Merge #5695

5695: Added completion for unstable features r=matklad a=Fihtangolz

Added xtask for downloading list of unstable features from the unstable book and codegen for it. Also included small changes from linter.

Co-authored-by: Dmitry <mamhigtt@gmail.com>
Co-authored-by: Dmitry Opokin <mamhigtt@gmail.com>

crates/hir/src/has_source.rs

@@ -1,4 +1,4 @@
-//! FIXME: write short doc here
+//! Provides set of implementation for hir's objects that allows get back location in file.
 
 use either::Either;
 use hir_def::{

crates/ide/src/completion.rs

@@ -18,6 +18,7 @@ mod complete_unqualified_path;
 mod complete_postfix;
 mod complete_macro_in_item_position;
 mod complete_trait_impl;
+mod unstable_feature_descriptor;
 
 use ide_db::RootDatabase;
 
@@ -29,6 +30,11 @@ use crate::{
     FilePosition,
 };
 
+//FIXME: cyclic imports caused by xtask generation, this should be better
+use crate::completion::{
+    complete_attribute::LintCompletion, unstable_feature_descriptor::UNSTABLE_FEATURE_DESCRIPTOR,
+};
+
 pub use crate::completion::{
     completion_config::CompletionConfig,
     completion_item::{CompletionItem, CompletionItemKind, CompletionScore, InsertTextFormat},

crates/ide/src/completion/complete_attribute.rs

@@ -9,6 +9,7 @@ use syntax::{ast, AstNode, SyntaxKind};
 use crate::completion::{
     completion_context::CompletionContext,
     completion_item::{CompletionItem, CompletionItemKind, CompletionKind, Completions},
+    UNSTABLE_FEATURE_DESCRIPTOR,
 };
 
 pub(super) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
@@ -17,12 +18,15 @@ pub(super) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext)
         (Some(path), Some(token_tree)) if path.to_string() == "derive" => {
             complete_derive(acc, ctx, token_tree)
         }
+        (Some(path), Some(token_tree)) if path.to_string() == "feature" => {
+            complete_lint(acc, ctx, token_tree, UNSTABLE_FEATURE_DESCRIPTOR)
+        }
         (Some(path), Some(token_tree))
             if ["allow", "warn", "deny", "forbid"]
                 .iter()
                 .any(|lint_level| lint_level == &path.to_string()) =>
         {
-            complete_lint(acc, ctx, token_tree)
+            complete_lint(acc, ctx, token_tree, DEFAULT_LINT_COMPLETIONS)
         }
         (_, Some(_token_tree)) => {}
         _ => complete_attribute_start(acc, ctx, attribute),
@@ -162,9 +166,14 @@ fn complete_derive(acc: &mut Completions, ctx: &CompletionContext, derive_input:
     }
 }
 
-fn complete_lint(acc: &mut Completions, ctx: &CompletionContext, derive_input: ast::TokenTree) {
+fn complete_lint(
+    acc: &mut Completions,
+    ctx: &CompletionContext,
+    derive_input: ast::TokenTree,
+    lints_completions: &[LintCompletion],
+) {
     if let Ok(existing_lints) = parse_comma_sep_input(derive_input) {
-        for lint_completion in DEFAULT_LINT_COMPLETIONS
+        for lint_completion in lints_completions
             .into_iter()
             .filter(|completion| !existing_lints.contains(completion.label))
         {
@@ -228,7 +237,7 @@ fn get_derive_names_in_scope(ctx: &CompletionContext) -> FxHashSet<String> {
     result
 }
 
-struct DeriveCompletion {
+pub(crate) struct DeriveCompletion {
     label: &'static str,
     dependencies: &'static [&'static str],
 }
@@ -248,9 +257,9 @@ const DEFAULT_DERIVE_COMPLETIONS: &[DeriveCompletion] = &[
     DeriveCompletion { label: "Ord", dependencies: &["PartialOrd", "Eq", "PartialEq"] },
 ];
 
-struct LintCompletion {
-    label: &'static str,
-    description: &'static str,
+pub(crate) struct LintCompletion {
+    pub(crate) label: &'static str,
+    pub(crate) description: &'static str,
 }
 
 #[rustfmt::skip]

xtask/src/codegen.rs

@@ -9,6 +9,7 @@ mod gen_syntax;
 mod gen_parser_tests;
 mod gen_assists_docs;
 mod gen_feature_docs;
+mod gen_unstable_future_descriptor;
 
 use std::{
     fmt, mem,
@@ -26,8 +27,12 @@ pub use self::{
     gen_feature_docs::generate_feature_docs,
     gen_parser_tests::generate_parser_tests,
     gen_syntax::generate_syntax,
+    gen_unstable_future_descriptor::generate_unstable_future_descriptor,
 };
 
+// Directory used by xtask
+const STORAGE: &str = ".xtask";
+
 const GRAMMAR_DIR: &str = "crates/parser/src/grammar";
 const OK_INLINE_TESTS_DIR: &str = "crates/syntax/test_data/parser/inline/ok";
 const ERR_INLINE_TESTS_DIR: &str = "crates/syntax/test_data/parser/inline/err";
@@ -39,6 +44,10 @@ const AST_TOKENS: &str = "crates/syntax/src/ast/generated/tokens.rs";
 const ASSISTS_DIR: &str = "crates/assists/src/handlers";
 const ASSISTS_TESTS: &str = "crates/assists/src/tests/generated.rs";
 
+const REPOSITORY_URL: &str = "https://github.com/rust-lang/rust";
+const UNSTABLE_FEATURE: &str = "crates/ide/src/completion/unstable_feature_descriptor.rs";
+const REPO_PATH: &str = "src/doc/unstable-book/src";
+
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum Mode {
     Overwrite,

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(())
+}

xtask/src/main.rs

@@ -77,6 +77,7 @@ FLAGS:
         "codegen" => {
             args.finish()?;
             codegen::generate_syntax(Mode::Overwrite)?;
+            codegen::generate_unstable_future_descriptor(Mode::Overwrite)?;
             codegen::generate_parser_tests(Mode::Overwrite)?;
             codegen::generate_assists_tests(Mode::Overwrite)?;
             codegen::generate_assists_docs(Mode::Overwrite)?;

xtask/tests/tidy.rs

@@ -112,6 +112,8 @@ fn check_todo(path: &Path, text: &str) {
         // To support generating `todo!()` in assists, we have `expr_todo()` in
         // `ast::make`.
         "ast/make.rs",
+        // The documentation in string literals may contain anything for its own purposes
+        "completion/unstable_feature_descriptor.rs",
     ];
     if need_todo.iter().any(|p| path.ends_with(p)) {
         return;