howto run the examples (#1593)

examples/README

@@ -0,0 +1,11 @@
+For each example to compile, you will need to first run the following:
+
+    rustup component add rustc-dev llvm-tools
+
+To create an executable:
+
+    rustc rustc-driver-example.rs
+
+To run an executable:
+
+    rustup run nightly ./rustc-driver-example

examples/rustc-driver-example.rs

@@ -1,18 +1,13 @@
 #![feature(rustc_private)]
 
-// NOTE: For the example to compile, you will need to first run the following:
-//   rustup component add rustc-dev llvm-tools-preview
-
-// version: rustc 1.68.0-nightly (935dc0721 2022-12-19)
-
+extern crate rustc_driver;
 extern crate rustc_error_codes;
 extern crate rustc_errors;
 extern crate rustc_hash;
 extern crate rustc_hir;
 extern crate rustc_interface;
 extern crate rustc_session;
 extern crate rustc_span;
-extern crate rustc_driver;
 
 use std::{path, process, str};
 
@@ -47,9 +42,9 @@ fn main() {
 "#
             .into(),
         },
-        output_dir: None,  // Option<PathBuf>
-        output_file: None, // Option<PathBuf>
-        file_loader: None, // Option<Box<dyn FileLoader + Send + Sync>>
+        output_dir: None,                // Option<PathBuf>
+        output_file: None,               // Option<PathBuf>
+        file_loader: None,               // Option<Box<dyn FileLoader + Send + Sync>>
         lint_caps: FxHashMap::default(), // FxHashMap<lint::LintId, lint::Level>
         // This is a callback from the driver that is called when [`ParseSess`] is created.
         parse_sess_created: None, //Option<Box<dyn FnOnce(&mut ParseSess) + Send>>

examples/rustc-driver-getting-diagnostics.rs

@@ -1,18 +1,13 @@
 #![feature(rustc_private)]
 
-// NOTE: For the example to compile, you will need to first run the following:
-//   rustup component add rustc-dev llvm-tools-preview
-
-// version: rustc 1.68.0-nightly (935dc0721 2022-12-19)
-
+extern crate rustc_driver;
 extern crate rustc_error_codes;
 extern crate rustc_errors;
 extern crate rustc_hash;
 extern crate rustc_hir;
 extern crate rustc_interface;
 extern crate rustc_session;
 extern crate rustc_span;
-extern crate rustc_driver;
 
 use rustc_errors::registry;
 use rustc_session::config::{self, CheckCfg};

examples/rustc-driver-interacting-with-the-ast.rs

@@ -1,19 +1,14 @@
 #![feature(rustc_private)]
 
-// NOTE: For the example to compile, you will need to first run the following:
-//   rustup component add rustc-dev llvm-tools-preview
-
-// version: rustc 1.68.0-nightly (935dc0721 2022-12-19)
-
 extern crate rustc_ast_pretty;
+extern crate rustc_driver;
 extern crate rustc_error_codes;
 extern crate rustc_errors;
 extern crate rustc_hash;
 extern crate rustc_hir;
 extern crate rustc_interface;
 extern crate rustc_session;
 extern crate rustc_span;
-extern crate rustc_driver;
 
 use std::{path, process, str};