https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97452
--- Comment #4 from David Ledger <davidledger at live dot com.au> --- @Iain Sandoe In terms of the standard do you think this is technically undefined behaviour? I tried bring this up with Std-Proposals but got no response at all. I believe either I'm very bad at writing (likely), or nobody knows whether or not this is undefined behaviour and therefore the conversation didn't start. If this is undefined behaviour I believe a defect report is in order.