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Update panic!() documentation about non-string panics.
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m-ou-se committed Feb 2, 2021
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15 changes: 8 additions & 7 deletions library/core/src/macros/panic.md
Original file line number Diff line number Diff line change
Expand Up @@ -10,22 +10,23 @@ tests. `panic!` is closely tied with the `unwrap` method of both
`panic!` when they are set to [`None`] or [`Err`] variants.

This macro is used to inject panic into a Rust thread, causing the thread to
panic entirely. Each thread's panic can be reaped as the [`Box`]`<`[`Any`]`>` type,
and the single-argument form of the `panic!` macro will be the value which
is transmitted.
panic entirely. This macro panics with a string and uses the [`format!`] syntax
for building the message.

Each thread's panic can be reaped as the [`Box`]`<`[`Any`]`>` type,
which contains either a `&str` or `String` for regular `panic!()` invocations.
To panic with a value of another other type, [`panic_any`] can be used.

[`Result`] enum is often a better solution for recovering from errors than
using the `panic!` macro. This macro should be used to avoid proceeding using
incorrect values, such as from external sources. Detailed information about
error handling is found in the [book].

The multi-argument form of this macro panics with a string and has the
[`format!`] syntax for building a string.

See also the macro [`compile_error!`], for raising errors during compilation.

[ounwrap]: Option::unwrap
[runwrap]: Result::unwrap
[`panic_any`]: ../std/panic/fn.panic_any.html
[`Box`]: ../std/boxed/struct.Box.html
[`Any`]: crate::any::Any
[`format!`]: ../std/macro.format.html
Expand All @@ -42,6 +43,6 @@ program with code `101`.
# #![allow(unreachable_code)]
panic!();
panic!("this is a terrible mistake!");
panic!(4); // panic with the value of 4 to be collected elsewhere
panic!("this is a {} {message}", "fancy", message = "message");
std::panic::panic_any(4); // panic with the value of 4 to be collected elsewhere
```

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