avoid code duplication by including files in docs (#1598)

Author: tshepang

Diff for: src/rustc-driver-getting-diagnostics.md

@@ -7,34 +7,8 @@
 To get diagnostics from the compiler,
 configure `rustc_interface::Config` to output diagnostic to a buffer,
 and run `TyCtxt.analysis`. The following was tested
-with <!-- date-check: Feb 2023 --> `nightly-2023-02-06` (See [here][example]
-for the complete example):
-
-[example]: https://github.com/rust-lang/rustc-dev-guide/blob/master/examples/rustc-driver-getting-diagnostics.rs
+with <!-- date-check: Feb 2023 --> `nightly-2023-02-13`:
 
 ```rust
-let buffer = sync::Arc::new(sync::Mutex::new(Vec::new()));
-let config = rustc_interface::Config {
-    opts: config::Options {
-        // Configure the compiler to emit diagnostics in compact JSON format.
-        error_format: config::ErrorOutputType::Json {
-            pretty: false,
-            json_rendered: rustc_errors::emitter::HumanReadableErrorType::Default(
-                rustc_errors::emitter::ColorConfig::Never,
-            ),
-        },
-        /* other config */
-    },   
-    /* other config */
-};
-rustc_interface::run_compiler(config, |compiler| {
-    compiler.enter(|queries| {
-        queries.global_ctxt().unwrap().enter(|tcx| {
-            // Run the analysis phase on the local crate to trigger the type error.
-            let _ = tcx.analysis(());
-        });
-    });
-});
-// Read buffered diagnostics.
-let diagnostics = String::from_utf8(buffer.lock().unwrap().clone()).unwrap();
+{{#include ../examples/rustc-driver-getting-diagnostics.rs}}
 ```

Diff for: src/rustc-driver-interacting-with-the-ast.md

@@ -5,45 +5,8 @@
 ## Getting the type of an expression
 
 To get the type of an expression, use the `global_ctxt` to get a `TyCtxt`.
-The following was tested with <!-- date-check: Feb 2023 --> `nightly-2023-02-06`
-(see [here][example] for the complete example):
-
-[example]: https://github.com/rust-lang/rustc-dev-guide/blob/master/examples/rustc-driver-interacting-with-the-ast.rs
+The following was tested with <!-- date-check: Feb 2023 --> `nightly-2023-02-13`:
 
 ```rust
-let config = rustc_interface::Config {
-    input: config::Input::Str {
-        name: source_map::FileName::Custom("main.rs".to_string()),
-        input: "fn main() { let message = \"Hello, world!\"; println!(\"{}\", message); }"
-            .to_string(),
-    },
-    /* other config */
-};
-rustc_interface::run_compiler(config, |compiler| {
-    compiler.enter(|queries| {
-        // Analyze the crate and inspect the types under the cursor.
-        queries.global_ctxt().unwrap().enter(|tcx| {
-            // Every compilation contains a single crate.
-            let hir_krate = tcx.hir();
-            // Iterate over the top-level items in the crate, looking for the main function.
-            for id in hir_krate.items() {
-                let item = hir_krate.item(id);
-                // Use pattern-matching to find a specific node inside the main function.
-                if let rustc_hir::ItemKind::Fn(_, _, body_id) = item.kind {
-                    let expr = &tcx.hir().body(body_id).value;
-                    if let rustc_hir::ExprKind::Block(block, _) = expr.kind {
-                        if let rustc_hir::StmtKind::Local(local) = block.stmts[0].kind {
-                            if let Some(expr) = local.init {
-                                let hir_id = expr.hir_id; // hir_id identifies the string "Hello, world!"
-                                let def_id = item.hir_id().owner.def_id; // def_id identifies the main function
-                                let ty = tcx.typeck(def_id).node_type(hir_id);
-                                println!("{expr:#?}: {ty:?}");
-                            }
-                        }
-                    }
-                }
-            }
-        })
-    });
-});
+{{#include ../examples/rustc-driver-interacting-with-the-ast.rs}}
 ```