Rollup merge of #44160 - AndyGauge:api-docs-macros, r=steveklabnik
API docs: macros. Standard Documentation Checklist Fixes #29381 r? @steveklabnik
This commit is contained in:
commit
c0812c8458
3 changed files with 165 additions and 42 deletions
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@ -8,12 +8,12 @@
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/// Creates a `Vec` containing the arguments.
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/// Creates a [`Vec`] containing the arguments.
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///
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/// `vec!` allows `Vec`s to be defined with the same syntax as array expressions.
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/// There are two forms of this macro:
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///
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/// - Create a `Vec` containing a given list of elements:
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/// - Create a [`Vec`] containing a given list of elements:
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///
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/// ```
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/// let v = vec![1, 2, 3];
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@ -22,7 +22,7 @@
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/// assert_eq!(v[2], 3);
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/// ```
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///
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/// - Create a `Vec` from a given element and size:
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/// - Create a [`Vec`] from a given element and size:
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///
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/// ```
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/// let v = vec![1; 3];
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@ -30,14 +30,17 @@
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/// ```
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///
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/// Note that unlike array expressions this syntax supports all elements
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/// which implement `Clone` and the number of elements doesn't have to be
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/// which implement [`Clone`] and the number of elements doesn't have to be
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/// a constant.
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///
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/// This will use `clone()` to duplicate an expression, so one should be careful
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/// This will use `clone` to duplicate an expression, so one should be careful
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/// using this with types having a nonstandard `Clone` implementation. For
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/// example, `vec![Rc::new(1); 5]` will create a vector of five references
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/// to the same boxed integer value, not five references pointing to independently
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/// boxed integers.
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///
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/// [`Vec`]: ../std/vec/struct.Vec.html
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/// [`Clone`]: ../std/clone/trait.Clone.html
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#[cfg(not(test))]
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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@ -67,10 +70,22 @@ macro_rules! vec {
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($($x:expr,)*) => (vec![$($x),*])
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}
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/// Use the syntax described in `std::fmt` to create a value of type `String`.
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/// See [`std::fmt`][fmt] for more information.
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/// Creates a `String` using interpolation of runtime expressions.
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///
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/// The first argument `format!` recieves is a format string. This must be a string
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/// literal. The power of the formatting string is in the `{}`s contained.
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///
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/// Additional parameters passed to `format!` replace the `{}`s within the
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/// formatting string in the order given unless named or positional parameters
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/// are used, see [`std::fmt`][fmt] for more information.
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///
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/// A common use for `format!` is concatenation and interpolation of strings.
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/// The same convention is used with [`print!`] and [`write!`] macros,
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/// depending on the intended destination of the string.
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///
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/// [fmt]: ../std/fmt/index.html
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/// [`print!`]: ../std/macro.print.html
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/// [`write!`]: ../std/macro.write.html
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///
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/// # Panics
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///
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@ -62,11 +62,13 @@ macro_rules! panic {
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/// # Custom Messages
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///
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/// This macro has a second form, where a custom panic message can
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/// be provided with or without arguments for formatting.
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/// be provided with or without arguments for formatting. See [`std::fmt`]
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/// for syntax for this form.
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///
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/// [`panic!`]: macro.panic.html
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/// [`debug_assert!`]: macro.debug_assert.html
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/// [testing]: ../book/first-edition/testing.html
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/// [testing]: ../book/second-edition/ch11-01-writing-tests.html#checking-results-with-the-assert-macro
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/// [`std::fmt`]: ../std/fmt/index.html
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///
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/// # Examples
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///
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@ -252,13 +254,15 @@ macro_rules! debug_assert {
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/// On panic, this macro will print the values of the expressions with their
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/// debug representations.
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///
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/// Unlike `assert_eq!`, `debug_assert_eq!` statements are only enabled in non
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/// Unlike [`assert_eq!`], `debug_assert_eq!` statements are only enabled in non
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/// optimized builds by default. An optimized build will omit all
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/// `debug_assert_eq!` statements unless `-C debug-assertions` is passed to the
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/// compiler. This makes `debug_assert_eq!` useful for checks that are too
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/// expensive to be present in a release build but may be helpful during
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/// development.
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///
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/// [`assert_eq!`]: ../std/macro.assert_eq.html
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///
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/// # Examples
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///
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/// ```
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@ -277,13 +281,15 @@ macro_rules! debug_assert_eq {
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/// On panic, this macro will print the values of the expressions with their
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/// debug representations.
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///
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/// Unlike `assert_ne!`, `debug_assert_ne!` statements are only enabled in non
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/// Unlike [`assert_ne!`], `debug_assert_ne!` statements are only enabled in non
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/// optimized builds by default. An optimized build will omit all
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/// `debug_assert_ne!` statements unless `-C debug-assertions` is passed to the
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/// compiler. This makes `debug_assert_ne!` useful for checks that are too
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/// expensive to be present in a release build but may be helpful during
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/// development.
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///
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/// [`assert_ne!`]: ../std/macro.assert_ne.html
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///
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/// # Examples
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///
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/// ```
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@ -300,10 +306,9 @@ macro_rules! debug_assert_ne {
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/// Helper macro for reducing boilerplate code for matching `Result` together
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/// with converting downstream errors.
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///
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/// Prefer using `?` syntax to `try!`. `?` is built in to the language and is
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/// more succinct than `try!`. It is the standard method for error propagation.
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/// The `?` operator was added to replace `try!` and should be used instead.
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///
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/// `try!` matches the given `Result`. In case of the `Ok` variant, the
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/// `try!` matches the given [`Result`]. In case of the `Ok` variant, the
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/// expression has the value of the wrapped value.
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///
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/// In case of the `Err` variant, it retrieves the inner error. `try!` then
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@ -312,7 +317,9 @@ macro_rules! debug_assert_ne {
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/// error is then immediately returned.
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///
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/// Because of the early return, `try!` can only be used in functions that
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/// return `Result`.
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/// return [`Result`].
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///
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/// [`Result`]: ../std/result/enum.Result.html
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///
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/// # Examples
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///
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@ -331,12 +338,19 @@ macro_rules! debug_assert_ne {
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/// }
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/// }
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///
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/// // The prefered method of quick returning Errors
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/// fn write_to_file_question() -> Result<(), MyError> {
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/// let mut file = File::create("my_best_friends.txt")?;
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/// Ok(())
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/// }
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///
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/// // The previous method of quick returning Errors
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/// fn write_to_file_using_try() -> Result<(), MyError> {
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/// let mut file = try!(File::create("my_best_friends.txt"));
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/// try!(file.write_all(b"This is a list of my best friends."));
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/// println!("I wrote to the file");
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/// Ok(())
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/// }
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///
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/// // This is equivalent to:
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/// fn write_to_file_using_match() -> Result<(), MyError> {
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/// let mut file = try!(File::create("my_best_friends.txt"));
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@ -344,7 +358,6 @@ macro_rules! debug_assert_ne {
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/// Ok(v) => v,
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/// Err(e) => return Err(From::from(e)),
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/// }
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/// println!("I wrote to the file");
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/// Ok(())
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/// }
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/// ```
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@ -365,7 +378,7 @@ macro_rules! try {
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/// formatted according to the specified format string and the result will be passed to the writer.
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/// The writer may be any value with a `write_fmt` method; generally this comes from an
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/// implementation of either the [`std::fmt::Write`] or the [`std::io::Write`] trait. The macro
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/// returns whatever the 'write_fmt' method returns; commonly a [`std::fmt::Result`], or an
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/// returns whatever the `write_fmt` method returns; commonly a [`std::fmt::Result`], or an
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/// [`io::Result`].
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///
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/// See [`std::fmt`] for more information on the format string syntax.
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@ -470,10 +483,20 @@ macro_rules! writeln {
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/// * Loops that dynamically terminate.
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/// * Iterators that dynamically terminate.
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///
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/// If the determination that the code is unreachable proves incorrect, the
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/// program immediately terminates with a [`panic!`]. The function [`unreachable`],
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/// which belongs to the [`std::intrinsics`] module, informs the compilier to
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/// optimize the code out of the release version entirely.
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///
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/// [`panic!`]: ../std/macro.panic.html
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/// [`unreachable`]: ../std/intrinsics/fn.unreachable.html
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/// [`std::intrinsics`]: ../std/intrinsics/index.html
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///
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/// # Panics
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///
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/// This will always [panic!](macro.panic.html)
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/// This will always [`panic!`]
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///
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/// [`panic!`]: ../std/macro.panic.html
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/// # Examples
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///
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/// Match arms:
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@ -516,13 +539,18 @@ macro_rules! unreachable {
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});
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}
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/// A standardized placeholder for marking unfinished code. It panics with the
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/// message `"not yet implemented"` when executed.
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/// A standardized placeholder for marking unfinished code.
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///
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/// It panics with the message `"not yet implemented"` when executed.
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///
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/// This can be useful if you are prototyping and are just looking to have your
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/// code typecheck, or if you're implementing a trait that requires multiple
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/// methods, and you're only planning on using one of them.
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///
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/// # Panics
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///
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/// This macro always panics.
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///
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/// # Examples
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///
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/// Here's an example of some in-progress code. We have a trait `Foo`:
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@ -26,13 +26,33 @@ macro_rules! __rust_unstable_column {
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/// The entry point for panic of Rust threads.
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///
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/// This allows a program to to terminate immediately and provide feedback
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/// to the caller of the program. `panic!` should be used when a program reaches
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/// an unrecoverable problem.
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///
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/// This macro is the perfect way to assert conditions in example code and in
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/// tests. `panic!` is closely tied with the `unwrap` method of both [`Option`]
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/// and [`Result`][runwrap] enums. Both implementations call `panic!` when they are set
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/// to None or Err variants.
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///
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/// This macro is used to inject panic into a Rust thread, causing the thread to
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/// panic entirely. Each thread's panic can be reaped as the `Box<Any>` type,
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/// and the single-argument form of the `panic!` macro will be the value which
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/// is transmitted.
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///
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/// [`Result`] enum is often a better solution for recovering from errors than
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/// using the `panic!` macro. This macro should be used to avoid proceeding using
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/// incorrect values, such as from external sources. Detailed information about
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/// error handling is found in the [book].
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///
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/// The multi-argument form of this macro panics with a string and has the
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/// `format!` syntax for building a string.
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/// [`format!`] syntax for building a string.
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///
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/// [runwrap]: ../std/result/enum.Result.html#method.unwrap
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/// [`Option`]: ../std/option/enum.Option.html#method.unwrap
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/// [`Result`]: ../std/result/enum.Result.html
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/// [`format!`]: ../std/macro.format.html
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/// [book]: ../book/second-edition/ch09-01-unrecoverable-errors-with-panic.html
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///
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/// # Current implementation
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///
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@ -78,15 +98,19 @@ macro_rules! panic {
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/// Macro for printing to the standard output.
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///
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/// Equivalent to the `println!` macro except that a newline is not printed at
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/// Equivalent to the [`println!`] macro except that a newline is not printed at
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/// the end of the message.
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///
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/// Note that stdout is frequently line-buffered by default so it may be
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/// necessary to use `io::stdout().flush()` to ensure the output is emitted
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/// necessary to use [`io::stdout().flush()`][flush] to ensure the output is emitted
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/// immediately.
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///
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/// Use `print!` only for the primary output of your program. Use
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/// `eprint!` instead to print error and progress messages.
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/// [`eprint!`] instead to print error and progress messages.
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///
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/// [`println!`]: ../std/macro.println.html
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/// [flush]: ../std/io/trait.Write.html#tymethod.flush
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/// [`eprint!`]: ../std/macro.eprint.html
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///
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/// # Panics
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///
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@ -118,16 +142,20 @@ macro_rules! print {
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($($arg:tt)*) => ($crate::io::_print(format_args!($($arg)*)));
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}
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/// Macro for printing to the standard output, with a newline. On all
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/// platforms, the newline is the LINE FEED character (`\n`/`U+000A`) alone
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/// Macro for printing to the standard output, with a newline.
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///
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/// On all platforms, the newline is the LINE FEED character (`\n`/`U+000A`) alone
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/// (no additional CARRIAGE RETURN (`\r`/`U+000D`).
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///
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/// Use the `format!` syntax to write data to the standard output.
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/// See `std::fmt` for more information.
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/// Use the [`format!`] syntax to write data to the standard output.
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/// See [`std::fmt`] for more information.
|
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///
|
||||
/// Use `println!` only for the primary output of your program. Use
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||||
/// `eprintln!` instead to print error and progress messages.
|
||||
/// [`eprintln!`] instead to print error and progress messages.
|
||||
///
|
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/// [`format!`]: ../std/macro.format.html
|
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/// [`std::fmt`]: ../std/fmt/index.html
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||||
/// [`eprintln!`]: ../std/macro.eprint.html
|
||||
/// # Panics
|
||||
///
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||||
/// Panics if writing to `io::stdout` fails.
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@ -149,16 +177,25 @@ macro_rules! println {
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/// Macro for printing to the standard error.
|
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///
|
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/// Equivalent to the `print!` macro, except that output goes to
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/// `io::stderr` instead of `io::stdout`. See `print!` for
|
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/// Equivalent to the [`print!`] macro, except that output goes to
|
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/// [`io::stderr`] instead of `io::stdout`. See [`print!`] for
|
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/// example usage.
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||||
///
|
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/// Use `eprint!` only for error and progress messages. Use `print!`
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/// instead for the primary output of your program.
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///
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||||
/// [`io::stderr`]: ../std/io/struct.Stderr.html
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/// [`print!`]: ../std/macro.print.html
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||||
///
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||||
/// # Panics
|
||||
///
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||||
/// Panics if writing to `io::stderr` fails.
|
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///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
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/// eprint!("Error: Could not complete task");
|
||||
/// ```
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#[macro_export]
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#[stable(feature = "eprint", since = "1.19.0")]
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#[allow_internal_unstable]
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|
@ -168,16 +205,25 @@ macro_rules! eprint {
|
|||
|
||||
/// Macro for printing to the standard error, with a newline.
|
||||
///
|
||||
/// Equivalent to the `println!` macro, except that output goes to
|
||||
/// `io::stderr` instead of `io::stdout`. See `println!` for
|
||||
/// Equivalent to the [`println!`] macro, except that output goes to
|
||||
/// [`io::stderr`] instead of `io::stdout`. See [`println!`] for
|
||||
/// example usage.
|
||||
///
|
||||
/// Use `eprintln!` only for error and progress messages. Use `println!`
|
||||
/// instead for the primary output of your program.
|
||||
///
|
||||
/// [`io::stderr`]: ../std/io/struct.Stderr.html
|
||||
/// [`println!`]: ../std/macro.println.html
|
||||
///
|
||||
/// # Panics
|
||||
///
|
||||
/// Panics if writing to `io::stderr` fails.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
/// eprintln!("Error: Could not complete task");
|
||||
/// ```
|
||||
#[macro_export]
|
||||
#[stable(feature = "eprint", since = "1.19.0")]
|
||||
macro_rules! eprintln {
|
||||
|
@ -267,13 +313,23 @@ pub mod builtin {
|
|||
|
||||
/// The core macro for formatted string creation & output.
|
||||
///
|
||||
/// This macro functions by taking a formatting string literal containing
|
||||
/// `{}` for each additional argument passed. `format_args!` prepares the
|
||||
/// additional parameters to ensure the output can be interpreted as a string
|
||||
/// and canonicalizes the arguments into a single type. Any value that implements
|
||||
/// the [`Display`] trait can be passed to `format_args!`, as can any
|
||||
/// [`Debug`] implementation be passed to a `{:?}` within the formatting string.
|
||||
///
|
||||
/// This macro produces a value of type [`fmt::Arguments`]. This value can be
|
||||
/// passed to the functions in [`std::fmt`] for performing useful functions.
|
||||
/// passed to the macros within [`std::fmt`] for performing useful redirection.
|
||||
/// All other formatting macros ([`format!`], [`write!`], [`println!`], etc) are
|
||||
/// proxied through this one.
|
||||
/// proxied through this one. `format_args!`, unlike its derived macros, avoids
|
||||
/// heap allocations.
|
||||
///
|
||||
/// For more information, see the documentation in [`std::fmt`].
|
||||
///
|
||||
/// [`Display`]: ../std/fmt/trait.Display.html
|
||||
/// [`Debug`]: ../std/fmt/trait.Debug.html
|
||||
/// [`fmt::Arguments`]: ../std/fmt/struct.Arguments.html
|
||||
/// [`std::fmt`]: ../std/fmt/index.html
|
||||
/// [`format!`]: ../std/macro.format.html
|
||||
|
@ -301,9 +357,11 @@ pub mod builtin {
|
|||
/// compile time, yielding an expression of type `&'static str`.
|
||||
///
|
||||
/// If the environment variable is not defined, then a compilation error
|
||||
/// will be emitted. To not emit a compile error, use the `option_env!`
|
||||
/// will be emitted. To not emit a compile error, use the [`option_env!`]
|
||||
/// macro instead.
|
||||
///
|
||||
/// [`option_env!`]: ../std/macro.option_env.html
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
|
@ -319,11 +377,14 @@ pub mod builtin {
|
|||
/// If the named environment variable is present at compile time, this will
|
||||
/// expand into an expression of type `Option<&'static str>` whose value is
|
||||
/// `Some` of the value of the environment variable. If the environment
|
||||
/// variable is not present, then this will expand to `None`.
|
||||
/// variable is not present, then this will expand to `None`. See
|
||||
/// [`Option<T>`][option] for more information on this type.
|
||||
///
|
||||
/// A compile time error is never emitted when using this macro regardless
|
||||
/// of whether the environment variable is present or not.
|
||||
///
|
||||
/// [option]: ../std/option/enum.Option.html
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
|
@ -385,10 +446,16 @@ pub mod builtin {
|
|||
|
||||
/// A macro which expands to the line number on which it was invoked.
|
||||
///
|
||||
/// With [`column!`] and [`file!`], these macros provide debugging information for
|
||||
/// developers about the location within the source.
|
||||
///
|
||||
/// The expanded expression has type `u32`, and the returned line is not
|
||||
/// the invocation of the `line!()` macro itself, but rather the first macro
|
||||
/// invocation leading up to the invocation of the `line!()` macro.
|
||||
///
|
||||
/// [`column!`]: macro.column.html
|
||||
/// [`file!`]: macro.file.html
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
|
@ -401,9 +468,15 @@ pub mod builtin {
|
|||
|
||||
/// A macro which expands to the column number on which it was invoked.
|
||||
///
|
||||
/// With [`line!`] and [`file!`], these macros provide debugging information for
|
||||
/// developers about the location within the source.
|
||||
///
|
||||
/// The expanded expression has type `u32`, and the returned column is not
|
||||
/// the invocation of the `column!()` macro itself, but rather the first macro
|
||||
/// invocation leading up to the invocation of the `column!()` macro.
|
||||
/// the invocation of the `column!` macro itself, but rather the first macro
|
||||
/// invocation leading up to the invocation of the `column!` macro.
|
||||
///
|
||||
/// [`line!`]: macro.line.html
|
||||
/// [`file!`]: macro.file.html
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
|
@ -417,11 +490,18 @@ pub mod builtin {
|
|||
|
||||
/// A macro which expands to the file name from which it was invoked.
|
||||
///
|
||||
/// With [`line!`] and [`column!`], these macros provide debugging information for
|
||||
/// developers about the location within the source.
|
||||
///
|
||||
///
|
||||
/// The expanded expression has type `&'static str`, and the returned file
|
||||
/// is not the invocation of the `file!()` macro itself, but rather the
|
||||
/// first macro invocation leading up to the invocation of the `file!()`
|
||||
/// is not the invocation of the `file!` macro itself, but rather the
|
||||
/// first macro invocation leading up to the invocation of the `file!`
|
||||
/// macro.
|
||||
///
|
||||
/// [`line!`]: macro.line.html
|
||||
/// [`column!`]: macro.column.html
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```
|
||||
|
|
Loading…
Reference in a new issue