Re: [ANN] Lua 5.2.0 (rc2) now available
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: [ANN] Lua 5.2.0 (rc2) now available
- From: Georg Lehner <jorge-lua@...>
- Date: 2011年11月30日 00:22:25 +0100
Hello!
Visual Studio 2008 Professional with Win32 and ARMV4I compilers here
Using Warning Level 4:
----------------------
return (exit(status), 0);
-> warning C4702: unreachable code
if (L) exit(status);
return 0;
-> no warning
exit(status);
return 0;
-> warning C4702: unreachable code
Using Warning Level 3:
----------------------
return (exit(status), 0);
-> no warning
if (L) exit(status);
return 0;
-> no warning
exit(status);
return 0;
-> no warning
- - -
exit() is annotated as "noreturning" in Microsofts stdlib headers, so
the compiler expects not to return
after exit().
- - -
When compiling the complete lua5.2 DLL with warning level 4, I get
several reasonable "possible loss of data"
warnings which could be avoided by proper explicit casting.
Then I get some "unreachable" code warnings in places where
luaG_runerror() is followed by "return 0;".
This is understandable, since luaG_runerror() is annotated as
"noreturning" via "l_noret".
To be consistent, either don't use l_noret in Lua code, use "return 0"
after not-returning function calls
and use compiler warning settings to filter the "unreachable code"
warning messages with "smart" compilers --
or use l_noret wherever applicable, remove the "return 0" after
not-returning function calls and use
compiler warning settings to filter the "function must return a value"
warning messages with the "dumb" compilers.
Another idea: Is it feasible to redeclare exit() this way:
extern l_noret exit(int code);
inside some appropriate Lua header to help "not so dumb" compilers which
have stdlib.h headers without annotation?
Best Regards,
Jorge-León
On 11/29/11 13:19, Roberto Ierusalimschy wrote:
return (exit(status), 0);
if (L) exit(status); /* test to avoid warnings of 'exit' x 'return' */
return 0;
I have tested the previous two patches on the bunch of compilers
currently installed on my computer.
None of them produced a warning for both tricks.
The first one is probably better because it avoids an additional
useless test-and-jump.
According to [1], something similar to the first option gave warnings
in MSVC2005.
[1] http://lua-users.org/lists/lua-l/2008-01/msg00375.html
It would be nice if other people could try these options in their
systems.
-- Roberto