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).

7 files changed, 217 insertions, 0 deletions

diff --git a/src/test/run-pass/panic-runtime/abort-link-to-unwinding-crates.rs b/src/test/run-pass/panic-runtime/abort-link-to-unwinding-crates.rs
new file mode 100644
index 00000000000..71c1a61062d
--- /dev/null
+++ b/src/test/run-pass/panic-runtime/abort-link-to-unwinding-crates.rs
@@ -0,0 +1,35 @@
+// 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
+// aux-build:exit-success-if-unwind.rs
+// no-prefer-dynamic
+
+extern crate exit_success_if_unwind;
+
+use std::process::Command;
+use std::env;
+
+fn main() {
+    let mut args = env::args_os();
+    let me = args.next().unwrap();
+
+    if let Some(s) = args.next() {
+        if &*s == "foo" {
+            exit_success_if_unwind::bar(do_panic);
+        }
+    }
+    let s = Command::new(env::args_os().next().unwrap()).arg("foo").status();
+    assert!(s.unwrap().code() != Some(0));
+}
+
+fn do_panic() {
+    panic!("try to catch me");
+}
diff --git a/src/test/run-pass/panic-runtime/abort.rs b/src/test/run-pass/panic-runtime/abort.rs
new file mode 100644
index 00000000000..2fc9d6cfd04
--- /dev/null
+++ b/src/test/run-pass/panic-runtime/abort.rs
@@ -0,0 +1,39 @@
+// 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
+
+use std::process::Command;
+use std::env;
+
+struct Bomb;
+
+impl Drop for Bomb {
+    fn drop(&mut self) {
+        std::process::exit(0);
+    }
+}
+
+fn main() {
+    let mut args = env::args_os();
+    let me = args.next().unwrap();
+
+    if let Some(s) = args.next() {
+        if &*s == "foo" {
+
+            let _bomb = Bomb;
+
+            panic!("try to catch me");
+        }
+    }
+    let s = Command::new(env::args_os().next().unwrap()).arg("foo").status();
+    assert!(s.unwrap().code() != Some(0));
+}
diff --git a/src/test/run-pass/panic-runtime/auxiliary/exit-success-if-unwind.rs b/src/test/run-pass/panic-runtime/auxiliary/exit-success-if-unwind.rs
new file mode 100644
index 00000000000..9e5fc592b1a
--- /dev/null
+++ b/src/test/run-pass/panic-runtime/auxiliary/exit-success-if-unwind.rs
@@ -0,0 +1,26 @@
+// 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"]
+
+struct Bomb;
+
+impl Drop for Bomb {
+    fn drop(&mut self) {
+        std::process::exit(0);
+    }
+}
+
+pub fn bar(f: fn()) {
+    let _bomb = Bomb;
+    f();
+}
diff --git a/src/test/run-pass/panic-runtime/link-to-abort.rs b/src/test/run-pass/panic-runtime/link-to-abort.rs
new file mode 100644
index 00000000000..71e35e41fc0
--- /dev/null
+++ b/src/test/run-pass/panic-runtime/link-to-abort.rs
@@ -0,0 +1,19 @@
+// 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_abort)]
+
+extern crate panic_abort;
+
+fn main() {
+}
diff --git a/src/test/run-pass/panic-runtime/link-to-unwind.rs b/src/test/run-pass/panic-runtime/link-to-unwind.rs
new file mode 100644
index 00000000000..dec8f738d32
--- /dev/null
+++ b/src/test/run-pass/panic-runtime/link-to-unwind.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_unwind)]
+
+extern crate panic_unwind;
+
+fn main() {
+}
diff --git a/src/test/run-pass/panic-runtime/lto-abort.rs b/src/test/run-pass/panic-runtime/lto-abort.rs
new file mode 100644
index 00000000000..09e33b88189
--- /dev/null
+++ b/src/test/run-pass/panic-runtime/lto-abort.rs
@@ -0,0 +1,39 @@
+// 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 lto -C panic=abort
+// no-prefer-dynamic
+
+use std::process::Command;
+use std::env;
+
+struct Bomb;
+
+impl Drop for Bomb {
+    fn drop(&mut self) {
+        std::process::exit(0);
+    }
+}
+
+fn main() {
+    let mut args = env::args_os();
+    let me = args.next().unwrap();
+
+    if let Some(s) = args.next() {
+        if &*s == "foo" {
+
+            let _bomb = Bomb;
+
+            panic!("try to catch me");
+        }
+    }
+    let s = Command::new(env::args_os().next().unwrap()).arg("foo").status();
+    assert!(s.unwrap().code() != Some(0));
+}
diff --git a/src/test/run-pass/panic-runtime/lto-unwind.rs b/src/test/run-pass/panic-runtime/lto-unwind.rs
new file mode 100644
index 00000000000..10e633b3775
--- /dev/null
+++ b/src/test/run-pass/panic-runtime/lto-unwind.rs
@@ -0,0 +1,41 @@
+// 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 lto -C panic=unwind
+// no-prefer-dynamic
+
+use std::process::Command;
+use std::env;
+
+struct Bomb;
+
+impl Drop for Bomb {
+    fn drop(&mut self) {
+        println!("hurray you ran me");
+    }
+}
+
+fn main() {
+    let mut args = env::args_os();
+    let me = args.next().unwrap();
+
+    if let Some(s) = args.next() {
+        if &*s == "foo" {
+
+            let _bomb = Bomb;
+
+            panic!("try to catch me");
+        }
+    }
+    let s = Command::new(env::args_os().next().unwrap()).arg("foo").output();
+    let s = s.unwrap();
+    assert!(!s.status.success());
+    assert!(String::from_utf8_lossy(&s.stdout).contains("hurray you ran me"));
+}