[Bug #21345] Fix accepting multiple rest patterns with leading match

Related:
* https://bugs.ruby-lang.org/issues/20765
* #2915

Author: Earlopain

src/prism.c

@@ -17675,7 +17675,7 @@ parse_pattern(pm_parser_t *parser, pm_constant_id_list_t *captures, uint8_t flag
         // Gather up all of the patterns into the list.
         while (accept1(parser, PM_TOKEN_COMMA)) {
             // Break early here in case we have a trailing comma.
-            if (match9(parser, PM_TOKEN_KEYWORD_THEN, PM_TOKEN_BRACE_RIGHT, PM_TOKEN_BRACKET_RIGHT, PM_TOKEN_PARENTHESIS_RIGHT, PM_TOKEN_SEMICOLON, PM_TOKEN_NEWLINE, PM_TOKEN_EOF,PM_TOKEN_KEYWORD_AND, PM_TOKEN_KEYWORD_OR)) {
+            if (match7(parser, PM_TOKEN_KEYWORD_THEN, PM_TOKEN_BRACE_RIGHT, PM_TOKEN_BRACKET_RIGHT, PM_TOKEN_PARENTHESIS_RIGHT, PM_TOKEN_SEMICOLON, PM_TOKEN_KEYWORD_AND, PM_TOKEN_KEYWORD_OR)) {
                 node = (pm_node_t *) pm_implicit_rest_node_create(parser, &parser->previous);
                 pm_node_list_append(&nodes, node);
                 trailing_rest = true;

test/prism/errors/pattern_match_implicit_rest.txt

@@ -0,0 +1,3 @@
+a=>b, *,
+        ^ expected a pattern expression after `,`
+