const T some_array[]; is compiled as static mut some_array: [T; 0usize];, which seems wrong.

[thomcc]

For some reason, a C header containing a declaration like:

extern const char some_static_string[];

is compiled to a rust bindings file with the following declaration:

extern "C" {
    pub static mut some_static_string: [::std::os::raw::c_char; 0usize];
}

This is wrong for a few reasons:

1. It's static mut, even though the input is a constant (in readonly memory, even).
2. It may be UB to read past the end (possibly even if done carefully with something core::ptr::addr_of! or similar): See Are statics confined to the size indicated by their type? unsafe-code-guidelines#259.

In theory the second might be a bigger problem (since maybe it would cause the symbol not to point at the right thing), but in practice it doesn't seem like anything goes wrong. And I have no suggestion for an alternative.

The first is less subtle, and has a more obvious fix (ditch the mut), so it's probably worth fixing. That said, it's probably harmless (so long as you never write to it... which requires unsafe anyway).

[pvdrz]

So this basically happens because clang is not able to evaluate some_static_string due to being external and at the same time clang_isConstQualifiedType returns false (not sure why though). This seems like a similar instance of #1727 so maybe we should special case incomplete arrays too.