Created attachment 7767 Remove-pure-attribute-of-function-that-returns-void.patch According to GCC's manual[1]: "(...) Because a pure function cannot have any side effects it does not make sense for such a function to return void. Declaring such a function is diagnosed." The attached patch removes this attribute of "void exo_noop (void)" thus eliminating warnings emitted by recent versions of GCC. 1 - https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes
Andre Miranda referenced this bugreport in commit 0406e7e44edae712537d84035539a484c1eaa26a Remove pure attribute of function that returns void (bug 14427) https://git.xfce.org/xfce/exo/commit?id=0406e7e44edae712537d84035539a484c1eaa26a
Thanks for the patch! Applied at the above commit.