symbol/type.c: bug_pindown

* ext/-test-/symbol/type.c (bug_pindown): method for debug, which
  pins down the given symbol.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45780 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/-test-/symbol/extconf.rb

@@ -3,4 +3,5 @@ inits = $srcs.map {|s| File.basename(s, ".*")}
 inits.delete("init")
 inits.map! {|s|"X(#{s})"}
 $defs << "-DTEST_INIT_FUNCS(X)=\"#{inits.join(' ')}\""
+have_func("rb_pin_dynamic_symbol")
 create_makefile("-test-/symbol")

ext/-test-/symbol/type.c

@@ -53,6 +53,17 @@ bug_dynamic_p(VALUE self, VALUE sym)
     return DYNAMIC_SYM_P(sym) ? Qtrue : Qfalse;
 }
 
+#ifdef HAVE_RB_PIN_DYNAMIC_SYMBOL
+ID rb_pin_dynamic_symbol(VALUE);
+
+static VALUE
+bug_pindown(VALUE self, VALUE sym)
+{
+    rb_pin_dynamic_symbol(sym);
+    return sym;
+}
+#endif
+
 void
 Init_type(VALUE klass)
 {
@@ -61,4 +72,7 @@ Init_type(VALUE klass)
     rb_define_singleton_method(klass, "id2str", bug_id2str, 1);
     rb_define_singleton_method(klass, "static?", bug_static_p, 1);
     rb_define_singleton_method(klass, "dynamic?", bug_dynamic_p, 1);
+#ifdef HAVE_RB_PIN_DYNAMIC_SYMBOL
+    rb_define_singleton_method(klass, "pindown", bug_pindown, 1);
+#endif
 }