src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute.rs

   1 //! Completion for (built-in) attributes, derives and lints.
   2 //!
   3 //! This module uses a bit of static metadata to provide completions for builtin-in attributes and lints.
   4
   5 use ide_db::{
   6     generated::lints::{
   7         Lint, CLIPPY_LINTS, CLIPPY_LINT_GROUPS, DEFAULT_LINTS, FEATURES, RUSTDOC_LINTS,
   8     },
   9     syntax_helpers::node_ext::parse_tt_as_comma_sep_paths,
  10     FxHashMap, SymbolKind,
  11 };
  12 use itertools::Itertools;
  13 use once_cell::sync::Lazy;
  14 use syntax::{
  15     ast::{self, AttrKind},
  16     AstNode, SyntaxKind, T,
  17 };
  18
  19 use crate::{
  20     context::{AttrCtx, CompletionContext, PathCompletionCtx, Qualified},
  21     item::CompletionItem,
  22     Completions,
  23 };
  24
  25 mod cfg;
  26 mod derive;
  27 mod lint;
  28 mod repr;
  29
  30 pub(crate) use self::derive::complete_derive_path;
  31
  32 /// Complete inputs to known builtin attributes as well as derive attributes
  33 pub(crate) fn complete_known_attribute_input(
  34     acc: &mut Completions,
  35     ctx: &CompletionContext<'_>,
  36     &colon_prefix: &bool,
  37     fake_attribute_under_caret: &ast::Attr,
  38 ) -> Option<()> {
  39     let attribute = fake_attribute_under_caret;
  40     let name_ref = match attribute.path() {
  41         Some(p) => Some(p.as_single_name_ref()?),
  42         None => None,
  43     };
  44     let (path, tt) = name_ref.zip(attribute.token_tree())?;
  45     if tt.l_paren_token().is_none() {
  46         return None;
  47     }
  48
  49     match path.text().as_str() {
  50         "repr" => repr::complete_repr(acc, ctx, tt),
  51         "feature" => {
  52             lint::complete_lint(acc, ctx, colon_prefix, &parse_tt_as_comma_sep_paths(tt)?, FEATURES)
  53         }
  54         "allow" | "warn" | "deny" | "forbid" => {
  55             let existing_lints = parse_tt_as_comma_sep_paths(tt)?;
  56
  57             let lints: Vec<Lint> = CLIPPY_LINT_GROUPS
  58                 .iter()
  59                 .map(|g| &g.lint)
  60                 .chain(DEFAULT_LINTS)
  61                 .chain(CLIPPY_LINTS)
  62                 .chain(RUSTDOC_LINTS)
  63                 .cloned()
  64                 .collect();
  65
  66             lint::complete_lint(acc, ctx, colon_prefix, &existing_lints, &lints);
  67         }
  68         "cfg" => cfg::complete_cfg(acc, ctx),
  69         _ => (),
  70     }
  71     Some(())
  72 }
  73
  74 pub(crate) fn complete_attribute_path(
  75     acc: &mut Completions,
  76     ctx: &CompletionContext<'_>,
  77     path_ctx @ PathCompletionCtx { qualified, .. }: &PathCompletionCtx,
  78     &AttrCtx { kind, annotated_item_kind }: &AttrCtx,
  79 ) {
  80     let is_inner = kind == AttrKind::Inner;
  81
  82     match qualified {
  83         Qualified::With {
  84             resolution: Some(hir::PathResolution::Def(hir::ModuleDef::Module(module))),
  85             super_chain_len,
  86             ..
  87         } => {
  88             acc.add_super_keyword(ctx, *super_chain_len);
  89
  90             for (name, def) in module.scope(ctx.db, Some(ctx.module)) {
  91                 match def {
  92                     hir::ScopeDef::ModuleDef(hir::ModuleDef::Macro(m)) if m.is_attr(ctx.db) => {
  93                         acc.add_macro(ctx, path_ctx, m, name)
  94                     }
  95                     hir::ScopeDef::ModuleDef(hir::ModuleDef::Module(m)) => {
  96                         acc.add_module(ctx, path_ctx, m, name)
  97                     }
  98                     _ => (),
  99                 }
 100             }
 101             return;
 102         }
 103         // fresh use tree with leading colon2, only show crate roots
 104         Qualified::Absolute => acc.add_crate_roots(ctx, path_ctx),
 105         // only show modules in a fresh UseTree
 106         Qualified::No => {
 107             ctx.process_all_names(&mut |name, def| match def {
 108                 hir::ScopeDef::ModuleDef(hir::ModuleDef::Macro(m)) if m.is_attr(ctx.db) => {
 109                     acc.add_macro(ctx, path_ctx, m, name)
 110                 }
 111                 hir::ScopeDef::ModuleDef(hir::ModuleDef::Module(m)) => {
 112                     acc.add_module(ctx, path_ctx, m, name)
 113                 }
 114                 _ => (),
 115             });
 116             acc.add_nameref_keywords_with_colon(ctx);
 117         }
 118         Qualified::TypeAnchor { .. } | Qualified::With { .. } => {}
 119     }
 120
 121     let attributes = annotated_item_kind.and_then(|kind| {
 122         if ast::Expr::can_cast(kind) {
 123             Some(EXPR_ATTRIBUTES)
 124         } else {
 125             KIND_TO_ATTRIBUTES.get(&kind).copied()
 126         }
 127     });
 128
 129     let add_completion = |attr_completion: &AttrCompletion| {
 130         let mut item =
 131             CompletionItem::new(SymbolKind::Attribute, ctx.source_range(), attr_completion.label);
 132
 133         if let Some(lookup) = attr_completion.lookup {
 134             item.lookup_by(lookup);
 135         }
 136
 137         if let Some((snippet, cap)) = attr_completion.snippet.zip(ctx.config.snippet_cap) {
 138             item.insert_snippet(cap, snippet);
 139         }
 140
 141         if is_inner || !attr_completion.prefer_inner {
 142             item.add_to(acc);
 143         }
 144     };
 145
 146     match attributes {
 147         Some(applicable) => applicable
 148             .iter()
 149             .flat_map(|name| ATTRIBUTES.binary_search_by(|attr| attr.key().cmp(name)).ok())
 150             .flat_map(|idx| ATTRIBUTES.get(idx))
 151             .for_each(add_completion),
 152         None if is_inner => ATTRIBUTES.iter().for_each(add_completion),
 153         None => ATTRIBUTES.iter().filter(|compl| !compl.prefer_inner).for_each(add_completion),
 154     }
 155 }
 156
 157 struct AttrCompletion {
 158     label: &'static str,
 159     lookup: Option<&'static str>,
 160     snippet: Option<&'static str>,
 161     prefer_inner: bool,
 162 }
 163
 164 impl AttrCompletion {
 165     fn key(&self) -> &'static str {
 166         self.lookup.unwrap_or(self.label)
 167     }
 168
 169     const fn prefer_inner(self) -> AttrCompletion {
 170         AttrCompletion { prefer_inner: true, ..self }
 171     }
 172 }
 173
 174 const fn attr(
 175     label: &'static str,
 176     lookup: Option<&'static str>,
 177     snippet: Option<&'static str>,
 178 ) -> AttrCompletion {
 179     AttrCompletion { label, lookup, snippet, prefer_inner: false }
 180 }
 181
 182 macro_rules! attrs {
 183     // attributes applicable to all items
 184     [@ { item $($tt:tt)* } {$($acc:tt)*}] => {
 185         attrs!(@ { $($tt)* } { $($acc)*, "deprecated", "doc", "dochidden", "docalias", "must_use", "no_mangle" })
 186     };
 187     // attributes applicable to all adts
 188     [@ { adt $($tt:tt)* } {$($acc:tt)*}] => {
 189         attrs!(@ { $($tt)* } { $($acc)*, "derive", "repr" })
 190     };
 191     // attributes applicable to all linkable things aka functions/statics
 192     [@ { linkable $($tt:tt)* } {$($acc:tt)*}] => {
 193         attrs!(@ { $($tt)* } { $($acc)*, "export_name", "link_name", "link_section" })
 194     };
 195     // error fallback for nicer error message
 196     [@ { $ty:ident $($tt:tt)* } {$($acc:tt)*}] => {
 197         compile_error!(concat!("unknown attr subtype ", stringify!($ty)))
 198     };
 199     // general push down accumulation
 200     [@ { $lit:literal $($tt:tt)*} {$($acc:tt)*}] => {
 201         attrs!(@ { $($tt)* } { $($acc)*, $lit })
 202     };
 203     [@ {$($tt:tt)+} {$($tt2:tt)*}] => {
 204         compile_error!(concat!("Unexpected input ", stringify!($($tt)+)))
 205     };
 206     // final output construction
 207     [@ {} {$($tt:tt)*}] => { &[$($tt)*] as _ };
 208     // starting matcher
 209     [$($tt:tt),*] => {
 210         attrs!(@ { $($tt)* } { "allow", "cfg", "cfg_attr", "deny", "forbid", "warn" })
 211     };
 212 }
 213
 214 #[rustfmt::skip]
 215 static KIND_TO_ATTRIBUTES: Lazy<FxHashMap<SyntaxKind, &[&str]>> = Lazy::new(|| {
 216     use SyntaxKind::*;
 217     [
 218         (
 219             SOURCE_FILE,
 220             attrs!(
 221                 item,
 222                 "crate_name", "feature", "no_implicit_prelude", "no_main", "no_std",
 223                 "recursion_limit", "type_length_limit", "windows_subsystem"
 224             ),
 225         ),
 226         (MODULE, attrs!(item, "macro_use", "no_implicit_prelude", "path")),
 227         (ITEM_LIST, attrs!(item, "no_implicit_prelude")),
 228         (MACRO_RULES, attrs!(item, "macro_export", "macro_use")),
 229         (MACRO_DEF, attrs!(item)),
 230         (EXTERN_CRATE, attrs!(item, "macro_use", "no_link")),
 231         (USE, attrs!(item)),
 232         (TYPE_ALIAS, attrs!(item)),
 233         (STRUCT, attrs!(item, adt, "non_exhaustive")),
 234         (ENUM, attrs!(item, adt, "non_exhaustive")),
 235         (UNION, attrs!(item, adt)),
 236         (CONST, attrs!(item)),
 237         (
 238             FN,
 239             attrs!(
 240                 item, linkable,
 241                 "cold", "ignore", "inline", "must_use", "panic_handler", "proc_macro",
 242                 "proc_macro_derive", "proc_macro_attribute", "should_panic", "target_feature",
 243                 "test", "track_caller"
 244             ),
 245         ),
 246         (STATIC, attrs!(item, linkable, "global_allocator", "used")),
 247         (TRAIT, attrs!(item, "must_use")),
 248         (IMPL, attrs!(item, "automatically_derived")),
 249         (ASSOC_ITEM_LIST, attrs!(item)),
 250         (EXTERN_BLOCK, attrs!(item, "link")),
 251         (EXTERN_ITEM_LIST, attrs!(item, "link")),
 252         (MACRO_CALL, attrs!()),
 253         (SELF_PARAM, attrs!()),
 254         (PARAM, attrs!()),
 255         (RECORD_FIELD, attrs!()),
 256         (VARIANT, attrs!("non_exhaustive")),
 257         (TYPE_PARAM, attrs!()),
 258         (CONST_PARAM, attrs!()),
 259         (LIFETIME_PARAM, attrs!()),
 260         (LET_STMT, attrs!()),
 261         (EXPR_STMT, attrs!()),
 262         (LITERAL, attrs!()),
 263         (RECORD_EXPR_FIELD_LIST, attrs!()),
 264         (RECORD_EXPR_FIELD, attrs!()),
 265         (MATCH_ARM_LIST, attrs!()),
 266         (MATCH_ARM, attrs!()),
 267         (IDENT_PAT, attrs!()),
 268         (RECORD_PAT_FIELD, attrs!()),
 269     ]
 270     .into_iter()
 271     .collect()
 272 });
 273 const EXPR_ATTRIBUTES: &[&str] = attrs!();
 274
 275 /// <https://doc.rust-lang.org/reference/attributes.html#built-in-attributes-index>
 276 // Keep these sorted for the binary search!
 277 const ATTRIBUTES: &[AttrCompletion] = &[
 278     attr("allow(…)", Some("allow"), Some("allow(${0:lint})")),
 279     attr("automatically_derived", None, None),
 280     attr("cfg(…)", Some("cfg"), Some("cfg(${0:predicate})")),
 281     attr("cfg_attr(…)", Some("cfg_attr"), Some("cfg_attr(${1:predicate}, ${0:attr})")),
 282     attr("cold", None, None),
 283     attr(r#"crate_name = """#, Some("crate_name"), Some(r#"crate_name = "${0:crate_name}""#))
 284         .prefer_inner(),
 285     attr("deny(…)", Some("deny"), Some("deny(${0:lint})")),
 286     attr(r#"deprecated"#, Some("deprecated"), Some(r#"deprecated"#)),
 287     attr("derive(…)", Some("derive"), Some(r#"derive(${0:Debug})"#)),
 288     attr(r#"doc = "…""#, Some("doc"), Some(r#"doc = "${0:docs}""#)),
 289     attr(r#"doc(alias = "…")"#, Some("docalias"), Some(r#"doc(alias = "${0:docs}")"#)),
 290     attr(r#"doc(hidden)"#, Some("dochidden"), Some(r#"doc(hidden)"#)),
 291     attr(
 292         r#"export_name = "…""#,
 293         Some("export_name"),
 294         Some(r#"export_name = "${0:exported_symbol_name}""#),
 295     ),
 296     attr("feature(…)", Some("feature"), Some("feature(${0:flag})")).prefer_inner(),
 297     attr("forbid(…)", Some("forbid"), Some("forbid(${0:lint})")),
 298     attr("global_allocator", None, None),
 299     attr(r#"ignore = "…""#, Some("ignore"), Some(r#"ignore = "${0:reason}""#)),
 300     attr("inline", Some("inline"), Some("inline")),
 301     attr("link", None, None),
 302     attr(r#"link_name = "…""#, Some("link_name"), Some(r#"link_name = "${0:symbol_name}""#)),
 303     attr(
 304         r#"link_section = "…""#,
 305         Some("link_section"),
 306         Some(r#"link_section = "${0:section_name}""#),
 307     ),
 308     attr("macro_export", None, None),
 309     attr("macro_use", None, None),
 310     attr(r#"must_use"#, Some("must_use"), Some(r#"must_use"#)),
 311     attr("no_implicit_prelude", None, None).prefer_inner(),
 312     attr("no_link", None, None).prefer_inner(),
 313     attr("no_main", None, None).prefer_inner(),
 314     attr("no_mangle", None, None),
 315     attr("no_std", None, None).prefer_inner(),
 316     attr("non_exhaustive", None, None),
 317     attr("panic_handler", None, None),
 318     attr(r#"path = "…""#, Some("path"), Some(r#"path ="${0:path}""#)),
 319     attr("proc_macro", None, None),
 320     attr("proc_macro_attribute", None, None),
 321     attr("proc_macro_derive(…)", Some("proc_macro_derive"), Some("proc_macro_derive(${0:Trait})")),
 322     attr(
 323         r#"recursion_limit = "…""#,
 324         Some("recursion_limit"),
 325         Some(r#"recursion_limit = "${0:128}""#),
 326     )
 327     .prefer_inner(),
 328     attr("repr(…)", Some("repr"), Some("repr(${0:C})")),
 329     attr("should_panic", Some("should_panic"), Some(r#"should_panic"#)),
 330     attr(
 331         r#"target_feature(enable = "…")"#,
 332         Some("target_feature"),
 333         Some(r#"target_feature(enable = "${0:feature}")"#),
 334     ),
 335     attr("test", None, None),
 336     attr("track_caller", None, None),
 337     attr("type_length_limit = …", Some("type_length_limit"), Some("type_length_limit = ${0:128}"))
 338         .prefer_inner(),
 339     attr("used", None, None),
 340     attr("warn(…)", Some("warn"), Some("warn(${0:lint})")),
 341     attr(
 342         r#"windows_subsystem = "…""#,
 343         Some("windows_subsystem"),
 344         Some(r#"windows_subsystem = "${0:subsystem}""#),
 345     )
 346     .prefer_inner(),
 347 ];
 348
 349 fn parse_comma_sep_expr(input: ast::TokenTree) -> Option<Vec<ast::Expr>> {
 350     let r_paren = input.r_paren_token()?;
 351     let tokens = input
 352         .syntax()
 353         .children_with_tokens()
 354         .skip(1)
 355         .take_while(|it| it.as_token() != Some(&r_paren));
 356     let input_expressions = tokens.group_by(|tok| tok.kind() == T![,]);
 357     Some(
 358         input_expressions
 359             .into_iter()
 360             .filter_map(|(is_sep, group)| (!is_sep).then(|| group))
 361             .filter_map(|mut tokens| syntax::hacks::parse_expr_from_str(&tokens.join("")))
 362             .collect::<Vec<ast::Expr>>(),
 363     )
 364 }
 365
 366 #[test]
 367 fn attributes_are_sorted() {
 368     let mut attrs = ATTRIBUTES.iter().map(|attr| attr.key());
 369     let mut prev = attrs.next().unwrap();
 370
 371     attrs.for_each(|next| {
 372         assert!(
 373             prev < next,
 374             r#"ATTRIBUTES array is not sorted, "{}" should come after "{}""#,
 375             prev,
 376             next
 377         );
 378         prev = next;
 379     });
 380 }