--wrap-static-fns generates invalid C for pointer-to-array parameters and returns

[lwz23]

Input C/C++ Header

static inline int (*phase8_array_identity(int (*value)[4]))[4] {
    return value;
}

Bindgen Invocation

$ bindgen input.h \
    --wrap-static-fns \
    --wrap-static-fns-path wrapper \
    --rust-target 1.75 \
    --no-layout-tests \
    --no-rustfmt-bindings \
    --output bindings.rs

Actual Results

The Rust declaration has the expected pointer-to-array type:

extern "C" {
    #[link_name = "phase8_array_identity__extern"]
    pub fn phase8_array_identity(
        value: *mut [::std::os::raw::c_int; 4usize],
    ) -> *mut [::std::os::raw::c_int; 4usize];
}

The generated wrapper.c does not preserve the C declarator:

int * [4] phase8_array_identity__extern(int *value [4]) {
    return phase8_array_identity(value);
}

Clang rejects it:

error: brackets are not allowed here
error: function cannot return array type 'int *[4]'
error: incompatible pointer types passing 'int **' to parameter of type 'int (*)[4]'

The parameter is wrong as well as the return type. In a parameter list,
int *value[4] is adjusted to int **; it is not int (*)[4].

Expected Results

The generated wrapper needs parentheses around the pointer declarators:

int (*phase8_array_identity__extern(int (*value)[4]))[4] {
    return phase8_array_identity(value);
}

I compiled that wrapper and linked it to a Rust caller using the generated
bindings.rs without edits. The direct C caller and the Rust caller both
printed:

identity=1 sum=10 first=1 last=4

Environment

bindgen current main: 9d26c6eddeff9192ddedb563192abe3128fc5aae
bindgen release:      0.72.1
clang:                15.0.7
rustc:                1.75.0
target:               x86_64-unknown-linux-gnu

The same generated C compile failure occurs with current main and 0.72.1,
at both O0 and O2.

Additional notes

This looks like a declarator serialization problem. The array serializer
appends [length], while the pointer serializer pushes * onto the type
string. That is not enough to represent cases where the * must be
parenthesized.