Change default panic handler message format.

2 files changed, 10 insertions, 6 deletions

diff --git a/library/core/src/error.md b/library/core/src/error.md
index 78808d489b2..7771b8adc92 100644
--- a/library/core/src/error.md
+++ b/library/core/src/error.md
@@ -93,7 +93,8 @@ information that is already communicated by the source error being
 unwrapped:
 
 ```text
-thread 'main' panicked at 'env variable `IMPORTANT_PATH` is not set: NotPresent', src/main.rs:4:6
+thread 'main' panicked at src/main.rs:4:6:
+env variable `IMPORTANT_PATH` is not set: NotPresent
 ```
 
 In this example we end up mentioning that an env variable is not set,
@@ -109,7 +110,8 @@ prevent the source error, we end up introducing new information that is
 independent from our source error.
 
 ```text
-thread 'main' panicked at 'env variable `IMPORTANT_PATH` should be set by `wrapper_script.sh`: NotPresent', src/main.rs:4:6
+thread 'main' panicked at src/main.rs:4:6:
+env variable `IMPORTANT_PATH` should be set by `wrapper_script.sh`: NotPresent
 ```
 
 In this example we are communicating not only the name of the
diff --git a/library/core/src/panic/panic_info.rs b/library/core/src/panic/panic_info.rs
index 5576adde84b..c7f04f11ef6 100644
--- a/library/core/src/panic/panic_info.rs
+++ b/library/core/src/panic/panic_info.rs
@@ -147,16 +147,18 @@ impl<'a> PanicInfo<'a> {
 impl fmt::Display for PanicInfo<'_> {
     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
         formatter.write_str("panicked at ")?;
+        self.location.fmt(formatter)?;
         if let Some(message) = self.message {
-            write!(formatter, "'{}', ", message)?
+            formatter.write_str(":\n")?;
+            formatter.write_fmt(*message)?;
         } else if let Some(payload) = self.payload.downcast_ref::<&'static str>() {
-            write!(formatter, "'{}', ", payload)?
+            formatter.write_str(":\n")?;
+            formatter.write_str(payload)?;
         }
         // NOTE: we cannot use downcast_ref::<String>() here
         // since String is not available in core!
         // The payload is a String when `std::panic!` is called with multiple arguments,
         // but in that case the message is also available.
-
-        self.location.fmt(formatter)
+        Ok(())
     }
 }