[PATCH v2 3/4] add configuration variable corresponding to --overwrite-same-content

[Jonathan Bressat <git.jonathan.bressat@gmail.com>]

Configuration variable merge.overwritesamecontent corresponding to
the --overwrite-same-content option.

This allow merge to overwrite untracked files that have the same
content, a configuration variable is interressant because some people
may want this activated as default to not have to use the option every
time

Signed-off-by: Jonathan Bressat <git.jonathan.bressat@gmail.com>
Signed-off-by: COGONI Guillaume <cogoni.guillaume@gmail.com>
---
 Documentation/config/merge.txt |  5 +++++
 builtin/merge.c                |  2 ++
 t/t7615-merge-untracked.sh     | 21 +++++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/Documentation/config/merge.txt b/Documentation/config/merge.txt
index 99e83dd36e..2824dd19c7 100644
--- a/Documentation/config/merge.txt
+++ b/Documentation/config/merge.txt
@@ -89,6 +89,11 @@ merge.autoStash::
 	`--autostash` options of linkgit:git-merge[1].
 	Defaults to false.
 
+merge.overwritesamecontent::
+    When set to true, it will modify the behavior of git merge 
+    to overwrite untracked files that have the same name and 
+    content than files in the merged commit.	
+
 merge.tool::
 	Controls which merge tool is used by linkgit:git-mergetool[1].
 	The list below shows the valid built-in values.
diff --git a/builtin/merge.c b/builtin/merge.c
index fffae81068..936cb8480d 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -658,6 +658,8 @@ static int git_merge_config(const char *k, const char *v, void *cb)
 	} else if (!strcmp(k, "merge.autostash")) {
 		autostash = git_config_bool(k, v);
 		return 0;
+	} else if (!strcmp(k,"merge.overwritesamecontent")) {
+		overwrite_same_content = git_config_bool(k, v);
 	}
 
 	status = fmt_merge_msg_config(k, v, cb);
diff --git a/t/t7615-merge-untracked.sh b/t/t7615-merge-untracked.sh
index 05a34cf03f..cfefd8f473 100755
--- a/t/t7615-merge-untracked.sh
+++ b/t/t7615-merge-untracked.sh
@@ -60,4 +60,25 @@ test_expect_success 'merge fail when tracked file modification is unstaged' '
 	test_must_fail git merge --overwrite-same-content B
 '
 
+test_expect_success 'fastforward overwrite untracked file that has the same content with the configuration variable' '
+	test_when_finished "git branch -D B && git reset --hard init && git clean --force" &&
+	test_config merge.overwritesamecontent true &&
+	git checkout -b B &&
+	test_commit --no-tag "tracked" file "content" &&
+	git checkout A &&
+	echo content >file &&
+	git merge B
+'
+
+test_expect_success 'normal merge overwrite untracked file that has the same content with the configuration variable' '
+	test_when_finished "git branch -D B && git reset --hard init && git clean --force" &&
+	test_config merge.overwritesamecontent true &&
+	git checkout -b B &&
+	test_commit --no-tag "tracked" file "content" fileB "content" &&
+	git switch A &&
+	test_commit --no-tag "exA" fileA "content" &&
+	echo content >file &&
+	git merge B
+'
+
 test_done
-- 
2.35.1.10.g88248585b1.dirty