Which Clang warning is equivalent to Wzero-as-null-pointer-constant from GCC?

Question

Our project uses C++11/14, and we want to use nullptr instead of 0 or NULL with pointers, even when 0 (as an integer literal) is allowed.

I have the following code:

int main()
{
    int *ptr1 = nullptr; // #1
    int *ptr2 = 0;       // #2
}

If I compile with GCC (5.3.0) and the flag -Wzero-as-null-pointer-constant it warnings in #2, but I can't find a similar flag in Clang. If I compile the code with Clang (3.7.1) and the flag -Weverything, I don't get any warning about #2.

So, is there any way to get a similar warning for this in Clang?

Provisional

It's even worse than that. In C++ you're allowed to use any integer constant expression evaluating to zero, not just a literal... e.g. !!!!!1. – Hhd

@Hhd I think that was the behavior in C++98, but C++14 seems to change that. See this answer. If I understand correctly, !!!!!1 is an integral constant expression (that evaluates to false) and not an integer literal. – Provisional

IIRC clang actually comes with a tool to automatically replace old null pointer constants with nullptr. – Litmus

Answer 1

Clang doesn't support these kind of warnings (i.e., there's no -Wzero-as-null-pointer-constant equivalent in Clang). You can see it your self if you add -Weverything option (mind do it only for testing), which enables all Clang's warnings.

Live Demo

Azimuth

This is no longer true. – Illaudable

Answer 2

clang has this warning as of 5.0; I added it here.

Tuchman

Answer 3

Use -Wzero-as-null-pointer-constant.

• Available at least since clang10 (around 2017).
• Same as gcc flag.

so bad it is not enabled by default by -Wall -Wextra...

Helmholtz