Merge #912

912: Make goto definition/hover work for associated items r=matklad a=kjeremy

Just functions so far. Looking for comments.

Fixes #911
Towards #832

Co-authored-by: kjeremy <[email protected]>
Co-authored-by: Jeremy Kolb <[email protected]>

3 files changed, 62 insertions, 5 deletions

diff --git a/crates/ra_ide_api/src/goto_definition.rs b/crates/ra_ide_api/src/goto_definition.rs
index 9ec179593..364263d9b 100644
--- a/crates/ra_ide_api/src/goto_definition.rs
+++ b/crates/ra_ide_api/src/goto_definition.rs
@@ -47,9 +47,10 @@ pub(crate) fn reference_definition(
     name_ref: &ast::NameRef,
 ) -> ReferenceResult {
     use self::ReferenceResult::*;
-    if let Some(function) =
-        hir::source_binder::function_from_child_node(db, file_id, name_ref.syntax())
-    {
+
+    let function = hir::source_binder::function_from_child_node(db, file_id, name_ref.syntax());
+
+    if let Some(function) = function {
         // Check if it is a method
         if let Some(method_call) = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast) {
             tested_by!(goto_definition_works_for_methods);
@@ -122,9 +123,29 @@ pub(crate) fn reference_definition(
             Some(Resolution::SelfType(_impl_block)) => {
                 // TODO: go to the implemented type
             }
-            None => {}
+            None => {
+                // If we failed to resolve then check associated items
+                if let Some(function) = function {
+                    // Should we do this above and then grab path from the PathExpr?
+                    if let Some(path_expr) =
+                        name_ref.syntax().ancestors().find_map(ast::PathExpr::cast)
+                    {
+                        let infer_result = function.infer(db);
+                        let source_map = function.body_source_map(db);
+                        let expr = ast::Expr::cast(path_expr.syntax()).unwrap();
+
+                        if let Some(res) = source_map
+                            .node_expr(expr)
+                            .and_then(|it| infer_result.assoc_resolutions_for_expr(it.into()))
+                        {
+                            return Exact(NavigationTarget::from_impl_item(db, res));
+                        }
+                    }
+                }
+            }
         }
     }
+
     // If that fails try the index based approach.
     let navs = crate::symbol_index::index_resolve(db, name_ref)
         .into_iter()
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 8ec60090d..bcd052c8b 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -512,4 +512,26 @@ mod tests {
         let hover = analysis.hover(position).unwrap().unwrap();
         assert_eq!(trim_markup_opt(hover.info.first()), Some("Thing"));
     }
+
+    #[test]
+    fn test_hover_infer_associated_method_exact() {
+        let (analysis, position) = single_file_with_position(
+            "
+            struct Thing { x: u32 }
+
+            impl Thing {
+                fn new() -> Thing {
+                    Thing { x: 0 }
+                }
+            }
+
+            fn main() {
+                let foo_test = Thing::new<|>();
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("fn new() -> Thing"));
+        assert_eq!(hover.info.is_exact(), true);
+    }
 }
diff --git a/crates/ra_ide_api/src/navigation_target.rs b/crates/ra_ide_api/src/navigation_target.rs
index 6538081ac..d806cb368 100644
--- a/crates/ra_ide_api/src/navigation_target.rs
+++ b/crates/ra_ide_api/src/navigation_target.rs
@@ -3,7 +3,7 @@ use ra_syntax::{
     SyntaxNode, SyntaxNodePtr, AstNode, SmolStr, TextRange, ast,
     SyntaxKind::{self, NAME},
 };
-use hir::{ModuleSource, FieldSource, Name};
+use hir::{ModuleSource, FieldSource, Name, ImplItem};
 
 use crate::{FileSymbol, db::RootDatabase};
 
@@ -174,6 +174,20 @@ impl NavigationTarget {
         )
     }
 
+    pub(crate) fn from_impl_item(db: &RootDatabase, impl_item: hir::ImplItem) -> NavigationTarget {
+        match impl_item {
+            ImplItem::Method(f) => NavigationTarget::from_function(db, f),
+            ImplItem::Const(c) => {
+                let (file_id, node) = c.source(db);
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
+            }
+            ImplItem::TypeAlias(a) => {
+                let (file_id, node) = a.source(db);
+                NavigationTarget::from_named(file_id.original_file(db), &*node)
+            }
+        }
+    }
+
     #[cfg(test)]
     pub(crate) fn assert_match(&self, expected: &str) {
         let actual = self.debug_render();