Rollup merge of rust-lang#59747 - gruberb:copy-book-toml-unstable-book, r=ehuss

Copy book.toml unstable book generator

Solves rust-lang#59554 and adds a book title to the unstable book.

I assume that [copy_recursive](https://github.com/rust-lang/rust/blob/acd8dd6a50d505057a7d7ad8d0d7a4c2bd274200/src/tools/unstable-book-gen/src/main.rs#L105) will take files regardless of their type (`.md` or `.toml`).

Although I had a hard time time testing it. A second pair of eyes is definitely needed.

Author: Centril

src/doc/unstable-book/book.toml

@@ -1,2 +1,3 @@
 [book]
 title = "The Rust Unstable Book"
+author = "The Rust Community"

src/tools/tidy/src/unstable_book.rs

@@ -3,13 +3,13 @@ use std::fs;
 use std::path;
 use crate::features::{collect_lang_features, collect_lib_features, Features, Status};
 
-pub const PATH_STR: &str = "doc/unstable-book/src";
+pub const PATH_STR: &str = "doc/unstable-book";
 
-pub const COMPILER_FLAGS_DIR: &str = "compiler-flags";
+pub const COMPILER_FLAGS_DIR: &str = "src/compiler-flags";
 
-pub const LANG_FEATURES_DIR: &str = "language-features";
+pub const LANG_FEATURES_DIR: &str = "src/language-features";
 
-pub const LIB_FEATURES_DIR: &str = "library-features";
+pub const LIB_FEATURES_DIR: &str = "src/library-features";
 
 /// Builds the path to the Unstable Book source directory from the Rust 'src' directory.
 pub fn unstable_book_path(base_src_path: &path::Path) -> path::PathBuf {

src/tools/unstable-book-gen/src/main.rs

@@ -52,7 +52,7 @@ fn set_to_summary_str(set: &BTreeSet<String>, dir: &str
 
 fn generate_summary(path: &Path, lang_features: &Features, lib_features: &Features) {
     let compiler_flags = collect_unstable_book_section_file_names(
-        &path.join("compiler-flags"));
+        &path.join("src/compiler-flags"));
 
     let compiler_flags_str = set_to_summary_str(&compiler_flags,
                                                 "compiler-flags");
@@ -61,11 +61,11 @@ fn generate_summary(path: &Path, lang_features: &Features, lib_features: &Featur
     let unstable_lib_features = collect_unstable_feature_names(&lib_features);
 
     let lang_features_str = set_to_summary_str(&unstable_lang_features,
-                                               LANG_FEATURES_DIR);
+                                               "language-features");
     let lib_features_str = set_to_summary_str(&unstable_lib_features,
-                                              LIB_FEATURES_DIR);
+                                              "library-features");
 
-    let mut file = t!(File::create(&path.join("SUMMARY.md")));
+    let mut file = t!(File::create(&path.join("src/SUMMARY.md")));
     t!(file.write_fmt(format_args!(include_str!("SUMMARY.md"),
                                    compiler_flags = compiler_flags_str,
                                    language_features = lang_features_str,
@@ -102,8 +102,8 @@ fn generate_unstable_book_files(src :&Path, out: &Path, features :&Features) {
     }
 }
 
-fn copy_recursive(path: &Path, to: &Path) {
-    for entry in t!(fs::read_dir(path)) {
+fn copy_recursive(from: &Path, to: &Path) {
+    for entry in t!(fs::read_dir(from)) {
         let e = t!(entry);
         let t = t!(e.metadata());
         let dest = &to.join(e.file_name());
@@ -120,7 +120,7 @@ fn main() {
     let src_path_str = env::args_os().skip(1).next().expect("source path required");
     let dest_path_str = env::args_os().skip(2).next().expect("destination path required");
     let src_path = Path::new(&src_path_str);
-    let dest_path = Path::new(&dest_path_str).join("src");
+    let dest_path = Path::new(&dest_path_str);
 
     let lang_features = collect_lang_features(src_path, &mut false);
     let lib_features = collect_lib_features(src_path).into_iter().filter(|&(ref name, _)| {