Re: [ANN] Lua 5.3.0 (rc3) now available
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: [ANN] Lua 5.3.0 (rc3) now available
- From: Roberto Ierusalimschy <roberto@...>
- Date: Fri, 2 Jan 2015 15:35:56 -0200
> On 2 January 2015 at 08:36, Luiz Henrique de Figueiredo
> <lhf@tecgraf.puc-rio.br> wrote:
> > We expect the compilation will go smoothly as usual
> > but please report any warnings or other glitches.
>
> Compiling with gcc's --pedantic gives a single warning:
>
> loadlib.c: In function ‘lsys_sym’:
> loadlib.c:151:21: warning: ISO C forbids conversion of object pointer
> to function pointer type [-Wpedantic]
> lua_CFunction f = (lua_CFunction)dlsym(lib, sym);
> ^
This code has been like this for more than 10 years. Why did you wait for
'rc3' to complain? :-)
> To get around this, you need to use this hack: (as seem in dlsym manpage/POSIX):
>
> double (*cosine)(double);
>
> /* Writing: cosine = (double (*)(double)) dlsym(handle, "cos");
> would seem more natural, but the C99 standard leaves
> casting from "void *" to a function pointer undefined.
> The assignment used below is the POSIX.1-2003 (Technical
> Corrigendum 1) workaround; see the Rationale for the
> POSIX specification of dlsym(). */
>
> *(void **) (&cosine) = dlsym(handle, "cos");
This hack is as undefined in C99 as ours, but we can change that if
it removes the warning.
-- Roberto