Possible compiler bug with const_fn (Calling a function with bad signature)

[johalun]

Error when building following:

Tested with:

rustc 1.16.0-nightly (7821a9b99 2017-01-23)

Build with:

xargo build --target x86_64-kernel-freebsd

this code

#![no_std]
#![feature(const_fn)]
#![feature(lang_items)]
#![allow(dead_code)]
#![allow(unused_imports)]

extern crate spin;

use spin::Mutex;
use core::cell::UnsafeCell;
use core::sync::atomic::{AtomicBool, Ordering, ATOMIC_BOOL_INIT};

// Compile error
// static mut Y1: Mutex<i32> = Mutex::new(0i32);

// No compile error (requires making Mutex members public in spin crate)
static mut Y2: Mutex<i32> = Mutex
{
    lock: ATOMIC_BOOL_INIT,
    data: UnsafeCell::new(0i32),
};

#[lang = "eh_personality"]
extern "C" fn eh_personality() {}
#[lang = "eh_unwind_resume"]
extern "C" fn eh_unwind_resume() {}
#[lang = "panic_fmt"]
extern "C" fn panic_impl(_: core::fmt::Arguments, _: &'static str, _: u32) -> ! {loop {}}

causes error:

Assertion failed: ((Args.size() == FTy->getNumParams() || (FTy->isVarArg() && Args.size() > FTy->getNumParams())) && "Calling a function with bad signature!"), function init, file /buildslave/rust-buildbot/slave/nightly-dist-rustc-cross-host-linux/build/src/llvm/lib/IR/Instructions.cpp, line 258.

Target configuration (x86_64-kernel-freebsd.json)

{
	"llvm-target": "x86_64-unknown-freebsd",
	"target-endian": "little",
	"target-pointer-width": "64",
	"os": "none",
	"arch": "x86_64",
	"data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
	"pre-link-args": [ "-m64" ],
	"cpu": "x86-64",
	"features": "+soft-float,-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2",
	"disable-redzone":         true,
	"custom-unwind-resume":    true,
	"eliminate-frame-pointer": true,
	"linker-is-gnu":           true,
	"no-compiler-rt":          true,
	"archive-format":          "gnu",
	"code-model":              "kernel",
	"relocation-model":        "static"
}

[johalun]

I've been digging a bit further and the follow code simplifies things a bit.

#![no_std]
#![feature(const_fn)]
#![feature(lang_items)]
#![allow(dead_code)]
#![allow(unused_imports)]
#![feature(optin_builtin_traits)]

use core::sync::atomic::{AtomicBool, Ordering, ATOMIC_BOOL_INIT};

pub struct UnsafeCell<T: ?Sized> {
    value: T,
}
impl<T> UnsafeCell<T> {
    pub const fn new(value: T) -> UnsafeCell<T> {
        UnsafeCell { value: value }
    }
}

pub struct Mut<T: ?Sized> {
    data: UnsafeCell<T>
}
impl<T> Mut<T> {
    pub const fn new(user_data: T) -> Mut<T>
    {
        Mut
        {
            // data: UnsafeCell { value: user_data }, // no error
            data: UnsafeCell::new(user_data),  // compile error
        }
    }
}
static mut X: UnsafeCell<i32> = UnsafeCell::new(0i32); // no error
static mut Y: Mut<i32> = Mut::new(0i32); // error if use Unsafecell::new()

#[lang = "eh_personality"]
extern "C" fn eh_personality() {}
#[lang = "eh_unwind_resume"]
extern "C" fn eh_unwind_resume() {}
#[lang = "panic_fmt"]
extern "C" fn panic_impl(_: core::fmt::Arguments, _: &'static str, _: u32) -> ! {
    loop {}
}

[johalun]

I think I found the problem. After I played around with the target config json file I found the "custom-unwind-resume": true caused the error.

Keeping it true while adding

[profile.dev]
panic = "abort"
[profile.release]
panic = "abort"

to Cargo.toml seem to have solved the problem. I though I had added that but apparently lost it somewhere on the way....