crates/ide_completion/src/completions/attribute.rs

   1 //! Completion for attributes
   2 //!
   3 //! This module uses a bit of static metadata to provide completions
   4 //! for built-in attributes.
   5
   6 use once_cell::sync::Lazy;
   7 use rustc_hash::{FxHashMap, FxHashSet};
   8 use syntax::{ast, AstNode, SyntaxKind, T};
   9
  10 use crate::{
  11     context::CompletionContext,
  12     generated_lint_completions::{CLIPPY_LINTS, FEATURES},
  13     item::{CompletionItem, CompletionItemKind, CompletionKind},
  14     Completions,
  15 };
  16
  17 mod derive;
  18 mod lint;
  19 pub(crate) use self::lint::LintCompletion;
  20
  21 pub(crate) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
  22     if ctx.mod_declaration_under_caret.is_some() {
  23         return None;
  24     }
  25
  26     let attribute = ctx.attribute_under_caret.as_ref()?;
  27     match (attribute.path().and_then(|p| p.as_single_name_ref()), attribute.token_tree()) {
  28         (Some(path), Some(token_tree)) => match path.text().as_str() {
  29             "derive" => derive::complete_derive(acc, ctx, token_tree),
  30             "feature" => lint::complete_lint(acc, ctx, token_tree, FEATURES),
  31             "allow" | "warn" | "deny" | "forbid" => {
  32                 lint::complete_lint(acc, ctx, token_tree.clone(), lint::DEFAULT_LINT_COMPLETIONS);
  33                 lint::complete_lint(acc, ctx, token_tree, CLIPPY_LINTS);
  34             }
  35             _ => (),
  36         },
  37         (None, Some(_)) => (),
  38         _ => complete_new_attribute(acc, ctx, attribute),
  39     }
  40     Some(())
  41 }
  42
  43 fn complete_new_attribute(acc: &mut Completions, ctx: &CompletionContext, attribute: &ast::Attr) {
  44     let attribute_annotated_item_kind = attribute.syntax().parent().map(|it| it.kind());
  45     let attributes = attribute_annotated_item_kind.and_then(|kind| {
  46         if ast::Expr::can_cast(kind) {
  47             Some(EXPR_ATTRIBUTES)
  48         } else {
  49             KIND_TO_ATTRIBUTES.get(&kind).copied()
  50         }
  51     });
  52     let is_inner = attribute.kind() == ast::AttrKind::Inner;
  53
  54     let add_completion = |attr_completion: &AttrCompletion| {
  55         let mut item = CompletionItem::new(
  56             CompletionKind::Attribute,
  57             ctx.source_range(),
  58             attr_completion.label,
  59         );
  60         item.kind(CompletionItemKind::Attribute);
  61
  62         if let Some(lookup) = attr_completion.lookup {
  63             item.lookup_by(lookup);
  64         }
  65
  66         if let Some((snippet, cap)) = attr_completion.snippet.zip(ctx.config.snippet_cap) {
  67             item.insert_snippet(cap, snippet);
  68         }
  69
  70         if is_inner || !attr_completion.prefer_inner {
  71             acc.add(item.build());
  72         }
  73     };
  74
  75     match attributes {
  76         Some(applicable) => applicable
  77             .iter()
  78             .flat_map(|name| ATTRIBUTES.binary_search_by(|attr| attr.key().cmp(name)).ok())
  79             .flat_map(|idx| ATTRIBUTES.get(idx))
  80             .for_each(add_completion),
  81         None if is_inner => ATTRIBUTES.iter().for_each(add_completion),
  82         None => ATTRIBUTES.iter().filter(|compl| !compl.prefer_inner).for_each(add_completion),
  83     }
  84 }
  85
  86 struct AttrCompletion {
  87     label: &'static str,
  88     lookup: Option<&'static str>,
  89     snippet: Option<&'static str>,
  90     prefer_inner: bool,
  91 }
  92
  93 impl AttrCompletion {
  94     fn key(&self) -> &'static str {
  95         self.lookup.unwrap_or(self.label)
  96     }
  97
  98     const fn prefer_inner(self) -> AttrCompletion {
  99         AttrCompletion { prefer_inner: true, ..self }
 100     }
 101 }
 102
 103 const fn attr(
 104     label: &'static str,
 105     lookup: Option<&'static str>,
 106     snippet: Option<&'static str>,
 107 ) -> AttrCompletion {
 108     AttrCompletion { label, lookup, snippet, prefer_inner: false }
 109 }
 110
 111 macro_rules! attrs {
 112     [@ { item $($tt:tt)* } {$($acc:tt)*}] => {
 113         attrs!(@ { $($tt)* } { $($acc)*, "deprecated", "doc", "dochidden", "docalias", "must_use", "no_mangle" })
 114     };
 115     [@ { adt $($tt:tt)* } {$($acc:tt)*}] => {
 116         attrs!(@ { $($tt)* } { $($acc)*, "derive", "repr" })
 117     };
 118     [@ { linkable $($tt:tt)* } {$($acc:tt)*}] => {
 119         attrs!(@ { $($tt)* } { $($acc)*, "export_name", "link_name", "link_section" }) };
 120     [@ { $ty:ident $($tt:tt)* } {$($acc:tt)*}] => { compile_error!(concat!("unknown attr subtype ", stringify!($ty)))
 121     };
 122     [@ { $lit:literal $($tt:tt)*} {$($acc:tt)*}] => {
 123         attrs!(@ { $($tt)* } { $($acc)*, $lit })
 124     };
 125     [@ {$($tt:tt)+} {$($tt2:tt)*}] => {
 126         compile_error!(concat!("Unexpected input ", stringify!($($tt)+)))
 127     };
 128     [@ {} {$($tt:tt)*}] => { &[$($tt)*] as _ };
 129     [$($tt:tt),*] => {
 130         attrs!(@ { $($tt)* } { "allow", "cfg", "cfg_attr", "deny", "forbid", "warn" })
 131     };
 132 }
 133
 134 #[rustfmt::skip]
 135 static KIND_TO_ATTRIBUTES: Lazy<FxHashMap<SyntaxKind, &[&str]>> = Lazy::new(|| {
 136     std::array::IntoIter::new([
 137         (
 138             SyntaxKind::SOURCE_FILE,
 139             attrs!(
 140                 item,
 141                 "crate_name", "feature", "no_implicit_prelude", "no_main", "no_std",
 142                 "recursion_limit", "type_length_limit", "windows_subsystem"
 143             ),
 144         ),
 145         (SyntaxKind::MODULE, attrs!(item, "no_implicit_prelude", "path")),
 146         (SyntaxKind::ITEM_LIST, attrs!(item, "no_implicit_prelude")),
 147         (SyntaxKind::MACRO_RULES, attrs!(item, "macro_export", "macro_use")),
 148         (SyntaxKind::MACRO_DEF, attrs!(item)),
 149         (SyntaxKind::EXTERN_CRATE, attrs!(item, "macro_use", "no_link")),
 150         (SyntaxKind::USE, attrs!(item)),
 151         (SyntaxKind::TYPE_ALIAS, attrs!(item)),
 152         (SyntaxKind::STRUCT, attrs!(item, adt, "non_exhaustive")),
 153         (SyntaxKind::ENUM, attrs!(item, adt, "non_exhaustive")),
 154         (SyntaxKind::UNION, attrs!(item, adt)),
 155         (SyntaxKind::CONST, attrs!(item)),
 156         (
 157             SyntaxKind::FN,
 158             attrs!(
 159                 item, linkable,
 160                 "cold", "ignore", "inline", "must_use", "panic_handler", "proc_macro",
 161                 "proc_macro_derive", "proc_macro_attribute", "should_panic", "target_feature",
 162                 "test", "track_caller"
 163             ),
 164         ),
 165         (SyntaxKind::STATIC, attrs!(item, linkable, "global_allocator", "used")),
 166         (SyntaxKind::TRAIT, attrs!(item, "must_use")),
 167         (SyntaxKind::IMPL, attrs!(item, "automatically_derived")),
 168         (SyntaxKind::ASSOC_ITEM_LIST, attrs!(item)),
 169         (SyntaxKind::EXTERN_BLOCK, attrs!(item, "link")),
 170         (SyntaxKind::EXTERN_ITEM_LIST, attrs!(item, "link")),
 171         (SyntaxKind::MACRO_CALL, attrs!()),
 172         (SyntaxKind::SELF_PARAM, attrs!()),
 173         (SyntaxKind::PARAM, attrs!()),
 174         (SyntaxKind::RECORD_FIELD, attrs!()),
 175         (SyntaxKind::VARIANT, attrs!("non_exhaustive")),
 176         (SyntaxKind::TYPE_PARAM, attrs!()),
 177         (SyntaxKind::CONST_PARAM, attrs!()),
 178         (SyntaxKind::LIFETIME_PARAM, attrs!()),
 179         (SyntaxKind::LET_STMT, attrs!()),
 180         (SyntaxKind::EXPR_STMT, attrs!()),
 181         (SyntaxKind::LITERAL, attrs!()),
 182         (SyntaxKind::RECORD_EXPR_FIELD_LIST, attrs!()),
 183         (SyntaxKind::RECORD_EXPR_FIELD, attrs!()),
 184         (SyntaxKind::MATCH_ARM_LIST, attrs!()),
 185         (SyntaxKind::MATCH_ARM, attrs!()),
 186         (SyntaxKind::IDENT_PAT, attrs!()),
 187         (SyntaxKind::RECORD_PAT_FIELD, attrs!()),
 188     ])
 189     .collect()
 190 });
 191 const EXPR_ATTRIBUTES: &[&str] = attrs!();
 192
 193 /// https://doc.rust-lang.org/reference/attributes.html#built-in-attributes-index
 194 // Keep these sorted for the binary search!
 195 const ATTRIBUTES: &[AttrCompletion] = &[
 196     attr("allow(…)", Some("allow"), Some("allow(${0:lint})")),
 197     attr("automatically_derived", None, None),
 198     attr("cfg(…)", Some("cfg"), Some("cfg(${0:predicate})")),
 199     attr("cfg_attr(…)", Some("cfg_attr"), Some("cfg_attr(${1:predicate}, ${0:attr})")),
 200     attr("cold", None, None),
 201     attr(r#"crate_name = """#, Some("crate_name"), Some(r#"crate_name = "${0:crate_name}""#))
 202         .prefer_inner(),
 203     attr("deny(…)", Some("deny"), Some("deny(${0:lint})")),
 204     attr(r#"deprecated"#, Some("deprecated"), Some(r#"deprecated"#)),
 205     attr("derive(…)", Some("derive"), Some(r#"derive(${0:Debug})"#)),
 206     attr(r#"doc = "…""#, Some("doc"), Some(r#"doc = "${0:docs}""#)),
 207     attr(r#"doc(alias = "…")"#, Some("docalias"), Some(r#"doc(alias = "${0:docs}")"#)),
 208     attr(r#"doc(hidden)"#, Some("dochidden"), Some(r#"doc(hidden)"#)),
 209     attr(
 210         r#"export_name = "…""#,
 211         Some("export_name"),
 212         Some(r#"export_name = "${0:exported_symbol_name}""#),
 213     ),
 214     attr("feature(…)", Some("feature"), Some("feature(${0:flag})")).prefer_inner(),
 215     attr("forbid(…)", Some("forbid"), Some("forbid(${0:lint})")),
 216     // FIXME: resolve through macro resolution?
 217     attr("global_allocator", None, None).prefer_inner(),
 218     attr(r#"ignore = "…""#, Some("ignore"), Some(r#"ignore = "${0:reason}""#)),
 219     attr("inline", Some("inline"), Some("inline")),
 220     attr("link", None, None),
 221     attr(r#"link_name = "…""#, Some("link_name"), Some(r#"link_name = "${0:symbol_name}""#)),
 222     attr(
 223         r#"link_section = "…""#,
 224         Some("link_section"),
 225         Some(r#"link_section = "${0:section_name}""#),
 226     ),
 227     attr("macro_export", None, None),
 228     attr("macro_use", None, None),
 229     attr(r#"must_use"#, Some("must_use"), Some(r#"must_use"#)),
 230     attr("no_implicit_prelude", None, None).prefer_inner(),
 231     attr("no_link", None, None).prefer_inner(),
 232     attr("no_main", None, None).prefer_inner(),
 233     attr("no_mangle", None, None),
 234     attr("no_std", None, None).prefer_inner(),
 235     attr("non_exhaustive", None, None),
 236     attr("panic_handler", None, None).prefer_inner(),
 237     attr(r#"path = "…""#, Some("path"), Some(r#"path ="${0:path}""#)),
 238     attr("proc_macro", None, None),
 239     attr("proc_macro_attribute", None, None),
 240     attr("proc_macro_derive(…)", Some("proc_macro_derive"), Some("proc_macro_derive(${0:Trait})")),
 241     attr("recursion_limit = …", Some("recursion_limit"), Some("recursion_limit = ${0:128}"))
 242         .prefer_inner(),
 243     attr("repr(…)", Some("repr"), Some("repr(${0:C})")),
 244     attr("should_panic", Some("should_panic"), Some(r#"should_panic"#)),
 245     attr(
 246         r#"target_feature = "…""#,
 247         Some("target_feature"),
 248         Some(r#"target_feature = "${0:feature}""#),
 249     ),
 250     attr("test", None, None),
 251     attr("track_caller", None, None),
 252     attr("type_length_limit = …", Some("type_length_limit"), Some("type_length_limit = ${0:128}"))
 253         .prefer_inner(),
 254     attr("used", None, None),
 255     attr("warn(…)", Some("warn"), Some("warn(${0:lint})")),
 256     attr(
 257         r#"windows_subsystem = "…""#,
 258         Some("windows_subsystem"),
 259         Some(r#"windows_subsystem = "${0:subsystem}""#),
 260     )
 261     .prefer_inner(),
 262 ];
 263
 264 #[test]
 265 fn attributes_are_sorted() {
 266     let mut attrs = ATTRIBUTES.iter().map(|attr| attr.key());
 267     let mut prev = attrs.next().unwrap();
 268
 269     attrs.for_each(|next| {
 270         assert!(
 271             prev < next,
 272             r#"Attributes are not sorted, "{}" should come after "{}""#,
 273             prev,
 274             next
 275         );
 276         prev = next;
 277     });
 278 }
 279
 280 fn parse_comma_sep_input(derive_input: ast::TokenTree) -> Result<FxHashSet<String>, ()> {
 281     match (derive_input.left_delimiter_token(), derive_input.right_delimiter_token()) {
 282         (Some(left_paren), Some(right_paren))
 283             if left_paren.kind() == T!['('] && right_paren.kind() == T![')'] =>
 284         {
 285             let mut input_derives = FxHashSet::default();
 286             let mut current_derive = String::new();
 287             for token in derive_input
 288                 .syntax()
 289                 .children_with_tokens()
 290                 .filter_map(|token| token.into_token())
 291                 .skip_while(|token| token != &left_paren)
 292                 .skip(1)
 293                 .take_while(|token| token != &right_paren)
 294             {
 295                 if T![,] == token.kind() {
 296                     if !current_derive.is_empty() {
 297                         input_derives.insert(current_derive);
 298                         current_derive = String::new();
 299                     }
 300                 } else {
 301                     current_derive.push_str(token.text().trim());
 302                 }
 303             }
 304
 305             if !current_derive.is_empty() {
 306                 input_derives.insert(current_derive);
 307             }
 308             Ok(input_derives)
 309         }
 310         _ => Err(()),
 311     }
 312 }
 313
 314 #[cfg(test)]
 315 mod tests {
 316     use expect_test::{expect, Expect};
 317
 318     use crate::{test_utils::completion_list, CompletionKind};
 319
 320     fn check(ra_fixture: &str, expect: Expect) {
 321         let actual = completion_list(ra_fixture, CompletionKind::Attribute);
 322         expect.assert_eq(&actual);
 323     }
 324
 325     #[test]
 326     fn complete_attribute_on_struct() {
 327         check(
 328             r#"
 329 #[$0]
 330 struct Test {}
 331         "#,
 332             expect![[r#"
 333                 at allow(…)
 334                 at cfg(…)
 335                 at cfg_attr(…)
 336                 at deny(…)
 337                 at forbid(…)
 338                 at warn(…)
 339                 at deprecated
 340                 at must_use
 341             "#]],
 342         );
 343     }
 344     #[test]
 345     fn test_attribute_completion_inside_nested_attr() {
 346         check(r#"#[cfg($0)]"#, expect![[]])
 347     }
 348 }