From 0bb1c5beac8ccf0fbfb497653560a4d5962126b0 Mon Sep 17 00:00:00 2001
From: Caio <c410.f3r@gmail.com>
Date: Tue, 19 May 2020 12:46:56 -0300
Subject: [PATCH] Relax Default impl constraint (#664)
* Relax Default impl constraint
For EmptyMutation and EmptySubscription. The built-in derive
expects `T: Default`, which is not necessary for a PhantomData
wrapper.
* Add test
---
juniper/src/types/scalars.rs | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/juniper/src/types/scalars.rs b/juniper/src/types/scalars.rs
index 1e9c29b5..a9443df4 100644
--- a/juniper/src/types/scalars.rs
+++ b/juniper/src/types/scalars.rs
@@ -324,7 +324,7 @@ where
///
/// If you instantiate `RootNode` with this as the mutation, no mutation will be
/// generated for the schema.
-#[derive(Debug, Default)]
+#[derive(Debug)]
pub struct EmptyMutation<T> {
phantom: PhantomData<T>,
}
@@ -370,11 +370,18 @@ where
{
}
+impl<T> Default for EmptyMutation<T> {
+ fn default() -> Self {
+ Self {
+ phantom: PhantomData,
+ }
+ }
+}
+
/// Utillity type to define read-only schemas
///
/// If you instantiate `RootNode` with this as the subscription,
/// no subscriptions will be generated for the schema.
-#[derive(Default)]
pub struct EmptySubscription<T> {
phantom: PhantomData<T>,
}
@@ -420,6 +427,14 @@ where
{
}
+impl<T> Default for EmptySubscription<T> {
+ fn default() -> Self {
+ Self {
+ phantom: PhantomData,
+ }
+ }
+}
+
#[cfg(test)]
mod tests {
use super::{EmptyMutation, EmptySubscription, ID};
@@ -481,4 +496,11 @@ mod tests {
fn check_if_send<T: Send>() {}
check_if_send::<EmptySubscription<()>>();
}
+
+ #[test]
+ fn default_is_invariant_over_type() {
+ struct Bar;
+ let _ = EmptySubscription::<Bar>::default();
+ let _ = EmptyMutation::<Bar>::default();
+ }
}