diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs index cfc1cabe229..b20e60ad96d 100644 --- a/library/core/src/macros/mod.rs +++ b/library/core/src/macros/mod.rs @@ -1312,28 +1312,52 @@ macro_rules! cfg { /* compiler built-in */ }; } - + /// Parses a file as an expression or an item according to the context. /// - /// The file is located relative to the current file (similarly to how - /// modules are found). The provided path is interpreted in a platform-specific - /// way at compile time. So, for instance, an invocation with a Windows path - /// containing backslashes `\` would not compile correctly on Unix. + ///
+ ///
     ///
-    /// Using this macro is often a bad idea, because if the file is
-    /// parsed as an expression, it is going to be placed in the
-    /// surrounding code unhygienically. This could result in variables
-    /// or functions being different from what the file expected if
-    /// there are variables or functions that have the same name in
-    /// the current file.
+    /// **Warning**: For multi-file Rust projects, the `include!` macro is probably not what you
+    /// are looking for. Usually, multi-file Rust projects use
+    /// [modules](https://doc.rust-lang.org/reference/items/modules.html). Multi-file projects and
+    /// modules are explained in the Rust-by-Example book
+    /// [here](https://doc.rust-lang.org/rust-by-example/mod/split.html) and the module system is
+    /// explained in the Rust Book
+    /// [here](https://doc.rust-lang.org/book/ch07-02-defining-modules-to-control-scope-and-privacy.html).
     ///
+    /// 
+ ///
+ /// + /// If the included file is parsed as an expression, it is placed in the surrounding code + /// [unhygienically](https://doc.rust-lang.org/reference/macros-by-example.html#hygiene). This + /// could result in variables or functions being different from what the file expected if there + /// are variables or functions that have the same name in the current file. + /// + /// The included file is located relative to the current file (similarly to how modules are + /// found). The provided path is interpreted in a platform-specific way at compile time. So, + /// for instance, an invocation with a Windows path containing backslashes `\` would not + /// compile correctly on Unix. + /// + /// # Uses + /// + /// The `include!` macro is primarily used for two purposes. It is used to include + /// documentation that is written in a separate file and it is used to include [build artifacts + /// usually as a result from the `build.rs` + /// script](https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script). + /// + /// When using the `include` macro to include stretches of documentation, remember that the + /// included file still needs to be a valid rust syntax. It is also possible to + /// use the [`include_str`] macro as `#![doc = include_str!("...")]` (at the module level) or + /// `#[doc = include_str!("...")]` (at the item level) to include documentation from a plain + /// text or markdown file. + /// /// # Examples - /// - /// Assume there are two files in the same directory with the following - /// contents: - /// + /// + /// Assume there are two files in the same directory with the following contents: + /// /// File 'monkeys.in': - /// + /// /// ```ignore (only-for-syntax-highlight) /// ['🙈', '🙊', '🙉'] /// .iter() @@ -1341,9 +1365,9 @@ macro_rules! cfg { /// .take(6) /// .collect::() /// ``` - /// + /// /// File 'main.rs': - /// + /// /// ```ignore (cannot-doctest-external-file-dependency) /// fn main() { /// let my_string = include!("monkeys.in"); @@ -1351,7 +1375,7 @@ macro_rules! cfg { /// println!("{my_string}"); /// } /// ``` - /// + /// /// Compiling 'main.rs' and running the resulting binary will print /// "🙈🙊🙉🙈🙊🙉". #[stable(feature = "rust1", since = "1.0.0")]