I'm somewhat convinced you can replicate that last feature (staging arbitrary / sub-line pieces of your changes) through ediff-staging (E s), but ediff is a complex tool in itself, and I don't know how to use it properly yet.

(Ediff is a 2-way / 3-way interactive diffing interface, built into Emacs, with plenty of features for surgical diffing of files, buffers, directories and whatnot.)

Magit has great support for staging parts of lines - select the section you want to stage and press 's'.

> Magit has great support for staging parts of lines

This is news to me.

> select the section you want to stage and press 's'.

It stages line-wise for me. How do I get it to stage less than an entire line?

When your press 's', you should have a region selected, in order to stage that region - if your cursor is just sitting on a line without selecting part of it, you'll (probably) just get the whole line staged.

When I press s, the entire line is staged even if my region is a subset of that line.

...huh. I just tested this in my Emacs instance and it works as you describe.

I could swear I remember this working in the past, but I can find no hint of it in a few quick searches, so I'm likely mistaken.

I'm sorry for the misinformation.Thanks for saying something.

The second line you quoted tells you how.

It does not. As I said, pressing s does not stage less than a line for me, even if my region is a subset of the line.

When selecting only part of line, 's' will still stage the full line for me.

Indeed.

  cd $(mktemp -d)
  git init
  echo bar > file.txt
  git add file.txt
  git commit -m "init"
  echo foo_bar_baz > file.txt
  # select only "foo_" in magit-status and press "s"
  git diff --cached

will show

  diff --git a/file.txt b/file.txt
  index 5716ca5..2fd000c 100644
  --- a/file.txt
  +++ b/file.txt
  @@ -1 +1,2 @@
   bar
  +foo_bar_baz

rather than the desired

  diff --git a/file.txt b/file.txt
  index 5716ca5..2fd000c 100644
  --- a/file.txt
  +++ b/file.txt
  @@ -1 +1,2 @@
  -bar
  +foo_bar

I can't really imagine this feature working that well with just selection. Editing of the diff seems required.

I just updated magit, too. It seems to have been published 3 days ago.

..huh. I just tested this in my Emacs instance and it works as you describe.

I could swear I remember this working in the past, but I can find no hint of it in a few quick searches, so I'm likely mistaken.

I'm sorry for the misinformation. Thanks for saying something.

What percentage of git users do this compared to the percentage of magit users staging line-by-line or confidently amending/cherry-picking/interactive-rebasing?