Re: ffi.copy/ffi.string fails with volatile-qualified char array
- From: Mike Pall <mike-1311@xxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Mon, 4 Nov 2013 13:49:18 +0100
Philipp Kutin wrote:
> > av = ffi.new "volatile char [12]"
> > aa = ffi.new "char [12]"
> > ffi.copy(aa, av, 1)
> stdin:1: bad argument #2 to 'copy' (cannot convert 'volatile char
> [12]' to 'const void *')
This is in line with C semantics:
#include <string.h>
void foo(char *a, volatile char *b)
{
memcpy(a, b, 4);
}
$ gcc -c test.c
test.c: In function 'foo':
test.c:5:3: warning: passing argument 2 of 'memcpy' discards 'volatile'
qualifier from pointer target type [enabled by default]
In file included from test.c:1:0:
/usr/include/string.h:42:14: note: expected 'const void * __restrict__' but
argument is of type 'volatile char *'
Ok, so GCC treats it as a warning and the FFI treats it as an
error. But implicit removal of qualifiers violates C semantics.
--Mike
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