rustc: implement arithmetic overflow checking

Adds overflow checking to integer addition, multiplication, and subtraction
when `-Z force-overflow-checks` is true, or if `--cfg ndebug` is not passed to
the compiler. On overflow, it panics with `arithmetic operation overflowed`.
Also adds `overflowing_add`, `overflowing_sub`, and `overflowing_mul`
intrinsics for doing unchecked arithmetic.

[breaking-change]

3 files changed, 45 insertions, 0 deletions

diff --git a/src/test/run-fail/overflowing-add.rs b/src/test/run-fail/overflowing-add.rs
new file mode 100644
index 00000000000..c3e41110d20
--- /dev/null
+++ b/src/test/run-fail/overflowing-add.rs
@@ -0,0 +1,15 @@
+// Copyright 2015 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:thread '<main>' panicked at 'arithmatic operation overflowed'
+
+fn main() {
+    let x = 200u8 + 200u8 + 200u8;
+}
diff --git a/src/test/run-fail/overflowing-mul.rs b/src/test/run-fail/overflowing-mul.rs
new file mode 100644
index 00000000000..bf7a9d07586
--- /dev/null
+++ b/src/test/run-fail/overflowing-mul.rs
@@ -0,0 +1,15 @@
+// Copyright 2015 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:thread '<main>' panicked at 'arithmatic operation overflowed'
+
+fn main() {
+    let x = 200u8 + 4u8;
+}
diff --git a/src/test/run-fail/overflowing-sub.rs b/src/test/run-fail/overflowing-sub.rs
new file mode 100644
index 00000000000..961b36d322c
--- /dev/null
+++ b/src/test/run-fail/overflowing-sub.rs
@@ -0,0 +1,15 @@
+// Copyright 2015 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:thread '<main>' panicked at 'arithmatic operation overflowed'
+
+fn main() {
+    let x = 42u8 - 43u8;
+}