1 files changed, 61 insertions, 0 deletions

diff --git a/xtask/src/codegen/gen_unstable_future_descriptor.rs b/xtask/src/codegen/gen_unstable_future_descriptor.rs
new file mode 100644
index 000000000..907a9afae
--- /dev/null
+++ b/xtask/src/codegen/gen_unstable_future_descriptor.rs
@@ -0,0 +1,61 @@
+//! Generates descriptors structure for unstable feature from Unstable Book
+
+use crate::codegen::{self, project_root, Mode, Result};
+use crate::codegen::{reformat, update};
+use crate::not_bash::{fs2, pushd, run};
+use proc_macro2::TokenStream;
+use quote::quote;
+use std::path::PathBuf;
+use walkdir::WalkDir;
+
+fn generate_descriptor(src_dir: PathBuf) -> Result<TokenStream> {
+    let files = WalkDir::new(src_dir.join("language-features"))
+        .into_iter()
+        .chain(WalkDir::new(src_dir.join("library-features")))
+        .filter_map(|e| e.ok())
+        .filter(|entry| {
+            // Get all `.md ` files
+            entry.file_type().is_file() && entry.path().extension().unwrap_or_default() == "md"
+        })
+        .collect::<Vec<_>>();
+
+    let definitions = files
+        .iter()
+        .map(|entry| {
+            let path = entry.path();
+            let feature_ident =
+                format!("{}", path.file_stem().unwrap().to_str().unwrap().replace("-", "_"));
+            let doc = format!("{}", std::fs::read_to_string(path).unwrap());
+
+            quote! { LintCompletion { label: #feature_ident, description: #doc } }
+        })
+        .collect::<Vec<_>>();
+
+    let ts = quote! {
+        use crate::completion::LintCompletion;
+
+        pub(crate) const UNSTABLE_FEATURE_DESCRIPTOR:  &[LintCompletion] = &[
+            #(#definitions),*
+        ];
+    };
+    Ok(ts)
+}
+
+pub fn generate_unstable_future_descriptor(mode: Mode) -> Result<()> {
+    let path = project_root().join(codegen::STORAGE);
+    fs2::create_dir_all(path.clone())?;
+
+    let _d = pushd(path.clone());
+    run!("git init")?;
+    run!("git remote add -f origin {}", codegen::REPOSITORY_URL)?;
+    run!("git pull origin master")?;
+
+    let src_dir = path.join(codegen::REPO_PATH);
+    let content = generate_descriptor(src_dir)?.to_string();
+
+    let contents = reformat(content)?;
+    let destination = project_root().join(codegen::UNSTABLE_FEATURE);
+    update(destination.as_path(), &contents, mode)?;
+
+    Ok(())
+}