Ooh, really cool. The comment about function-pointer comparisons was a pretty funny ramification I hadn't considered too. Real "wtf" debugging case I bet.
I wonder what the standard says about it, what the linker can/could typically prove is "safe", and what performance/size changes are seen in practice.
The paper Safe ICF in Gold[0] says that they get between 4 to 7% savings on code size. A safer version that omits functions that have their address taken was 97% as effective.
The talk Diet Templates[1] has some suggestions for how to reduce template bloat.
I wonder what the standard says about it, what the linker can/could typically prove is "safe", and what performance/size changes are seen in practice.