debuginfo: Add a test case for issue rust-lang#12886.

src/test/debug-info/issue12886.rs

@@ -0,0 +1,35 @@
+// Copyright 2013-2014 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.
+
+// ignore-android: FIXME(#10381)
+
+// compile-flags:-g
+// debugger:break issue12886.rs:29
+// debugger:run
+// debugger:next
+// check:[...]30[...]s
+// debugger:continue
+
+// IF YOU MODIFY THIS FILE, BE CAREFUL TO ADAPT THE LINE NUMBERS IN THE DEBUGGER COMMANDS
+
+// This test makes sure that gdb does not set unwanted breakpoints in inlined functions. If a
+// breakpoint existed in unwrap(), then calling `next` would (when stopped at line 27) would stop
+// in unwrap() instead of stepping over the function invocation. By making sure that `s` is
+// contained in the output, after calling `next` just once, we can be sure that we did not stop in
+// unwrap(). (The testing framework doesn't allow for checking that some text is *not* contained in
+// the output, which is why we have to make the test in this kind of roundabout way)
+fn bar() -> int {
+    let s = Some(5).unwrap();
+    s
+}
+
+fn main() {
+    let _ = bar();
+}