Break accidental references in Parser::__clone

If you have a reference *to* an object field (anywhere in the call
stack) when you clone the object, the field will be cloned as a
reference rather than as a value.

So we have to break those unexpected references in the cloned object
manually, which is easy enough by making a non-reference copy and then
rebinding the cloned object's reference to this copy.

Bug: 56226
Change-Id: I9c600e9c0845b4fde0366126ce3809d74e2240b4

diff --git a/includes/parser/Parser.php b/includes/parser/Parser.php
index 84bb224..8bd96b5 100644 (file)
--- a/includes/parser/Parser.php
+++ b/includes/parser/Parser.php
@@ -258,6 +258,21 @@ class Parser {
         */
        public function __clone() {
                $this->mInParse = false;
+
+               // Bug 56226: When you create a reference "to" an object field, that
+               // makes the object field itself be a reference too (until the other
+               // reference goes out of scope). When cloning, any field that's a
+               // reference is copied as a reference in the new object. Both of these
+               // are defined PHP5 behaviors, as inconvenient as it is for us when old
+               // hooks from PHP4 days are passing fields by reference.
+               foreach ( array( 'mStripState', 'mVarCache' ) as $k ) {
+                       // Make a non-reference copy of the field, then rebind the field to
+                       // reference the new copy.
+                       $tmp = $this->$k;
+                       $this->$k =& $tmp;
+                       unset( $tmp );
+               }
+
                wfRunHooks( 'ParserCloned', array( $this ) );
        }