//@ normalize-stderr-test: "(abi|pref|unadjusted_abi_align): Align\([1-8] bytes\)" -> "$1: $$SOME_ALIGN"
/*!
C doesn't have zero-sized types... except it does.

Standard C doesn't, but some C compilers, like GCC, implement ZSTs as a compiler extension.
This historically has wound up interacting with processor-specific ABIs in fairly ad-hoc ways.
e.g. despite being "zero-sized", sometimes C compilers decide ZSTs consume registers.

That means these two function signatures may not be compatible:

```
extern "C" fn((), i32, i32);
extern "C" fn(i32, (), i32);
```
*/

/*
 * ZST IN "C" IS ZERO-SIZED
 */

//@ revisions: aarch64-darwin
//@[aarch64-darwin] compile-flags: --target aarch64-apple-darwin
//@[aarch64-darwin] needs-llvm-components: aarch64

//@ revisions: x86_64-linux
//@[x86_64-linux] compile-flags: --target x86_64-unknown-linux-gnu
//@[x86_64-linux] needs-llvm-components: x86


/*
 * ZST IN "C" IS PASS-BY-POINTER
 */

// according to the SRV4 ABI, an aggregate is always passed in registers,
// and it so happens the GCC extension for ZSTs considers them as structs.
//@ revisions: powerpc-linux
//@[powerpc-linux] compile-flags: --target powerpc-unknown-linux-gnu
//@[powerpc-linux] needs-llvm-components: powerpc

//@ revisions: s390x-linux
//@[s390x-linux] compile-flags: --target s390x-unknown-linux-gnu
//@[s390x-linux] needs-llvm-components: systemz

//@ revisions: sparc64-linux
//@[sparc64-linux] compile-flags: --target sparc64-unknown-linux-gnu
//@[sparc64-linux] needs-llvm-components: sparc

// The Win64 ABI uses slightly different handling for power-of-2 sizes in the ABI,
// so GCC decided that ZSTs are pass-by-pointer, as `0.is_power_of_two() == false`
//@ revisions: x86_64-pc-windows-gnu
//@[x86_64-pc-windows-gnu] compile-flags: --target x86_64-pc-windows-gnu
//@[x86_64-pc-windows-gnu] needs-llvm-components: x86


#![feature(lang_items, no_core, rustc_attrs)]
#![no_core]
#![crate_type = "lib"]

#[lang = "sized"]
trait Sized {}

#[rustc_abi(debug)]
extern "C" fn pass_zst(_: ()) {} //~ ERROR: fn_abi