Source location of return instruction in a with block is incorrect

[iritkatriel]

def f():
 with x:
   return 42

import dis
from pprint import pprint as pp
def pos(p):
    return (p.lineno, p.end_lineno, p.col_offset, p.end_col_offset)

pp([(pos(x.positions), x.opname, x.argval) for x in dis.get_instructions(f)])

Output:

[((1, 1, 0, 0), 'RESUME', 0),
 ((2, 2, 6, 7), 'LOAD_GLOBAL', 'x'),
 ((2, 3, 1, 12), 'BEFORE_WITH', None),
 ((2, 3, 1, 12), 'POP_TOP', None),
 ((3, 3, 10, 12), 'NOP', None),
 ((2, 3, 1, 12), 'LOAD_CONST', None),
 ((2, 3, 1, 12), 'LOAD_CONST', None),
 ((2, 3, 1, 12), 'LOAD_CONST', None),
 ((2, 3, 1, 12), 'CALL', 2),
 ((2, 3, 1, 12), 'POP_TOP', None),
 ((2, 3, 1, 12), 'LOAD_CONST', 42),                 <-- incorrect
 ((2, 3, 1, 12), 'RETURN_VALUE', None),             <-- incorrect
 ((2, 3, 1, 12), 'PUSH_EXC_INFO', None),
 ((2, 3, 1, 12), 'WITH_EXCEPT_START', None),
 ((2, 3, 1, 12), 'POP_JUMP_IF_TRUE', 50),
 ((2, 3, 1, 12), 'RERAISE', 2),
 ((2, 3, 1, 12), 'POP_TOP', None),
 ((2, 3, 1, 12), 'POP_EXCEPT', None),
 ((2, 3, 1, 12), 'POP_TOP', None),
 ((2, 3, 1, 12), 'POP_TOP', None),
 ((2, 3, 1, 12), 'LOAD_CONST', None),
 ((2, 3, 1, 12), 'RETURN_VALUE', None),
 ((None, None, None, None), 'COPY', 3),
 ((None, None, None, None), 'POP_EXCEPT', None),
 ((None, None, None, None), 'RERAISE', 1)]

Linked PRs

• gh-98442: fix locations of with statement's cleanup instructions #120763
• [3.13] gh-98442: fix locations of with statement's cleanup instructions (GH-120763) #120786
• [3.12] gh-98442: fix locations of with statement's cleanup instructions (GH-120763) #120787

[iritkatriel]

@nedbat FYI.

[iritkatriel]

This is now less wrong, but still there are instructions (in the __exit__ call) that span the whole body of the with-block:

The return instruction takes its location from there, so it will be fixed once this is.

[((1, 1, 0, 0), 'RESUME', 0),
 ((2, 2, 6, 7), 'LOAD_GLOBAL', 'x'),
 ((2, 2, 6, 7), 'COPY', 1),
 ((2, 2, 6, 7), 'LOAD_SPECIAL', 1),
 ((2, 2, 6, 7), 'SWAP', 2),
 ((2, 2, 6, 7), 'SWAP', 3),
 ((2, 2, 6, 7), 'LOAD_SPECIAL', 0),
 ((2, 2, 6, 7), 'CALL', 0),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((3, 3, 10, 12), 'NOP', None),
 ((2, 3, 1, 12), 'LOAD_CONST', None),      <-- Too wide
 ((2, 3, 1, 12), 'LOAD_CONST', None),
 ((2, 3, 1, 12), 'LOAD_CONST', None),
 ((2, 3, 1, 12), 'CALL', 3),
 ((2, 3, 1, 12), 'POP_TOP', None),
 ((2, 3, 1, 12), 'RETURN_CONST', 42),
 ((2, 2, 6, 7), 'PUSH_EXC_INFO', None),
 ((2, 2, 6, 7), 'WITH_EXCEPT_START', None),
 ((2, 2, 6, 7), 'TO_BOOL', None),
 ((2, 2, 6, 7), 'POP_JUMP_IF_TRUE', 70),
 ((2, 2, 6, 7), 'RERAISE', 2),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'POP_EXCEPT', None),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'RETURN_CONST', None),
 ((None, None, None, None), 'COPY', 3),
 ((None, None, None, None), 'POP_EXCEPT', None),
 ((None, None, None, None), 'RERAISE', 1)]

[iritkatriel]

With the fix in the PR we get:

[((1, 1, 0, 0), 'RESUME', 0),
 ((2, 2, 6, 7), 'LOAD_GLOBAL', 'x'),
 ((2, 2, 6, 7), 'COPY', 1),
 ((2, 2, 6, 7), 'LOAD_SPECIAL', 1),
 ((2, 2, 6, 7), 'SWAP', 2),
 ((2, 2, 6, 7), 'SWAP', 3),
 ((2, 2, 6, 7), 'LOAD_SPECIAL', 0),
 ((2, 2, 6, 7), 'CALL', 0),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((3, 3, 10, 12), 'NOP', None),
 ((2, 2, 6, 7), 'LOAD_CONST', None),
 ((2, 2, 6, 7), 'LOAD_CONST', None),
 ((2, 2, 6, 7), 'LOAD_CONST', None),
 ((2, 2, 6, 7), 'CALL', 3),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'RETURN_CONST', 42),
 ((2, 2, 6, 7), 'PUSH_EXC_INFO', None),
 ((2, 2, 6, 7), 'WITH_EXCEPT_START', None),
 ((2, 2, 6, 7), 'TO_BOOL', None),
 ((2, 2, 6, 7), 'POP_JUMP_IF_TRUE', 70),
 ((2, 2, 6, 7), 'RERAISE', 2),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'POP_EXCEPT', None),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'POP_TOP', None),
 ((2, 2, 6, 7), 'RETURN_CONST', None),
 ((None, None, None, None), 'COPY', 3),
 ((None, None, None, None), 'POP_EXCEPT', None),
 ((None, None, None, None), 'RERAISE', 1)]