Auto merge of #67887 - anp:tracked-std-panics, r=<try>

`Option::{expect,unwrap}` and `Result::{expect, expect_err, unwrap, unwrap_err}` have `#[track_caller]`

The annotated functions now produce panic messages pointing to the location where they were called, rather than `core`'s internals.

Author: bors

src/libcore/option.rs

@@ -341,6 +341,7 @@ impl<T> Option<T> {
     /// x.expect("the world is ending"); // panics with `the world is ending`
     /// ```
     #[inline]
+    #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn expect(self, msg: &str) -> T {
         match self {
@@ -374,6 +375,7 @@ impl<T> Option<T> {
     /// assert_eq!(x.unwrap(), "air"); // fails
     /// ```
     #[inline]
+    #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn unwrap(self) -> T {
         match self {
@@ -1015,6 +1017,7 @@ impl<T: fmt::Debug> Option<T> {
     /// }
     /// ```
     #[inline]
+    #[track_caller]
     #[unstable(feature = "option_expect_none", reason = "newly added", issue = "62633")]
     pub fn expect_none(self, msg: &str) {
         if let Some(val) = self {
@@ -1057,6 +1060,7 @@ impl<T: fmt::Debug> Option<T> {
     /// }
     /// ```
     #[inline]
+    #[track_caller]
     #[unstable(feature = "option_unwrap_none", reason = "newly added", issue = "62633")]
     pub fn unwrap_none(self) {
         if let Some(val) = self {
@@ -1184,13 +1188,15 @@ impl<T, E> Option<Result<T, E>> {
 // This is a separate function to reduce the code size of .expect() itself.
 #[inline(never)]
 #[cold]
+#[track_caller]
 fn expect_failed(msg: &str) -> ! {
     panic!("{}", msg)
 }
 
 // This is a separate function to reduce the code size of .expect_none() itself.
 #[inline(never)]
 #[cold]
+#[track_caller]
 fn expect_none_failed(msg: &str, value: &dyn fmt::Debug) -> ! {
     panic!("{}: {:?}", msg, value)
 }

src/libcore/result.rs

@@ -957,6 +957,7 @@ impl<T, E: fmt::Debug> Result<T, E> {
     /// x.unwrap(); // panics with `emergency failure`
     /// ```
     #[inline]
+    #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn unwrap(self) -> T {
         match self {
@@ -984,6 +985,7 @@ impl<T, E: fmt::Debug> Result<T, E> {
     /// x.expect("Testing expect"); // panics with `Testing expect: emergency failure`
     /// ```
     #[inline]
+    #[track_caller]
     #[stable(feature = "result_expect", since = "1.4.0")]
     pub fn expect(self, msg: &str) -> T {
         match self {
@@ -1017,6 +1019,7 @@ impl<T: fmt::Debug, E> Result<T, E> {
     /// assert_eq!(x.unwrap_err(), "emergency failure");
     /// ```
     #[inline]
+    #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn unwrap_err(self) -> E {
         match self {
@@ -1044,6 +1047,7 @@ impl<T: fmt::Debug, E> Result<T, E> {
     /// x.expect_err("Testing expect_err"); // panics with `Testing expect_err: 10`
     /// ```
     #[inline]
+    #[track_caller]
     #[stable(feature = "result_expect_err", since = "1.17.0")]
     pub fn expect_err(self, msg: &str) -> E {
         match self {
@@ -1188,6 +1192,7 @@ impl<T, E> Result<Option<T>, E> {
 // This is a separate function to reduce the code size of the methods
 #[inline(never)]
 #[cold]
+#[track_caller]
 fn unwrap_failed(msg: &str, error: &dyn fmt::Debug) -> ! {
     panic!("{}: {:?}", msg, error)
 }

src/test/ui/rfc-2091-track-caller/std-panic-locations.rs

@@ -0,0 +1,37 @@
+// run-pass
+
+#![feature(option_expect_none, option_unwrap_none)]
+
+//! Test that panic locations for `#[track_caller]` functions in std have the correct
+//! location reported.
+
+fn main() {
+    // inspect the `PanicInfo` we receive to ensure the right file is the source
+    std::panic::set_hook(Box::new(|info| {
+        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(""));
+}