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UnifiedDiffParserException on apparently sane file (2nd variant) #107

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moio opened this issue Dec 14, 2020 · 13 comments
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UnifiedDiffParserException on apparently sane file (2nd variant) #107

moio opened this issue Dec 14, 2020 · 13 comments
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@moio
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moio commented Dec 14, 2020

Describe the bug
UnifiedDiffReader.parseUnifiedDiff throws UnifiedDiffParserException on a patch which apparently looks good:

https://raw.githubusercontent.com/bazelbuild/bazel/master/third_party/aws-sdk-auth-lite/patches-vs-1.11.297/01-bazel-strip-unused.patch

To Reproduce
Run this program:

String patch = new Scanner(new URL(
    "https://raw.githubusercontent.com/bazelbuild/bazel/master/third_party/aws-sdk-auth-lite/patches-vs-1.11.297/01-bazel-strip-unused.patch"
).openStream(), "UTF-8").useDelimiter("\\A").next();

UnifiedDiffReader.parseUnifiedDiff(new StringBufferInputStream(patch));

Expected behavior

No Exceptions.

Actual behavior

Dec 14, 2020 9:49:46 PM com.github.difflib.unifieddiff.UnifiedDiffReader processLine
WARNING: >>> no rule matched \ No newline at end of file
Exception in thread "main" com.github.difflib.unifieddiff.UnifiedDiffParserException: expected file start line not found
at com.github.difflib.unifieddiff.UnifiedDiffReader.parse(UnifiedDiffReader.java:95)
at com.github.difflib.unifieddiff.UnifiedDiffReader.parseUnifiedDiff(UnifiedDiffReader.java:146)
...

System

  • Java version: openjdk-11
  • Version: 4.9

Notes

👋 java-diff-utils maintainers again! Here is another corner case I found. The patch comes from the Bazel project, so once again it's OK to include in tests.
@moio moio mentioned this issue Dec 14, 2020
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@wumpz
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wumpz commented Dec 17, 2020

That is a nice huge diff. The new implementation of java-diff-utils will gain a lot of testing on this large file base. I will look into it.

@wumpz wumpz added the bug label Dec 17, 2020
@wumpz wumpz self-assigned this Dec 17, 2020
@wumpz wumpz pinned this issue Dec 17, 2020
@moio
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moio commented Dec 18, 2020

Thanks a lot @wumpz! I might have other cases as well for you later, as I plan to test each and every patch from CentOS and likely other open source projects as well 😉

@wumpz
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wumpz commented Dec 18, 2020

To somehow document this: https://stackoverflow.com/questions/5813311/no-newline-at-end-of-file.

This weird

\ No newline at end of file

is put into a diff by Git to signal, that there is no linefeed at the end of the last line of this diff.

@wumpz
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wumpz commented Dec 18, 2020

So my implementation stores this as a flag within UnifiedDiffFile, so the write can write those lines without putting a linefeed at the end. I hope that is right.

@wumpz wumpz closed this as completed in 445381b Dec 18, 2020
wumpz added a commit that referenced this issue Dec 18, 2020
@wumpz
fixes #107 process "\ No newline at end of file"
e59e9e8
@wumpz wumpz reopened this Dec 18, 2020
@wumpz wumpz closed this as completed in 642dc65 Dec 18, 2020
@wumpz
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wumpz commented Dec 18, 2020

Just deployed a new version.

wumpz added a commit that referenced this issue Dec 18, 2020
@wumpz
fixes #107 process "\ No newline at end of file"
fb0837f
@wumpz wumpz unpinned this issue Dec 21, 2020
@elanzini
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elanzini commented May 4, 2021

@wumpz I am still getting the same exact error when I try to parse this patch from this JIRA ticket.

@wumpz wumpz reopened this May 4, 2021
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wumpz commented May 4, 2021

@elanzini I will look into it.

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wumpz commented May 4, 2021

@elanzini May I include this patch as test data into java-diff-utils? I already solved the problem and would like to use your test data.

@elanzini
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elanzini commented May 5, 2021 •
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@wumpz by all means! And thanks for the quick fix! I will open new issues as I find more edge cases where it breaks.

@elanzini
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elanzini commented May 5, 2021

@wumpz I found other examples for this problem pgjdbc/pgjdbc@cdeeaca or apache/cxf@1cf4fed. For both, if you try to parse the diff, you get the same complaint WARNING: >>> no rule matched \ No newline at end of file.

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wumpz commented May 5, 2021

@elanzini I included all three of your tests. They are now succeeding.

@wumpz wumpz closed this as completed in 3d5343c May 5, 2021
@williamfzc
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williamfzc commented Jul 22, 2021 •
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same problem here :)
I just found that the latest released version (4.10) did not contain this change
When will 4.11 be released? Looking forward to it and thanks!

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wumpz commented Aug 14, 2021

Still no valid date there, since I wanted to include the new implementation of meyers linear space diff algorithm.

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