René Scharfe <l.s.r@xxxxxx> writes:
> Changes involving only blank lines are hidden with --ignore-blank-lines,
> unless they appear in the context lines of other changes. This is
> handled by xdl_get_hunk() for context added by --inter-hunk-context, -u
> and -U.
>
> Function context for -W and --function-context added by xdl_emit_diff()
> doesn't pay attention to such ignored changes; it relies fully on
> xdl_get_hunk() and shows just the post-image of ignored changes
> appearing in function context. That's inconsistent and confusing.
>
> Improve the result of using --ignore-blank-lines and --function-context
> together by fully showing ignored changes if they happen to fall within
> function context.
>
> Signed-off-by: René Scharfe <l.s.r@xxxxxx>
> ---
> t/t4015-diff-whitespace.sh | 6 +-----
> xdiff/xemit.c | 17 +++++++++++++++++
> 2 files changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
> index eadaf57262..5888ae5ed3 100755
> --- a/t/t4015-diff-whitespace.sh
> +++ b/t/t4015-diff-whitespace.sh
> @@ -2025,11 +2025,6 @@ test_expect_success 'compare mixed whitespace delta across moved blocks' '
> test_cmp expected actual
> '
>
> -# Note that the "6" in the expected hunk header below is funny, since we only
> -# show 5 lines (the missing one was blank and thus ignored). This is how
> -# --ignore-blank-lines behaves even without --function-context, and this test
> -# is just checking the interaction of the two features. Don't take it as an
> -# endorsement of that output.
Nice to see that somebody anticipated that we may fix this some day.
> @@ -2039,6 +2034,7 @@ test_expect_success 'combine --ignore-blank-lines with --function-context' '
> cat <<-\EOF >expect &&
> @@ -1,6 +1,4 @@
> 1
> + -
> 2
> 3
> 4
And I think this is a more intuitive outcome people would expect.
> diff --git a/xdiff/xemit.c b/xdiff/xemit.c
> index 30713ae9a9..9d7d6c5087 100644
> --- a/xdiff/xemit.c
> +++ b/xdiff/xemit.c
> @@ -172,10 +172,12 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
> struct func_line func_line = { 0 };
>
> for (xch = xscr; xch; xch = xche->next) {
> + xdchange_t *xchp = xch;
> xche = xdl_get_hunk(&xch, xecfg);
> if (!xch)
> break;
>
> +pre_context_calculation:
> s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
> s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
>
> @@ -212,6 +214,21 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
> if (fs1 < s1) {
> s2 = XDL_MAX(s2 - (s1 - fs1), 0);
> s1 = fs1;
> +
> + /*
> + * Did we extend context upwards into an
> + * ignored change?
> + */
> + while (xchp != xch &&
> + xchp->i1 + xchp->chg1 <= s1 &&
> + xchp->i2 + xchp->chg2 <= s2)
> + xchp = xchp->next;
> +
> + /* If so, show it after all. */
> + if (xchp != xch) {
> + xch = xchp;
> + goto pre_context_calculation;
> + }
> }
> }
>
> --
> 2.24.0
