'dlopen(null pointer)' does not work on the android

[jaeminMoon]

see rust/src/auxiliary/linkage-visibility.rs

#[no_mangle]
pub fn foo() { bar(); }

pub fn foo2<T>() {
    fn bar2() {
        bar();
    }
    bar2();
}

#[no_mangle]
fn bar() { }

#[no_mangle]
fn baz() { }

pub fn test() {
    let lib = DynamicLibrary::open(None).unwrap();
    unsafe {
        assert!(lib.symbol::<int>("foo").is_ok());
        assert!(lib.symbol::<int>("baz").is_err());
        assert!(lib.symbol::<int>("bar").is_err());
    }
}

This test code is success on linux, but fail on android.

 failed at 'assertion failed: lib.symbol::<int>("foo").is_ok()'

I think dlopen(null pointer, RTLD_LAZY) have to return 'main program Handle', but do not run on android.

[alexcrichton]

I'm curious why DynamicLibrary::open didn't fail, but the later symbol lookups failed. Could you check to make sure that the symbols are actually present in the library? You should see that foo and test show up, along with possibly some other weirder ones.

[flaper87]

Triage bump.

I don't have a way to test this but the test in dynamic_lib is still disabled for android.

@jaeminMoon Do you have any input on this?

[tamird]

This is confirmed still broken on Android :(

EDIT: at least on the buildbots

[steveklabnik]

Triage: said test is here: https://github.com/rust-lang/rust/blob/f50dbd580f3d5d88a300da540db3c85164bfd0de/src/test/run-pass-fulldeps/auxiliary/linkage-visibility.rs

I don't see anything disabled on android by what @flaper87 suggested.

@tamird suggests this is broken on the bots, but I don't know enough about them to make the same evaluation.

[sfackler]

That's the auxiliary file - the test itself is disabled:

rust/src/test/run-pass-fulldeps/linkage-visibility.rs

Line 12 in f50dbd5

// ignore-android: FIXME(#10356)

[steveklabnik]

Triage: no change