Enabling loading of static compiled extensions about sqlx HOT 2 OPEN

pub type SqliteExtensionInit = extern "C" fn(*mut sqlite3, *mut *const c_char, *mut sqlite3_api_routines) -> c_int;

impl SqliteConnectOptions {

    /// Add a statically linked extension to the database by directly calling its init function.
    ///
    /// This is similar to [`sqlite3_auto_extension()`](https://www.sqlite.org/c3ref/auto_extension.html)
    /// but is constrained just to databases created with this `SqliteConnectOptions`.
    ///
    /// ### SAFETY
    /// The function pointer must be safe to call from any thread for the lifetime of this `SqliteConnectOptions`.
    ///
    /// If you wish to dynamically load an extension, consider [`Self::extension()`] or [`Self::extension_with_entrypoint()`] instead.
    pub unsafe fn extension_with_init(
        &mut self,
        init: SqliteExtensionInit,
    ) -> &mut Self {
        // ..
    }
}

use sqlite_vss::{sqlite3_vector_init, sqlite3_vss_init};

unsafe {
    let vss_vector_init = sqlite3_vector_init as *const ();
    let vss_vector_init_correct: extern "C" fn(
        db: *mut sqlite3,
        pzErrMsg: *mut *const c_char,
        pThunk: *const sqlite3_api_routines,
    ) -> i32 = std::mem::transmute(vss_vector_init);
    libsqlite3_sys::sqlite3_auto_extension(Some(vss_vector_init_correct));

    let vss_init = sqlite3_vss_init as *const ();
    let vss_init_correct: extern "C" fn(
        db: *mut sqlite3,
        pzErrMsg: *mut *const c_char,
        pThunk: *const sqlite3_api_routines,
    ) -> i32 = std::mem::transmute(vss_init);
    libsqlite3_sys::sqlite3_auto_extension(Some(vss_init_correct));
}

fn main() {
    if cfg!(target_os = "macos") {
        println!("cargo:rustc-link-arg=-Wl,-undefined,dynamic_lookup,-lomp,-L/opt/homebrew/opt/libomp/lib");
    } else if cfg!(target_os = "linux") {
        println!("cargo:rustc-link-arg=-Wl,-undefined,dynamic_lookup,-lstdc++");
    }
}