[Tinycc-devel] sizeof() on structure with VLA member gives wrong results

[John Scott]

Hi,

GCC supports VLAs as structure and union members as an extension, and it
appears that TinyCC supports this as well. However, sizeof() seems to do
the wrong thing:

#include <stdio.h>
int main(void) {
        const int k = 16;
        printf("%zu\n", sizeof(struct { char b[k]; }));
}.

This prints 16 with GCC and Clang on an x86_64 Debian Bookworm machine,
but 8 under TinyCC, which obviously cannot be a legitimate size for the
structure. I don't know that there has been any particular effort in
TinyCC to support this extension or whether the presence of this
"feature" is merely incidental, but I wonder if this bug would be
feasible to fix?

I for one think this extension has good use cases (especially with
unions) which I shall not elaborate on here, and would like to see
TinyCC continue to support it.

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