Strange diff output for C++

[krobelus]

I get a strange output when using gumtree diff on these input files. The output from gumtree jsondiff seems normal, so this is most likely a bug. Note that I didn't minimize the test example, so it could be smaller.

I'm using commit 786aa9f

left.cpp

class Foo {
  void bar() { ; }
};

right.cpp

class Foo {
  void bar() {
    if (1) {
      ;
    }
  }
};

$ gumtree diff left.cpp right.cpp
yields

Insert block(12) into function(13) at 3
Insert 3357(11) into block(12) at 0
Insert -861311717(7) into 3357(11) at 0
Insert 3558941(10) into 3357(11) at 1
Insert 3127797(6) into -861311717(7) at 0
Insert block(9) into 3558941(10) at 0
Insert 182460591: 1(5) into 3127797(6) at 0
Move empty_stmt(5) into block(9) at 0
Delete block(6)

[jrfaller]

Hi and thanks for trying out GumTree!

The strange thing in this diff is the lines such as Insert -861311717(7) into 3357(11) at 0 right?

[krobelus]

yes, the output from gumtree jsondiff does not include huge numbers for this example

[jrfaller]

I will investigate, thanks for noticing the problem!

[UlrichThomasGabor]

There are other problems as well in the C++ variant. For example given a change from

int main(int argc, char** argv) {
	int a = 5;

	a = argc;

	return a;
}

to

int main(int argc, char** argv) {
	int a = 6;

	a = argc;

	return a;
}

the changes are detected correctly, but it seems the positions are wrong, thus the webdiff view is showing weird results.

[jrfaller]

This have been fixed thanks to a pull request. However there might be some other clients that are affected in addition to the webdiff one.