Re: including sparse headers in C++ code

[Tomas Klacko <tomas.klacko@gmail.com>]

On Sat, Oct 16, 2010 at 9:11 PM, Josh Triplett <josh@joshtriplett.org> wrote:
> On Sat, Oct 16, 2010 at 06:03:53PM +0200, Tomas Klacko wrote:
>> On Wed, Oct 13, 2010 at 2:37 AM, Christopher Li <sparse@chrisli.org> wrote:
>> > On Tue, Oct 12, 2010 at 3:45 PM, Tomas Klacko <tomas.klacko@gmail.com> wrote:

>> >>  /* Silly type-safety check ;) */
>> >>  #define DECLARE_PTR_LIST(listname,type)        struct listname { type *list[1]; }
>> >> -#define CHECK_TYPE(head,ptr)           (void)(&(ptr) == &(head)->list[0])
>> >>  #define TYPEOF(head)                   __typeof__(&(head)->list[0])
>> >>  #define VRFY_PTR_LIST(head)            (void)(sizeof((head)->list[0]))
>> >>
>> >> +#ifndef __cplusplus
>> >> +#define CHECK_TYPE(head,ptr)           (void)(&(ptr) == &(head)->list[0])
>> >> +#else
>> >> +/* I don't know yet how to do this better in C++. */
>> >> +#define CHECK_TYPE(head,ptr) (void)((void*)&(ptr) == (void*)&(head)->list[0])
>> >> +#endif
>> >
>> > If you can't get CHECK_TYPE work in C++, you might just make it an empty define
>> > instead of doing useless point dancing. At least it is clear that it does not
>> > do any thing here.
>>
>> True. How about
>> #define CHECK_TYPE (head,ptr)   (void)(1)
>> ?
>
> As far as I can tell, CHECK_TYPE works just fine in C++.  I could easily
> compile an invocation of CHECK_TYPE, as well as some simple examples
> that called the macros which invoked CHECK_TYPE.  When I tried
> FOR_EACH_PTR, I encountered *other* warnings (related to assigning (void
> *) to some other type without a cast), but those warnings didn't come
> from CHECK_TYPE.

Maybe I did not investigate deeply enough to find out the origin of
the warnings.
But I get no warnings/errors, when I disable CHECK_TYPE in C++ code.

> What warning do you encounter about CHECK_TYPE?

In the following code1 (file main.cc):
int main(int argc, char* argv[])
{
    struct string_list *files=NULL;

    void* file_void;
    char* file_char;

    struct symbol_list *symbols=NULL;
    struct symbol_list *all_symbols=NULL;

    symbols=sparse_initialize(argc, argv, &files);
    concat_symbol_list(symbols, &all_symbols);

    FOR_EACH_PTR_NOTAG(files, file_void) {  // line 19
        file_char=(char*)file_void;
        symbols=sparse(file_char);
        concat_symbol_list(symbols, &all_symbols);
    } END_FOR_EACH_PTR_NOTAG(file_void);

    exit(EXIT_SUCCESS);
}

I get:
main.cc: In function ‘int main(int, char**)’:
main.cc:19: error: comparison between distinct pointer types ‘void*’
and ‘char*’ lacks a cast

compiler and (important) flags:
g++ (GCC) 4.2.4 (Ubuntu 4.2.4-1ubuntu4), -Wall -Werror


Now, the code2 (file main.cc):
int main(int argc, char* argv[])
{
    struct string_list *files=NULL;

    char* file_char;

    struct symbol_list *symbols=NULL;
    struct symbol_list *all_symbols=NULL;

    symbols=sparse_initialize(argc, argv, &files);
    concat_symbol_list(symbols, &all_symbols);

    FOR_EACH_PTR_NOTAG(files, file_char) {  // line 18
        symbols=sparse(file_char);
        concat_symbol_list(symbols, &all_symbols);
    } END_FOR_EACH_PTR_NOTAG(file_char);

    exit(EXIT_SUCCESS);
}

I get error:
main.cc: In function ‘int main(int, char**)’:
main.cc:18: error: invalid conversion from ‘void*’ to ‘char*’


sparse headers included (in both code examples):

#ifdef __cplusplus
extern "C" {
#endif

#include <sparse/allocate.h>
#include <sparse/expression.h>
#include <sparse/lib.h>
#include <sparse/linearize.h>
#include <sparse/token.h>
#include <sparse/parse.h>
#include <sparse/symbol.h>

#ifdef __cplusplus
}
#endif

Tomas Klacko
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