3.9 KiB
How to report a Bug
The difficulty of the problem
This decompiler is a constant work in progress: Python keeps changing, and so does its code generation.
There is no Python decompiler yet that I know about that will decompyle everything. Overall, I think this one probably does the best job of any Python decompiler.
But at any given time, there are maybe dozens of valid Python bytecode files that I know of that will cause problems. And when I get through those, along with all the issues of bugs that are currently logged, I could probably easily find dozens more bugs just by doing a decompile of all the Python bytecode one of my computers. Unless you want to help out by fixing bug, or are willing to do work by isolating and narrowing problems, don't feel you are doing me a favor by doing scans on your favorite byteocde.
I have found bugs in every Python decompiler I have tried. Even those where authors/maintainers claim that they have used it on the entire Python standard library.
So it is likely you'll find a mistranslation in decompiling.
Is it really a bug?
If the code emitted is semantically equivalent, then this isn't a bug.
For example the code might be
if a:
if b:
x = 1
and we might produce:
if a and b:
x = 1
These are equivalent. Sometimes
else:
if ...
may out as elif.
As mentioned in the README. It is possible that Python changes what you write to be more efficient. For example, for:
if True:
x = 5
Python will generate code like:
x = 5
So just because the text isn't the same, does not necessarily mean there's a bug.
What to send (minimum requirements)
The basic requirement is pretty simple:
- Python bytecode
- Python source text
Please don't put files on download services that one has to register for or can't get to by issuing curl or wget. If you can't attach it to the issue, or create a github gist, then the code you are sending is too large.
Also try to narrow the bug. See below.
What to send (additional helpful information)
Some kind folks also give the invocation they used and the output which usually includes an error message produced. This is helpful. I can figure out what OS you are running this on and what version of uncomplye6 was used. Therefore, if you don't provide the input command and the output from that, please give:
- uncompyle6 version used
- OS that you used this on
- Python interpreter version used
But I don't have the source code!
Sure, I get it. No problem. There is Python assembly code on parse errors, so simply by hand decompile that. To get a full disassembly, use pydisasm from the xdis package. Opcodes are described in the documentation for the dis module.
But I don't have the source code and am incapable of figuring how how to do a hand disassembly!
Well, you could learn. No one is born into this world knowing how to disassemble Python bytecode. And as Richard Feynman once said, "What one fool can learn, so can another."
Narrowing the problem
I don't need or want the entire source code base for which one file or module can't be decompiled. I just need that one file or module only. If there are several files, file a bug report for each file.
Python modules can get quite large, and usually decompilation problems occur in a single function or maybe the main-line code but not any of the functions or classes. So please chop down the source code by removing those parts that do to decompile properly.
By doing this, you'll probably have a better sense of what exactly is the problem. Perhaps you can find the boundary of what decompiles, and what doesn't. That is useful. Or maybe the same file will decompile properly on a neighboring version of Python. That is helpful too.
In sum, the more you can isolate or narrow the problem, the more likley the problem will be fixed and fixed sooner.