Ripper: Fix duplicate regexp errors

Author: nobu

parse.y

@@ -13186,7 +13186,13 @@ new_regexp(struct parser_params *p, NODE *node, int options, const YYLTYPE *loc)
         nd_set_loc(node, loc);
         rb_node_dregx_t *const dreg = RNODE_DREGX(node);
         dreg->as.nd_cflag = options & RE_OPTION_MASK;
-        if (dreg->string) reg_fragment_check(p, dreg->string, options);
+        if (!dreg->nd_next) {
+            /* Check string is valid regex */
+            reg_compile(p, dreg->string, options);
+        }
+        else if (dreg->string) {
+            reg_fragment_check(p, dreg->string, options);
+        }
         prev = node;
         for (list = dreg->nd_next; list; list = RNODE_LIST(list->nd_next)) {
             NODE *frag = list->nd_head;
@@ -13212,10 +13218,6 @@ new_regexp(struct parser_params *p, NODE *node, int options, const YYLTYPE *loc)
                 prev = 0;
             }
         }
-        if (!dreg->nd_next) {
-            /* Check string is valid regex */
-            reg_compile(p, dreg->string, options);
-        }
         if (options & RE_OPTION_ONCE) {
             node = NEW_ONCE(node, loc);
         }

test/ripper/test_ripper.rb

@@ -156,14 +156,15 @@ def test_assignable_in_regexp
   end
 
   def test_invalid_multibyte_character_in_regexp
-    lex = Ripper.lex(%q[/#{"\xcd"}/])
+    lex = Ripper::Lexer.new(%q[/#{"\xcd"}/]).scan.map(&:to_a)
     assert_equal([[1, 0], :on_regexp_beg, "/", state(:EXPR_BEG)], lex.shift)
     assert_equal([[1, 1], :on_embexpr_beg, "\#{", state(:EXPR_BEG)], lex.shift)
     assert_equal([[1, 3], :on_tstring_beg, "\"", state(:EXPR_BEG)], lex.shift)
     assert_equal([[1, 4], :on_tstring_content, "\\xcd", state(:EXPR_BEG)], lex.shift)
     assert_equal([[1, 8], :on_tstring_end, "\"", state(:EXPR_END)], lex.shift)
     assert_equal([[1, 9], :on_embexpr_end, "}", state(:EXPR_END)], lex.shift)
     assert_equal([[1, 10], :on_regexp_end, "/", state(:EXPR_BEG)], lex.shift)
+    assert_equal([[1, 11], :compile_error, "", state(:EXPR_END), "invalid multibyte character: /\\xCD/"], lex.shift)
     assert_empty(lex)
   end