Comment by lukasgelbmann

7 hours ago

Yes, and variable length arrays were made an optional part of the standard in C11. Whereas flexible array members remain a standard required feature.

Flexible array members don’t allocate a dynamic amount of memory on the stack.

3 comments

lukasgelbmann

uecker 7 hours ago

VLAs are supported by basically all modern C compilers though, and I do not think adding them was a mistake (I certainly use them a lot!). They got a bad reputation due to stack clash attacks, but in the past some compilers did not implement stack probing (clang was very late). But this was fixed a decade ago.

david2ndaccount 5 hours ago

Their specification is pretty bad, allowing code like:

    #include <stdio.h>
    #include <stddef.h>
    void v(int y[printf("hello world!\n")]){ 
    }

    int main(){
        v(NULL);
        typedef int wut[printf("oh no\n")];
    }
    $ cc vla.c && ./a.out
    hello world!
    oh no

`typedef`s with side effects...