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
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