Merge #11481

11481: Display parameter names when hovering over a function pointer r=Veykril a=Vannevelj

Implements #11474

The idea is pretty straightforward: previously we constructed the hover based on just the parameter types, now we pass in the parameter names as well. I went for a quick-hit approach here but I expect someone will be able to point me to a better way of resolving the identifier.

I haven't figured out yet how to actually run my rust-analyzer locally so I can see it in action but the unit test indicates it should work.

Co-authored-by: Jeroen Vannevel <jer_vannevel@outlook.com>

crates/ide/src/hover/tests.rs

@@ -1310,6 +1310,60 @@ fn test_hover_function_show_qualifiers() {
     );
 }
 
+#[test]
+fn test_hover_function_show_types() {
+    check(
+        r#"fn foo$0(a: i32, b:i32) -> i32 { 0 }"#,
+        expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                fn foo(a: i32, b: i32) -> i32
+                ```
+            "#]],
+    );
+}
+
+#[test]
+fn test_hover_function_pointer_show_identifiers() {
+    check(
+        r#"type foo$0 = fn(a: i32, b: i32) -> i32;"#,
+        expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                type foo = fn(a: i32, b: i32) -> i32
+                ```
+            "#]],
+    );
+}
+
+#[test]
+fn test_hover_function_pointer_no_identifier() {
+    check(
+        r#"type foo$0 = fn(i32, _: i32) -> i32;"#,
+        expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                type foo = fn(i32, i32) -> i32
+                ```
+            "#]],
+    );
+}
+
 #[test]
 fn test_hover_trait_show_qualifiers() {
     check_actions(