Compatible types and structures in C

Question

I have the following code:

int main(void)
{
    struct { int x; } a, b;
    struct { int x; } c;
    struct { int x; } *p;

    b = a;   /* OK */
    c = a;          


        

Answer 1

Interestingly Clang gives the following:

error: incompatible type assigning 'struct ', expected 'struct '

warning: incompatible pointer types assigning 'struct  *', expected 'struct  *'

It seems that if two (or more) anonymous structs are declared then the compiler does some internal magic which specifies which specific anonymous struct is being referred too.