Implicit member variables (in C++).

Now let's use #define to shadow the variable as field of a struct field of a scruct. Something like that.

Pointer as array as pointer and the associated arithmetics. Where are we in the buffer again?

Also for loops assign and compare and assign. And of course at lot of UB.

Etc.

every C compiler vendor should be pressured to implement gnu-style statement expressions so that you can just do:

#define IS_EQUAL(x, y) \
(sizeof(({ \
[[maybe_unused]] __typeof(x) *y_= &(y); \
0; \
})), \
memcmp(&(x), &(y), sizeof(x)) == 0)