From 0b2329da9a9a61dc70f9e607628977302f8144b4 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Tue, 10 Mar 2020 10:31:03 +0100
Subject: [PATCH] also make panic_fmt track_caller

---
 src/libcore/macros/mod.rs | 21 +++++++++++++++++++++
 src/libcore/panicking.rs  | 22 +++++++++++++++-------
 2 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/src/libcore/macros/mod.rs b/src/libcore/macros/mod.rs
index 76e58f0cc62..04af5b5f768 100644
--- a/src/libcore/macros/mod.rs
+++ b/src/libcore/macros/mod.rs
@@ -1,3 +1,4 @@
+#[cfg(bootstrap)]
 #[doc(include = "panic.md")]
 #[macro_export]
 #[allow_internal_unstable(core_panic, track_caller)]
@@ -20,6 +21,26 @@ macro_rules! panic {
     );
 }
 
+#[cfg(not(bootstrap))]
+#[doc(include = "panic.md")]
+#[macro_export]
+#[allow_internal_unstable(core_panic, track_caller)]
+#[stable(feature = "core", since = "1.6.0")]
+macro_rules! panic {
+    () => (
+        $crate::panic!("explicit panic")
+    );
+    ($msg:expr) => (
+        $crate::panicking::panic($msg)
+    );
+    ($msg:expr,) => (
+        $crate::panic!($msg)
+    );
+    ($fmt:expr, $($arg:tt)+) => (
+        $crate::panicking::panic_fmt($crate::format_args!($fmt, $($arg)+))
+    );
+}
+
 /// Asserts that two expressions are equal to each other (using [`PartialEq`]).
 ///
 /// On panic, this macro will print the values of the expressions with their
diff --git a/src/libcore/panicking.rs b/src/libcore/panicking.rs
index d58a7cfec95..3587f3f0ebf 100644
--- a/src/libcore/panicking.rs
+++ b/src/libcore/panicking.rs
@@ -32,6 +32,7 @@
 use crate::fmt;
 use crate::panic::{Location, PanicInfo};
 
+/// The underlying implementation of libcore's `panic!` macro when no formatting is used.
 #[cold]
 // never inline unless panic_immediate_abort to avoid code
 // bloat at the call sites as much as possible
@@ -49,7 +50,10 @@ pub fn panic(expr: &str) -> ! {
     // truncation and padding (even though none is used here). Using
     // Arguments::new_v1 may allow the compiler to omit Formatter::pad from the
     // output binary, saving up to a few kilobytes.
-    panic_fmt(fmt::Arguments::new_v1(&[expr], &[]), Location::caller())
+    #[cfg(not(bootstrap))]
+    panic_fmt(fmt::Arguments::new_v1(&[expr], &[]));
+    #[cfg(bootstrap)]
+    panic_fmt(fmt::Arguments::new_v1(&[expr], &[]), Location::caller());
 }
 
 #[cfg(not(bootstrap))]
@@ -62,13 +66,11 @@ fn panic_bounds_check(index: usize, len: usize) -> ! {
         unsafe { super::intrinsics::abort() }
     }
 
-    panic_fmt(
-        format_args!("index out of bounds: the len is {} but the index is {}", len, index),
-        Location::caller(),
-    )
+    panic!("index out of bounds: the len is {} but the index is {}", len, index)
 }
 
-// For bootstrap, we need a variant with the old argument order.
+// For bootstrap, we need a variant with the old argument order, and a corresponding
+// `panic_fmt`.
 #[cfg(bootstrap)]
 #[cold]
 #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
@@ -84,10 +86,12 @@ fn panic_bounds_check(location: &Location<'_>, index: usize, len: usize) -> ! {
     )
 }
 
+/// The underlying implementation of libcore's `panic!` macro when formatting is used.
 #[cold]
 #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
 #[cfg_attr(feature = "panic_immediate_abort", inline)]
-pub fn panic_fmt(fmt: fmt::Arguments<'_>, location: &Location<'_>) -> ! {
+#[cfg_attr(not(bootstrap), track_caller)]
+pub fn panic_fmt(fmt: fmt::Arguments<'_>, #[cfg(bootstrap)] location: &Location<'_>) -> ! {
     if cfg!(feature = "panic_immediate_abort") {
         unsafe { super::intrinsics::abort() }
     }
@@ -99,6 +103,10 @@ pub fn panic_fmt(fmt: fmt::Arguments<'_>, location: &Location<'_>) -> ! {
         fn panic_impl(pi: &PanicInfo<'_>) -> !;
     }
 
+    #[cfg(bootstrap)]
     let pi = PanicInfo::internal_constructor(Some(&fmt), location);
+    #[cfg(not(bootstrap))]
+    let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller());
+
     unsafe { panic_impl(&pi) }
 }