fix argparse --help

Also stop special-casing `printf` as if it were a syntactical keyword
with respect to handling `printf --help`. It should use the same pattern
as every other builtin command.

src/builtin.cpp

@@ -107,7 +107,7 @@ void builtin_wperror(const wchar_t *s, io_streams_t &streams) {
     }
 }
 
-static const wchar_t *short_options = L":h";
+static const wchar_t *short_options = L"+:h";
 static const struct woption long_options[] = {{L"help", no_argument, NULL, 'h'},
                                               {NULL, 0, NULL, 0}};
 
@@ -491,9 +491,9 @@ void builtin_destroy() {}
 /// Is there a builtin command with the given name?
 bool builtin_exists(const wcstring &cmd) { return static_cast<bool>(builtin_lookup(cmd)); }
 
-/// Is the command a keyword or a builtin we need to special-case the handling of `-h` and `--help`.
+/// Is the command a keyword we need to special-case the handling of `-h` and `--help`.
 static const wcstring_list_t help_builtins({L"for", L"while", L"function", L"if", L"end", L"switch",
-                                            L"case", L"printf"});
+                                            L"case"});
 static bool cmd_needs_help(const wchar_t *cmd) { return contains(help_builtins, cmd); }
 
 /// Execute a builtin command

src/builtin_argparse.cpp

@@ -397,6 +397,8 @@ static int parse_cmd_opts(argparse_cmd_opts_t &opts, int *optind,  //!OCLINT(hig
         }
     }
 
+    if (opts.print_help) return STATUS_CMD_OK;
+
     if (argc == w.woptind || wcscmp(L"--", argv[w.woptind - 1]) == 0) {
         // The user didn't specify any option specs.
         streams.err.append_format(_(L"%ls: No option specs were provided\n"), cmd);

src/builtin_printf.cpp

@@ -719,21 +719,31 @@ int builtin_printf_state_t::print_formatted(const wchar_t *format, int argc, wch
 
 /// The printf builtin.
 int builtin_printf(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
-    UNUSED(parser);
-    builtin_printf_state_t state(streams);
-
-    wchar_t *format;
-    int args_used;
+    const wchar_t *cmd = argv[0];
     int argc = builtin_count_args(argv);
+    help_only_cmd_opts_t opts;
 
-    if (argc <= 1) {
-        state.fatal_error(_(L"printf: not enough arguments"));
+    int optind;
+    int retval = parse_help_only_cmd_opts(opts, &optind, argc, argv, parser, streams);
+    if (retval != STATUS_CMD_OK) return retval;
+
+    if (opts.print_help) {
+        builtin_print_help(parser, streams, cmd, streams.out);
+        return STATUS_CMD_OK;
+    }
+
+    argc -= optind;
+    argv += optind;
+    if (argc < 1) {
+        streams.err.append_format(BUILTIN_ERR_MIN_ARG_COUNT1, cmd, 1, argc);
         return STATUS_INVALID_ARGS;
     }
 
-    format = argv[1];
-    argc -= 2;
-    argv += 2;
+    builtin_printf_state_t state(streams);
+    int args_used;
+    wchar_t *format = argv[0];
+    argc--;
+    argv++;
 
     do {
         args_used = state.print_formatted(format, argc, argv);