3.14 is missing a bytecode line number for one-line conditionals

Bug report

Bug description:

(from https://github.com/nedbat/coveragepy/issues/1991)

Here is b1991.py:

% cat b1991.py
def func(x, y):
    for size in (x or ()) if y else ():
        print(size)

func([3], True)

The disassembly looks like this:

% python3.14 -m dis -O b1991.py
  0          0       RESUME                   0

  1          2       LOAD_CONST               0 (<code object func at 0x1045ef0e0, file "b1991.py", line 1>)
             4       MAKE_FUNCTION
             6       STORE_NAME               0 (func)

  5          8       LOAD_NAME                0 (func)
            10       PUSH_NULL
            12       LOAD_SMALL_INT           3
            14       BUILD_LIST               1
            16       LOAD_CONST               1 (True)
            18       CALL                     2
            26       POP_TOP
            28       LOAD_CONST               2 (None)
            30       RETURN_VALUE

Disassembly of <code object func at 0x1045ef0e0, file "b1991.py", line 1>:
   1          0       RESUME                   0

   2          2       LOAD_FAST_BORROW         1 (y)
              4       TO_BOOL
             12       POP_JUMP_IF_FALSE       13 (to L2)
             16       NOT_TAKEN
             18       LOAD_FAST                0 (x)
             20       COPY                     1
             22       TO_BOOL
             30       POP_JUMP_IF_TRUE         3 (to L1)
             34       NOT_TAKEN
             36       POP_TOP
             38       LOAD_CONST               1 (())

  --   L1:   40       JUMP_FORWARD             1 (to L3)               <----------###

   2   L2:   42       LOAD_CONST               1 (())
       L3:   44       GET_ITER
       L4:   46       FOR_ITER                14 (to L5)
             50       STORE_FAST               2 (size)

   3         52       LOAD_GLOBAL              1 (print + NULL)
             62       LOAD_FAST_BORROW         2 (size)
             64       CALL                     1
             72       POP_TOP
             74       JUMP_BACKWARD           16 (to L4)

   2   L5:   78       END_FOR
             80       POP_ITER
             82       LOAD_CONST               0 (None)
             84       RETURN_VALUE

Offset 40 has no line number, but shouldn't it be attributed to line 2? The same problem happens on 3.13 and on the tip of main.

CPython versions tested on:

3.14, 3.15, CPython main branch, 3.13

Operating systems tested on:

macOS

Linked PRs

• gh-136923

Reproduisez le rapport de b1991.py avec python3.14 -m dis -O b1991.py, puis examinez comment les informations de ligne sont attribuées à la conditionnelle sur une seule ligne dans le désassemblage généré. La modification est terminée lorsque l’offset 40 est attribué à la ligne 2 sans provoquer de régression dans les autres associations de lignes affichées ; gh-136923 indique qu’un travail connexe est peut-être déjà en cours.