This function sets all the relevant flags to disabled state, so that
no code that checks only one of them get it wrong.

Then we call this new function everywhere where diff merges output
suppression is needed.

Signed-off-by: Sergey Organov <redacted>
---
 builtin/merge.c |  3 ++-
 diff-merges.c   | 18 ++++++++++++++----
 diff-merges.h   |  2 ++
 fmt-merge-msg.c |  3 ++-
 4 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index 9d5359edc2f7..1f7b69982b40 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c

@@ -14,6 +14,7 @@
 #include "lockfile.h"
 #include "run-command.h"
 #include "diff.h"
+#include "diff-merges.h"
 #include "refs.h"
 #include "refspec.h"
 #include "commit.h"

@@ -400,7 +401,7 @@ static void squash_message(struct commit *commit, struct commit_list *remotehead
        printf(_("Squash commit -- not updating HEAD\n"));

        repo_init_revisions(the_repository, &rev, NULL);
-       rev.ignore_merges = 1;
+       diff_merges_suppress(&rev);
        rev.commit_format = CMIT_FMT_MEDIUM;

        commit->object.flags |= UNINTERESTING;

diff --git a/diff-merges.c b/diff-merges.c
index 8536941e0b56..25bd9b12e667 100644
--- a/diff-merges.c
+++ b/diff-merges.c

@@ -2,6 +2,13 @@

 #include "revision.h"

+static void suppress(struct rev_info *revs) {
+       revs->ignore_merges = 1;
+       revs->first_parent_merges = 0;
+       revs->combine_merges = 0;
+       revs->dense_combined_merges = 0;
+}

+
 /*
  * Public functions. They are in the order they are called.
  */

@@ -29,16 +36,15 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv) {
                revs->combine_merges = 1;
        } else if (!strcmp(arg, "--cc")) {
                revs->diff = 1;
-               revs->dense_combined_merges = 1;
-               revs->combine_merges = 1;
+               set_dense_combined(revs);
        } else if (!strcmp(arg, "--no-diff-merges")) {
-               revs->ignore_merges = 1;
+               suppress(revs);
        } else if (!strcmp(arg, "--combined-all-paths")) {
                revs->diff = 1;
                revs->combined_all_paths = 1;
        } else if ((argcount = parse_long_opt("diff-merges", argv, &optarg))) {
                if (!strcmp(optarg, "off")) {
-                       revs->ignore_merges = 1;
+                       suppress(revs);
                } else {
                        die(_("unknown value for --diff-merges: %s"), optarg);
                }

@@ -48,6 +54,10 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv) {
        return 1;
 }

+void diff_merges_suppress(struct rev_info *revs) {
+       suppress(revs);
+}

+
 void diff_merges_default_to_first_parent(struct rev_info *revs) {
        if (revs->ignore_merges < 0)            /* No -m */
                revs->ignore_merges = 0;

diff --git a/diff-merges.h b/diff-merges.h
index 4b023c385d00..32720bc9b40f 100644
--- a/diff-merges.h
+++ b/diff-merges.h

@@ -7,6 +7,8 @@ void diff_merges_init_revs(struct rev_info *revs);

 int diff_merges_parse_opts(struct rev_info *revs, const char **argv);

+void diff_merges_suppress(struct rev_info *revs);
+
 void diff_merges_default_to_first_parent(struct rev_info *revs);

 void diff_merges_default_to_dense_combined(struct rev_info *revs);

diff --git a/fmt-merge-msg.c b/fmt-merge-msg.c
index bd22e1ea8865..abc3403fb820 100644
--- a/fmt-merge-msg.c
+++ b/fmt-merge-msg.c

@@ -2,6 +2,7 @@
 #include "refs.h"
 #include "object-store.h"
 #include "diff.h"
+#include "diff-merges.h"
 #include "revision.h"
 #include "tag.h"
 #include "string-list.h"

@@ -668,7 +669,7 @@ int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
                head = lookup_commit_or_die(&head_oid, "HEAD");
                repo_init_revisions(the_repository, &rev, NULL);
                rev.commit_format = CMIT_FMT_ONELINE;
-               rev.ignore_merges = 1;
+               diff_merges_suppress(&rev);
                rev.limited = 1;

                strbuf_complete_line(out);
--

2.25.1