svn commit: r287217 - head/usr.sbin/syslogd

[Bruce Evans]

On Fri, 28 Aug 2015, Joerg Sonnenberger wrote:

> On Fri, Aug 28, 2015 at 10:17:56PM +1000, Bruce Evans wrote:
>>> -static void	die(int);
>>> +static void	die(int) __dead2;
>>
>> Since the function is static, it is very easy for the compiler to see
>> that it doesn't return.
>
> But the compiler can't tell if it is the *intention* that the function
> never returns. The warning behavior exists because that can easily
> change with macros etc.

The compiler should trust the programmer to write correct functions.

>> Even gcc-4.2.1 does this by default, since
>> -O implies -funit-at-a-time for gcc-4.2.1.  For clang, there is no way
>> to prevent this (except possibly -O0) since, since -fno-unit-at-a-time
>> is broken in clang.
>
> It is not broken. It is loadly ignored as unsupported. The very
> existance of the option in GCC has always been a concession to broken
> and badly written code, including of course GCC's own CRT.

Unsupported == incompatible == broken.

My use of this option can probably be reduced to -fno-toplevel-reorder,
but that is even more broken in clang (it and -ftoplevel-reorder are
"unknown arguments", while -fno-unit-at-a-time is an "unsupported
optimization", and -funit-at-a-time works).

Bruce