1 files changed, 151 insertions, 0 deletions

diff --git a/crates/ide/src/goto_type_definition.rs b/crates/ide/src/goto_type_definition.rs
new file mode 100644
index 000000000..4a151b150
--- /dev/null
+++ b/crates/ide/src/goto_type_definition.rs
@@ -0,0 +1,151 @@
+use ide_db::RootDatabase;
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
+
+use crate::{display::ToNav, FilePosition, NavigationTarget, RangeInfo};
+
+// Feature: Go to Type Definition
+//
+// Navigates to the type of an identifier.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Go to Type Definition*
+// |===
+pub(crate) fn goto_type_definition(
+    db: &RootDatabase,
+    position: FilePosition,
+) -> Option<RangeInfo<Vec<NavigationTarget>>> {
+    let sema = hir::Semantics::new(db);
+
+    let file: ast::SourceFile = sema.parse(position.file_id);
+    let token: SyntaxToken = pick_best(file.syntax().token_at_offset(position.offset))?;
+    let token: SyntaxToken = sema.descend_into_macros(token);
+
+    let (ty, node) = sema.ancestors_with_macros(token.parent()).find_map(|node| {
+        let ty = match_ast! {
+            match node {
+                ast::Expr(it) => sema.type_of_expr(&it)?,
+                ast::Pat(it) => sema.type_of_pat(&it)?,
+                ast::SelfParam(it) => sema.type_of_self(&it)?,
+                _ => return None,
+            }
+        };
+
+        Some((ty, node))
+    })?;
+
+    let adt_def = ty.autoderef(db).filter_map(|ty| ty.as_adt()).last()?;
+
+    let nav = adt_def.to_nav(db);
+    Some(RangeInfo::new(node.text_range(), vec![nav]))
+}
+
+fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
+    return tokens.max_by_key(priority);
+    fn priority(n: &SyntaxToken) -> usize {
+        match n.kind() {
+            IDENT | INT_NUMBER | T![self] => 2,
+            kind if kind.is_trivia() => 0,
+            _ => 1,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use base_db::FileRange;
+
+    use crate::mock_analysis::MockAnalysis;
+
+    fn check(ra_fixture: &str) {
+        let (mock, position) = MockAnalysis::with_files_and_position(ra_fixture);
+        let (expected, data) = mock.annotation();
+        assert!(data.is_empty());
+        let analysis = mock.analysis();
+
+        let mut navs = analysis.goto_type_definition(position).unwrap().unwrap().info;
+        assert_eq!(navs.len(), 1);
+        let nav = navs.pop().unwrap();
+        assert_eq!(expected, FileRange { file_id: nav.file_id, range: nav.focus_or_full_range() });
+    }
+
+    #[test]
+    fn goto_type_definition_works_simple() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+fn foo() {
+    let f: Foo; f<|>
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_works_simple_ref() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+fn foo() {
+    let f: &Foo; f<|>
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_works_through_macro() {
+        check(
+            r#"
+macro_rules! id { ($($tt:tt)*) => { $($tt)* } }
+struct Foo {}
+     //^^^
+id! {
+    fn bar() { let f<|> = Foo {}; }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_for_param() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+fn foo(<|>f: Foo) {}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_for_tuple_field() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+struct Bar(Foo);
+fn foo() {
+    let bar = Bar(Foo);
+    bar.<|>0;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_self_param() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+impl Foo {
+    fn f(&self<|>) {}
+}
+"#,
+        )
+    }
+}