http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52938
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-04-11 20:57:18 UTC --- (In reply to comment #2) > Why do I see memory is being reallocated even though the string x content can > fit within what I requested in my reserve call? Because GCC's std::string uses copy-on-write, so the original memory is shared between x and y. When x is modified that memory must be un-shared (i.e. make a copy of the shared data before doing a write to x). It's not possible to alter y when assigning to x, so x must be altered. I suppose it would be possible to ensure that when x copies the data it copies the full capacity, but I don't think we want to change std::string in that way, so I suggest this should be closed WONTFIX.
