Use the same abstraction for attrs and docs

Doc comments *are* attributes, so there's no reason to have two crates
here.

Author: matklad

crates/hir/src/code_model.rs

@@ -1771,21 +1771,16 @@ impl_from!(
 
 pub trait HasAttrs {
     fn attrs(self, db: &dyn HirDatabase) -> Attrs;
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation>;
 }
 
 impl<T: Into<AttrDef>> HasAttrs for T {
     fn attrs(self, db: &dyn HirDatabase) -> Attrs {
         let def: AttrDef = self.into();
         db.attrs(def.into())
     }
-}
-
-pub trait Docs {
-    fn docs(&self, db: &dyn HirDatabase) -> Option<Documentation>;
-}
-impl<T: Into<AttrDef> + Copy> Docs for T {
-    fn docs(&self, db: &dyn HirDatabase) -> Option<Documentation> {
-        let def: AttrDef = (*self).into();
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+        let def: AttrDef = self.into();
         db.documentation(def.into())
     }
 }

crates/hir/src/lib.rs

@@ -34,7 +34,7 @@ mod has_source;
 pub use crate::{
     code_model::{
         Access, Adt, AsAssocItem, AssocItem, AssocItemContainer, AttrDef, Callable, CallableKind,
-        Const, Crate, CrateDependency, DefWithBody, Docs, Enum, EnumVariant, Field, FieldSource,
+        Const, Crate, CrateDependency, DefWithBody, Enum, EnumVariant, Field, FieldSource,
         Function, GenericDef, HasAttrs, HasVisibility, ImplDef, Local, MacroDef, Module, ModuleDef,
         ScopeDef, Static, Struct, Trait, Type, TypeAlias, TypeParam, Union, VariantDef, Visibility,
     },

crates/ide/src/call_info.rs

@@ -1,6 +1,6 @@
 //! FIXME: write short doc here
 use either::Either;
-use hir::{Docs, HirDisplay, Semantics, Type};
+use hir::{HasAttrs, HirDisplay, Semantics, Type};
 use ide_db::RootDatabase;
 use stdx::format_to;
 use syntax::{

crates/ide/src/completion/complete_trait_impl.rs

@@ -32,7 +32,7 @@
 //! ```
 
 use assists::utils::get_missing_assoc_items;
-use hir::{self, Docs, HasSource};
+use hir::{self, HasAttrs, HasSource};
 use syntax::{
     ast::{self, edit, Impl},
     AstNode, SyntaxKind, SyntaxNode, TextRange, T,

crates/ide/src/completion/presentation.rs

@@ -1,7 +1,7 @@
 //! This modules takes care of rendering various definitions as completion items.
 //! It also handles scoring (sorting) completions.
 
-use hir::{Docs, HasAttrs, HasSource, HirDisplay, ModPath, ScopeDef, StructKind, Type};
+use hir::{HasAttrs, HasSource, HirDisplay, ModPath, ScopeDef, StructKind, Type};
 use itertools::Itertools;
 use syntax::ast::NameOwner;
 use test_utils::mark;