improve rustc_interface examples a little (#1362)

examples/rustc-driver-example.rs

@@ -13,13 +13,12 @@ extern crate rustc_interface;
 extern crate rustc_session;
 extern crate rustc_span;
 
+use std::{path, process, str};
+
 use rustc_errors::registry;
 use rustc_hash::{FxHashMap, FxHashSet};
 use rustc_session::config::{self, CheckCfg};
 use rustc_span::source_map;
-use std::path;
-use std::process;
-use std::str;
 
 fn main() {
     let out = process::Command::new("rustc")
@@ -38,9 +37,14 @@ fn main() {
         crate_cfg: FxHashSet::default(), // FxHashSet<(String, Option<String>)>
         crate_check_cfg: CheckCfg::default(), // CheckCfg
         input: config::Input::Str {
-            name: source_map::FileName::Custom("main.rs".to_string()),
-            input: "static HELLO: &str = \"Hello, world!\"; fn main() { println!(\"{}\", HELLO); }"
-                .to_string(),
+            name: source_map::FileName::Custom("main.rs".into()),
+            input: r#"
+static HELLO: &str = "Hello, world!";
+fn main() {
+    println!("{HELLO}");
+}
+"#
+            .into(),
         },
         input_path: None,  // Option<PathBuf>
         output_dir: None,  // Option<PathBuf>
@@ -69,16 +73,17 @@ fn main() {
         compiler.enter(|queries| {
             // Parse the program and print the syntax tree.
             let parse = queries.parse().unwrap().take();
-            println!("{:#?}", parse);
+            println!("{parse:?}");
             // Analyze the program and inspect the types of definitions.
             queries.global_ctxt().unwrap().take().enter(|tcx| {
                 for id in tcx.hir().items() {
-                    let item = tcx.hir().item(id);
+                    let hir = tcx.hir();
+                    let item = hir.item(id);
                     match item.kind {
                         rustc_hir::ItemKind::Static(_, _, _) | rustc_hir::ItemKind::Fn(_, _, _) => {
                             let name = item.ident;
-                            let ty = tcx.type_of(tcx.hir().local_def_id(item.hir_id()));
-                            println!("{:?}:\t{:?}", name, ty)
+                            let ty = tcx.type_of(hir.local_def_id(item.hir_id()));
+                            println!("{name:?}:\t{ty:?}")
                         }
                         _ => (),
                     }

examples/rustc-driver-getting-diagnostics.rs

@@ -57,8 +57,13 @@ fn main() {
         },
         // This program contains a type error.
         input: config::Input::Str {
-            name: source_map::FileName::Custom("main.rs".to_string()),
-            input: "fn main() { let x: &str = 1; }".to_string(),
+            name: source_map::FileName::Custom("main.rs".into()),
+            input: "
+fn main() {
+    let x: &str = 1;
+}
+"
+            .into(),
         },
         // Redirect the diagnostic output of the compiler to a buffer.
         diagnostic_output: rustc_session::DiagnosticOutput::Raw(Box::from(DiagnosticSink(
@@ -87,5 +92,5 @@ fn main() {
     });
     // Read buffered diagnostics.
     let diagnostics = String::from_utf8(buffer.lock().unwrap().clone()).unwrap();
-    println!("{}", diagnostics);
+    println!("{diagnostics}");
 }

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

@@ -14,13 +14,12 @@ extern crate rustc_interface;
 extern crate rustc_session;
 extern crate rustc_span;
 
+use std::{path, process, str};
+
 use rustc_ast_pretty::pprust::item_to_string;
 use rustc_errors::registry;
 use rustc_session::config::{self, CheckCfg};
 use rustc_span::source_map;
-use std::path;
-use std::process;
-use std::str;
 
 fn main() {
     let out = process::Command::new("rustc")
@@ -36,8 +35,13 @@ fn main() {
         },
         input: config::Input::Str {
             name: source_map::FileName::Custom("main.rs".to_string()),
-            input: "fn main() { let message = \"Hello, world!\"; println!(\"{}\", message); }"
-                .to_string(),
+            input: r#"
+fn main() {
+    let message = "Hello, World!";
+    println!("{message}");
+}
+"#
+            .to_string(),
         },
         diagnostic_output: rustc_session::DiagnosticOutput::Default,
         crate_cfg: rustc_hash::FxHashSet::default(),
@@ -77,7 +81,7 @@ fn main() {
                                     let hir_id = expr.hir_id; // hir_id identifies the string "Hello, world!"
                                     let def_id = tcx.hir().local_def_id(item.hir_id()); // def_id identifies the main function
                                     let ty = tcx.typeck(def_id).node_type(hir_id);
-                                    println!("{:?}: {:?}", expr, ty);
+                                    println!("{expr:#?}: {ty:?}");
                                 }
                             }
                         }

src/rustc-driver-getting-diagnostics.md

@@ -7,7 +7,7 @@
 To get diagnostics from the compiler,
 configure `rustc_interface::Config` to output diagnostic to a buffer,
 and run `TyCtxt.analysis`. The following should be compiled
-with <!-- date: 2022-05 --> `nightly-2021-04-30` (See [here][example]
+with <!-- date: 2022-06 --> `nightly-2022-06-05` (See [here][example]
 for the complete example):
 
 [example]: https://github.com/rust-lang/rustc-dev-guide/blob/master/examples/rustc-driver-getting-diagnostics.rs

src/rustc-driver-interacting-with-the-ast.md

@@ -5,7 +5,7 @@
 ## Getting the type of an expression
 
 To get the type of an expression, use the `global_ctxt` to get a `TyCtxt`.
-The following should be compiled with <!-- date: 2022-05 --> `nightly-2022-04-30`
+The following should be compiled with <!-- date: 2022-06 --> `nightly-2022-06-05`
 (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