libclang wants arm64-apple-XX instead of aarch-apple-XX

[ArtBlnd]

Input C/C++ Header

Those NSS related headers.
https://github.com/mozilla/neqo/tree/main/neqo-crypto/bindings

Bindgen Invocation

https://github.com/mozilla/neqo/blob/adbdb256ab6444e7906de3afef849eeb9e6204a6/neqo-crypto/build.rs#L228-L285

Actual Results

--- stderr
clang version 10.0.0 
Target: aarch64-apple-ios
Thread model: posix
InstalledDir: 
thread 'main' panicked at 'libclang error; possible causes include:
- Invalid flag syntax
- Unrecognized flags
- Invalid flag arguments
- File I/O errors
- Host vs. target architecture mismatch
If you encounter an error missing from this list, please file an issue or a PR!', /Users/jujunryoung/.cargo/registry/src/jiasu.xzqcsaa.nyc.mn-1ecc6299db9ec823/bindgen-0.53.3/src/ir/context.rs:567:13
stack backtrace:
   0:        0x109c0621e - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h26e8f1b884bae128
   1:        0x109c2ce5c - core::fmt::write::ha0b53fc066268c71
   2:        0x109c02977 - std::io::Write::write_fmt::h410b83a4c70c6549
   3:        0x109c08405 - std::panicking::default_hook::{{closure}}::h70c11ad9e0ccd806
   4:        0x109c08142 - std::panicking::default_hook::hd9eda5765f18f021
   5:        0x109c089bd - std::panicking::rust_panic_with_hook::h3fc8a110bc9d166f
   6:        0x109c08592 - rust_begin_unwind
   7:        0x109c3d08f - core::panicking::panic_fmt::h04439fd445b5f690
   8:        0x109c3cf1a - core::option::expect_failed::h2cafbfb636f224cf
   9:        0x109b0e4c9 - bindgen::ir::context::BindgenContext::new::h43977ed84c226e7c
  10:        0x109ae132b - bindgen::Builder::generate::h2b57f01365a8288c
  11:        0x109a7311b - build_script_build::main::hf9e2ed509ece4751
  12:        0x109a6c036 - std::rt::lang_start::{{closure}}::h0f2b4e0c6bd159dc
  13:        0x109c08d49 - std::rt::lang_start_internal::hbec44ff873a30990
  14:        0x109a73f09 - main

see detail explains here: mozilla/neqo#922

[ArtBlnd]

This is not build environment related issues. it does same one clean macos one.

[ArtBlnd]

If builder does not select target. it will set-up libclang target automatically.
Seems libclang does not recognize aarch64-apple-ios which rust supports.

fn find_effective_target(clang_args: &[String]) -> (String, bool) {
    use std::env;

    let mut args = clang_args.iter();
    while let Some(opt) = args.next() {
        if opt.starts_with("--target=") {
            let mut split = opt.split('=');
            split.next();
            return (split.next().unwrap().to_owned(), true);
        }

        if opt == "-target" {
            if let Some(target) = args.next() {
                return (target.clone(), true);
            }
        }
    }

    // If we're running from a build script, try to find the cargo target.
    if let Ok(t) = env::var("TARGET") {
        return (t, false);
    }

    (HOST_TARGET.to_owned(), false)
}

do I need to generate aarch64-apple-ios bind with apple-clang toolchain?(libclang)

[ArtBlnd]

Seems libclang wants arm64-apple-ios instead of aarch64-apple-ios. and rustc is exporting TARGET env as aarch64-apple-ios

[simlay]

This issue looks like a dup of #1211.

[emilio]

Yep, that's #1211.