Prevent dictionary key being GC while unmarshal a value class (#1220)

* Prevent dictionary key being GC while unmarshal a value class

* Fix GC issue with string keys

1 files changed, 16 insertions, 2 deletions

diff --git a/ruby/src/IceRuby/Types.cpp b/ruby/src/IceRuby/Types.cpp
index fb9aefe3ce8..324f8778793 100644
--- a/ruby/src/IceRuby/Types.cpp
+++ b/ruby/src/IceRuby/Types.cpp
@@ -1853,7 +1853,18 @@ IceRuby::DictionaryInfo::unmarshal(Ice::InputStream* is, const UnmarshalCallback
         //
         keyType->unmarshal(is, keyCB, Qnil, 0, false);
         assert(!NIL_P(keyCB->key));
-
+        if (valueType->usesClasses())
+        {
+            // Temporarily set the entry with a Qnil value to ensure the key is not GC
+            // while unmarshaling a value class
+            if (RB_TYPE_P(keyCB->key, T_STRING))
+            {
+                // For string keys create a frozen string to ensure that the key used
+                // in the map matches the one keep in the closure
+                keyCB->key = rb_str_new_frozen(keyCB->key);
+            }
+            callRuby(rb_hash_aset, hash, keyCB->key, Qnil);
+        }
         //
         // The callback will set the dictionary entry with the unmarshaled value,
         // so we pass it the key.
@@ -2744,7 +2755,10 @@ IceRuby::ReadObjectCallback::invoke(const Ice::ObjectPtr& p)
             ex.expectedType = _info->id;
             throw ex;
         }
-
+#ifndef NDEBUG
+        // With debug builds we force a GC to ensure that all data members are correctly keep alive.
+        rb_gc();
+#endif
         _cb->unmarshaled(obj, _target, _closure);
     }
     else