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authorJunio C Hamano <gitster@pobox.com>2019-12-06 13:03:53 -0800
committerJunio C Hamano <gitster@pobox.com>2019-12-06 13:03:53 -0800
commite0522318ac56aeb88f14e72ba2db25912e9972de (patch)
tree0ef580a236e0f87db9d61f54fa2db96ce4d5101d
parent2d72b8cffed019aeecc9015be1a2eca4a853db4b (diff)
parent0bb313a5529390276cf5c415891c804dea44fa34 (diff)
The "diff" machinery learned not to lose added/removed blank lines
in the context when --ignore-blank-lines and --function-context are
used at the same time.

* rs/xdiff-ignore-ws-w-func-context:
  xdiff: unignore changes in function context
-rwxr-xr-xt/t4015-diff-whitespace.sh6
-rw-r--r--xdiff/xemit.c17
2 files changed, 18 insertions, 5 deletions
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 4c540b1d70..65615e2fa9 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -2050,11 +2050,6 @@ 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.
 test_expect_success 'combine --ignore-blank-lines with --function-context' '
         test_write_lines 1 "" 2 3 4 5 >a &&
         test_write_lines 1    2 3 4   >b &&
@@ -2064,6 +2059,7 @@ test_expect_success 'combine --ignore-blank-lines with --function-context' '
         cat <<-\EOF >expect &&
         @@ -1,6 +1,4 @@
          1
+        -
          2
          3
          4
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;
+                                }
                         }
                 }