Re: [Tinycc-devel] { .field = value } struct initialization alternative

[Michael Matz]

Hi,

On Sun, 21 Jul 2019, Ivan Medoedov wrote:

> Typo:
>
> Foo* foo = ALLOC_INIT(Foo, { .field = 123, .field2 = 456 });

Next time, please be specific in your bug reports, it should contain a 
self-contained example of the problem you're seeing.  With the info 
available I constructed the example below, and it works just fine.

Then I realized that maybe you indeed mean GNU designated initializers and 
the runtime behaviour instead of not being able to compile something.  I 
was able to generate a segfault at runtime when using the GNU form (i.e.
'{ foo: val }').  That's now fixed in mob.

% cat alloc-init.c
typedef __SIZE_TYPE__ size_t;
struct S {
    int a, b;
};

extern void * malloc(size_t);
extern void * memcpy(void *, const void *, size_t);
extern int printf(const char *, ...);
void *memdup(const void *src, size_t sz);
#define ALLOC_INIT(type, ...)   \
        (type *)memdup((type[]){ __VA_ARGS__ }, sizeof(type))

int main()
{
  struct S *ps = ALLOC_INIT(struct S, {.a = 3, .b = 4});
  printf("%d %d\n", ps->a, ps->b);
  return 0;
}

void *memdup(const void *src, size_t sz) {
        void *mem = malloc(sz);
        return mem ? memcpy(mem, src, sz) : 0;
}

Ciao,
Michael.

> On Sun, Jul 21, 2019 at 7:56 PM Ivan Medoedov <address@hidden>
> wrote:
>       Indeed. Sorry, my bad.
> Looks like the error is caused by __VA_ARGS__
>
> I'm using the following macro: 
>
> #define ALLOC_INIT(type, ...) (type *)memdup((type[]){ __VA_ARGS__ },
> sizeof(type))
>
> https://tia.mat.br/posts/2015/05/01/initializing_a_heap_allocated_structure
> _in_c.html
>
> Foo* foo = ALLOC_INIT(Foo, { field: 123, field2: 456 });
>
> error: field expected
>
> This macro works fine with GCC and Clang.
>
>
> On Sun, Jul 21, 2019 at 6:50 PM Michael Matz <address@hidden>
> wrote:
>       Hi,
>
>       On Sun, 21 Jul 2019, Ivan Medoedov wrote:
>
>       > Hello,
>       > { .field = value } syntax is not supported by TCC.
>
>       Why do you think so?
>
>       % cat designated-init.c
>       struct S {
>            int a, b;
>       };
>
>       struct S s = {.a = 2, .b = 3};
>       % ./tcc -c designated-init.c && echo ok
>       ok
>       %
>
>
>       Ciao,
>       Michael.
>
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