Auto merge of #1144 - RalfJung:panic-location, r=RalfJung

test that unwrap gets us the right panic location

Make sure this stuff works in Miri as well -- basically, an integration test for `track_caller` and the panic machinery (we already have more focused tests as well).

rust-version

@@ -1 +1 @@
-ebbb2bf37aedaaa64dfaa52ba337ca6efb6b9093
+adc65725004c8aac16392fe4052c3e347181157d

tests/run-pass/panic/std-panic-locations.rs

@@ -0,0 +1,45 @@
+// ignore-windows: Unwind panicking does not currently work on Windows
+#![feature(option_expect_none, option_unwrap_none)]
+//! Test that panic locations for `#[track_caller]` functions in std have the correct
+//! location reported.
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+static HOOK_COUNT: AtomicUsize = AtomicUsize::new(0);
+
+fn main() {
+    // inspect the `PanicInfo` we receive to ensure the right file is the source
+    std::panic::set_hook(Box::new(|info| {
+        HOOK_COUNT.fetch_add(1, Ordering::Relaxed);
+        let actual = info.location().unwrap();
+        if actual.file() != file!() {
+            eprintln!("expected a location in the test file, found {:?}", actual);
+            panic!();
+        }
+    }));
+
+    fn assert_panicked(f: impl FnOnce() + std::panic::UnwindSafe) {
+        std::panic::catch_unwind(f).unwrap_err();
+    }
+
+    let nope: Option<()> = None;
+    assert_panicked(|| nope.unwrap());
+    assert_panicked(|| nope.expect(""));
+
+    let yep: Option<()> = Some(());
+    assert_panicked(|| yep.unwrap_none());
+    assert_panicked(|| yep.expect_none(""));
+
+    let oops: Result<(), ()> = Err(());
+    assert_panicked(|| oops.unwrap());
+    assert_panicked(|| oops.expect(""));
+
+    let fine: Result<(), ()> = Ok(());
+    assert_panicked(|| fine.unwrap_err());
+    assert_panicked(|| fine.expect_err(""));
+
+    // Cleanup: reset to default hook.
+    drop(std::panic::take_hook());
+
+    assert_eq!(HOOK_COUNT.load(Ordering::Relaxed), 8);
+}