Why is a space missing in the result of git diff --color-words?

Question

result of git diff =>

diff --git a/test.txt b/test.txt
index 064858a..31140d8 100644
--- a/test.txt
+++ b/test.txt
@@ -1 +1 @@
-There is a problem.
+There is problem.

result of git diff --color-words =>

diff --git a/test.txt b/test.txt
index 064858a..31140d8 100644
--- a/test.txt
+++ b/test.txt
@@ -1 +1 @@
There isa problem.

Why is it "There isa problem." and not "There is a problem."? A space is missing.

Answer 1

That's the expected behavior of git word-diff in any shell. If you remove a word in the middle of a line, it will not show the leading whitespace. You could have any number of spaces between is and problem in your original text, and the output would be the same.

git diff --color-words is the same as git word-diff=color.

Without specifying a custom regex, word-diff is only capable of showing you differences in runs of non-whitespace characters. As per the docs, the "output may be ambiguous" when there are changes made to the whitespace.

To get a better understanding of how this output works, try running it as git word-diff=plain.

If you look at this readme for the library gitwdiff, you can see a comparison between the outputs of a standard git word-diff and their version gitwdiff. It clearly shows that removed words in word-diff do not render the whitespace change.

wdiff is a more specialized command-line utility for diffing words, and it shows the output with the expected whitespace, so you may prefer that.