JSON::Ext::Parser mark the name cache entries when not on the heap

ext/json/ext/parser/extconf.rb

@@ -1,9 +1,8 @@
 # frozen_string_literal: true
 require 'mkmf'
 
-have_func("rb_enc_raise", "ruby.h")
-have_func("rb_enc_interned_str", "ruby.h")
-
+have_func("rb_enc_interned_str", "ruby.h") # RUBY_VERSION >= 3.0
+have_func("rb_gc_mark_locations") # Missing on TruffleRuby
 append_cflags("-std=c99")
 
 create_makefile 'json/ext/parser'

ext/json/ext/parser/parser.c

@@ -2399,6 +2399,19 @@ case 9:
     }
 }
 
+#ifndef HAVE_RB_GC_MARK_LOCATIONS
+// For TruffleRuby
+void rb_gc_mark_locations(const VALUE *start, const VALUE *end)
+{
+    VALUE *value = start;
+
+    while (value < end) {
+        rb_gc_mark(*value);
+        value++;
+    }
+}
+#endif
+
 static void JSON_mark(void *ptr)
 {
     JSON_Parser *json = ptr;
@@ -2408,6 +2421,8 @@ static void JSON_mark(void *ptr)
     rb_gc_mark(json->array_class);
     rb_gc_mark(json->decimal_class);
     rb_gc_mark(json->match_string);
+    const VALUE *name_cache_entries = &json->name_cache.entries[0];
+    rb_gc_mark_locations(name_cache_entries, name_cache_entries + json->name_cache.length);
 }
 
 static void JSON_free(void *ptr)

ext/json/ext/parser/parser.rl

@@ -1019,6 +1019,19 @@ static VALUE cParser_m_parse(VALUE klass, VALUE source, VALUE opts)
     }
 }
 
+#ifndef HAVE_RB_GC_MARK_LOCATIONS
+// For TruffleRuby
+void rb_gc_mark_locations(const VALUE *start, const VALUE *end)
+{
+    VALUE *value = start;
+
+    while (value < end) {
+        rb_gc_mark(*value);
+        value++;
+    }
+}
+#endif
+
 static void JSON_mark(void *ptr)
 {
     JSON_Parser *json = ptr;
@@ -1028,6 +1041,8 @@ static void JSON_mark(void *ptr)
     rb_gc_mark(json->array_class);
     rb_gc_mark(json->decimal_class);
     rb_gc_mark(json->match_string);
+    const VALUE *name_cache_entries = &json->name_cache.entries[0];
+    rb_gc_mark_locations(name_cache_entries, name_cache_entries + json->name_cache.length);
 }
 
 static void JSON_free(void *ptr)

test/json/json_ext_parser_test.rb

@@ -27,6 +27,26 @@ def test_error_messages
       assert_equal "unexpected token at 'NaN'", ex.message
     end
 
+    if GC.respond_to?(:stress=)
+      def test_gc_stress_parser_new
+        payload = JSON.dump([{ foo: 1, bar: 2, baz: 3, egg: { spam: 4 } }] * 10)
+
+        previous_stress = GC.stress
+        JSON::Parser.new(payload).parse
+      ensure
+        GC.stress = previous_stress
+      end
+
+      def test_gc_stress
+        payload = JSON.dump([{ foo: 1, bar: 2, baz: 3, egg: { spam: 4 } }] * 10)
+
+        previous_stress = GC.stress
+        JSON.parse(payload)
+      ensure
+        GC.stress = previous_stress
+      end
+    end
+
     def parse(json)
       JSON::Ext::Parser.new(json).parse
     end

test/json/test_helper.rb

@@ -19,6 +19,24 @@
 rescue LoadError
 end
 
+if GC.respond_to?(:verify_compaction_references)
+  # This method was added in Ruby 3.0.0. Calling it this way asks the GC to
+  # move objects around, helping to find object movement bugs.
+  begin
+    GC.verify_compaction_references(double_heap: true, toward: :empty)
+  rescue NotImplementedError
+    # Some platforms don't support compaction
+  end
+end
+
+if GC.respond_to?(:auto_compact=)
+  begin
+    GC.auto_compact = true
+  rescue NotImplementedError
+    # Some platforms don't support compaction
+  end
+end
+
 unless defined?(Test::Unit::CoreAssertions)
   require "core_assertions"
   Test::Unit::TestCase.include Test::Unit::CoreAssertions