Re: [Libguestfs] [libnbd PATCH 3/5] libev: Check for old compiler

>> +    AC_MSG_CHECKING([if the compiler is new enough for good aliasing >> rules]) >> +    AC_COMPILE_IFELSE([ >> +        AC_LANG_PROGRAM([ >> +            #include <ev.h> >> + >> +            static void cb (struct ev_loop *l, ev_timer *t, int e) { } >> +            static ev_timer timer; >> +        ], [ >> +            ev_timer_init (&timer, cb, 0, .1); >> +        ]) >> +    ], [ >> +        AC_MSG_RESULT([yes]) >> +    ], [ >> +        AC_MSG_RESULT([no]) >> +        AC_SUBST([LIBEV_CFLAGS], [""]) >> +        AC_SUBST([LIBEV_LIBS], [""]) >> +        AC_MSG_WARN([compiler is probably too old to compile with >> libev without errors, some examples will not be compiled]) > > Do we really need to skip compiling the example altogether, or can we > just modify CFLAGS to add -Wno-strict-aliasing to prevent the failure? > This is one of the results that I was not sure about.  We could just add no-strict-aliasing for that one particular example of course.  I figured it is just an example and it only causes an issue on CentOS 7, OpenSUSE Leap 15.2, Ubuntu 18.04 and some similarly old systems if I remember correctly.  But changing the LIBEV_CFLAGS seems more fit for the purpose.