From 85633656dfc3ad4516a99e3062599e3ee85a578d Mon Sep 17 00:00:00 2001
From: Florian Diebold <flodiebold@gmail.com>
Date: Sun, 28 Apr 2019 15:43:10 +0200
Subject: Fix hover on the beginning of a nested expression

E.g. in
```
let foo = 1u32;
if true {
   <|>foo;
}
```
the hover shows `()`, the type of the whole if expression, instead of the more
sensible `u32`. The reason for this was that the search for an expression was
slightly left-biased: When on the edge between two tokens, it first looked at
all ancestors of the left token and then of the right token. Instead merge the
ancestors in ascending order, so that we get the smaller of the two possible
expressions.
---
 crates/ra_ide_api/src/goto_definition.rs |  1 +
 crates/ra_ide_api/src/hover.rs           | 21 ++++++++++++++-------
 2 files changed, 15 insertions(+), 7 deletions(-)

(limited to 'crates/ra_ide_api')

diff --git a/crates/ra_ide_api/src/goto_definition.rs b/crates/ra_ide_api/src/goto_definition.rs
index 40a2bd148..163781f88 100644
--- a/crates/ra_ide_api/src/goto_definition.rs
+++ b/crates/ra_ide_api/src/goto_definition.rs
@@ -25,6 +25,7 @@ pub(crate) fn goto_definition(
     None
 }
 
+#[derive(Debug)]
 pub(crate) enum ReferenceResult {
     Exact(NavigationTarget),
     Approximate(Vec<NavigationTarget>),
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 397b56786..6545a2581 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -1,7 +1,7 @@
 use ra_db::SourceDatabase;
 use ra_syntax::{
     AstNode, ast,
-    algo::{find_covering_element, find_node_at_offset, find_token_at_offset},
+    algo::{find_covering_element, find_node_at_offset, ancestors_at_offset},
 };
 use hir::HirDisplay;
 
@@ -104,12 +104,8 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
     }
 
     if range.is_none() {
-        let node = find_token_at_offset(file.syntax(), position.offset).find_map(|token| {
-            token
-                .parent()
-                .ancestors()
-                .find(|n| ast::Expr::cast(*n).is_some() || ast::Pat::cast(*n).is_some())
-        })?;
+        let node = ancestors_at_offset(file.syntax(), position.offset)
+            .find(|n| ast::Expr::cast(*n).is_some() || ast::Pat::cast(*n).is_some())?;
         let frange = FileRange { file_id: position.file_id, range: node.range() };
         res.extend(type_of(db, frange).map(rust_code_markup));
         range = Some(node.range());
@@ -397,6 +393,17 @@ The Some variant
         assert_eq!(trim_markup_opt(hover.info.first()), Some("i32"));
     }
 
+    #[test]
+    fn hover_local_var_edge() {
+        let (analysis, position) = single_file_with_position(
+            "
+fn func(foo: i32) { if true { <|>foo; }; }
+",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("i32"));
+    }
+
     #[test]
     fn test_type_of_for_function() {
         let (analysis, range) = single_file_with_range(
-- 
cgit v1.2.3