5 files changed, 859 insertions, 359 deletions

diff --git a/crates/ide_completion/Cargo.toml b/crates/ide_completion/Cargo.toml
index 6bd8a5500..ba81c9e04 100644
--- a/crates/ide_completion/Cargo.toml
+++ b/crates/ide_completion/Cargo.toml
@@ -15,6 +15,7 @@ itertools = "0.10.0"
 log = "0.4.8"
 rustc-hash = "1.1.0"
 either = "1.6.1"
+once_cell = "1.7"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
diff --git a/crates/ide_completion/src/completions/attribute.rs b/crates/ide_completion/src/completions/attribute.rs
index b1505c74b..610fec65a 100644
--- a/crates/ide_completion/src/completions/attribute.rs
+++ b/crates/ide_completion/src/completions/attribute.rs
@@ -3,9 +3,11 @@
 //! This module uses a bit of static metadata to provide completions
 //! for built-in attributes.
 
-use itertools::Itertools;
-use rustc_hash::FxHashSet;
-use syntax::{ast, AstNode, T};
+use std::mem;
+
+use once_cell::sync::Lazy;
+use rustc_hash::{FxHashMap, FxHashSet};
+use syntax::{ast, AstNode, NodeOrToken, SyntaxKind, T};
 
 use crate::{
     context::CompletionContext,
@@ -14,33 +16,40 @@ use crate::{
     Completions,
 };
 
-pub(crate) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
-    if ctx.mod_declaration_under_caret.is_some() {
-        return None;
-    }
+mod derive;
+mod lint;
+pub(crate) use self::lint::LintCompletion;
 
+pub(crate) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
     let attribute = ctx.attribute_under_caret.as_ref()?;
-    match (attribute.path(), attribute.token_tree()) {
-        (Some(path), Some(token_tree)) => {
-            let path = path.syntax().text();
-            if path == "derive" {
-                complete_derive(acc, ctx, token_tree)
-            } else if path == "feature" {
-                complete_lint(acc, ctx, token_tree, FEATURES)
-            } else if path == "allow" || path == "warn" || path == "deny" || path == "forbid" {
-                complete_lint(acc, ctx, token_tree.clone(), DEFAULT_LINT_COMPLETIONS);
-                complete_lint(acc, ctx, token_tree, CLIPPY_LINTS);
+    match (attribute.path().and_then(|p| p.as_single_name_ref()), attribute.token_tree()) {
+        (Some(path), Some(token_tree)) => match path.text().as_str() {
+            "derive" => derive::complete_derive(acc, ctx, token_tree),
+            "feature" => lint::complete_lint(acc, ctx, token_tree, FEATURES),
+            "allow" | "warn" | "deny" | "forbid" => {
+                lint::complete_lint(acc, ctx, token_tree.clone(), lint::DEFAULT_LINT_COMPLETIONS);
+                lint::complete_lint(acc, ctx, token_tree, CLIPPY_LINTS);
             }
-        }
-        (_, Some(_token_tree)) => {}
-        _ => complete_attribute_start(acc, ctx, attribute),
+            _ => (),
+        },
+        (None, Some(_)) => (),
+        _ => complete_new_attribute(acc, ctx, attribute),
     }
     Some(())
 }
 
-fn complete_attribute_start(acc: &mut Completions, ctx: &CompletionContext, attribute: &ast::Attr) {
+fn complete_new_attribute(acc: &mut Completions, ctx: &CompletionContext, attribute: &ast::Attr) {
+    let attribute_annotated_item_kind = attribute.syntax().parent().map(|it| it.kind());
+    let attributes = attribute_annotated_item_kind.and_then(|kind| {
+        if ast::Expr::can_cast(kind) {
+            Some(EXPR_ATTRIBUTES)
+        } else {
+            KIND_TO_ATTRIBUTES.get(&kind).copied()
+        }
+    });
     let is_inner = attribute.kind() == ast::AttrKind::Inner;
-    for attr_completion in ATTRIBUTES.iter().filter(|compl| is_inner || !compl.prefer_inner) {
+
+    let add_completion = |attr_completion: &AttrCompletion| {
         let mut item = CompletionItem::new(
             CompletionKind::Attribute,
             ctx.source_range(),
@@ -56,9 +65,19 @@ fn complete_attribute_start(acc: &mut Completions, ctx: &CompletionContext, attr
             item.insert_snippet(cap, snippet);
         }
 
-        if attribute.kind() == ast::AttrKind::Inner || !attr_completion.prefer_inner {
+        if is_inner || !attr_completion.prefer_inner {
             acc.add(item.build());
         }
+    };
+
+    match attributes {
+        Some(applicable) => applicable
+            .iter()
+            .flat_map(|name| ATTRIBUTES.binary_search_by(|attr| attr.key().cmp(name)).ok())
+            .flat_map(|idx| ATTRIBUTES.get(idx))
+            .for_each(add_completion),
+        None if is_inner => ATTRIBUTES.iter().for_each(add_completion),
+        None => ATTRIBUTES.iter().filter(|compl| !compl.prefer_inner).for_each(add_completion),
     }
 }
 
@@ -70,6 +89,10 @@ struct AttrCompletion {
 }
 
 impl AttrCompletion {
+    fn key(&self) -> &'static str {
+        self.lookup.unwrap_or(self.label)
+    }
+
     const fn prefer_inner(self) -> AttrCompletion {
         AttrCompletion { prefer_inner: true, ..self }
     }
@@ -83,26 +106,119 @@ const fn attr(
     AttrCompletion { label, lookup, snippet, prefer_inner: false }
 }
 
+macro_rules! attrs {
+    // attributes applicable to all items
+    [@ { item $($tt:tt)* } {$($acc:tt)*}] => {
+        attrs!(@ { $($tt)* } { $($acc)*, "deprecated", "doc", "dochidden", "docalias", "must_use", "no_mangle" })
+    };
+    // attributes applicable to all adts
+    [@ { adt $($tt:tt)* } {$($acc:tt)*}] => {
+        attrs!(@ { $($tt)* } { $($acc)*, "derive", "repr" })
+    };
+    // attributes applicable to all linkable things aka functions/statics
+    [@ { linkable $($tt:tt)* } {$($acc:tt)*}] => {
+        attrs!(@ { $($tt)* } { $($acc)*, "export_name", "link_name", "link_section" })
+    };
+    // error fallback for nicer error message
+    [@ { $ty:ident $($tt:tt)* } {$($acc:tt)*}] => {
+        compile_error!(concat!("unknown attr subtype ", stringify!($ty)))
+    };
+    // general push down accumulation
+    [@ { $lit:literal $($tt:tt)*} {$($acc:tt)*}] => {
+        attrs!(@ { $($tt)* } { $($acc)*, $lit })
+    };
+    [@ {$($tt:tt)+} {$($tt2:tt)*}] => {
+        compile_error!(concat!("Unexpected input ", stringify!($($tt)+)))
+    };
+    // final output construction
+    [@ {} {$($tt:tt)*}] => { &[$($tt)*] as _ };
+    // starting matcher
+    [$($tt:tt),*] => {
+        attrs!(@ { $($tt)* } { "allow", "cfg", "cfg_attr", "deny", "forbid", "warn" })
+    };
+}
+
+#[rustfmt::skip]
+static KIND_TO_ATTRIBUTES: Lazy<FxHashMap<SyntaxKind, &[&str]>> = Lazy::new(|| {
+    use SyntaxKind::*;
+    std::array::IntoIter::new([
+        (
+            SOURCE_FILE,
+            attrs!(
+                item,
+                "crate_name", "feature", "no_implicit_prelude", "no_main", "no_std",
+                "recursion_limit", "type_length_limit", "windows_subsystem"
+            ),
+        ),
+        (MODULE, attrs!(item, "no_implicit_prelude", "path")),
+        (ITEM_LIST, attrs!(item, "no_implicit_prelude")),
+        (MACRO_RULES, attrs!(item, "macro_export", "macro_use")),
+        (MACRO_DEF, attrs!(item)),
+        (EXTERN_CRATE, attrs!(item, "macro_use", "no_link")),
+        (USE, attrs!(item)),
+        (TYPE_ALIAS, attrs!(item)),
+        (STRUCT, attrs!(item, adt, "non_exhaustive")),
+        (ENUM, attrs!(item, adt, "non_exhaustive")),
+        (UNION, attrs!(item, adt)),
+        (CONST, attrs!(item)),
+        (
+            FN,
+            attrs!(
+                item, linkable,
+                "cold", "ignore", "inline", "must_use", "panic_handler", "proc_macro",
+                "proc_macro_derive", "proc_macro_attribute", "should_panic", "target_feature",
+                "test", "track_caller"
+            ),
+        ),
+        (STATIC, attrs!(item, linkable, "global_allocator", "used")),
+        (TRAIT, attrs!(item, "must_use")),
+        (IMPL, attrs!(item, "automatically_derived")),
+        (ASSOC_ITEM_LIST, attrs!(item)),
+        (EXTERN_BLOCK, attrs!(item, "link")),
+        (EXTERN_ITEM_LIST, attrs!(item, "link")),
+        (MACRO_CALL, attrs!()),
+        (SELF_PARAM, attrs!()),
+        (PARAM, attrs!()),
+        (RECORD_FIELD, attrs!()),
+        (VARIANT, attrs!("non_exhaustive")),
+        (TYPE_PARAM, attrs!()),
+        (CONST_PARAM, attrs!()),
+        (LIFETIME_PARAM, attrs!()),
+        (LET_STMT, attrs!()),
+        (EXPR_STMT, attrs!()),
+        (LITERAL, attrs!()),
+        (RECORD_EXPR_FIELD_LIST, attrs!()),
+        (RECORD_EXPR_FIELD, attrs!()),
+        (MATCH_ARM_LIST, attrs!()),
+        (MATCH_ARM, attrs!()),
+        (IDENT_PAT, attrs!()),
+        (RECORD_PAT_FIELD, attrs!()),
+    ])
+    .collect()
+});
+const EXPR_ATTRIBUTES: &[&str] = attrs!();
+
 /// https://doc.rust-lang.org/reference/attributes.html#built-in-attributes-index
+// Keep these sorted for the binary search!
 const ATTRIBUTES: &[AttrCompletion] = &[
     attr("allow(…)", Some("allow"), Some("allow(${0:lint})")),
     attr("automatically_derived", None, None),
-    attr("cfg_attr(…)", Some("cfg_attr"), Some("cfg_attr(${1:predicate}, ${0:attr})")),
     attr("cfg(…)", Some("cfg"), Some("cfg(${0:predicate})")),
+    attr("cfg_attr(…)", Some("cfg_attr"), Some("cfg_attr(${1:predicate}, ${0:attr})")),
     attr("cold", None, None),
     attr(r#"crate_name = """#, Some("crate_name"), Some(r#"crate_name = "${0:crate_name}""#))
         .prefer_inner(),
     attr("deny(…)", Some("deny"), Some("deny(${0:lint})")),
     attr(r#"deprecated"#, Some("deprecated"), Some(r#"deprecated"#)),
     attr("derive(…)", Some("derive"), Some(r#"derive(${0:Debug})"#)),
+    attr(r#"doc = "…""#, Some("doc"), Some(r#"doc = "${0:docs}""#)),
+    attr(r#"doc(alias = "…")"#, Some("docalias"), Some(r#"doc(alias = "${0:docs}")"#)),
+    attr(r#"doc(hidden)"#, Some("dochidden"), Some(r#"doc(hidden)"#)),
     attr(
         r#"export_name = "…""#,
         Some("export_name"),
         Some(r#"export_name = "${0:exported_symbol_name}""#),
     ),
-    attr(r#"doc(alias = "…")"#, Some("docalias"), Some(r#"doc(alias = "${0:docs}")"#)),
-    attr(r#"doc = "…""#, Some("doc"), Some(r#"doc = "${0:docs}""#)),
-    attr(r#"doc(hidden)"#, Some("dochidden"), Some(r#"doc(hidden)"#)),
     attr("feature(…)", Some("feature"), Some("feature(${0:flag})")).prefer_inner(),
     attr("forbid(…)", Some("forbid"), Some("forbid(${0:lint})")),
     // FIXME: resolve through macro resolution?
@@ -119,8 +235,8 @@ const ATTRIBUTES: &[AttrCompletion] = &[
     attr("macro_export", None, None),
     attr("macro_use", None, None),
     attr(r#"must_use"#, Some("must_use"), Some(r#"must_use"#)),
-    attr("no_link", None, None).prefer_inner(),
     attr("no_implicit_prelude", None, None).prefer_inner(),
+    attr("no_link", None, None).prefer_inner(),
     attr("no_main", None, None).prefer_inner(),
     attr("no_mangle", None, None),
     attr("no_std", None, None).prefer_inner(),
@@ -153,412 +269,492 @@ const ATTRIBUTES: &[AttrCompletion] = &[
     .prefer_inner(),
 ];
 
-fn complete_derive(acc: &mut Completions, ctx: &CompletionContext, derive_input: ast::TokenTree) {
-    if let Ok(existing_derives) = parse_comma_sep_input(derive_input) {
-        for derive_completion in DEFAULT_DERIVE_COMPLETIONS
-            .iter()
-            .filter(|completion| !existing_derives.contains(completion.label))
-        {
-            let mut components = vec![derive_completion.label];
-            components.extend(
-                derive_completion
-                    .dependencies
-                    .iter()
-                    .filter(|&&dependency| !existing_derives.contains(dependency)),
-            );
-            let lookup = components.join(", ");
-            let label = components.iter().rev().join(", ");
-            let mut item =
-                CompletionItem::new(CompletionKind::Attribute, ctx.source_range(), label);
-            item.lookup_by(lookup).kind(CompletionItemKind::Attribute);
-            item.add_to(acc);
-        }
-
-        for custom_derive_name in get_derive_names_in_scope(ctx).difference(&existing_derives) {
-            let mut item = CompletionItem::new(
-                CompletionKind::Attribute,
-                ctx.source_range(),
-                custom_derive_name,
-            );
-            item.kind(CompletionItemKind::Attribute);
-            item.add_to(acc);
-        }
-    }
-}
-
-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 lints_completions
-            .into_iter()
-            .filter(|completion| !existing_lints.contains(completion.label))
-        {
-            let mut item = CompletionItem::new(
-                CompletionKind::Attribute,
-                ctx.source_range(),
-                lint_completion.label,
-            );
-            item.kind(CompletionItemKind::Attribute).detail(lint_completion.description);
-            item.add_to(acc)
-        }
-    }
-}
-
-fn parse_comma_sep_input(derive_input: ast::TokenTree) -> Result<FxHashSet<String>, ()> {
-    match (derive_input.left_delimiter_token(), derive_input.right_delimiter_token()) {
-        (Some(left_paren), Some(right_paren))
-            if left_paren.kind() == T!['('] && right_paren.kind() == T![')'] =>
-        {
-            let mut input_derives = FxHashSet::default();
-            let mut current_derive = String::new();
-            for token in derive_input
-                .syntax()
-                .children_with_tokens()
-                .filter_map(|token| token.into_token())
-                .skip_while(|token| token != &left_paren)
-                .skip(1)
-                .take_while(|token| token != &right_paren)
-            {
-                if T![,] == token.kind() {
-                    if !current_derive.is_empty() {
-                        input_derives.insert(current_derive);
-                        current_derive = String::new();
-                    }
-                } else {
-                    current_derive.push_str(token.text().trim());
-                }
-            }
-
+fn parse_comma_sep_input(derive_input: ast::TokenTree) -> Option<FxHashSet<String>> {
+    let (l_paren, r_paren) = derive_input.l_paren_token().zip(derive_input.r_paren_token())?;
+    let mut input_derives = FxHashSet::default();
+    let mut current_derive = String::new();
+    for token in derive_input
+        .syntax()
+        .children_with_tokens()
+        .filter_map(NodeOrToken::into_token)
+        .skip_while(|token| token != &l_paren)
+        .skip(1)
+        .take_while(|token| token != &r_paren)
+    {
+        if token.kind() == T![,] {
             if !current_derive.is_empty() {
-                input_derives.insert(current_derive);
+                input_derives.insert(mem::take(&mut current_derive));
             }
-            Ok(input_derives)
+        } else {
+            current_derive.push_str(token.text().trim());
         }
-        _ => Err(()),
     }
-}
-
-fn get_derive_names_in_scope(ctx: &CompletionContext) -> FxHashSet<String> {
-    let mut result = FxHashSet::default();
-    ctx.scope.process_all_names(&mut |name, scope_def| {
-        if let hir::ScopeDef::MacroDef(mac) = scope_def {
-            // FIXME kind() doesn't check whether proc-macro is a derive
-            if mac.kind() == hir::MacroKind::Derive || mac.kind() == hir::MacroKind::ProcMacro {
-                result.insert(name.to_string());
-            }
-        }
-    });
-    result
-}
-
-struct DeriveCompletion {
-    label: &'static str,
-    dependencies: &'static [&'static str],
-}
-
-/// Standard Rust derives and the information about their dependencies
-/// (the dependencies are needed so that the main derive don't break the compilation when added)
-const DEFAULT_DERIVE_COMPLETIONS: &[DeriveCompletion] = &[
-    DeriveCompletion { label: "Clone", dependencies: &[] },
-    DeriveCompletion { label: "Copy", dependencies: &["Clone"] },
-    DeriveCompletion { label: "Debug", dependencies: &[] },
-    DeriveCompletion { label: "Default", dependencies: &[] },
-    DeriveCompletion { label: "Hash", dependencies: &[] },
-    DeriveCompletion { label: "PartialEq", dependencies: &[] },
-    DeriveCompletion { label: "Eq", dependencies: &["PartialEq"] },
-    DeriveCompletion { label: "PartialOrd", dependencies: &["PartialEq"] },
-    DeriveCompletion { label: "Ord", dependencies: &["PartialOrd", "Eq", "PartialEq"] },
-];
 
-pub(crate) struct LintCompletion {
-    pub(crate) label: &'static str,
-    pub(crate) description: &'static str,
+    if !current_derive.is_empty() {
+        input_derives.insert(current_derive);
+    }
+    Some(input_derives)
 }
 
-#[rustfmt::skip]
-const DEFAULT_LINT_COMPLETIONS: &[LintCompletion] = &[
-    LintCompletion { label: "absolute_paths_not_starting_with_crate", description: r#"fully qualified paths that start with a module name instead of `crate`, `self`, or an extern crate name"# },
-    LintCompletion { label: "anonymous_parameters", description: r#"detects anonymous parameters"# },
-    LintCompletion { label: "box_pointers", description: r#"use of owned (Box type) heap memory"# },
-    LintCompletion { label: "deprecated_in_future", description: r#"detects use of items that will be deprecated in a future version"# },
-    LintCompletion { label: "elided_lifetimes_in_paths", description: r#"hidden lifetime parameters in types are deprecated"# },
-    LintCompletion { label: "explicit_outlives_requirements", description: r#"outlives requirements can be inferred"# },
-    LintCompletion { label: "indirect_structural_match", description: r#"pattern with const indirectly referencing non-structural-match type"# },
-    LintCompletion { label: "keyword_idents", description: r#"detects edition keywords being used as an identifier"# },
-    LintCompletion { label: "macro_use_extern_crate", description: r#"the `#[macro_use]` attribute is now deprecated in favor of using macros via the module system"# },
-    LintCompletion { label: "meta_variable_misuse", description: r#"possible meta-variable misuse at macro definition"# },
-    LintCompletion { label: "missing_copy_implementations", description: r#"detects potentially-forgotten implementations of `Copy`"# },
-    LintCompletion { label: "missing_crate_level_docs", description: r#"detects crates with no crate-level documentation"# },
-    LintCompletion { label: "missing_debug_implementations", description: r#"detects missing implementations of Debug"# },
-    LintCompletion { label: "missing_docs", description: r#"detects missing documentation for public members"# },
-    LintCompletion { label: "missing_doc_code_examples", description: r#"detects publicly-exported items without code samples in their documentation"# },
-    LintCompletion { label: "non_ascii_idents", description: r#"detects non-ASCII identifiers"# },
-    LintCompletion { label: "private_doc_tests", description: r#"detects code samples in docs of private items not documented by rustdoc"# },
-    LintCompletion { label: "single_use_lifetimes", description: r#"detects lifetime parameters that are only used once"# },
-    LintCompletion { label: "trivial_casts", description: r#"detects trivial casts which could be removed"# },
-    LintCompletion { label: "trivial_numeric_casts", description: r#"detects trivial casts of numeric types which could be removed"# },
-    LintCompletion { label: "unaligned_references", description: r#"detects unaligned references to fields of packed structs"# },
-    LintCompletion { label: "unreachable_pub", description: r#"`pub` items not reachable from crate root"# },
-    LintCompletion { label: "unsafe_code", description: r#"usage of `unsafe` code"# },
-    LintCompletion { label: "unsafe_op_in_unsafe_fn", description: r#"unsafe operations in unsafe functions without an explicit unsafe block are deprecated"# },
-    LintCompletion { label: "unstable_features", description: r#"enabling unstable features (deprecated. do not use)"# },
-    LintCompletion { label: "unused_crate_dependencies", description: r#"crate dependencies that are never used"# },
-    LintCompletion { label: "unused_extern_crates", description: r#"extern crates that are never used"# },
-    LintCompletion { label: "unused_import_braces", description: r#"unnecessary braces around an imported item"# },
-    LintCompletion { label: "unused_lifetimes", description: r#"detects lifetime parameters that are never used"# },
-    LintCompletion { label: "unused_qualifications", description: r#"detects unnecessarily qualified names"# },
-    LintCompletion { label: "unused_results", description: r#"unused result of an expression in a statement"# },
-    LintCompletion { label: "variant_size_differences", description: r#"detects enums with widely varying variant sizes"# },
-    LintCompletion { label: "array_into_iter", description: r#"detects calling `into_iter` on arrays"# },
-    LintCompletion { label: "asm_sub_register", description: r#"using only a subset of a register for inline asm inputs"# },
-    LintCompletion { label: "bare_trait_objects", description: r#"suggest using `dyn Trait` for trait objects"# },
-    LintCompletion { label: "bindings_with_variant_name", description: r#"detects pattern bindings with the same name as one of the matched variants"# },
-    LintCompletion { label: "cenum_impl_drop_cast", description: r#"a C-like enum implementing Drop is cast"# },
-    LintCompletion { label: "clashing_extern_declarations", description: r#"detects when an extern fn has been declared with the same name but different types"# },
-    LintCompletion { label: "coherence_leak_check", description: r#"distinct impls distinguished only by the leak-check code"# },
-    LintCompletion { label: "confusable_idents", description: r#"detects visually confusable pairs between identifiers"# },
-    LintCompletion { label: "dead_code", description: r#"detect unused, unexported items"# },
-    LintCompletion { label: "deprecated", description: r#"detects use of deprecated items"# },
-    LintCompletion { label: "ellipsis_inclusive_range_patterns", description: r#"`...` range patterns are deprecated"# },
-    LintCompletion { label: "exported_private_dependencies", description: r#"public interface leaks type from a private dependency"# },
-    LintCompletion { label: "illegal_floating_point_literal_pattern", description: r#"floating-point literals cannot be used in patterns"# },
-    LintCompletion { label: "improper_ctypes", description: r#"proper use of libc types in foreign modules"# },
-    LintCompletion { label: "improper_ctypes_definitions", description: r#"proper use of libc types in foreign item definitions"# },
-    LintCompletion { label: "incomplete_features", description: r#"incomplete features that may function improperly in some or all cases"# },
-    LintCompletion { label: "inline_no_sanitize", description: r#"detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`"# },
-    LintCompletion { label: "intra_doc_link_resolution_failure", description: r#"failures in resolving intra-doc link targets"# },
-    LintCompletion { label: "invalid_codeblock_attributes", description: r#"codeblock attribute looks a lot like a known one"# },
-    LintCompletion { label: "invalid_value", description: r#"an invalid value is being created (such as a NULL reference)"# },
-    LintCompletion { label: "irrefutable_let_patterns", description: r#"detects irrefutable patterns in if-let and while-let statements"# },
-    LintCompletion { label: "late_bound_lifetime_arguments", description: r#"detects generic lifetime arguments in path segments with late bound lifetime parameters"# },
-    LintCompletion { label: "mixed_script_confusables", description: r#"detects Unicode scripts whose mixed script confusables codepoints are solely used"# },
-    LintCompletion { label: "mutable_borrow_reservation_conflict", description: r#"reservation of a two-phased borrow conflicts with other shared borrows"# },
-    LintCompletion { label: "non_camel_case_types", description: r#"types, variants, traits and type parameters should have camel case names"# },
-    LintCompletion { label: "non_shorthand_field_patterns", description: r#"using `Struct { x: x }` instead of `Struct { x }` in a pattern"# },
-    LintCompletion { label: "non_snake_case", description: r#"variables, methods, functions, lifetime parameters and modules should have snake case names"# },
-    LintCompletion { label: "non_upper_case_globals", description: r#"static constants should have uppercase identifiers"# },
-    LintCompletion { label: "no_mangle_generic_items", description: r#"generic items must be mangled"# },
-    LintCompletion { label: "overlapping_patterns", description: r#"detects overlapping patterns"# },
-    LintCompletion { label: "path_statements", description: r#"path statements with no effect"# },
-    LintCompletion { label: "private_in_public", description: r#"detect private items in public interfaces not caught by the old implementation"# },
-    LintCompletion { label: "proc_macro_derive_resolution_fallback", description: r#"detects proc macro derives using inaccessible names from parent modules"# },
-    LintCompletion { label: "redundant_semicolons", description: r#"detects unnecessary trailing semicolons"# },
-    LintCompletion { label: "renamed_and_removed_lints", description: r#"lints that have been renamed or removed"# },
-    LintCompletion { label: "safe_packed_borrows", description: r#"safe borrows of fields of packed structs were erroneously allowed"# },
-    LintCompletion { label: "stable_features", description: r#"stable features found in `#[feature]` directive"# },
-    LintCompletion { label: "trivial_bounds", description: r#"these bounds don't depend on an type parameters"# },
-    LintCompletion { label: "type_alias_bounds", description: r#"bounds in type aliases are not enforced"# },
-    LintCompletion { label: "tyvar_behind_raw_pointer", description: r#"raw pointer to an inference variable"# },
-    LintCompletion { label: "uncommon_codepoints", description: r#"detects uncommon Unicode codepoints in identifiers"# },
-    LintCompletion { label: "unconditional_recursion", description: r#"functions that cannot return without calling themselves"# },
-    LintCompletion { label: "unknown_lints", description: r#"unrecognized lint attribute"# },
-    LintCompletion { label: "unnameable_test_items", description: r#"detects an item that cannot be named being marked as `#[test_case]`"# },
-    LintCompletion { label: "unreachable_code", description: r#"detects unreachable code paths"# },
-    LintCompletion { label: "unreachable_patterns", description: r#"detects unreachable patterns"# },
-    LintCompletion { label: "unstable_name_collisions", description: r#"detects name collision with an existing but unstable method"# },
-    LintCompletion { label: "unused_allocation", description: r#"detects unnecessary allocations that can be eliminated"# },
-    LintCompletion { label: "unused_assignments", description: r#"detect assignments that will never be read"# },
-    LintCompletion { label: "unused_attributes", description: r#"detects attributes that were not used by the compiler"# },
-    LintCompletion { label: "unused_braces", description: r#"unnecessary braces around an expression"# },
-    LintCompletion { label: "unused_comparisons", description: r#"comparisons made useless by limits of the types involved"# },
-    LintCompletion { label: "unused_doc_comments", description: r#"detects doc comments that aren't used by rustdoc"# },
-    LintCompletion { label: "unused_features", description: r#"unused features found in crate-level `#[feature]` directives"# },
-    LintCompletion { label: "unused_imports", description: r#"imports that are never used"# },
-    LintCompletion { label: "unused_labels", description: r#"detects labels that are never used"# },
-    LintCompletion { label: "unused_macros", description: r#"detects macros that were not used"# },
-    LintCompletion { label: "unused_must_use", description: r#"unused result of a type flagged as `#[must_use]`"# },
-    LintCompletion { label: "unused_mut", description: r#"detect mut variables which don't need to be mutable"# },
-    LintCompletion { label: "unused_parens", description: r#"`if`, `match`, `while` and `return` do not need parentheses"# },
-    LintCompletion { label: "unused_unsafe", description: r#"unnecessary use of an `unsafe` block"# },
-    LintCompletion { label: "unused_variables", description: r#"detect variables which are not used in any way"# },
-    LintCompletion { label: "warnings", description: r#"mass-change the level for lints which produce warnings"# },
-    LintCompletion { label: "where_clauses_object_safety", description: r#"checks the object safety of where clauses"# },
-    LintCompletion { label: "while_true", description: r#"suggest using `loop { }` instead of `while true { }`"# },
-    LintCompletion { label: "ambiguous_associated_items", description: r#"ambiguous associated items"# },
-    LintCompletion { label: "arithmetic_overflow", description: r#"arithmetic operation overflows"# },
-    LintCompletion { label: "conflicting_repr_hints", description: r#"conflicts between `#[repr(..)]` hints that were previously accepted and used in practice"# },
-    LintCompletion { label: "const_err", description: r#"constant evaluation detected erroneous expression"# },
-    LintCompletion { label: "ill_formed_attribute_input", description: r#"ill-formed attribute inputs that were previously accepted and used in practice"# },
-    LintCompletion { label: "incomplete_include", description: r#"trailing content in included file"# },
-    LintCompletion { label: "invalid_type_param_default", description: r#"type parameter default erroneously allowed in invalid location"# },
-    LintCompletion { label: "macro_expanded_macro_exports_accessed_by_absolute_paths", description: r#"macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths"# },
-    LintCompletion { label: "missing_fragment_specifier", description: r#"detects missing fragment specifiers in unused `macro_rules!` patterns"# },
-    LintCompletion { label: "mutable_transmutes", description: r#"mutating transmuted &mut T from &T may cause undefined behavior"# },
-    LintCompletion { label: "no_mangle_const_items", description: r#"const items will not have their symbols exported"# },
-    LintCompletion { label: "order_dependent_trait_objects", description: r#"trait-object types were treated as different depending on marker-trait order"# },
-    LintCompletion { label: "overflowing_literals", description: r#"literal out of range for its type"# },
-    LintCompletion { label: "patterns_in_fns_without_body", description: r#"patterns in functions without body were erroneously allowed"# },
-    LintCompletion { label: "pub_use_of_private_extern_crate", description: r#"detect public re-exports of private extern crates"# },
-    LintCompletion { label: "soft_unstable", description: r#"a feature gate that doesn't break dependent crates"# },
-    LintCompletion { label: "unconditional_panic", description: r#"operation will cause a panic at runtime"# },
-    LintCompletion { label: "unknown_crate_types", description: r#"unknown crate type found in `#[crate_type]` directive"# },
-];
-
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     use expect_test::{expect, Expect};
 
     use crate::{test_utils::completion_list, CompletionKind};
 
+    #[test]
+    fn attributes_are_sorted() {
+        let mut attrs = ATTRIBUTES.iter().map(|attr| attr.key());
+        let mut prev = attrs.next().unwrap();
+
+        attrs.for_each(|next| {
+            assert!(
+                prev < next,
+                r#"ATTRIBUTES array is not sorted, "{}" should come after "{}""#,
+                prev,
+                next
+            );
+            prev = next;
+        });
+    }
+
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Attribute);
         expect.assert_eq(&actual);
     }
 
     #[test]
-    fn empty_derive_completion() {
+    fn test_attribute_completion_inside_nested_attr() {
+        check(r#"#[cfg($0)]"#, expect![[]])
+    }
+
+    #[test]
+    fn test_attribute_completion_with_existing_attr() {
+        check(
+            r#"#[no_mangle] #[$0] mcall!();"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+            "#]],
+        )
+    }
+
+    #[test]
+    fn complete_attribute_on_source_file() {
         check(
-            r#"
-#[derive($0)]
-struct Test {}
-        "#,
+            r#"#![$0]"#,
             expect![[r#"
-                at Clone
-                at Clone, Copy
-                at Debug
-                at Default
-                at Hash
-                at PartialEq
-                at PartialEq, Eq
-                at PartialEq, PartialOrd
-                at PartialEq, Eq, PartialOrd, Ord
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at crate_name = ""
+                at feature(…)
+                at no_implicit_prelude
+                at no_main
+                at no_std
+                at recursion_limit = …
+                at type_length_limit = …
+                at windows_subsystem = "…"
             "#]],
         );
     }
 
     #[test]
-    fn no_completion_for_incorrect_derive() {
+    fn complete_attribute_on_module() {
         check(
-            r#"
-#[derive{$0)]
-struct Test {}
-"#,
-            expect![[r#""#]],
-        )
+            r#"#[$0] mod foo;"#,
+            expect![[r#"
+            at allow(…)
+            at cfg(…)
+            at cfg_attr(…)
+            at deny(…)
+            at forbid(…)
+            at warn(…)
+            at deprecated
+            at doc = "…"
+            at doc(hidden)
+            at doc(alias = "…")
+            at must_use
+            at no_mangle
+            at path = "…"
+        "#]],
+        );
+        check(
+            r#"mod foo {#![$0]}"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at no_implicit_prelude
+            "#]],
+        );
     }
 
     #[test]
-    fn derive_with_input_completion() {
+    fn complete_attribute_on_macro_rules() {
         check(
-            r#"
-#[derive(serde::Serialize, PartialEq, $0)]
-struct Test {}
-"#,
+            r#"#[$0] macro_rules! foo {}"#,
             expect![[r#"
-                at Clone
-                at Clone, Copy
-                at Debug
-                at Default
-                at Hash
-                at Eq
-                at PartialOrd
-                at Eq, PartialOrd, Ord
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at macro_export
+                at macro_use
             "#]],
-        )
+        );
     }
 
     #[test]
-    fn test_attribute_completion() {
+    fn complete_attribute_on_macro_def() {
         check(
-            r#"#[$0]"#,
+            r#"#[$0] macro foo {}"#,
             expect![[r#"
                 at allow(…)
-                at automatically_derived
+                at cfg(…)
                 at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_extern_crate() {
+        check(
+            r#"#[$0] extern crate foo;"#,
+            expect![[r#"
+                at allow(…)
                 at cfg(…)
-                at cold
+                at cfg_attr(…)
                 at deny(…)
+                at forbid(…)
+                at warn(…)
                 at deprecated
-                at derive(…)
-                at export_name = "…"
+                at doc = "…"
+                at doc(hidden)
                 at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at macro_use
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_use() {
+        check(
+            r#"#[$0] use foo;"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
                 at doc = "…"
                 at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_type_alias() {
+        check(
+            r#"#[$0] type foo = ();"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
                 at forbid(…)
-                at ignore = "…"
-                at inline
-                at link
-                at link_name = "…"
-                at link_section = "…"
-                at macro_export
-                at macro_use
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
                 at must_use
                 at no_mangle
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_struct() {
+        check(
+            r#"#[$0] struct Foo;"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at derive(…)
+                at repr(…)
                 at non_exhaustive
-                at path = "…"
-                at proc_macro
-                at proc_macro_attribute
-                at proc_macro_derive(…)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_enum() {
+        check(
+            r#"#[$0] enum Foo {}"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at derive(…)
                 at repr(…)
-                at should_panic
-                at target_feature = "…"
-                at test
-                at track_caller
-                at used
+                at non_exhaustive
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_const() {
+        check(
+            r#"#[$0] const FOO: () = ();"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
                 at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
             "#]],
-        )
+        );
     }
 
     #[test]
-    fn test_attribute_completion_inside_nested_attr() {
-        check(r#"#[cfg($0)]"#, expect![[]])
+    fn complete_attribute_on_static() {
+        check(
+            r#"#[$0] static FOO: () = ()"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at export_name = "…"
+                at link_name = "…"
+                at link_section = "…"
+                at used
+            "#]],
+        );
     }
 
     #[test]
-    fn test_inner_attribute_completion() {
+    fn complete_attribute_on_trait() {
         check(
-            r"#![$0]",
+            r#"#[$0] trait Foo {}"#,
             expect![[r#"
                 at allow(…)
-                at automatically_derived
+                at cfg(…)
                 at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at must_use
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_impl() {
+        check(
+            r#"#[$0] impl () {}"#,
+            expect![[r#"
+                at allow(…)
                 at cfg(…)
-                at cold
-                at crate_name = ""
+                at cfg_attr(…)
                 at deny(…)
+                at forbid(…)
+                at warn(…)
                 at deprecated
-                at derive(…)
-                at export_name = "…"
+                at doc = "…"
+                at doc(hidden)
                 at doc(alias = "…")
+                at must_use
+                at no_mangle
+                at automatically_derived
+            "#]],
+        );
+        check(
+            r#"impl () {#![$0]}"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
                 at doc = "…"
                 at doc(hidden)
-                at feature(…)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_extern_block() {
+        check(
+            r#"#[$0] extern {}"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
                 at forbid(…)
-                at global_allocator
-                at ignore = "…"
-                at inline
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
+                at must_use
+                at no_mangle
                 at link
-                at link_name = "…"
-                at link_section = "…"
-                at macro_export
-                at macro_use
+            "#]],
+        );
+        check(
+            r#"extern {#![$0]}"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+                at deprecated
+                at doc = "…"
+                at doc(hidden)
+                at doc(alias = "…")
                 at must_use
-                at no_link
-                at no_implicit_prelude
-                at no_main
                 at no_mangle
-                at no_std
+                at link
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_variant() {
+        check(
+            r#"enum Foo { #[$0] Bar }"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
                 at non_exhaustive
-                at panic_handler
-                at path = "…"
-                at proc_macro
-                at proc_macro_attribute
-                at proc_macro_derive(…)
-                at recursion_limit = …
-                at repr(…)
-                at should_panic
-                at target_feature = "…"
-                at test
-                at track_caller
-                at type_length_limit = …
-                at used
+            "#]],
+        );
+    }
+
+    #[test]
+    fn complete_attribute_on_expr() {
+        check(
+            r#"fn main() { #[$0] foo() }"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
+                at warn(…)
+            "#]],
+        );
+        check(
+            r#"fn main() { #[$0] foo(); }"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at forbid(…)
                 at warn(…)
-                at windows_subsystem = "…"
             "#]],
         );
     }
diff --git a/crates/ide_completion/src/completions/attribute/derive.rs b/crates/ide_completion/src/completions/attribute/derive.rs
new file mode 100644
index 000000000..7b0a778a2
--- /dev/null
+++ b/crates/ide_completion/src/completions/attribute/derive.rs
@@ -0,0 +1,142 @@
+//! Completion for derives
+use itertools::Itertools;
+use rustc_hash::FxHashSet;
+use syntax::ast;
+
+use crate::{
+    context::CompletionContext,
+    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    Completions,
+};
+
+pub(super) fn complete_derive(
+    acc: &mut Completions,
+    ctx: &CompletionContext,
+    derive_input: ast::TokenTree,
+) {
+    if let Some(existing_derives) = super::parse_comma_sep_input(derive_input) {
+        for derive_completion in DEFAULT_DERIVE_COMPLETIONS
+            .iter()
+            .filter(|completion| !existing_derives.contains(completion.label))
+        {
+            let mut components = vec![derive_completion.label];
+            components.extend(
+                derive_completion
+                    .dependencies
+                    .iter()
+                    .filter(|&&dependency| !existing_derives.contains(dependency)),
+            );
+            let lookup = components.join(", ");
+            let label = components.iter().rev().join(", ");
+            let mut item =
+                CompletionItem::new(CompletionKind::Attribute, ctx.source_range(), label);
+            item.lookup_by(lookup).kind(CompletionItemKind::Attribute);
+            item.add_to(acc);
+        }
+
+        for custom_derive_name in get_derive_names_in_scope(ctx).difference(&existing_derives) {
+            let mut item = CompletionItem::new(
+                CompletionKind::Attribute,
+                ctx.source_range(),
+                custom_derive_name,
+            );
+            item.kind(CompletionItemKind::Attribute);
+            item.add_to(acc);
+        }
+    }
+}
+fn get_derive_names_in_scope(ctx: &CompletionContext) -> FxHashSet<String> {
+    let mut result = FxHashSet::default();
+    ctx.scope.process_all_names(&mut |name, scope_def| {
+        if let hir::ScopeDef::MacroDef(mac) = scope_def {
+            // FIXME kind() doesn't check whether proc-macro is a derive
+            if mac.kind() == hir::MacroKind::Derive || mac.kind() == hir::MacroKind::ProcMacro {
+                result.insert(name.to_string());
+            }
+        }
+    });
+    result
+}
+
+struct DeriveCompletion {
+    label: &'static str,
+    dependencies: &'static [&'static str],
+}
+
+/// Standard Rust derives and the information about their dependencies
+/// (the dependencies are needed so that the main derive don't break the compilation when added)
+const DEFAULT_DERIVE_COMPLETIONS: &[DeriveCompletion] = &[
+    DeriveCompletion { label: "Clone", dependencies: &[] },
+    DeriveCompletion { label: "Copy", dependencies: &["Clone"] },
+    DeriveCompletion { label: "Debug", dependencies: &[] },
+    DeriveCompletion { label: "Default", dependencies: &[] },
+    DeriveCompletion { label: "Hash", dependencies: &[] },
+    DeriveCompletion { label: "PartialEq", dependencies: &[] },
+    DeriveCompletion { label: "Eq", dependencies: &["PartialEq"] },
+    DeriveCompletion { label: "PartialOrd", dependencies: &["PartialEq"] },
+    DeriveCompletion { label: "Ord", dependencies: &["PartialOrd", "Eq", "PartialEq"] },
+];
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Attribute);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn empty_derive_completion() {
+        check(
+            r#"
+#[derive($0)]
+struct Test {}
+        "#,
+            expect![[r#"
+                at Clone
+                at Clone, Copy
+                at Debug
+                at Default
+                at Hash
+                at PartialEq
+                at PartialEq, Eq
+                at PartialEq, PartialOrd
+                at PartialEq, Eq, PartialOrd, Ord
+            "#]],
+        );
+    }
+
+    #[test]
+    fn no_completion_for_incorrect_derive() {
+        check(
+            r#"
+#[derive{$0)]
+struct Test {}
+"#,
+            expect![[r#""#]],
+        )
+    }
+
+    #[test]
+    fn derive_with_input_completion() {
+        check(
+            r#"
+#[derive(serde::Serialize, PartialEq, $0)]
+struct Test {}
+"#,
+            expect![[r#"
+                at Clone
+                at Clone, Copy
+                at Debug
+                at Default
+                at Hash
+                at Eq
+                at PartialOrd
+                at Eq, PartialOrd, Ord
+            "#]],
+        )
+    }
+}
diff --git a/crates/ide_completion/src/completions/attribute/lint.rs b/crates/ide_completion/src/completions/attribute/lint.rs
new file mode 100644
index 000000000..115c6cfe0
--- /dev/null
+++ b/crates/ide_completion/src/completions/attribute/lint.rs
@@ -0,0 +1,154 @@
+//! Completion for lints
+use syntax::ast;
+
+use crate::{
+    context::CompletionContext,
+    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    Completions,
+};
+
+pub(super) fn complete_lint(
+    acc: &mut Completions,
+    ctx: &CompletionContext,
+    derive_input: ast::TokenTree,
+    lints_completions: &[LintCompletion],
+) {
+    if let Some(existing_lints) = super::parse_comma_sep_input(derive_input) {
+        for lint_completion in lints_completions
+            .into_iter()
+            .filter(|completion| !existing_lints.contains(completion.label))
+        {
+            let mut item = CompletionItem::new(
+                CompletionKind::Attribute,
+                ctx.source_range(),
+                lint_completion.label,
+            );
+            item.kind(CompletionItemKind::Attribute).detail(lint_completion.description);
+            item.add_to(acc)
+        }
+    }
+}
+
+pub(crate) struct LintCompletion {
+    pub(crate) label: &'static str,
+    pub(crate) description: &'static str,
+}
+
+#[rustfmt::skip]
+pub(super) const DEFAULT_LINT_COMPLETIONS: &[LintCompletion] = &[
+    LintCompletion { label: "absolute_paths_not_starting_with_crate", description: r#"fully qualified paths that start with a module name instead of `crate`, `self`, or an extern crate name"# },
+    LintCompletion { label: "anonymous_parameters", description: r#"detects anonymous parameters"# },
+    LintCompletion { label: "box_pointers", description: r#"use of owned (Box type) heap memory"# },
+    LintCompletion { label: "deprecated_in_future", description: r#"detects use of items that will be deprecated in a future version"# },
+    LintCompletion { label: "elided_lifetimes_in_paths", description: r#"hidden lifetime parameters in types are deprecated"# },
+    LintCompletion { label: "explicit_outlives_requirements", description: r#"outlives requirements can be inferred"# },
+    LintCompletion { label: "indirect_structural_match", description: r#"pattern with const indirectly referencing non-structural-match type"# },
+    LintCompletion { label: "keyword_idents", description: r#"detects edition keywords being used as an identifier"# },
+    LintCompletion { label: "macro_use_extern_crate", description: r#"the `#[macro_use]` attribute is now deprecated in favor of using macros via the module system"# },
+    LintCompletion { label: "meta_variable_misuse", description: r#"possible meta-variable misuse at macro definition"# },
+    LintCompletion { label: "missing_copy_implementations", description: r#"detects potentially-forgotten implementations of `Copy`"# },
+    LintCompletion { label: "missing_crate_level_docs", description: r#"detects crates with no crate-level documentation"# },
+    LintCompletion { label: "missing_debug_implementations", description: r#"detects missing implementations of Debug"# },
+    LintCompletion { label: "missing_docs", description: r#"detects missing documentation for public members"# },
+    LintCompletion { label: "missing_doc_code_examples", description: r#"detects publicly-exported items without code samples in their documentation"# },
+    LintCompletion { label: "non_ascii_idents", description: r#"detects non-ASCII identifiers"# },
+    LintCompletion { label: "private_doc_tests", description: r#"detects code samples in docs of private items not documented by rustdoc"# },
+    LintCompletion { label: "single_use_lifetimes", description: r#"detects lifetime parameters that are only used once"# },
+    LintCompletion { label: "trivial_casts", description: r#"detects trivial casts which could be removed"# },
+    LintCompletion { label: "trivial_numeric_casts", description: r#"detects trivial casts of numeric types which could be removed"# },
+    LintCompletion { label: "unaligned_references", description: r#"detects unaligned references to fields of packed structs"# },
+    LintCompletion { label: "unreachable_pub", description: r#"`pub` items not reachable from crate root"# },
+    LintCompletion { label: "unsafe_code", description: r#"usage of `unsafe` code"# },
+    LintCompletion { label: "unsafe_op_in_unsafe_fn", description: r#"unsafe operations in unsafe functions without an explicit unsafe block are deprecated"# },
+    LintCompletion { label: "unstable_features", description: r#"enabling unstable features (deprecated. do not use)"# },
+    LintCompletion { label: "unused_crate_dependencies", description: r#"crate dependencies that are never used"# },
+    LintCompletion { label: "unused_extern_crates", description: r#"extern crates that are never used"# },
+    LintCompletion { label: "unused_import_braces", description: r#"unnecessary braces around an imported item"# },
+    LintCompletion { label: "unused_lifetimes", description: r#"detects lifetime parameters that are never used"# },
+    LintCompletion { label: "unused_qualifications", description: r#"detects unnecessarily qualified names"# },
+    LintCompletion { label: "unused_results", description: r#"unused result of an expression in a statement"# },
+    LintCompletion { label: "variant_size_differences", description: r#"detects enums with widely varying variant sizes"# },
+    LintCompletion { label: "array_into_iter", description: r#"detects calling `into_iter` on arrays"# },
+    LintCompletion { label: "asm_sub_register", description: r#"using only a subset of a register for inline asm inputs"# },
+    LintCompletion { label: "bare_trait_objects", description: r#"suggest using `dyn Trait` for trait objects"# },
+    LintCompletion { label: "bindings_with_variant_name", description: r#"detects pattern bindings with the same name as one of the matched variants"# },
+    LintCompletion { label: "cenum_impl_drop_cast", description: r#"a C-like enum implementing Drop is cast"# },
+    LintCompletion { label: "clashing_extern_declarations", description: r#"detects when an extern fn has been declared with the same name but different types"# },
+    LintCompletion { label: "coherence_leak_check", description: r#"distinct impls distinguished only by the leak-check code"# },
+    LintCompletion { label: "confusable_idents", description: r#"detects visually confusable pairs between identifiers"# },
+    LintCompletion { label: "dead_code", description: r#"detect unused, unexported items"# },
+    LintCompletion { label: "deprecated", description: r#"detects use of deprecated items"# },
+    LintCompletion { label: "ellipsis_inclusive_range_patterns", description: r#"`...` range patterns are deprecated"# },
+    LintCompletion { label: "exported_private_dependencies", description: r#"public interface leaks type from a private dependency"# },
+    LintCompletion { label: "illegal_floating_point_literal_pattern", description: r#"floating-point literals cannot be used in patterns"# },
+    LintCompletion { label: "improper_ctypes", description: r#"proper use of libc types in foreign modules"# },
+    LintCompletion { label: "improper_ctypes_definitions", description: r#"proper use of libc types in foreign item definitions"# },
+    LintCompletion { label: "incomplete_features", description: r#"incomplete features that may function improperly in some or all cases"# },
+    LintCompletion { label: "inline_no_sanitize", description: r#"detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`"# },
+    LintCompletion { label: "intra_doc_link_resolution_failure", description: r#"failures in resolving intra-doc link targets"# },
+    LintCompletion { label: "invalid_codeblock_attributes", description: r#"codeblock attribute looks a lot like a known one"# },
+    LintCompletion { label: "invalid_value", description: r#"an invalid value is being created (such as a NULL reference)"# },
+    LintCompletion { label: "irrefutable_let_patterns", description: r#"detects irrefutable patterns in if-let and while-let statements"# },
+    LintCompletion { label: "late_bound_lifetime_arguments", description: r#"detects generic lifetime arguments in path segments with late bound lifetime parameters"# },
+    LintCompletion { label: "mixed_script_confusables", description: r#"detects Unicode scripts whose mixed script confusables codepoints are solely used"# },
+    LintCompletion { label: "mutable_borrow_reservation_conflict", description: r#"reservation of a two-phased borrow conflicts with other shared borrows"# },
+    LintCompletion { label: "non_camel_case_types", description: r#"types, variants, traits and type parameters should have camel case names"# },
+    LintCompletion { label: "non_shorthand_field_patterns", description: r#"using `Struct { x: x }` instead of `Struct { x }` in a pattern"# },
+    LintCompletion { label: "non_snake_case", description: r#"variables, methods, functions, lifetime parameters and modules should have snake case names"# },
+    LintCompletion { label: "non_upper_case_globals", description: r#"static constants should have uppercase identifiers"# },
+    LintCompletion { label: "no_mangle_generic_items", description: r#"generic items must be mangled"# },
+    LintCompletion { label: "overlapping_patterns", description: r#"detects overlapping patterns"# },
+    LintCompletion { label: "path_statements", description: r#"path statements with no effect"# },
+    LintCompletion { label: "private_in_public", description: r#"detect private items in public interfaces not caught by the old implementation"# },
+    LintCompletion { label: "proc_macro_derive_resolution_fallback", description: r#"detects proc macro derives using inaccessible names from parent modules"# },
+    LintCompletion { label: "redundant_semicolons", description: r#"detects unnecessary trailing semicolons"# },
+    LintCompletion { label: "renamed_and_removed_lints", description: r#"lints that have been renamed or removed"# },
+    LintCompletion { label: "safe_packed_borrows", description: r#"safe borrows of fields of packed structs were erroneously allowed"# },
+    LintCompletion { label: "stable_features", description: r#"stable features found in `#[feature]` directive"# },
+    LintCompletion { label: "trivial_bounds", description: r#"these bounds don't depend on an type parameters"# },
+    LintCompletion { label: "type_alias_bounds", description: r#"bounds in type aliases are not enforced"# },
+    LintCompletion { label: "tyvar_behind_raw_pointer", description: r#"raw pointer to an inference variable"# },
+    LintCompletion { label: "uncommon_codepoints", description: r#"detects uncommon Unicode codepoints in identifiers"# },
+    LintCompletion { label: "unconditional_recursion", description: r#"functions that cannot return without calling themselves"# },
+    LintCompletion { label: "unknown_lints", description: r#"unrecognized lint attribute"# },
+    LintCompletion { label: "unnameable_test_items", description: r#"detects an item that cannot be named being marked as `#[test_case]`"# },
+    LintCompletion { label: "unreachable_code", description: r#"detects unreachable code paths"# },
+    LintCompletion { label: "unreachable_patterns", description: r#"detects unreachable patterns"# },
+    LintCompletion { label: "unstable_name_collisions", description: r#"detects name collision with an existing but unstable method"# },
+    LintCompletion { label: "unused_allocation", description: r#"detects unnecessary allocations that can be eliminated"# },
+    LintCompletion { label: "unused_assignments", description: r#"detect assignments that will never be read"# },
+    LintCompletion { label: "unused_attributes", description: r#"detects attributes that were not used by the compiler"# },
+    LintCompletion { label: "unused_braces", description: r#"unnecessary braces around an expression"# },
+    LintCompletion { label: "unused_comparisons", description: r#"comparisons made useless by limits of the types involved"# },
+    LintCompletion { label: "unused_doc_comments", description: r#"detects doc comments that aren't used by rustdoc"# },
+    LintCompletion { label: "unused_features", description: r#"unused features found in crate-level `#[feature]` directives"# },
+    LintCompletion { label: "unused_imports", description: r#"imports that are never used"# },
+    LintCompletion { label: "unused_labels", description: r#"detects labels that are never used"# },
+    LintCompletion { label: "unused_macros", description: r#"detects macros that were not used"# },
+    LintCompletion { label: "unused_must_use", description: r#"unused result of a type flagged as `#[must_use]`"# },
+    LintCompletion { label: "unused_mut", description: r#"detect mut variables which don't need to be mutable"# },
+    LintCompletion { label: "unused_parens", description: r#"`if`, `match`, `while` and `return` do not need parentheses"# },
+    LintCompletion { label: "unused_unsafe", description: r#"unnecessary use of an `unsafe` block"# },
+    LintCompletion { label: "unused_variables", description: r#"detect variables which are not used in any way"# },
+    LintCompletion { label: "warnings", description: r#"mass-change the level for lints which produce warnings"# },
+    LintCompletion { label: "where_clauses_object_safety", description: r#"checks the object safety of where clauses"# },
+    LintCompletion { label: "while_true", description: r#"suggest using `loop { }` instead of `while true { }`"# },
+    LintCompletion { label: "ambiguous_associated_items", description: r#"ambiguous associated items"# },
+    LintCompletion { label: "arithmetic_overflow", description: r#"arithmetic operation overflows"# },
+    LintCompletion { label: "conflicting_repr_hints", description: r#"conflicts between `#[repr(..)]` hints that were previously accepted and used in practice"# },
+    LintCompletion { label: "const_err", description: r#"constant evaluation detected erroneous expression"# },
+    LintCompletion { label: "ill_formed_attribute_input", description: r#"ill-formed attribute inputs that were previously accepted and used in practice"# },
+    LintCompletion { label: "incomplete_include", description: r#"trailing content in included file"# },
+    LintCompletion { label: "invalid_type_param_default", description: r#"type parameter default erroneously allowed in invalid location"# },
+    LintCompletion { label: "macro_expanded_macro_exports_accessed_by_absolute_paths", description: r#"macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths"# },
+    LintCompletion { label: "missing_fragment_specifier", description: r#"detects missing fragment specifiers in unused `macro_rules!` patterns"# },
+    LintCompletion { label: "mutable_transmutes", description: r#"mutating transmuted &mut T from &T may cause undefined behavior"# },
+    LintCompletion { label: "no_mangle_const_items", description: r#"const items will not have their symbols exported"# },
+    LintCompletion { label: "order_dependent_trait_objects", description: r#"trait-object types were treated as different depending on marker-trait order"# },
+    LintCompletion { label: "overflowing_literals", description: r#"literal out of range for its type"# },
+    LintCompletion { label: "patterns_in_fns_without_body", description: r#"patterns in functions without body were erroneously allowed"# },
+    LintCompletion { label: "pub_use_of_private_extern_crate", description: r#"detect public re-exports of private extern crates"# },
+    LintCompletion { label: "soft_unstable", description: r#"a feature gate that doesn't break dependent crates"# },
+    LintCompletion { label: "unconditional_panic", description: r#"operation will cause a panic at runtime"# },
+    LintCompletion { label: "unknown_crate_types", description: r#"unknown crate type found in `#[crate_type]` directive"# },
+];
diff --git a/crates/syntax/src/ast/node_ext.rs b/crates/syntax/src/ast/node_ext.rs
index df8f98b5b..884fe0739 100644
--- a/crates/syntax/src/ast/node_ext.rs
+++ b/crates/syntax/src/ast/node_ext.rs
@@ -243,6 +243,13 @@ impl ast::Path {
         }
     }
 
+    pub fn as_single_name_ref(&self) -> Option<ast::NameRef> {
+        match self.qualifier() {
+            Some(_) => None,
+            None => self.segment()?.name_ref(),
+        }
+    }
+
     pub fn first_qualifier_or_self(&self) -> ast::Path {
         successors(Some(self.clone()), ast::Path::qualifier).last().unwrap()
     }