Add tests for intrinsics::unreachable

Author: Keegan McAllister

src/test/run-make/intrinsic-unreachable/Makefile

@@ -0,0 +1,15 @@
+-include ../tools.mk
+
+ifndef IS_WINDOWS
+# The assembly for exit-unreachable.rs should be shorter because it's missing
+# (at minimum) a return instruction.
+
+all:
+	$(RUSTC) -O --emit asm exit-ret.rs
+	$(RUSTC) -O --emit asm exit-unreachable.rs
+	test `wc -l < $(TMPDIR)/exit-unreachable.s` -lt `wc -l < $(TMPDIR)/exit-ret.s`
+else
+# Because of Windows exception handling, the code is not necessarily any shorter.
+# https://github.com/llvm-mirror/llvm/commit/64b2297786f7fd6f5fa24cdd4db0298fbf211466
+all:
+endif

src/test/run-make/intrinsic-unreachable/exit-ret.rs

@@ -0,0 +1,20 @@
+// Copyright 2014 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.
+
+#![feature(asm)]
+#![crate_type="lib"]
+
+pub fn exit(n: uint) {
+    unsafe {
+        // Pretend this asm is an exit() syscall.
+        asm!("" :: "r"(n) :: "volatile");
+        // Can't actually reach this point, but rustc doesn't know that.
+    }
+}

src/test/run-make/intrinsic-unreachable/exit-unreachable.rs

@@ -0,0 +1,22 @@
+// Copyright 2014 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.
+
+#![feature(asm)]
+#![crate_type="lib"]
+
+use std::intrinsics;
+
+pub fn exit(n: uint) -> ! {
+    unsafe {
+        // Pretend this asm is an exit() syscall.
+        asm!("" :: "r"(n) :: "volatile");
+        intrinsics::unreachable()
+    }
+}

src/test/run-pass/intrinsic-unreachable.rs

@@ -0,0 +1,24 @@
+// Copyright 2014 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.
+
+use std::intrinsics;
+
+// See also src/test/run-make/intrinsic-unreachable.
+
+fn f(x: uint) -> uint {
+    match x {
+        17 => 23,
+        _ => unsafe { intrinsics::unreachable() },
+    }
+}
+
+fn main() {
+    assert_eq!(f(17), 23);
+}