Re-enable marks-based static checks in code generated by macros (#751)

- add associated type to IntoResolvable and IntoFieldResult traits allowing to name the GraphQLType being resolved
- relax Sized requirement on some IsInputType and IsOutputType impls

integration_tests/codegen_fail/fail/input-object/derive_incompatible_object.stderr

@@ -1,3 +1,12 @@
+error[E0277]: the trait bound `ObjectA: juniper::marker::IsInputType<__S>` is not satisfied
+ --> $DIR/derive_incompatible_object.rs:6:10
+  |
+6 | #[derive(juniper::GraphQLInputObject)]
+  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `juniper::marker::IsInputType<__S>` is not implemented for `ObjectA`
+  |
+  = note: required by `juniper::marker::IsInputType::mark`
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
 error[E0277]: the trait bound `ObjectA: juniper::FromInputValue<__S>` is not satisfied
  --> $DIR/derive_incompatible_object.rs:6:10
   |

integration_tests/codegen_fail/fail/object/impl_argument_no_object.stderr

@@ -1,3 +1,12 @@
+error[E0277]: the trait bound `Obj: juniper::marker::IsInputType<juniper::DefaultScalarValue>` is not satisfied
+ --> $DIR/impl_argument_no_object.rs:8:1
+  |
+8 | #[juniper::graphql_object]
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `juniper::marker::IsInputType<juniper::DefaultScalarValue>` is not implemented for `Obj`
+  |
+  = note: required by `juniper::marker::IsInputType::mark`
+  = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
 error[E0277]: the trait bound `Obj: juniper::FromInputValue` is not satisfied
  --> $DIR/impl_argument_no_object.rs:8:1
   |

integration_tests/juniper_tests/src/codegen/derive_input_object.rs

@@ -1,8 +1,8 @@
 use fnv::FnvHashMap;
 
 use juniper::{
-    DefaultScalarValue, FromInputValue, GraphQLInputObject, GraphQLType, GraphQLValue, InputValue,
+    marker, DefaultScalarValue, FromInputValue, GraphQLInputObject, GraphQLType, GraphQLValue,
-    ToInputValue,
+    InputValue, ToInputValue,
 };
 
 #[derive(GraphQLInputObject, Debug, PartialEq)]
@@ -50,6 +50,8 @@ struct OverrideDocComment {
 #[derive(Debug, PartialEq)]
 struct Fake;
 
+impl<'a> marker::IsInputType<DefaultScalarValue> for &'a Fake {}
+
 impl<'a> FromInputValue for &'a Fake {
     fn from_input_value(_v: &InputValue) -> Option<&'a Fake> {
         None

integration_tests/juniper_tests/src/codegen/impl_object.rs

@@ -3,7 +3,7 @@ use juniper::DefaultScalarValue;
 use juniper::Object;
 
 #[cfg(test)]
-use juniper::{self, execute, EmptyMutation, EmptySubscription, RootNode, Value, Variables};
+use juniper::{execute, EmptyMutation, EmptySubscription, FieldError, RootNode, Value, Variables};
 
 pub struct MyObject;
 
@@ -84,3 +84,16 @@ where
 
     f((type_info, fields));
 }
+
+mod fallible {
+    use super::*;
+
+    struct Obj;
+
+    #[juniper::graphql_object]
+    impl Obj {
+        fn test(&self, arg: String) -> Result<String, FieldError> {
+            Ok(arg)
+        }
+    }
+}

juniper/src/executor/mod.rs

@@ -253,6 +253,8 @@ where
     T: GraphQLValue<S>,
     S: ScalarValue,
 {
+    type Type;
+
     #[doc(hidden)]
     fn into(self, ctx: &'a C) -> FieldResult<Option<(&'a T::Context, T)>, S>;
 }
@@ -263,6 +265,8 @@ where
     S: ScalarValue,
     T::Context: FromContext<C>,
 {
+    type Type = T;
+
     fn into(self, ctx: &'a C) -> FieldResult<Option<(&'a T::Context, T)>, S> {
         Ok(Some((FromContext::from(ctx), self)))
     }
@@ -274,6 +278,8 @@ where
     T: GraphQLValue<S>,
     T::Context: FromContext<C>,
 {
+    type Type = T;
+
     fn into(self, ctx: &'a C) -> FieldResult<Option<(&'a T::Context, T)>, S> {
         self.map(|v: T| Some((<T::Context as FromContext<C>>::from(ctx), v)))
             .map_err(IntoFieldError::into_field_error)
@@ -285,6 +291,8 @@ where
     S: ScalarValue,
     T: GraphQLValue<S>,
 {
+    type Type = T;
+
     fn into(self, _: &'a C) -> FieldResult<Option<(&'a T::Context, T)>, S> {
         Ok(Some(self))
     }
@@ -295,6 +303,8 @@ where
     S: ScalarValue,
     T: GraphQLValue<S>,
 {
+    type Type = T;
+
     fn into(self, _: &'a C) -> FieldResult<Option<(&'a T::Context, Option<T>)>, S> {
         Ok(self.map(|(ctx, v)| (ctx, Some(v))))
     }
@@ -305,6 +315,8 @@ where
     S: ScalarValue,
     T: GraphQLValue<S>,
 {
+    type Type = T;
+
     fn into(self, _: &'a C) -> FieldResult<Option<(&'a T::Context, T)>, S> {
         self.map(Some)
     }
@@ -316,6 +328,8 @@ where
     S: ScalarValue,
     T: GraphQLValue<S>,
 {
+    type Type = T;
+
     fn into(self, _: &'a C) -> FieldResult<Option<(&'a T::Context, Option<T>)>, S> {
         self.map(|o| o.map(|(ctx, v)| (ctx, Some(v))))
     }

juniper/src/lib.rs

@@ -183,7 +183,7 @@ pub use crate::{
     types::{
         async_await::{GraphQLTypeAsync, GraphQLValueAsync},
         base::{Arguments, GraphQLType, GraphQLValue, TypeKind},
-        marker::{self, GraphQLUnion},
+        marker::{self, GraphQLUnion, IsOutputType},
         scalars::{EmptyMutation, EmptySubscription, ID},
         subscriptions::{
             ExecutionOutput, GraphQLSubscriptionType, GraphQLSubscriptionValue,

juniper/src/macros/interface.rs

@@ -178,6 +178,10 @@ macro_rules! graphql_interface {
             }
         );
 
+        $crate::__juniper_impl_trait!(
+            impl<$($scalar)* $(, $lifetimes)* > IsOutputType for $name { }
+        );
+
         $crate::__juniper_impl_trait!(
             impl<$($scalar)* $(, $lifetimes)* > GraphQLValue for $name {
                 type Context = $ctx;

juniper/src/macros/subscription_helpers.rs

@@ -7,27 +7,36 @@ use futures::Stream;
 
 use crate::{FieldError, GraphQLValue, ScalarValue};
 
-/// Trait for converting  `T` to `Ok(T)` if T is not Result.
+/// Trait for wrapping [`Stream`] into [`Ok`] if it's not [`Result`].
-/// This is useful in subscription macros when user can provide type alias for
+///
-/// Stream or Result<Stream, _> and then a function on Stream should be called.
+/// Used in subscription macros when user can provide type alias for [`Stream`] or
+/// `Result<Stream, _>` and then a function on [`Stream`] should be called.
 pub trait IntoFieldResult<T, S> {
-    /// Turn current type into a generic result
+    /// Type of items yielded by this [`Stream`].
+    type Item;
+
+    /// Turns current [`Stream`] type into a generic [`Result`].
     fn into_result(self) -> Result<T, FieldError<S>>;
 }
 
 impl<T, E, S> IntoFieldResult<T, S> for Result<T, E>
 where
+    T: IntoFieldResult<T, S>,
     E: Into<FieldError<S>>,
 {
+    type Item = T::Item;
+
     fn into_result(self) -> Result<T, FieldError<S>> {
         self.map_err(|e| e.into())
     }
 }
 
-impl<T, I, S> IntoFieldResult<T, S> for T
+impl<T, S> IntoFieldResult<T, S> for T
 where
-    T: Stream<Item = I>,
+    T: Stream,
 {
+    type Item = T::Item;
+
     fn into_result(self) -> Result<T, FieldError<S>> {
         Ok(self)
     }

juniper/src/types/marker.rs

@@ -53,7 +53,8 @@ pub trait GraphQLUnion<S: ScalarValue>: GraphQLType<S> {
 /// types. Each type which can be used as an output type should
 /// implement this trait. The specification defines enum, scalar,
 /// object, union, and interface as output types.
-pub trait IsOutputType<S: ScalarValue>: GraphQLType<S> {
+// TODO: Re-enable GraphQLType requirement in #682
+pub trait IsOutputType<S: ScalarValue> /*: GraphQLType<S>*/ {
     /// An arbitrary function without meaning.
     ///
     /// May contain compile timed check logic which ensures that types
@@ -132,13 +133,13 @@ where
 
 impl<S, T> IsInputType<S> for Box<T>
 where
-    T: IsInputType<S>,
+    T: IsInputType<S> + ?Sized,
     S: ScalarValue,
 {
 }
 impl<S, T> IsOutputType<S> for Box<T>
 where
-    T: IsOutputType<S>,
+    T: IsOutputType<S> + ?Sized,
     S: ScalarValue,
 {
 }

juniper_codegen/src/derive_scalar_value.rs

@@ -195,6 +195,9 @@ fn impl_scalar_struct(
                 <#inner_ty as ::juniper::ParseScalarValue<S>>::from_str(value)
             }
         }
+
+        impl<S: ::juniper::ScalarValue> ::juniper::marker::IsOutputType<S> for #ident { }
+        impl<S: ::juniper::ScalarValue> ::juniper::marker::IsInputType<S> for #ident { }
     );
 
     Ok(content)

juniper_codegen/src/graphql_union/mod.rs

@@ -611,7 +611,7 @@ impl ToTokens for UnionDefinition {
                 #where_clause
             {
                 fn mark() {
-                    #( <#var_types as ::juniper::marker::GraphQLObjectType<#scalar>>::mark(); )*
+                    #( <#var_types as ::juniper::marker::IsOutputType<#scalar>>::mark(); )*
                 }
             }
         };

juniper_codegen/src/util/mod.rs

@@ -831,12 +831,9 @@ impl GraphQLTypeDefiniton {
         if self.scalar.is_none() && self.generic_scalar {
             // No custom scalar specified, but always generic specified.
             // Therefore we inject the generic scalar.
-
             generics.params.push(parse_quote!(__S));
-
+            generics
-            let where_clause = generics.where_clause.get_or_insert(parse_quote!(where));
+                .make_where_clause()
-            // Insert ScalarValue constraint.
-            where_clause
                 .predicates
                 .push(parse_quote!(__S: ::juniper::ScalarValue));
         }
@@ -962,26 +959,29 @@ impl GraphQLTypeDefiniton {
             )
         };
 
-        // FIXME: enable this if interfaces are supported
+        let marks = self.fields.iter().map(|field| {
-        // let marks = self.fields.iter().map(|field| {
+            let field_marks = field.args.iter().map(|arg| {
-        //     let field_ty = &field._type;
+                let arg_ty = &arg._type;
+                quote! { <#arg_ty as ::juniper::marker::IsInputType<#scalar>>::mark(); }
+            });
 
-        //     let field_marks = field.args.iter().map(|arg| {
+            let field_ty = &field._type;
-        //         let arg_ty = &arg._type;
+            let resolved_ty = quote! {
-        //         quote!(<#arg_ty as ::juniper::marker::IsInputType<#scalar>>::mark();)
+                <#field_ty as ::juniper::IntoResolvable<
-        //     });
+                    '_, #scalar, _, <Self as ::juniper::GraphQLValue<#scalar>>::Context,
+                >>::Type
+            };
 
-        //     quote!(
+            quote! {
-        //         #( #field_marks)*
+                #( #field_marks )*
-        //         <#field_ty as ::juniper::marker::IsOutputType<#scalar>>::mark();
+                <#resolved_ty as ::juniper::marker::IsOutputType<#scalar>>::mark();
-        //     )
+            }
-        // });
+        });
 
         let output = quote!(
             impl#impl_generics ::juniper::marker::IsOutputType<#scalar> for #ty #type_generics_tokens #where_clause {
                 fn mark() {
-                    // FIXME: enable this if interfaces are supported
+                    #( #marks )*
-                    // #( #marks )*
                 }
             }
 
@@ -1001,10 +1001,10 @@ impl GraphQLTypeDefiniton {
                 ) -> ::juniper::meta::MetaType<'r, #scalar>
                     where #scalar : 'r,
                 {
-                    let fields = vec![
+                    let fields = [
                         #( #field_definitions ),*
                     ];
-                    let meta = registry.build_object_type::<#ty>( info, &fields )
+                    let meta = registry.build_object_type::<#ty>(info, &fields)
                         #description
                         #interfaces;
                     meta.into_meta()
@@ -1226,7 +1226,37 @@ impl GraphQLTypeDefiniton {
             },
         );
 
+        let marks = self.fields.iter().map(|field| {
+            let field_marks = field.args.iter().map(|arg| {
+                let arg_ty = &arg._type;
+                quote! { <#arg_ty as ::juniper::marker::IsInputType<#scalar>>::mark(); }
+            });
+
+            let field_ty = &field._type;
+            let stream_item_ty = quote! {
+                <#field_ty as ::juniper::IntoFieldResult::<_, #scalar>>::Item
+            };
+            let resolved_ty = quote! {
+                <#stream_item_ty as ::juniper::IntoResolvable<
+                    '_, #scalar, _, <Self as ::juniper::GraphQLValue<#scalar>>::Context,
+                >>::Type
+            };
+
+            quote! {
+                #( #field_marks )*
+                <#resolved_ty as ::juniper::marker::IsOutputType<#scalar>>::mark();
+            }
+        });
+
         let graphql_implementation = quote!(
+            impl#impl_generics ::juniper::marker::IsOutputType<#scalar> for #ty #type_generics_tokens
+                #where_clause
+            {
+                fn mark() {
+                    #( #marks )*
+                }
+            }
+
             impl#impl_generics ::juniper::GraphQLType<#scalar> for #ty #type_generics_tokens
                 #where_clause
             {
@@ -1240,10 +1270,10 @@ impl GraphQLTypeDefiniton {
                     ) -> ::juniper::meta::MetaType<'r, #scalar>
                         where #scalar : 'r,
                     {
-                        let fields = vec![
+                        let fields = [
                             #( #field_definitions ),*
                         ];
-                        let meta = registry.build_object_type::<#ty>( info, &fields )
+                        let meta = registry.build_object_type::<#ty>(info, &fields)
                             #description
                             #interfaces;
                         meta.into_meta()
@@ -1690,18 +1720,16 @@ impl GraphQLTypeDefiniton {
             {}
         );
 
-        // FIXME: enable this if interfaces are supported
+        let marks = self.fields.iter().map(|field| {
-        // let marks = self.fields.iter().map(|field| {
+            let field_ty = &field._type;
-        //     let _ty = &field._type;
+            quote! { <#field_ty as ::juniper::marker::IsInputType<#scalar>>::mark(); }
-        //     quote!(<#_ty as ::juniper::marker::IsInputType<#scalar>>::mark();)
+        });
-        // });
 
         let mut body = quote!(
             impl#impl_generics ::juniper::marker::IsInputType<#scalar> for #ty #type_generics_tokens
                 #where_clause {
                     fn mark() {
-                        // FIXME: enable this if interfaces are supported
+                        #( #marks )*
-                        // #( #marks )*
                     }
                 }