From 8f1759143533d2b772efd5184ba02738f66fe1fc Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Tue, 19 Jul 2022 20:24:26 +0900
Subject: [PATCH] [Bug #18905] Check symbol name types more strictly

---
 symbol.c                       |  2 +-
 test/-ext-/symbol/test_type.rb |  9 ++++-----
 test/ruby/test_symbol.rb       | 13 +++++++++++++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/symbol.c b/symbol.c
index f5e876c7d7..dc7d72cb90 100644
--- a/symbol.c
+++ b/symbol.c
@@ -378,7 +378,7 @@ rb_enc_symname_type(const char *name, long len, rb_encoding *enc, unsigned int a
         if (m >= e || (*m != '_' && !ISALPHA(*m) && ISASCII(*m))) {
             if (len > 1 && *(e-1) == '=') {
                 type = rb_enc_symname_type(name, len-1, enc, allowed_attrset);
-                if (type != ID_ATTRSET) return ID_ATTRSET;
+                if (allowed_attrset & (1U << type)) return ID_ATTRSET;
             }
             return -1;
         }
diff --git a/test/-ext-/symbol/test_type.rb b/test/-ext-/symbol/test_type.rb
index 7cb3c7b6ef..fdee692fe4 100644
--- a/test/-ext-/symbol/test_type.rb
+++ b/test/-ext-/symbol/test_type.rb
@@ -93,16 +93,16 @@ module Test_Symbol
       assert_symtype("@foo=", :attrset?)
       assert_symtype("@@foo=", :attrset?)
       assert_symtype("$foo=", :attrset?)
-      assert_symtype("0=", :attrset?)
-      assert_symtype("@=", :attrset?)
-      assert_symtype("@@=", :attrset?)
+      assert_not_symtype("0=", :attrset?)
+      assert_not_symtype("@=", :attrset?)
+      assert_not_symtype("@@=", :attrset?)
       assert_not_symtype("foo", :attrset?)
       assert_not_symtype("Foo", :attrset?)
       assert_not_symtype("@foo", :attrset?)
       assert_not_symtype("@@foo", :attrset?)
       assert_not_symtype("$foo", :attrset?)
       assert_not_symtype("[foo]", :attrset?)
-      assert_symtype("[foo]=", :attrset?)
+      assert_not_symtype("[foo]=", :attrset?)
       assert_equal(:"foo=", Bug::Symbol.attrset("foo"))
       assert_symtype(Bug::Symbol.attrset("foo"), :attrset?)
       assert_equal(:"Foo=", Bug::Symbol.attrset("Foo"))
@@ -114,7 +114,6 @@ module Test_Symbol
       assert_equal(:"$foo=", Bug::Symbol.attrset("$foo"))
       assert_symtype(Bug::Symbol.attrset("$foo"), :attrset?)
       assert_equal(:"[foo]=", Bug::Symbol.attrset("[foo]"))
-      assert_symtype(Bug::Symbol.attrset("[foo]"), :attrset?)
       assert_equal(:[]=, Bug::Symbol.attrset(:[]))
       assert_symtype(Bug::Symbol.attrset("foo?="), :attrset?)
       assert_equal(:"foo?=", Bug::Symbol.attrset(:foo?))
diff --git a/test/ruby/test_symbol.rb b/test/ruby/test_symbol.rb
index f7f17b8d67..1d2a18d734 100644
--- a/test/ruby/test_symbol.rb
+++ b/test/ruby/test_symbol.rb
@@ -36,6 +36,19 @@ class TestSymbol < Test::Unit::TestCase
     assert_eval_inspected(:"@@1", false)
     assert_eval_inspected(:"@", false)
     assert_eval_inspected(:"@@", false)
+    assert_eval_inspected(:"[]=")
+    assert_eval_inspected(:"[][]", false)
+    assert_eval_inspected(:"[][]=", false)
+    assert_eval_inspected(:"@=", false)
+    assert_eval_inspected(:"@@=", false)
+    assert_eval_inspected(:"@x=", false)
+    assert_eval_inspected(:"@@x=", false)
+    assert_eval_inspected(:"$$=", false)
+    assert_eval_inspected(:"$==", false)
+    assert_eval_inspected(:"$x=", false)
+    assert_eval_inspected(:"$$$=", false)
+    assert_eval_inspected(:"foo?=", false)
+    assert_eval_inspected(:"foo!=", false)
   end
 
   def assert_inspect_evaled(n)