Jim Meyering <jim@xxxxxxxxxxxx> writes:
> I was surprised to see "git diff --word-diff" output a ton of
> garbage, and tracked it down to a bug that's triggered when the
> diff.suppress-blank-empty config option to true and when at least
> one of the context lines is empty.
Heh, I am not that surprised ;-)
I think the real culprit is a year-old 882749a (diff: add --word-diff
option that generalizes --color-words, 2010-04-14); it probably shows that
not many people use diff.s-b-e settings?
> printf 'a\n\n[-b-]{+c+}\n' > exp
> git init && git config diff.suppress-blank-empty true
> printf 'a\n\nb\n' > f && git add . && git commit -m. .
> printf 'a\n\nc\n' > f
> git diff --word-diff | tail -3 > out
> diff out exp
>
> Before the patch, the git diff ... command would read from beyond
> the end of a heap buffer, and "out" would contain far more than the
> expected 5 bytes.
It is a bit unfortunate that we cannot make this into a test script, as it
depends on what is on the uninitialized part of the heap, which might
happen to be a NUL in which case the test would pass.
Running tests under the valgrind mode may catch issues, though.
Thanks. Will queue with this test squashed in.
diff --git a/t/t4034-diff-words.sh b/t/t4034-diff-words.sh
index 37aeab0..c374aa4 100755
--- a/t/t4034-diff-words.sh
+++ b/t/t4034-diff-words.sh
@@ -307,4 +307,30 @@ test_language_driver python
test_language_driver ruby
test_language_driver tex
+test_expect_success 'word-diff with diff.sbe' '
+ cat >expect <<-\EOF &&
+ diff --git a/pre b/post
+ index a1a53b5..bc8fe6d 100644
+ --- a/pre
+ +++ b/post
+ @@ -1,3 +1,3 @@
+ a
+
+ [-b-]{+c+}
+ EOF
+ cat >pre <<-\EOF &&
+ a
+
+ b
+ EOF
+ cat >post <<-\EOF &&
+ a
+
+ c
+ EOF
+ test_when_finished "git config --unset diff.suppress-blank-empty" &&
+ git config diff.suppress-blank-empty true &&
+ word_diff --word-diff=plain
+'
+
test_done
--
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