Merge branch 'ts/alias-of-alias'

gitster · gitster · commit 506ee60d222f · 2018-10-16T16:15:59.000+09:00
An alias that expands to another alias has so far been forbidden,
but now it is allowed to create such an alias.

* ts/alias-of-alias:
  t0014: introduce an alias testing suite
  alias: show the call history when an alias is looping
  alias: add support for aliases of an alias
diff --git a/git.c b/git.c
@@ -675,6 +675,8 @@ static void execv_dashed_external(const char **argv)
 static int run_argv(int *argcp, const char ***argv)
 {
 	int done_alias = 0;
+	struct string_list cmd_list = STRING_LIST_INIT_NODUP;
+	struct string_list_item *seen;
 
 	while (1) {
 		/*
@@ -692,17 +694,37 @@ static int run_argv(int *argcp, const char ***argv)
 		/* .. then try the external ones */
 		execv_dashed_external(*argv);
 
-		/* It could be an alias -- this works around the insanity
+		seen = unsorted_string_list_lookup(&cmd_list, *argv[0]);
+		if (seen) {
+			int i;
+			struct strbuf sb = STRBUF_INIT;
+			for (i = 0; i < cmd_list.nr; i++) {
+				struct string_list_item *item = &cmd_list.items[i];
+
+				strbuf_addf(&sb, "\n  %s", item->string);
+				if (item == seen)
+					strbuf_addstr(&sb, " <==");
+				else if (i == cmd_list.nr - 1)
+					strbuf_addstr(&sb, " ==>");
+			}
+			die(_("alias loop detected: expansion of '%s' does"
+			      " not terminate:%s"), cmd_list.items[0].string, sb.buf);
+		}
+
+		string_list_append(&cmd_list, *argv[0]);
+
+		/*
+		 * It could be an alias -- this works around the insanity
 		 * of overriding "git log" with "git show" by having
 		 * alias.log = show
 		 */
-		if (done_alias)
-			break;
 		if (!handle_alias(argcp, argv))
 			break;
 		done_alias = 1;
 	}
 
+	string_list_clear(&cmd_list, 0);
+
 	return done_alias;
 }
 
diff --git a/t/t0014-alias.sh b/t/t0014-alias.sh
@@ -0,0 +1,40 @@
+#!/bin/sh
+
+test_description='git command aliasing'
+
+. ./test-lib.sh
+
+test_expect_success 'nested aliases - internal execution' '
+	git config alias.nested-internal-1 nested-internal-2 &&
+	git config alias.nested-internal-2 status &&
+	git nested-internal-1 >output &&
+	test_i18ngrep "^On branch " output
+'
+
+test_expect_success 'nested aliases - mixed execution' '
+	git config alias.nested-external-1 nested-external-2 &&
+	git config alias.nested-external-2 "!git nested-external-3" &&
+	git config alias.nested-external-3 status &&
+	git nested-external-1 >output &&
+	test_i18ngrep "^On branch " output
+'
+
+test_expect_success 'looping aliases - internal execution' '
+	git config alias.loop-internal-1 loop-internal-2 &&
+	git config alias.loop-internal-2 loop-internal-3 &&
+	git config alias.loop-internal-3 loop-internal-2 &&
+	test_must_fail git loop-internal-1 2>output &&
+	test_i18ngrep "^fatal: alias loop detected: expansion of" output
+'
+
+# This test is disabled until external loops are fixed, because would block
+# the test suite for a full minute.
+#
+#test_expect_failure 'looping aliases - mixed execution' '
+#	git config alias.loop-mixed-1 loop-mixed-2 &&
+#	git config alias.loop-mixed-2 "!git loop-mixed-1" &&
+#	test_must_fail git loop-mixed-1 2>output &&
+#	test_i18ngrep "^fatal: alias loop detected: expansion of" output
+#'
+
+test_done
