git format-patch return empty reponse on feature branch

Question

We have branch structure - master - develop - feature. We created feature from develop and made few changes in the branch. We don't want to merge all changes from branch . Therefore , trying to create the patch.

When i run git format-patch feature/branch-name , it returns empty response. But, when i run git format-patch origin , it returns the list of files missing between develop and master.

I am not sure why git format-patch will return empty response for branch?

Answer 1

What I am trying to achieve here is create patch for all the changes that are in feature and not in develop.

That should be:

git switch feature
git format-patch develop --stdout > feature_patches.patch

A simple git format-patch develop would create separate patch files for each commit.

But in that latter case, you might want to use the new --omit-empty option.

With Git 2.41 (Q2 2023), "git branch --format=..."^(man) and git format-patch --format=...^(man) learns --omit-empty to hide refs that whose formatting result becomes an empty string from the output.

See commit aabfdc9 (07 Apr 2023) by Øystein Walle (Osse).
^{(Merged by Junio C Hamano -- gitster -- in commit b64894c, 21 Apr 2023)}

branch, for-each-ref, tag: add option to omit empty lines

^{Signed-off-by: Øystein Walle}

If the given format string expands to the empty string, a newline is still printed.
This makes using the output linewise more tedious.
For example, git update-ref^(man) --stdin does not accept empty lines.

Add options to "git branch"^(man), "git for-each-ref"^(man), and "git tag"^(man) to not print these empty lines.
The default behavior remains the same.

git branch now includes in its man page:

git for-each-ref now includes in its man page:

git tag now includes in its man page:

--omit-empty

Do not print a newline after formatted refs where the format expands to the empty string.