Set documentation field in SCIP from doc comment

Previously, the documentation field was the same as the text shown to
users when they hover over that symbol. The documentation should
really just be the doc comment, and as of rust-lang#16179 the signature is
already stored in the signatureDocumentation field.

Author: Wilfred

crates/ide/src/static_index.rs

@@ -1,14 +1,16 @@
 //! This module provides `StaticIndex` which is used for powering
 //! read-only code browsers and emitting LSIF
 
-use hir::{db::HirDatabase, Crate, HirFileIdExt, Module};
+use hir::{db::HirDatabase, Crate, HirFileIdExt, Module, Semantics};
 use ide_db::{
     base_db::{FileId, FileRange, SourceDatabaseExt},
     defs::Definition,
+    documentation::Documentation,
+    famous_defs::FamousDefs,
     helpers::get_definition,
     FxHashMap, FxHashSet, RootDatabase,
 };
-use syntax::{AstNode, SyntaxKind::*, TextRange, T};
+use syntax::{AstNode, SyntaxKind::*, SyntaxNode, TextRange, T};
 
 use crate::inlay_hints::InlayFieldsToResolve;
 use crate::navigation_target::UpmappingResult;
@@ -22,7 +24,7 @@ use crate::{
 
 /// A static representation of fully analyzed source code.
 ///
-/// The intended use-case is powering read-only code browsers and emitting LSIF
+/// The intended use-case is powering read-only code browsers and emitting LSIF/SCIP.
 #[derive(Debug)]
 pub struct StaticIndex<'a> {
     pub files: Vec<StaticIndexedFile>,
@@ -40,6 +42,7 @@ pub struct ReferenceData {
 
 #[derive(Debug)]
 pub struct TokenStaticData {
+    pub documentation: Option<Documentation>,
     pub hover: Option<HoverResult>,
     pub definition: Option<FileRange>,
     pub references: Vec<ReferenceData>,
@@ -103,6 +106,19 @@ fn all_modules(db: &dyn HirDatabase) -> Vec<Module> {
     modules
 }
 
+fn documentation_for_definition(
+    sema: &Semantics<'_, RootDatabase>,
+    def: Definition,
+    scope_node: &SyntaxNode,
+) -> Option<Documentation> {
+    let famous_defs = match &def {
+        Definition::BuiltinType(_) => Some(FamousDefs(sema, sema.scope(scope_node)?.krate())),
+        _ => None,
+    };
+
+    def.docs(sema.db, famous_defs.as_ref())
+}
+
 impl StaticIndex<'_> {
     fn add_file(&mut self, file_id: FileId) {
         let current_crate = crates_for(self.db, file_id).pop().map(Into::into);
@@ -169,6 +185,7 @@ impl StaticIndex<'_> {
                 *it
             } else {
                 let it = self.tokens.insert(TokenStaticData {
+                    documentation: documentation_for_definition(&sema, def, &node),
                     hover: hover_for_definition(&sema, file_id, def, &node, &hover_config),
                     definition: def.try_to_nav(self.db).map(UpmappingResult::call_site).map(|it| {
                         FileRange { file_id: it.file_id, range: it.focus_or_full_range() }

crates/rust-analyzer/src/cli/scip.rs

@@ -135,12 +135,11 @@ impl flags::Scip {
                     }
 
                     if symbols_emitted.insert(id) {
-                        let documentation = token
-                            .hover
-                            .as_ref()
-                            .map(|hover| hover.markup.as_str())
-                            .filter(|it| !it.is_empty())
-                            .map(|it| vec![it.to_owned()]);
+                        let documentation = match &token.documentation {
+                            Some(doc) => vec![doc.as_str().to_owned()],
+                            None => vec![],
+                        };
+
                         let position_encoding =
                             scip_types::PositionEncoding::UTF8CodeUnitOffsetFromLineStart.into();
                         let signature_documentation =
@@ -153,7 +152,7 @@ impl flags::Scip {
                             });
                         let symbol_info = scip_types::SymbolInformation {
                             symbol: symbol.clone(),
-                            documentation: documentation.unwrap_or_default(),
+                            documentation,
                             relationships: Vec::new(),
                             special_fields: Default::default(),
                             kind: symbol_kind(token.kind).into(),
@@ -599,4 +598,22 @@ pub mod example_mod {
             "rust-analyzer cargo main . MyTypeAlias#",
         );
     }
+
+    #[test]
+    fn documentation_matches_doc_comment() {
+        let s = "/// foo\nfn bar() {}";
+
+        let mut host = AnalysisHost::default();
+        let change_fixture = ChangeFixture::parse(s);
+        host.raw_database_mut().apply_change(change_fixture.change);
+
+        let analysis = host.analysis();
+        let si = StaticIndex::compute(&analysis);
+
+        let file = si.files.first().unwrap();
+        let (_, token_id) = file.tokens.first().unwrap();
+        let token = si.tokens.get(*token_id).unwrap();
+
+        assert_eq!(token.documentation.as_ref().map(|d| d.as_str()), Some("foo"));
+    }
 }