rustc: Implement custom panic runtimes

This commit is an implementation of [RFC 1513] which allows applications to
alter the behavior of panics at compile time. A new compiler flag, `-C panic`,
is added and accepts the values `unwind` or `panic`, with the default being
`unwind`. This model affects how code is generated for the local crate, skipping
generation of landing pads with `-C panic=abort`.

[RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md

Panic implementations are then provided by crates tagged with
`#![panic_runtime]` and lazily required by crates with
`#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic
runtime must match the final product, and if the panic strategy is not `abort`
then the entire DAG must have the same panic strategy.

With the `-C panic=abort` strategy, users can expect a stable method to disable
generation of landing pads, improving optimization in niche scenarios,
decreasing compile time, and decreasing output binary size. With the `-C
panic=unwind` strategy users can expect the existing ability to isolate failure
in Rust code from the outside world.

Organizationally, this commit dismantles the `sys_common::unwind` module in
favor of some bits moving part of it to `libpanic_unwind` and the rest into the
`panicking` module in libstd. The custom panic runtime support is pretty similar
to the custom allocator support with the only major difference being how the
panic runtime is injected (takes the `-C panic` flag into account).

20 files changed, 395 insertions, 0 deletions

diff --git a/src/test/compile-fail/panic-runtime/abort-link-to-unwind-dylib.rs b/src/test/compile-fail/panic-runtime/abort-link-to-unwind-dylib.rs
new file mode 100644
index 00000000000..c3242a5082b
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/abort-link-to-unwind-dylib.rs
@@ -0,0 +1,24 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-C panic=abort -C prefer-dynamic
+// ignore-musl - no dylibs here
+// error-pattern:`panic_unwind` is not compiled with this crate's panic strategy
+
+// This is a test where the local crate, compiled with `panic=abort`, links to
+// the standard library **dynamically** which is already linked against
+// `panic=unwind`. We should fail because the linked panic runtime does not
+// correspond with our `-C panic` option.
+//
+// Note that this test assumes that the dynamic version of the standard library
+// is linked to `panic_unwind`, which is currently the case.
+
+fn main() {
+}
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/needs-panic-runtime.rs b/src/test/compile-fail/panic-runtime/auxiliary/needs-panic-runtime.rs
new file mode 100644
index 00000000000..d6c21fecf6b
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/needs-panic-runtime.rs
@@ -0,0 +1,16 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// no-prefer-dynamic
+
+#![feature(needs_panic_runtime)]
+#![crate_type = "rlib"]
+#![needs_panic_runtime]
+#![no_std]
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-abort.rs b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-abort.rs
new file mode 100644
index 00000000000..3b74156b6b0
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-abort.rs
@@ -0,0 +1,27 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-C panic=abort
+// no-prefer-dynamic
+
+#![feature(panic_runtime)]
+#![crate_type = "rlib"]
+
+#![no_std]
+#![panic_runtime]
+
+#[no_mangle]
+pub extern fn __rust_maybe_catch_panic() {}
+
+#[no_mangle]
+pub extern fn __rust_start_panic() {}
+
+#[no_mangle]
+pub extern fn rust_eh_personality() {}
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-lang-items.rs b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-lang-items.rs
new file mode 100644
index 00000000000..fbf70b3d3fe
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-lang-items.rs
@@ -0,0 +1,23 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// no-prefer-dynamic
+
+#![crate_type = "rlib"]
+
+#![no_std]
+#![feature(lang_items)]
+
+#[lang = "panic_fmt"]
+fn panic_fmt() {}
+#[lang = "eh_personality"]
+fn eh_personality() {}
+#[lang = "eh_unwind_resume"]
+fn eh_unwind_resume() {}
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-unwind.rs b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-unwind.rs
new file mode 100644
index 00000000000..4bb36839d98
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-unwind.rs
@@ -0,0 +1,27 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-C panic=unwind
+// no-prefer-dynamic
+
+#![feature(panic_runtime)]
+#![crate_type = "rlib"]
+
+#![no_std]
+#![panic_runtime]
+
+#[no_mangle]
+pub extern fn __rust_maybe_catch_panic() {}
+
+#[no_mangle]
+pub extern fn __rust_start_panic() {}
+
+#[no_mangle]
+pub extern fn rust_eh_personality() {}
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-unwind2.rs b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-unwind2.rs
new file mode 100644
index 00000000000..4bb36839d98
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/panic-runtime-unwind2.rs
@@ -0,0 +1,27 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-C panic=unwind
+// no-prefer-dynamic
+
+#![feature(panic_runtime)]
+#![crate_type = "rlib"]
+
+#![no_std]
+#![panic_runtime]
+
+#[no_mangle]
+pub extern fn __rust_maybe_catch_panic() {}
+
+#[no_mangle]
+pub extern fn __rust_start_panic() {}
+
+#[no_mangle]
+pub extern fn rust_eh_personality() {}
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/runtime-depending-on-panic-runtime.rs b/src/test/compile-fail/panic-runtime/auxiliary/runtime-depending-on-panic-runtime.rs
new file mode 100644
index 00000000000..b90dec9281b
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/runtime-depending-on-panic-runtime.rs
@@ -0,0 +1,18 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// no-prefer-dynamic
+
+#![feature(panic_runtime)]
+#![crate_type = "rlib"]
+#![panic_runtime]
+#![no_std]
+
+extern crate needs_panic_runtime;
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/wants-panic-runtime-abort.rs b/src/test/compile-fail/panic-runtime/auxiliary/wants-panic-runtime-abort.rs
new file mode 100644
index 00000000000..e1902e44a60
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/wants-panic-runtime-abort.rs
@@ -0,0 +1,17 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-C panic=abort
+// no-prefer-dynamic
+
+#![crate_type = "rlib"]
+#![no_std]
+
+extern crate panic_runtime_abort;
diff --git a/src/test/compile-fail/panic-runtime/auxiliary/wants-panic-runtime-unwind.rs b/src/test/compile-fail/panic-runtime/auxiliary/wants-panic-runtime-unwind.rs
new file mode 100644
index 00000000000..2183338b249
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/auxiliary/wants-panic-runtime-unwind.rs
@@ -0,0 +1,16 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// no-prefer-dynamic
+
+#![crate_type = "rlib"]
+#![no_std]
+
+extern crate panic_runtime_unwind;
diff --git a/src/test/compile-fail/panic-runtime/bad-panic-flag1.rs b/src/test/compile-fail/panic-runtime/bad-panic-flag1.rs
new file mode 100644
index 00000000000..f067b6b8349
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/bad-panic-flag1.rs
@@ -0,0 +1,14 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-C panic=foo
+// error-pattern:either `panic` or `abort` was expected
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/bad-panic-flag2.rs b/src/test/compile-fail/panic-runtime/bad-panic-flag2.rs
new file mode 100644
index 00000000000..0ecf65f080f
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/bad-panic-flag2.rs
@@ -0,0 +1,14 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-C panic
+// error-pattern:requires either `panic` or `abort`
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/libtest-unwinds.rs b/src/test/compile-fail/panic-runtime/libtest-unwinds.rs
new file mode 100644
index 00000000000..5f6f4ecbd6f
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/libtest-unwinds.rs
@@ -0,0 +1,20 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// error-pattern:is not compiled with this crate's panic strategy `abort`
+// compile-flags:-C panic=abort
+
+#![feature(test)]
+
+extern crate test;
+
+fn main() {
+}
+
diff --git a/src/test/compile-fail/panic-runtime/needs-gate.rs b/src/test/compile-fail/panic-runtime/needs-gate.rs
new file mode 100644
index 00000000000..02f3da58f1d
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/needs-gate.rs
@@ -0,0 +1,14 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![panic_runtime] //~ ERROR: is an experimental feature
+#![needs_panic_runtime] //~ ERROR: is an experimental feature
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/runtime-depend-on-needs-runtime.rs b/src/test/compile-fail/panic-runtime/runtime-depend-on-needs-runtime.rs
new file mode 100644
index 00000000000..0681f991067
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/runtime-depend-on-needs-runtime.rs
@@ -0,0 +1,15 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// aux-build:needs-panic-runtime.rs
+// aux-build:runtime-depending-on-panic-runtime.rs
+// error-pattern:cannot depend on a crate that needs a panic runtime
+
+extern crate runtime_depending_on_panic_runtime;
diff --git a/src/test/compile-fail/panic-runtime/transitive-link-a-bunch.rs b/src/test/compile-fail/panic-runtime/transitive-link-a-bunch.rs
new file mode 100644
index 00000000000..885b3e6dbb9
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/transitive-link-a-bunch.rs
@@ -0,0 +1,24 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// aux-build:panic-runtime-unwind.rs
+// aux-build:panic-runtime-abort.rs
+// aux-build:wants-panic-runtime-unwind.rs
+// aux-build:wants-panic-runtime-abort.rs
+// aux-build:panic-runtime-lang-items.rs
+// error-pattern: is not compiled with this crate's panic strategy `unwind`
+
+#![no_std]
+
+extern crate wants_panic_runtime_unwind;
+extern crate wants_panic_runtime_abort;
+extern crate panic_runtime_lang_items;
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/two-panic-runtimes.rs b/src/test/compile-fail/panic-runtime/two-panic-runtimes.rs
new file mode 100644
index 00000000000..0fe0da2fa2c
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/two-panic-runtimes.rs
@@ -0,0 +1,23 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// error-pattern:cannot link together two panic runtimes: panic_runtime_unwind and panic_runtime_unwind2
+// ignore-tidy-linelength
+// aux-build:panic-runtime-unwind.rs
+// aux-build:panic-runtime-unwind2.rs
+// aux-build:panic-runtime-lang-items.rs
+
+#![no_std]
+
+extern crate panic_runtime_unwind;
+extern crate panic_runtime_unwind2;
+extern crate panic_runtime_lang_items;
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/want-abort-got-unwind.rs b/src/test/compile-fail/panic-runtime/want-abort-got-unwind.rs
new file mode 100644
index 00000000000..b178006411b
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/want-abort-got-unwind.rs
@@ -0,0 +1,17 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// error-pattern:is not compiled with this crate's panic strategy `abort`
+// aux-build:panic-runtime-unwind.rs
+// compile-flags:-C panic=abort
+
+extern crate panic_runtime_unwind;
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/want-abort-got-unwind2.rs b/src/test/compile-fail/panic-runtime/want-abort-got-unwind2.rs
new file mode 100644
index 00000000000..de8e010c3cb
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/want-abort-got-unwind2.rs
@@ -0,0 +1,18 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// error-pattern:is not compiled with this crate's panic strategy `abort`
+// aux-build:panic-runtime-unwind.rs
+// aux-build:wants-panic-runtime-unwind.rs
+// compile-flags:-C panic=abort
+
+extern crate wants_panic_runtime_unwind;
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/want-unwind-got-abort.rs b/src/test/compile-fail/panic-runtime/want-unwind-got-abort.rs
new file mode 100644
index 00000000000..88ad36f310e
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/want-unwind-got-abort.rs
@@ -0,0 +1,20 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// error-pattern:is incompatible with this crate's strategy of `unwind`
+// aux-build:panic-runtime-abort.rs
+// aux-build:panic-runtime-lang-items.rs
+
+#![no_std]
+
+extern crate panic_runtime_abort;
+extern crate panic_runtime_lang_items;
+
+fn main() {}
diff --git a/src/test/compile-fail/panic-runtime/want-unwind-got-abort2.rs b/src/test/compile-fail/panic-runtime/want-unwind-got-abort2.rs
new file mode 100644
index 00000000000..c42a25a553a
--- /dev/null
+++ b/src/test/compile-fail/panic-runtime/want-unwind-got-abort2.rs
@@ -0,0 +1,21 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// error-pattern:is incompatible with this crate's strategy of `unwind`
+// aux-build:panic-runtime-abort.rs
+// aux-build:wants-panic-runtime-abort.rs
+// aux-build:panic-runtime-lang-items.rs
+
+#![no_std]
+
+extern crate wants_panic_runtime_abort;
+extern crate panic_runtime_lang_items;
+
+fn main() {}