line number for a return in a with block after 3.10 is that of the with, not the return statement #93975

gpshead · 2022-06-18T00:05:07Z

def foo() -> int:
    with open('/dev/null') as devnull:
        return 'a'

In Python 3.10 onwards, the reported line number for the return statement is incorrect.

Python main 3.12-main-ish not far from 3.11:

>>> def foo() -> int:
...   with open('a') as f:
...     return 'b'
... 
>>> dis.dis(foo)
  1           0 RESUME                   0

  2           2 LOAD_GLOBAL              1 (NULL + open)
             14 LOAD_CONST               1 ('a')
             16 CALL                     1
             26 BEFORE_WITH
             28 STORE_FAST               0 (f)

  3          30 NOP

  2          32 LOAD_CONST               0 (None)
             34 LOAD_CONST               0 (None)
             36 LOAD_CONST               0 (None)
             38 CALL                     2
             48 POP_TOP
             50 LOAD_CONST               2 ('b')
             52 RETURN_VALUE
        >>   54 PUSH_EXC_INFO
             56 WITH_EXCEPT_START
             58 POP_JUMP_FORWARD_IF_TRUE     4 (to 68)
             60 RERAISE                  2
        >>   62 COPY                     3
             64 POP_EXCEPT
             66 RERAISE                  1
        >>   68 POP_TOP
             70 POP_EXCEPT
             72 POP_TOP
             74 POP_TOP
             76 LOAD_CONST               0 (None)
             78 RETURN_VALUE
ExceptionTable:
  28 to 30 -> 54 [1] lasti
  54 to 60 -> 62 [3] lasti
  68 to 68 -> 62 [3] lasti
>>> sys.version_info
sys.version_info(major=3, minor=12, micro=0, releaselevel='alpha', serial=0)

The only thing attributed to line 3 is a NOP. The RETURN_VALUE of 'b' is listed as line 2. That is wrong.

Python 3.9:

>>> def foo() -> int:
...   with open('a') as f:
...     return 'b'
... 
>>> dis.dis(foo)
  2           0 LOAD_GLOBAL              0 (open)
              2 LOAD_CONST               1 ('a')
              4 CALL_FUNCTION            1
              6 SETUP_WITH              18 (to 26)
              8 STORE_FAST               0 (f)

  3          10 POP_BLOCK
             12 LOAD_CONST               0 (None)
             14 DUP_TOP
             16 DUP_TOP
             18 CALL_FUNCTION            3
             20 POP_TOP
             22 LOAD_CONST               2 ('b')
             24 RETURN_VALUE
        >>   26 WITH_EXCEPT_START
             28 POP_JUMP_IF_TRUE        32
             30 RERAISE
        >>   32 POP_TOP
             34 POP_TOP
             36 POP_TOP
             38 POP_EXCEPT
             40 POP_TOP
             42 LOAD_CONST               0 (None)
             44 RETURN_VALUE
>>> sys.version_info
sys.version_info(major=3, minor=9, micro=12, releaselevel='final', serial=0)

Noticed by @martindemello working on a 3.10 error attribution bug in pytype.

The text was updated successfully, but these errors were encountered:

dignissimus · 2022-06-18T09:31:34Z

The issue was introduced in 937cebc
See bpo-44298: #88464

The same behaviour occurs with try-finally blocks on both 3.9 and 3.10+

def function():
    try:
        return
    finally:
        pass

With the above code, disassembling on Python 3.10.5 produces the following

  1           0 LOAD_CONST               0 (<code object function at 0x7f96b4e0d000, file "a.py", line 1>)
              2 LOAD_CONST               1 ('function')
              4 MAKE_FUNCTION            0
              6 STORE_NAME               0 (function)
              8 LOAD_CONST               2 (None)
             10 RETURN_VALUE

Disassembly of <code object function at 0x7f96b4e0d000, file "tryfinally.py", line 1>:
  2           0 SETUP_FINALLY            3 (to 8)

  3           2 POP_BLOCK

  5           4 LOAD_CONST               0 (None)
              6 RETURN_VALUE
        >>    8 RERAISE                  0

And on 3.9.0

  1           0 LOAD_CONST               0 (<code object function at 0x7f72158a8be0, file "/tmp/a.py", line 1>)
              2 LOAD_CONST               1 ('function')
              4 MAKE_FUNCTION            0
              6 STORE_NAME               0 (function)
              8 LOAD_CONST               2 (None)
             10 RETURN_VALUE

Disassembly of <code object function at 0x7f72158a8be0, file "tryfinally.py", line 1>:
  2           0 SETUP_FINALLY            6 (to 8)

  3           2 POP_BLOCK
              4 LOAD_CONST               0 (None)
              6 RETURN_VALUE

  5     >>    8 RERAISE
             10 LOAD_CONST               0 (None)
             12 RETURN_VALUE

- gh-93957: Provide nicer error reporting from subprocesses in test_venv.EnsurePipTest.test_with_pip. - Update changelog This change does three things: 1. Extract a function for trapping output in subprocesses. 2. Emit both stdout and stderr when encountering an error. 3. Apply the change to `ensurepip._uninstall` check.

- gh-93957: Provide nicer error reporting from subprocesses in test_venv.EnsurePipTest.test_with_pip. - Update changelog This change does three things: 1. Extract a function for trapping output in subprocesses. 2. Emit both stdout and stderr when encountering an error. 3. Apply the change to `ensurepip._uninstall` check. (cherry picked from commit 6066f45) Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>

- gh-93957: Provide nicer error reporting from subprocesses in test_venv.EnsurePipTest.test_with_pip. - Update changelog This change does three things: 1. Extract a function for trapping output in subprocesses. 2. Emit both stdout and stderr when encountering an error. 3. Apply the change to `ensurepip._uninstall` check.. (cherry picked from commit 6066f45) Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>

gpshead added type-bug interpreter-core 3.11 3.10 3.12 labels Jun 18, 2022

gpshead assigned markshannon Jun 18, 2022

gpshead mentioned this issue Jun 20, 2022

3.10.0b2 traces with-exit before the break that caused the exit #88464

Closed

line number for a return in a with block after 3.10 is that of the with, not the return statement #93975

line number for a return in a with block after 3.10 is that of the with, not the return statement #93975

gpshead commented Jun 18, 2022

dignissimus commented Jun 18, 2022

line number for a return in a with block after 3.10 is that of the with, not the return statement #93975

line number for a return in a with block after 3.10 is that of the with, not the return statement #93975

Comments

gpshead commented Jun 18, 2022

dignissimus commented Jun 18, 2022