string.c: check just before modification

* string.c (rb_str_chomp_bang): check if modifiable after checking
  an argument and just before modification, as it can get frozen
  during the argument conversion to String.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59112 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 8 insertions, 0 deletions

diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index dc76b53810..0fd0538d00 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -444,6 +444,14 @@ CODE
 
     s = S("").freeze
     assert_raise_with_message(RuntimeError, /frozen/) {s.chomp!}
+
+    s = S("ax")
+    o = Struct.new(:s).new(s)
+    def o.to_str
+      s.freeze
+      "x"
+    end
+    assert_raise_with_message(RuntimeError, /frozen/) {s.chomp!(o)}
   ensure
     $/ = save
   end