Programmer Humor @lemmy.ml PeriodicallyPedantic @lemmy.ca 1y ago

diff tools cannot handle moving code blocks

Adding a line: ✅
Removing a line: ✅
Modifying a line: ✅
Moving a codeblock: ❌ i see you've rewritten everything, let me just highlight it all.

RIP reviewers on my PR.

(Meme created by my coworker)

36 comments

I’m surprised that after almost 20 years of versioning C code, git still manages to assign the closing brace of a function wrongly.
- Because text is text and all } are the same.
I'm convinced there must be a way of using ASTs to do more intelligent diffing of a given programming language, but I'm far too lazy to find out for myself.
- You mean like Difftastic?
  
  Hell yeah, being lazy paid off. Thanks.
- There is, but your dif tool would have to be language aware and likely be slower to show difs.
- There have been some attempts at semantic diffs, but it’s very uhh… difficult to gain traction with such a thing.
- Diffing algorithms on trees might not be as efficient, especially if they have to find arbitrary node moves.
  
  I wouldn't expect it to be, but I think modern processors can handle the load!
Me adding one if statement around around a code block. Ah shit I guess I own the whole function now.
- At least a good diff tool will ignore whitespace diffs.
laughs in IntelliJ
- that's not even a joke, I'm using intellij community as a merge and diff tool exclusively. it doesn't support the language I want but even without it it's better then anything else.
Beyond Compare is awesome and handles this and many other things quite well.
Most diff tools have an option to ignore leading or trailing whitespace changes.
- Me omw to shift the entire codebase to the right by one tab and claim authorship over every line in the project with a completely untraceable commit
- I think OP meant moving a code block up or down in a file, not left or right
  
  Yes, thank you. I probably should have been more clear
VSCode has had that feature for some months now. Maybe it's still hidden behind an off-by-default setting, but it's there and I use it.
- I'll have to take a look to see if I can use it to view (enterprise) GitHub PRs, because that'd be a huge help
  
  Good question. Maybe GitLens can help with that, if not the official GitHub extensions.
If you're going to rearrange code, have that as a separate check in from changing code.
Maybe specify a different diff algorithm? Histogram for example?
Give me some love for adding an indent level either showing nothing changed or you rewrote everything too.
Perforce diff works better than this. Even my basic Git/Gitlab diffs don't do this.
Try difftastic! https://github.com/Wilfred/difftastic
- That logo tho. oh noooooo
- It doesn't actually detect moved code, though, like git diff can? I gave it a shot and also there's a couple issues open about it, e.g. https://github.com/Wilfred/difftastic/issues/520 .
  
  Other than that, difftastic is quite nice.
How do you expect it to be shown though?
- For example, on side by side views, you can draw a box around it on both sides, and draw a line connecting the two
  
  I think Sublime Merge does this with the conflict resolution tool

36 comments