($($arg:tt)+) => (panic!("not yet implemented: {}", format_args!($($arg)*)));
}
+/// A standardized placeholder for marking unfinished code.
+///
+/// This can be useful if you are prototyping and are just looking to have your
+/// code typecheck. `todo!` works exactly like `unimplemented!`, there only
+/// difference between the two macros is the name.
+///
+/// # Panics
+///
+/// This will always [panic!](macro.panic.html)
+///
+/// # Examples
+///
+/// Here's an example of some in-progress code. We have a trait `Foo`:
+///
+/// ```
+/// trait Foo {
+/// fn bar(&self);
+/// fn baz(&self);
+/// }
+/// ```
+///
+/// We want to implement `Foo` on one of our types, but we also want to work on
+/// just `bar()` first. In order for our code to compile, we need to implement
+/// `baz()`, so we can use `todo!`:
+///
+/// ```
+/// #![feature(todo_macro)]
+///
+/// # trait Foo {
+/// # fn bar(&self);
+/// # fn baz(&self);
+/// # }
+/// struct MyStruct;
+///
+/// impl Foo for MyStruct {
+/// fn bar(&self) {
+/// // implementation goes here
+/// }
+///
+/// fn baz(&self) {
+/// // let's not worry about implementing baz() for now
+/// todo!();
+/// }
+/// }
+///
+/// fn main() {
+/// let s = MyStruct;
+/// s.bar();
+///
+/// // we aren't even using baz() yet, so this is fine.
+/// }
+/// ```
+#[macro_export]
+#[unstable(feature = "todo_macro", issue = "59277")]
+macro_rules! todo {
+ () => (panic!("not yet implemented"));
+ ($($arg:tt)+) => (panic!("not yet implemented: {}", format_args!($($arg)*)));
+}
+
/// A macro to create an array of [`MaybeUninit`]
///
/// This macro constructs an uninitialized array of the type `[MaybeUninit<K>; N]`.
#![feature(stmt_expr_attributes)]
#![feature(str_internals)]
#![feature(thread_local)]
+#![feature(todo_macro)]
#![feature(toowned_clone_into)]
#![feature(try_reserve)]
#![feature(unboxed_closures)]
#[stable(feature = "rust1", since = "1.0.0")]
pub use core::{assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne};
#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::{unreachable, unimplemented, write, writeln, r#try};
+pub use core::{unreachable, unimplemented, write, writeln, r#try, todo};
#[allow(unused_imports)] // macros from `alloc` are not used on all platforms
#[macro_use]