require_language.diff

diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index 991bb17..fbf821d 100644
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -85,6 +85,7 @@ char	   *inputdir = ".";
 char	   *outputdir = ".";
 char	   *psqldir = PGBINDIR;
 static _stringlist *loadlanguage = NULL;
+static _stringlist *requirelanguage = NULL;
 static int	max_connections = 0;
 static char *encoding = NULL;
 static _stringlist *schedulelist = NULL;
@@ -1798,6 +1799,24 @@ create_database(const char *dbname)
 		header(_("installing %s"), sl->str);
 		psql_command(dbname, "CREATE LANGUAGE \"%s\"", sl->str);
 	}
+
+	/*
+	 * Make sure any required procedural languages are installed.
+	 */
+	for (sl = requirelanguage; sl != NULL; sl = sl->next)
+	{
+		header(_("making sure %s is installed"), sl->str);
+		psql_command(dbname,
+				"DO LANGUAGE plpgsql $$"
+				"BEGIN"
+				"    IF NOT EXISTS"
+				"        (SELECT 1 FROM pg_catalog.pg_language WHERE lanname='%s')"
+				"    THEN"
+				"        CREATE LANGUAGE %s;"
+				"    END IF;"
+				"END"
+				"$$", sl->str, sl->str);
+	}
 }
 
 static void
@@ -1860,6 +1879,8 @@ help(void)
 	printf(_("  --inputdir=DIR            take input files from DIR (default \".\")\n"));
 	printf(_("  --load-language=lang      load the named language before running the\n"));
 	printf(_("                            tests; can appear multiple times\n"));
+	printf(_("  --require-language=lang   make sure the named language is loaded before\n"));
+	printf(_("                            running the tests; can appear multiple times\n"));
 	printf(_("  --create-role=ROLE        create the specified role before testing\n"));
 	printf(_("  --max-connections=N       maximum number of concurrent connections\n"));
 	printf(_("                            (default is 0 meaning unlimited)\n"));
@@ -1920,6 +1941,7 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 		{"create-role", required_argument, NULL, 18},
 		{"temp-config", required_argument, NULL, 19},
 		{"use-existing", no_argument, NULL, 20},
+		{"require-language", required_argument, NULL, 21},
 		{NULL, 0, NULL, 0}
 	};
 
@@ -2013,6 +2035,9 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 			case 20:
 				use_existing = true;
 				break;
+			case 21:
+				add_stringlist_item(&requirelanguage, optarg);
+				break;
 			default:
 				/* getopt_long already emitted a complaint */
 				fprintf(stderr, _("\nTry \"%s -h\" for more information.\n"),