Fix String#sub for GC compaction

peterzhu2118 · peterzhu2118 · commit 50bf4373411a · 2023-12-23T18:00:27.000-05:00
The test fails when RGENGC_CHECK_MODE is turned on:

    TestString#test_sub_gc_compact_stress = 9.42 s
    1) Failure:
    TestString#test_sub_gc_compact_stress [test/ruby/test_string.rb:2089]:
    &lt;"aaa [amp] yyy"&gt; expected but was
    &lt;"aaa [] yyy"&gt;.
diff --git a/string.c b/string.c
@@ -5816,6 +5816,8 @@ rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
         TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
         ENC_CODERANGE_SET(str, cr);
 
+        RB_GC_GUARD(match);
+
         return str;
     }
     return Qnil;
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
@@ -2081,6 +2081,15 @@ def o.to_s; self; end
     }
   end
 
+  def test_sub_gc_compact_stress
+    EnvUtil.under_gc_compact_stress do
+      m = /&(?<foo>.*?);/.match(S("aaa &amp; yyy"))
+      assert_equal("amp", m["foo"])
+
+      assert_equal("aaa [amp] yyy", S("aaa &amp; yyy").sub(/&(?<foo>.*?);/, S('[\k<foo>]')))
+    end
+  end
+
   def test_sub!
     a = S("hello")
     b = a.dup

Original file line number	Diff line number	Diff line change
`@@ -5816,6 +5816,8 @@ rb_str_sub_bang(int argc, VALUE *argv, VALUE str)`
`5816`	`5816`	`TERM_FILL(&RSTRING_PTR(str)[l D4F4 en], TERM_LEN(str));`
`5817`	`5817`	`ENC_CODERANGE_SET(str, cr);`
`5818`	`5818`
	`5819`	`+ RB_GC_GUARD(match);`
	`5820`	`+`
`5819`	`5821`	`return str;`
`5820`	`5822`	`}`
`5821`	`5823`	`return Qnil;`