It contains a static guard variable, so every user of the function outside of QtCore (at least QtNetwork contains one) will create its own copy of the guard variable. While mostly harmless, we'd be executing too many sigaction() calls this way. As a drive-by, remove the qatomic.h include and replace the C-style struct initialization (memset()) with C++-style (value-)initialization. I also tried C++20/C99 designated initializers, but they cannot be used here: some platforms #define sa_handler to some nested member accessor because they hold the field in a union. While .a.b is allowed in C99, it isn't in C++20, so we'd have to move this function's definition into a .c file to compile `{ .sa_handler = SIG_IGN }`. That'd be too much hassle. Mark the function as noexcept, because it is (sigaction(2) is not a Posix Cancellation Point), and, now that it's out-of-line, that actually matters to codegen. Change-Id: Iffab9e6b57822a4d1be8b81ed5948ce186df978e Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>