cleanup and formatting

Author: DebugSteven

library/core/src/panic/panic_info.rs

@@ -66,7 +66,7 @@ impl<'a> PanicInfo<'a> {
     }
 
     #[unstable(feature = "error_in_panic", issue = "none")]
-    /// The lower-level source of this panic, if any.
+    /// The [`Error`] that caused this panic, if known.
     pub fn source(&self) -> Option<&(dyn Error + 'static)> {
         self.source
     }

library/core/src/panicking.rs

@@ -51,18 +51,10 @@ const _: () = assert!(cfg!(panic = "abort"), "panic_immediate_abort requires -C
 #[rustc_do_not_const_check] // hooked by const-eval
 #[rustc_const_unstable(feature = "core_panic", issue = "none")]
 pub const fn panic_fmt(fmt: fmt::Arguments<'_>) -> ! {
-    //panic_source(fmt, None)
     if cfg!(feature = "panic_immediate_abort") {
         super::intrinsics::abort()
     }
 
-    // NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call
-    // that gets resolved to the `#[panic_handler]` function.
-    extern "Rust" {
-        #[lang = "panic_impl"]
-        fn panic_impl(pi: &PanicInfo<'_>) -> !;
-    }
-
     let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), None, true);
 
     // SAFETY: `panic_impl` is defined in safe Rust code and thus is safe to call.
@@ -82,19 +74,19 @@ pub const fn panic_source(fmt: fmt::Arguments<'_>, source: &(dyn Error + 'static
         super::intrinsics::abort()
     }
 
-    // NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call
-    // that gets resolved to the `#[panic_handler]` function.
-    extern "Rust" {
-        #[lang = "panic_impl"]
-        fn panic_impl(pi: &PanicInfo<'_>) -> !;
-    }
-
     let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), Some(source), true);
 
     // SAFETY: `panic_impl` is defined in safe Rust code and thus is safe to call.
     unsafe { panic_impl(&pi) }
 }
 
+// NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call
+// that gets resolved to the `#[panic_handler]` function.
+extern "Rust" {
+    #[lang = "panic_impl"]
+    fn panic_impl(pi: &PanicInfo<'_>) -> !;
+}
+
 /// Like `panic_fmt`, but for non-unwinding panics.
 ///
 /// Has to be a separate function so that it can carry the `rustc_nounwind` attribute.

library/std/src/panicking.rs

@@ -261,7 +261,7 @@ fn default_hook(info: &PanicInfo<'_>) {
         let _ = writeln!(err, "thread '{name}' panicked at '{msg}', {location}");
         if let Some(source) = info.source() {
             let report = Report::new(source).pretty(true);
-            let _ = writeln!(err, "Source: {report}");
+            let _ = writeln!(err, "\nSource: {report}\n");
         }
         static FIRST_PANIC: AtomicBool = AtomicBool::new(true);
 
@@ -578,23 +578,22 @@ pub fn begin_panic_handler(info: &PanicInfo<'_>) -> ! {
     }
 
     let loc = info.location().unwrap(); // The current implementation always returns Some
-    let source = info.source();
     let msg = info.message().unwrap(); // The current implementation always returns Some
     crate::sys_common::backtrace::__rust_end_short_backtrace(move || {
         if let Some(msg) = msg.as_str() {
             rust_panic_with_hook(
                 &mut StrPanicPayload(msg),
                 info.message(),
                 loc,
-                source,
+                info.source(),
                 info.can_unwind(),
             );
         } else {
             rust_panic_with_hook(
                 &mut PanicPayload::new(msg),
                 info.message(),
                 loc,
-                source,
+                info.source(),
                 info.can_unwind(),
             );
         }