arg=0, argval=0, argrepr='', offset=44, start_offset=44, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=3, argval='Hello world!', argrepr="'Hello world!'", offset=46, start_offset=46, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=2, argval='Hello world!', argrepr="'Hello world!'", offset=46, start_offset=46, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
   Instruction(opname='CALL', opcode=49, arg=7, argval=7, argrepr='', offset=48, start_offset=48, starts_line=False, line_number=7, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=56, start_offset=56, starts_line=False, line_number=7, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=81, arg=2, argval='f', argrepr='f', offset=58, start_offset=58, starts_line=True, line_number=8, label=None, positions=None, cache_info=None),
@@ -1763,13 +1765,13 @@ expected_opinfo_f = [
   Instruction(opname='MAKE_CELL', opcode=92, arg=0, argval='c', argrepr='c', offset=2, start_offset=2, starts_line=False, line_number=None, label=None, positions=None, cache_info=None),
   Instruction(opname='MAKE_CELL', opcode=92, arg=1, argval='d', argrepr='d', offset=4, start_offset=4, starts_line=False, line_number=None, label=None, positions=None, cache_info=None),
   Instruction(opname='RESUME', opcode=149, arg=0, argval=0, argrepr='', offset=6, start_offset=6, starts_line=True, line_number=2, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=2, argval=(5, 6), argrepr='(5, 6)', offset=8, start_offset=8, starts_line=True, line_number=3, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=1, argval=(5, 6), argrepr='(5, 6)', offset=8, start_offset=8, starts_line=True, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=81, arg=3, argval='a', argrepr='a', offset=10, start_offset=10, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=81, arg=4, argval='b', argrepr='b', offset=12, start_offset=12, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=81, arg=0, argval='c', argrepr='c', offset=14, start_offset=14, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST', opcode=81, arg=1, argval='d', argrepr='d', offset=16, start_offset=16, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='BUILD_TUPLE', opcode=48, arg=4, argval=4, argrepr='', offset=18, start_offset=18, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=1, argval=code_object_inner, argrepr=repr(code_object_inner), offset=20, start_offset=20, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=0, argval=code_object_inner, argrepr=repr(code_object_inner), offset=20, start_offset=20, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='MAKE_FUNCTION', opcode=23, arg=None, argval=None, argrepr='', offset=22, start_offset=22, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='SET_FUNCTION_ATTRIBUTE', opcode=103, arg=8, argval=8, argrepr='closure', offset=24, start_offset=24, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='SET_FUNCTION_ATTRIBUTE', opcode=103, arg=1, argval=1, argrepr='defaults', offset=26, start_offset=26, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
@@ -1827,7 +1829,7 @@ expected_opinfo_jumpy = [
   Instruction(opname='END_FOR', opcode=9, arg=None, argval=None, argrepr='', offset=88, start_offset=88, starts_line=True, line_number=3, label=4, positions=None, cache_info=None),
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=90, start_offset=90, starts_line=False, line_number=3, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_GLOBAL', opcode=87, arg=3, argval='print', argrepr='print + NULL', offset=92, start_offset=92, starts_line=True, line_number=10, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('index', 1, b'\x00\x00'), ('module_keys_version', 1, b'\x00\x00'), ('builtin_keys_version', 1, b'\x00\x00')]),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=1, argval='I can haz else clause?', argrepr="'I can haz else clause?'", offset=102, start_offset=102, starts_line=False, line_number=10, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=0, argval='I can haz else clause?', argrepr="'I can haz else clause?'", offset=102, start_offset=102, starts_line=False, line_number=10, label=None, positions=None, cache_info=None),
   Instruction(opname='CALL', opcode=49, arg=1, argval=1, argrepr='', offset=104, start_offset=104, starts_line=False, line_number=10, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=112, start_offset=112, starts_line=False, line_number=10, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_FAST_CHECK', opcode=83, arg=0, argval='i', argrepr='i', offset=114, start_offset=114, starts_line=True, line_number=11, label=5, positions=None, cache_info=None),
@@ -1853,7 +1855,7 @@ expected_opinfo_jumpy = [
   Instruction(opname='JUMP_BACKWARD', opcode=72, arg=39, argval=114, argrepr='to L5', offset=188, start_offset=188, starts_line=False, line_number=16, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00')]),
   Instruction(opname='JUMP_FORWARD', opcode=74, arg=11, argval=216, argrepr='to L9', offset=192, start_offset=192, starts_line=True, line_number=17, label=7, positions=None, cache_info=None),
   Instruction(opname='LOAD_GLOBAL', opcode=87, arg=3, argval='print', argrepr='print + NULL', offset=194, start_offset=194, starts_line=True, line_number=19, label=8, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('index', 1, b'\x00\x00'), ('module_keys_version', 1, b'\x00\x00'), ('builtin_keys_version', 1, b'\x00\x00')]),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=2, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=204, start_offset=204, starts_line=False, line_number=19, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=1, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=204, start_offset=204, starts_line=False, line_number=19, label=None, positions=None, cache_info=None),
   Instruction(opname='CALL', opcode=49, arg=1, argval=1, argrepr='', offset=206, start_offset=206, starts_line=False, line_number=19, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=214, start_offset=214, starts_line=False, line_number=19, label=None, positions=None, cache_info=None),
   Instruction(opname='NOP', opcode=27, arg=None, argval=None, argrepr='', offset=216, start_offset=216, starts_line=True, line_number=20, label=9, positions=None, cache_info=None),
@@ -1870,19 +1872,19 @@ expected_opinfo_jumpy = [
   Instruction(opname='CALL', opcode=49, arg=0, argval=0, argrepr='', offset=240, start_offset=240, starts_line=False, line_number=25, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='STORE_FAST', opcode=107, arg=1, argval='dodgy', argrepr='dodgy', offset=248, start_offset=248, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_GLOBAL', opcode=87, arg=3, argval='print', argrepr='print + NULL', offset=250, start_offset=250, starts_line=True, line_number=26, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('index', 1, b'\x00\x00'), ('module_keys_version', 1, b'\x00\x00'), ('builtin_keys_version', 1, b'\x00\x00')]),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=3, argval='Never reach this', argrepr="'Never reach this'", offset=260, start_offset=260, starts_line=False, line_number=26, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=2, argval='Never reach this', argrepr="'Never reach this'", offset=260, start_offset=260, starts_line=False, line_number=26, label=None, positions=None, cache_info=None),
   Instruction(opname='CALL', opcode=49, arg=1, argval=1, argrepr='', offset=262, start_offset=262, starts_line=False, line_number=26, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=270, start_offset=270, starts_line=False, line_number=26, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=0, argval=None, argrepr='None', offset=272, start_offset=272, starts_line=True, line_number=25, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=0, argval=None, argrepr='None', offset=274, start_offset=274, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=0, argval=None, argrepr='None', offset=276, start_offset=276, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=3, argval=None, argrepr='None', offset=272, start_offset=272, starts_line=True, line_number=25, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=3, argval=None, argrepr='None', offset=274, start_offset=274, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=3, argval=None, argrepr='None', offset=276, start_offset=276, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='CALL', opcode=49, arg=3, argval=3, argrepr='', offset=278, start_offset=278, starts_line=False, line_number=25, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=286, start_offset=286, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='LOAD_GLOBAL', opcode=87, arg=3, argval='print', argrepr='print + NULL', offset=288, start_offset=288, starts_line=True, line_number=28, label=10, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('index', 1, b'\x00\x00'), ('module_keys_version', 1, b'\x00\x00'), ('builtin_keys_version', 1, b'\x00\x00')]),
   Instruction(opname='LOAD_CONST', opcode=79, arg=5, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=298, start_offset=298, starts_line=False, line_number=28, label=None, positions=None, cache_info=None),
   Instruction(opname='CALL', opcode=49, arg=1, argval=1, argrepr='', offset=300, start_offset=300, starts_line=False, line_number=28, label=None, positions=None, cache_info=[('counter', 1, b'\x00\x00'), ('func_version', 2, b'\x00\x00\x00\x00')]),
   Instruction(opname='POP_TOP', opcode=29, arg=None, argval=None, argrepr='', offset=308, start_offset=308, starts_line=False, line_number=28, label=None, positions=None, cache_info=None),
-  Instruction(opname='LOAD_CONST', opcode=79, arg=0, argval=None, argrepr='None', offset=310, start_offset=310, starts_line=False, line_number=28, label=None, positions=None, cache_info=None),
+  Instruction(opname='LOAD_CONST', opcode=79, arg=3, argval=None, argrepr='None', offset=310, start_offset=310, starts_line=False, line_number=28, label=None, positions=None, cache_info=None),
   Instruction(opname='RETURN_VALUE', opcode=33, arg=None, argval=None, argrepr='', offset=312, start_offset=312, starts_line=False, line_number=28, label=None, positions=None, cache_info=None),
   Instruction(opname='PUSH_EXC_INFO', opcode=30, arg=None, argval=None, argrepr='', offset=314, start_offset=314, starts_line=True, line_number=25, label=None, positions=None, cache_info=None),
   Instruction(opname='WITH_EXCEPT_START', opcode=41, arg=None, argval=None, argrepr='', offset=316, start_offset=316, starts_line=False, line_number=25, label=None, positions=None, cache_info=None),

Lib/test/test_inspect/test_inspect.py

@@ -5373,7 +5373,7 @@ class TestSignatureBind(unittest.TestCase):
         # Issue #19611: getcallargs should work with comprehensions
         def make_set():
             return set(z * z for z in range(5))
-        gencomp_code = make_set.__code__.co_consts[1]
+        gencomp_code = make_set.__code__.co_consts[0]
         gencomp_func = types.FunctionType(gencomp_code, {})
 
         iterator = iter(range(5))

Misc/NEWS.d/next/Core_and_Builtins/2024-10-29-10-37-39.gh-issue-126072.XLKlxv.rst

@@ -0,0 +1,3 @@
+Add a new attribute in :attr:`~codeobject.co_flags` to indicate whether the
+first item in :attr:`~codeobject.co_consts` is the docstring. If a code
+object has no docstring, ``None`` will **NOT** be inserted.

Objects/funcobject.c

@@ -162,7 +162,8 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
     PyObject *consts = code_obj->co_consts;
     assert(PyTuple_Check(consts));
     PyObject *doc;
-    if (PyTuple_Size(consts) >= 1) {
+    if (code_obj->co_flags & CO_HAS_DOCSTRING) {
+        assert(PyTuple_Size(consts) >= 1);
         doc = PyTuple_GetItem(consts, 0);
         if (!PyUnicode_Check(doc)) {
             doc = Py_None;

Python/codegen.c

@@ -1243,10 +1243,10 @@ codegen_function_body(compiler *c, stmt_ty s, int is_async, Py_ssize_t funcflags
             _PyCompile_ExitScope(c);
             return ERROR;
         }
+        Py_ssize_t idx = _PyCompile_AddConst(c, docstring);
+        Py_DECREF(docstring);
+        RETURN_IF_ERROR_IN_SCOPE(c, idx < 0 ? ERROR : SUCCESS);
     }
-    Py_ssize_t idx = _PyCompile_AddConst(c, docstring ? docstring : Py_None);
-    Py_XDECREF(docstring);
-    RETURN_IF_ERROR_IN_SCOPE(c, idx < 0 ? ERROR : SUCCESS);
 
     NEW_JUMP_TARGET_LABEL(c, start);
     USE_LABEL(c, start);

Python/compile.c

@@ -1285,6 +1285,8 @@ compute_code_flags(compiler *c)
             flags |= CO_VARARGS;
         if (ste->ste_varkeywords)
             flags |= CO_VARKEYWORDS;
+        if (ste->ste_has_docstring)
+            flags |= CO_HAS_DOCSTRING;
     }
 
     if (ste->ste_coroutine && !ste->ste_generator) {

Python/symtable.c

@@ -136,6 +136,8 @@ ste_new(struct symtable *st, identifier name, _Py_block_ty block,
     ste->ste_needs_classdict = 0;
     ste->ste_annotation_block = NULL;
 
+    ste->ste_has_docstring = 0;
+
     ste->ste_symbols = PyDict_New();
     ste->ste_varnames = PyList_New(0);
     ste->ste_children = PyList_New(0);
@@ -1841,6 +1843,10 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
             return 0;
         }
 
+        if (_PyAST_GetDocString(s->v.FunctionDef.body)) {
+            new_ste->ste_has_docstring = 1;
+        }
+
         if (!symtable_visit_annotations(st, s, s->v.FunctionDef.args,
                                         s->v.FunctionDef.returns, new_ste)) {
             Py_DECREF(new_ste);
@@ -2168,6 +2174,10 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
             return 0;
         }
 
+        if (_PyAST_GetDocString(s->v.AsyncFunctionDef.body)) {
+            new_ste->ste_has_docstring = 1;
+        }
+
         if (!symtable_visit_annotations(st, s, s->v.AsyncFunctionDef.args,
                                         s->v.AsyncFunctionDef.returns, new_ste)) {
             Py_DECREF(new_ste);