https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66603
--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to gunney1 from comment #3) > Because of the effects of the stream insertion. But maybe I don't > understand very well their relationship. First, I guess it does not crash with icpc because icpc optimizes by default. g++ -O also optimizes 'a' away. Simply mentioning a huge stack array does not produce the crash. The issue is when something (anything, in this case placing the arguments for the function call) tries to use the stack after that array (outside of the stack, since the array is so large).
