Merge branch 'da/git-prefix-everywhere' into next

* da/git-prefix-everywhere:
  git-mergetool--lib: Make vimdiff retain the current directory
  git: Remove handling for GIT_PREFIX
  setup: Provide GIT_PREFIX to built-ins

git-mergetool--lib.sh

@@ -86,6 +86,11 @@ get_merge_tool_cmd () {
 }
 
 run_merge_tool () {
+	# If GIT_PREFIX is empty then we cannot use it in tools
+	# that expect to be able to chdir() to its value.
+	GIT_PREFIX=${GIT_PREFIX:-.}
+	export GIT_PREFIX
+
 	merge_tool_path="$(get_merge_tool_path "$1")" || exit
 	base_present="$2"
 	status=0
@@ -188,6 +193,7 @@ run_merge_tool () {
 			check_unchanged
 		else
 			"$merge_tool_path" -R -f -d -c "wincmd l" \
+				-c 'cd $GIT_PREFIX' \
 				"$LOCAL" "$REMOTE"
 		fi
 		;;
@@ -199,6 +205,7 @@ run_merge_tool () {
 			check_unchanged
 		else
 			"$merge_tool_path" -R -f -d -c "wincmd l" \
+				-c 'cd $GIT_PREFIX' \
 				"$LOCAL" "$REMOTE"
 		fi
 		;;

git.c

@@ -183,8 +183,6 @@ static int handle_alias(int *argcp, const char ***argv)
 		if (alias_string[0] == '!') {
 			const char **alias_argv;
 			int argc = *argcp, i;
-			struct strbuf sb = STRBUF_INIT;
-			const char *env[2];
 
 			commit_pager_choice();
 
@@ -195,13 +193,7 @@ static int handle_alias(int *argcp, const char ***argv)
 				alias_argv[i] = (*argv)[i];
 			alias_argv[argc] = NULL;
 
-			strbuf_addstr(&sb, "GIT_PREFIX=");
-			if (subdir)
-				strbuf_addstr(&sb, subdir);
-			env[0] = sb.buf;
-			env[1] = NULL;
-			ret = run_command_v_opt_cd_env(alias_argv, RUN_USING_SHELL, NULL, env);
-			strbuf_release(&sb);
+			ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 			if (ret >= 0)   /* normal exit */
 				exit(ret);
 

setup.c

@@ -710,6 +710,11 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	const char *prefix;
 
 	prefix = setup_git_directory_gently_1(nongit_ok);
+	if (prefix)
+		setenv("GIT_PREFIX", prefix, 1);
+	else
+		setenv("GIT_PREFIX", "", 1);
+
 	if (startup_info) {
 		startup_info->have_repository = !nongit_ok || !*nongit_ok;
 		startup_info->prefix = prefix;

t/t1020-subdirectory.sh

@@ -140,6 +140,22 @@ test_expect_success 'GIT_PREFIX for !alias' '
 	test_cmp expect actual
 '
 
+test_expect_success 'GIT_PREFIX for built-ins' '
+	# Use GIT_EXTERNAL_DIFF to test that the "diff" built-in
+	# receives the GIT_PREFIX variable.
+	printf "dir/" >expect &&
+	printf "#!/bin/sh\n" >diff &&
+	printf "printf \"\$GIT_PREFIX\"" >>diff &&
+	chmod +x diff &&
+	(
+		cd dir &&
+		printf "change" >two &&
+		env GIT_EXTERNAL_DIFF=./diff git diff >../actual
+		git checkout -- two
+	) &&
+	test_cmp expect actual
+'
+
 test_expect_success 'no file/rev ambiguity check inside .git' '
 	git commit -a -m 1 &&
 	(