Merge branch 'jc/you-still-use-whatchanged'

"git whatchanged" that is longer to type than "git log --raw"
which is its modern rough equivalent has outlived its usefulness
more than 10 years ago.  Plan to deprecate and remove it.

* jc/you-still-use-whatchanged:
  whatschanged: list it in BreakingChanges document
  whatchanged: remove when built with WITH_BREAKING_CHANGES
  whatchanged: require --i-still-use-this
  tests: prepare for a world without whatchanged
  doc: prepare for a world without whatchanged
  you-still-use-that??: help deprecating commands for removal

t/t4013-diff-various.sh

@@ -206,14 +206,30 @@ do
 	expect="$TEST_DIRECTORY/t4013/diff.$test"
 	actual="$pfx-diff.$test"
 
-	test_expect_success "git $cmd # magic is ${magic:-(not used)}" '
+	case "$cmd" in
+	whatchanged | whatchanged" "*)
+		prereq=!WITH_BREAKING_CHANGES
+		;;
+	*)
+		prereq=;;
+	esac
+
+	test_expect_success $prereq "git $cmd # magic is ${magic:-(not used)}" '
 		{
 			echo "$ git $cmd"
+
+			case "$cmd" in
+			whatchanged | whatchanged" "*)
+				run="whatchanged --i-still-use-this"
+				run="$run ${cmd#whatchanged}" ;;
+			*)
+				run=$cmd ;;
+			esac &&
 			case "$magic" in
 			"")
-				GIT_PRINT_SHA1_ELLIPSIS=yes git $cmd ;;
+				GIT_PRINT_SHA1_ELLIPSIS=yes git $run ;;
 			noellipses)
-				git $cmd ;;
+				git $run ;;
 			esac |
 			sed -e "s/^\\(-*\\)$V\\(-*\\)\$/\\1g-i-t--v-e-r-s-i-o-n\2/" \
 			    -e "s/^\\(.*mixed; boundary=\"-*\\)$V\\(-*\\)\"\$/\\1g-i-t--v-e-r-s-i-o-n\2\"/"
@@ -460,6 +476,11 @@ diff-tree --stat --compact-summary initial mode
 diff-tree -R --stat --compact-summary initial mode
 EOF
 
+test_expect_success !WITH_BREAKING_CHANGES 'whatchanged needs --i-still-use-this' '
+	test_must_fail git whatchanged >message 2>&1 &&
+	test_grep "nominated for removal" message
+'
+
 test_expect_success 'log -m matches pure log' '
 	git log master >result &&
 	process_diffs result >expected &&

t/t4202-log.sh

@@ -486,10 +486,16 @@ test_expect_success !FAIL_PREREQS 'log with various grep.patternType configurati
 	)
 '
 
-for cmd in show whatchanged reflog format-patch
+cmds="show reflog format-patch"
+if test_have_prereq !WITH_BREAKING_CHANGES
+then
+	cmds="$cmds whatchanged"
+fi
+for cmd in $cmds
 do
 	case "$cmd" in
 	format-patch) myarg="HEAD~.." ;;
+	whatchanged) myarg=--i-still-use-this ;;
 	*) myarg= ;;
 	esac
 
@@ -1201,20 +1207,27 @@ test_expect_success 'reflog is expected format' '
 	test_cmp expect actual
 '
 
-test_expect_success 'whatchanged is expected format' '
+test_expect_success !WITH_BREAKING_CHANGES 'whatchanged is expected format' '
+	whatchanged="whatchanged --i-still-use-this" &&
 	git log --no-merges --raw >expect &&
-	git whatchanged >actual &&
+	git $whatchanged >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'log.abbrevCommit configuration' '
+	whatchanged="whatchanged --i-still-use-this" &&
+
 	git log --abbrev-commit >expect.log.abbrev &&
 	git log --no-abbrev-commit >expect.log.full &&
 	git log --pretty=raw >expect.log.raw &&
 	git reflog --abbrev-commit >expect.reflog.abbrev &&
 	git reflog --no-abbrev-commit >expect.reflog.full &&
-	git whatchanged --abbrev-commit >expect.whatchanged.abbrev &&
-	git whatchanged --no-abbrev-commit >expect.whatchanged.full &&
+
+	if test_have_prereq !WITH_BREAKING_CHANGES
+	then
+		git $whatchanged --abbrev-commit >expect.whatchanged.abbrev &&
+		git $whatchanged --no-abbrev-commit >expect.whatchanged.full
+	fi &&
 
 	test_config log.abbrevCommit true &&
 
@@ -1231,10 +1244,13 @@ test_expect_success 'log.abbrevCommit configuration' '
 	git reflog --no-abbrev-commit >actual &&
 	test_cmp expect.reflog.full actual &&
 
-	git whatchanged >actual &&
-	test_cmp expect.whatchanged.abbrev actual &&
-	git whatchanged --no-abbrev-commit >actual &&
-	test_cmp expect.whatchanged.full actual
+	if test_have_prereq !WITH_BREAKING_CHANGES
+	then
+		git $whatchanged >actual &&
+		test_cmp expect.whatchanged.abbrev actual &&
+		git $whatchanged --no-abbrev-commit >actual &&
+		test_cmp expect.whatchanged.full actual
+	fi
 '
 
 test_expect_success '--abbrev-commit with core.abbrev=false' '

t/t5323-pack-redundant.sh

@@ -45,6 +45,11 @@ fi
 main_repo=main.git
 shared_repo=shared.git
 
+test_expect_success 'pack-redundant needs --i-still-use-this' '
+	test_must_fail git pack-redundant >message 2>&1 &&
+	test_grep "nominated for removal" message
+'
+
 git_pack_redundant='git pack-redundant --i-still-use-this'
 
 # Create commits in <repo> and assign each commit's oid to shell variables

t/t9300-fast-import.sh

@@ -120,7 +120,7 @@ test_expect_success 'A: create pack from stdin' '
 
 	INPUT_END
 	git fast-import --export-marks=marks.out <input &&
-	git whatchanged main
+	git log --raw main
 '
 
 test_expect_success 'A: verify pack' '
@@ -279,7 +279,7 @@ test_expect_success 'A: verify marks import does not crash' '
 	INPUT_END
 
 	git fast-import --import-marks=marks.out <input &&
-	git whatchanged verify--import-marks
+	git log --raw verify--import-marks
 '
 
 test_expect_success 'A: verify pack' '
@@ -652,7 +652,7 @@ test_expect_success 'C: incremental import create pack from stdin' '
 	INPUT_END
 
 	git fast-import <input &&
-	git whatchanged branch
+	git log --raw branch
 '
 
 test_expect_success 'C: verify pack' '
@@ -715,7 +715,7 @@ test_expect_success 'D: inline data in commit' '
 	INPUT_END
 
 	git fast-import <input &&
-	git whatchanged branch
+	git log --raw branch
 '
 
 test_expect_success 'D: verify pack' '
@@ -882,7 +882,7 @@ test_expect_success 'H: deletall, add 1' '
 
 	INPUT_END
 	git fast-import <input &&
-	git whatchanged H
+	git log --raw H
 '
 
 test_expect_success 'H: verify pack' '
@@ -2066,7 +2066,7 @@ test_expect_success 'Q: commit notes' '
 	INPUT_END
 
 	git fast-import <input &&
-	git whatchanged notes-test
+	git log --raw notes-test
 '
 
 test_expect_success 'Q: verify pack' '

t/t9301-fast-import-notes.sh

@@ -76,7 +76,7 @@ INPUT_END
 test_expect_success 'set up main branch' '
 
 	git fast-import <input &&
-	git whatchanged main
+	git log --raw main
 '
 
 commit4=$(git rev-parse refs/heads/main)