fix(assist): display where predicates when we want to generate impl

Signed-off-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>

crates/assists/src/handlers/generate_impl.rs

@@ -122,6 +122,31 @@ mod tests {
                 $0
             }"#,
         );
+
+        check_assist(
+            generate_impl,
+            r#"pub trait Trait {}
+struct Struct<T>$0
+where
+    T: Trait,
+{
+    inner: T,
+}"#,
+            r#"pub trait Trait {}
+struct Struct<T>
+where
+    T: Trait,
+{
+    inner: T,
+}
+
+impl<T> Struct<T>
+where
+    T: Trait,
+{
+    $0
+}"#,
+        );
     }
 
     #[test]

crates/assists/src/utils.rs

@@ -421,7 +421,14 @@ fn generate_impl_text_inner(adt: &ast::Adt, trait_text: Option<&str>, code: &str
         format_to!(buf, "<{}>", lifetime_params.chain(type_params).format(", "))
     }
 
-    format_to!(buf, " {{\n{}\n}}", code);
+    match adt.where_clause() {
+        Some(where_clause) => {
+            format_to!(buf, "\n{}\n{{\n{}\n}}", where_clause, code);
+        }
+        None => {
+            format_to!(buf, " {{\n{}\n}}", code);
+        }
+    }
 
     buf
 }