(Originally posted on opensource-dev)
Changeset 80af8db446df changes LLUIString::mArgs into a pointer. This pointer gets initialized with a new object in one of the constructors (the other constructors set it to NULL), or lazily (i.e. when still NULL when an actual object is required) through LLUIString::getArgs().
It looks like mArgs never gets deleted again, so it is probably being leaked.
As far as I can see, mArgs (which is private) doesn't get assigned any pointers from outside the LLUIString instance and is never passed out through any method, so it should be save to delete it in the (yet unwritten) destructor of LLUIString.