If lines are added at the end of a file, diff -W shows the whole file.
That's because get_func_line() only considers the pre-image and gives up
if it sees a record index beyond its end.
Consider the post-image as well to see if the added lines already make
up a full function. If it doesn't then search for the previous function
line by starting from the bottom of the pre-image, thereby avoiding to
confuse get_func_line().
Reuse the existing label called "again", as it's exactly where we need
to jump to when we're done handling the pre-context, but rename it to
"post_context_calculation" in order to document its new purpose better.
Reported-by: Junio C Hamano <gitster@pobox.com>
Initial-patch-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove the tests that checked against a fixed result and replace them
with more focused checks of desired properties of the created diffs.
That way we get more detailed and meaningful diagnostics.
Store test file contents in files in a subdirectory in order to avoid
cluttering the test script with them.
Use tagged commits to store the changes to test diff -W against instead
of using changes to the worktree. Use the worktree instead to try and
apply the generated patch in order to validate it.
Document unwanted features: trailing empty lines, too much context for
appended functions, insufficient context at the end with -U0.
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add the option -W/--function-context to git diff. It is similar to
the same option of git grep and expands the context of change hunks
so that the whole surrounding function is shown. This "natural"
context can allow changes to be understood better.
Note: GNU patch doesn't like diffs generated with the new option;
it seems to expect context lines to be the same before and after
changes. git apply doesn't complain.
This implementation has the same shortcoming as the one in grep,
namely that there is no way to explicitly find the end of a
function. That means that a few lines of extra context are shown,
right up to the next recognized function begins. It's already
useful in its current form, though.
The function get_func_line() in xdiff/xemit.c is extended to work
forward as well as backward to find post-context as well as
pre-context. It returns the position of the first found matching
line. The func_line parameter is made optional, as we don't need
it for -W.
The enhanced function is then used in xdl_emit_diff() to extend
the context as needed. If the added context overlaps with the
next change, it is merged into the current hunk.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
