merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 32 insertions, 15 deletions

diff --git a/third_party/git/diff-lib.c b/third_party/git/diff-lib.c
index 61812f48c273..f95c6de75fc8 100644
--- a/third_party/git/diff-lib.c
+++ b/third_party/git/diff-lib.c
@@ -177,9 +177,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 			i--;
 
 			if (revs->combine_merges && num_compare_stages == 2) {
-				show_combined_diff(dpath, 2,
-						   revs->dense_combined_merges,
-						   revs);
+				show_combined_diff(dpath, 2, revs);
 				free(dpath);
 				continue;
 			}
@@ -219,9 +217,9 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 				continue;
 			} else if (revs->diffopt.ita_invisible_in_index &&
 				   ce_intent_to_add(ce)) {
-				diff_addremove(&revs->diffopt, '+', ce->ce_mode,
-					       the_hash_algo->empty_tree, 0,
-					       ce->name, 0);
+				newmode = ce_mode_from_stat(ce, st.st_mode);
+				diff_addremove(&revs->diffopt, '+', newmode,
+					       &null_oid, 0, ce->name, 0);
 				continue;
 			}
 
@@ -361,7 +359,7 @@ static int show_modified(struct rev_info *revs,
 		p->parent[1].status = DIFF_STATUS_MODIFIED;
 		p->parent[1].mode = old_entry->ce_mode;
 		oidcpy(&p->parent[1].oid, &old_entry->oid);
-		show_combined_diff(p, 2, revs->dense_combined_merges, revs);
+		show_combined_diff(p, 2, revs);
 		free(p);
 		return 0;
 	}
@@ -405,14 +403,8 @@ static void do_oneway_diff(struct unpack_trees_options *o,
 	/* if the entry is not checked out, don't examine work tree */
 	cached = o->index_only ||
 		(idx && ((idx->ce_flags & CE_VALID) || ce_skip_worktree(idx)));
-	/*
-	 * Backward compatibility wart - "diff-index -m" does
-	 * not mean "do not ignore merges", but "match_missing".
-	 *
-	 * But with the revision flag parsing, that's found in
-	 * "!revs->ignore_merges".
-	 */
-	match_missing = !revs->ignore_merges;
+
+	match_missing = revs->match_missing;
 
 	if (cached && idx && ce_stage(idx)) {
 		struct diff_filepair *pair;
@@ -571,3 +563,28 @@ int index_differs_from(struct repository *r,
 	object_array_clear(&rev.pending);
 	return (rev.diffopt.flags.has_changes != 0);
 }
+
+static struct strbuf *idiff_prefix_cb(struct diff_options *opt, void *data)
+{
+	return data;
+}
+
+void show_interdiff(const struct object_id *oid1, const struct object_id *oid2,
+		    int indent, struct diff_options *diffopt)
+{
+	struct diff_options opts;
+	struct strbuf prefix = STRBUF_INIT;
+
+	memcpy(&opts, diffopt, sizeof(opts));
+	opts.output_format = DIFF_FORMAT_PATCH;
+	opts.output_prefix = idiff_prefix_cb;
+	strbuf_addchars(&prefix, ' ', indent);
+	opts.output_prefix_data = &prefix;
+	diff_setup_done(&opts);
+
+	diff_tree_oid(oid1, oid2, "", &opts);
+	diffcore_std(&opts);
+	diff_flush(&opts);
+
+	strbuf_release(&prefix);
+}