Bugs item #711268, was opened at 2003-03-28 07:47
Message generated for change (Comment added) made by facundobatista
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Category: Parser/Compiler
Group: Python 2.2.1
Status: Open
Resolution: None
Priority: 5
Submitted By: Bram Moolenaar (vimboss)
Assigned to: Nobody/Anonymous (nobody)
>Summary: A large block of commands after an "if" cannot be
Initial Comment:
A Generated Python script Contains the code:
if 1:
file = bugreport.vim
... long list of commands ....
Executing this code with:
exec cmds in globals(), globals()
Results in the error:
SystemError: com_backpatch: offset too large
Looking into the code for com_backpatch() it appears
that the code is more than what can be jumped over.
Possible solutions:
1. When there is too much code, use another jump
statement that allows for a larger offset.
2. Always use a jump statement with a large offset
3. When "if 1" is used, don't generate a jump
statement (not a real fix, but works for the situation
where I ran into the bug).
It looks like this bug exists in all versions of Python.
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>Comment By: Facundo Batista (facundobatista)
Date: 2004-12-26 12:00
Message:
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Can not reproduce the problem in Py2.3.4 using the method
posted by vimboss. It's already fixed?
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Comment By: Facundo Batista (facundobatista)
Date: 2004-12-26 12:00
Message:
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Please, could you verify if this problem persists in Python 2.3.4
or 2.4?
If yes, in which version? Can you provide a test case?
If the problem is solved, from which version?
Note that if you fail to answer in one month, I'll close this bug
as "Won't fix".
Thank you!
. Facundo
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Comment By: Bram Moolenaar (vimboss)
Date: 2003-03-28 17:03
Message:
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I can reproduce the problem with this text:
if 1:
a = "a"
Repeat the assignment 7282 times. Feed this text to "exec".
With 7281 assignments you do not get the error.
Looks like 9 bytes are produced per assignment.
Good luck fixing this!
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Comment By: Guido van Rossum (gvanrossum)
Date: 2003-03-28 16:18
Message:
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Hm, the 32-bit argument doesn't work because of what
backpatch does. It would require a totally different
approach to allow backpatching a larer offset, or we'd
always have to reserve 4 bytes for the offset. :-(
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Comment By: Guido van Rossum (gvanrossum)
Date: 2003-03-28 16:13
Message:
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Just curious. How big was the block of code?
Also, I wonder if the error message is bogus; opcode
arguments can now be 32 bits AFAIK.
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