chibicc accepts invalid code

[aalmkainzi]

Hi. I've been working on a fork of chibicc to implement my own ideas.
I noticed that chibicc accepts invalid code in many cases.

For example this code:

struct A
{
    struct { char b; } aa;
};

struct A
{
    float ff;
};

int foo(int i)
{
    return i;
}

int main()
{
    struct A a = 50;
    char *a = 100;
    return foo(a);
}

Something that should have been rejected:

• redefinition of struct
• assigning a struct variable with the wrong type
• assigning a char* variable with the wrong type
• re-declaring local variable with same name.
• calling a foo with char* when it takes int

I can try to make PRs for some of these, but I'm worried this project is abandoned and doesn't accept PRs anymore.

[fuhsnn]

I implemented most invalid assignment and redeclaration checks in my fork, though the code had diverged too much to be a simple merge. chibicc as-is doesn't track type qualifiers, nor same-name extern references scattered in parallel scopes, therefore covering all cases might be a bigger change than it seems.

    struct A a = 50;

This particular case is a funny one, what's missing here is actually an error for missing bracers, the parser treat this as-if inside an initializer list https://godbolt.org/z/b3o3sPs4z.

[aalmkainzi]

the parser treat this as-if inside an initializer list

I see. I also noticed that when omitting the braces, it only accepts it if you provide all members, in your godbolt link I tried struct A a = 123; and it says it expects a comma.

But it's not only that, there is no type checking for the RHS, for example this is accpeted:

struct B { char *s; };
struct A a = (struct B){"hello"};