From 1aac6b58bbff8913b2be93e981bde0d992401b14 Mon Sep 17 00:00:00 2001
From: Abhijeetsingh Meena <abhijeet040403@gmail.com>
Date: Mon, 7 Oct 2024 21:58:19 +0530
Subject: [PATCH] blame: respect .git-blame-ignore-revs automatically

Modify `git blame` to automatically respect a `.git-blame-ignore-revs`
file if it exists in the repository. This file is used by many projects
to ignore non-functional changes, such as reformatting or large-scale
refactoring, when generating blame information.

Before this change, users had to manually specify the file with the
`--ignore-revs-file` option. This update streamlines the process by
automatically detecting the `.git-blame-ignore-revs` file, reducing
manual effort.

This change aligns with the standardized practice in many repositories
and simplifies the workflow for users.

Signed-off-by: Abhijeetsingh Meena <abhijeet040403@gmail.com>
---
 builtin/blame.c                      |  8 ++++++++
 t/t8015-blame-default-ignore-revs.sh | 26 ++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 t/t8015-blame-default-ignore-revs.sh

diff --git a/builtin/blame.c b/builtin/blame.c
index e407a22da3bacf..1eddabaf60f4ea 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -1105,6 +1105,14 @@ int cmd_blame(int argc,
 		add_pending_object(&revs, &head_commit->object, "HEAD");
 	}
 
+	/*
+	* By default, add .git-blame-ignore-revs to the list of files
+	* containing revisions to ignore if it exists.
+	*/
+	if (access(".git-blame-ignore-revs", F_OK) == 0) {
+		string_list_append(&ignore_revs_file_list, ".git-blame-ignore-revs");
+	}
+
 	init_scoreboard(&sb);
 	sb.revs = &revs;
 	sb.contents_from = contents_from;
diff --git a/t/t8015-blame-default-ignore-revs.sh b/t/t8015-blame-default-ignore-revs.sh
new file mode 100644
index 00000000000000..84e1a9e87e6ae6
--- /dev/null
+++ b/t/t8015-blame-default-ignore-revs.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+test_description='default revisions to ignore when blaming'
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+test_expect_success 'blame: default-ignore-revs-file' '
+    test_commit first-commit hello.txt hello &&
+
+    echo world >>hello.txt &&
+    test_commit second-commit hello.txt &&
+
+    sed "1s/hello/hi/" <hello.txt > hello.txt.tmp &&
+    mv hello.txt.tmp hello.txt &&
+    test_commit third-commit hello.txt &&
+
+    git rev-parse HEAD >ignored-file &&
+    git blame --ignore-revs-file=ignored-file hello.txt >expect &&
+    git rev-parse HEAD >.git-blame-ignore-revs &&
+    git blame hello.txt >actual &&
+
+    test_cmp expect actual
+'
+
+test_done
\ No newline at end of file