Le 08/06/2016 à 14:53, G. Schlisio a écrit : > compiling libxcb 1.12 with gcc 5.3 and -O2 results in no crash in my > setup. looks like the bug is in gcc6 then. > thank you guys for helping! Does gcc's UBSan report anything? It could still very well be a bug in xcb. Cheers, Rémi