[Bug c/59668] extraneous error messages at -O1, -O2 and -O3 for valid code with string library functions

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59668

--- Comment #5 from Zhendong Su <su at cs dot ucdavis.edu> ---
> Because glibc decides only to implement the macro at -O and above but not
> when optimizing for size.

I see; thanks Andrew. 

BTW, is strcmp the only one like this, or there are others?