Merge branch 'jc/diff-exit-code-with-w-fixes' into maint-2.42

"git diff -w --exit-code" with various options did not work
correctly, which is being addressed.

* jc/diff-exit-code-with-w-fixes:
  diff: the -w option breaks --exit-code for --raw and other output modes
  t4040: remove test that succeeded for a wrong reason
  diff: teach "--stat -w --exit-code" to notice differences
  diff: mode-only change should be noticed by "--patch -w --exit-code"
  diff: move the fallback "--exit-code" code down

2 files changed, 39 insertions, 3 deletions

diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index b298f220e0..fcd2473e52 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 #
 # Copyright (c) 2006 Johannes E. Schindelin
-#
+# Copyright (c) 2023 Google LLC
 
 test_description='Test special whitespace in diff engine.
 
@@ -11,6 +11,43 @@ TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh
 
+for opt_res in --patch --quiet -s --stat --shortstat --dirstat=lines \
+	       --raw! --name-only! --name-status!
+do
+	opts=${opt_res%!} expect_failure=
+	test "$opts" = "$opt_res" ||
+		expect_failure="test_expect_code 1"
+
+	test_expect_success "status with $opts (different)" '
+		echo foo >x &&
+		git add x &&
+		echo bar >x &&
+		test_expect_code 1 git diff -w $opts --exit-code x
+	'
+
+	test_expect_success POSIXPERM "status with $opts (mode differs)" '
+		test_when_finished "git update-index --chmod=-x x" &&
+		echo foo >x &&
+		git add x &&
+		git update-index --chmod=+x x &&
+		test_expect_code 1 git diff -w $opts --exit-code x
+	'
+
+	test_expect_success "status with $opts (removing an empty file)" '
+		: >x &&
+		git add x &&
+		rm x &&
+		test_expect_code 1 git diff -w $opts --exit-code -- x
+	'
+
+	test_expect_success "status with $opts (different but equivalent)" '
+		echo foo >x &&
+		git add x &&
+		echo " foo" >x &&
+		$expect_failure git diff -w $opts --exit-code x
+	'
+done
+
 test_expect_success "Ray Lehtiniemi's example" '
 	cat <<-\EOF >x &&
 	do {
diff --git a/t/t4040-whitespace-status.sh b/t/t4040-whitespace-status.sh
index e70e020ae9..eec3d73dc2 100755
--- a/t/t4040-whitespace-status.sh
+++ b/t/t4040-whitespace-status.sh
@@ -28,8 +28,7 @@ test_expect_success 'diff-tree --exit-code' '
 
 test_expect_success 'diff-tree -b --exit-code' '
 	git diff -b --exit-code HEAD^ HEAD &&
-	git diff-tree -b -p --exit-code HEAD^ HEAD &&
-	git diff-tree -b --exit-code HEAD^ HEAD
+	git diff-tree -b -p --exit-code HEAD^ HEAD
 '
 
 test_expect_success 'diff-index --cached --exit-code' '