Implement #[derive(GraphQLInterface)] to use structs as GraphQL interfaces (#1026)

- support `#[graphql_interface]` on structs

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

@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `ObjectA: IsInputType<__S>` is not satisfied
- --> fail/input-object/derive_incompatible_object.rs:6:10
+ --> fail/input-object/derive_incompatible_object.rs:8:12
   |
-6 | #[derive(juniper::GraphQLInputObject)]
+8 |     field: ObjectA,
-  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `IsInputType<__S>` is not implemented for `ObjectA`
+  |            ^^^^^^^ the trait `IsInputType<__S>` is not implemented for `ObjectA`
-  |
-  = note: this error originates in the derive macro `juniper::GraphQLInputObject` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `ObjectA: FromInputValue<__S>` is not satisfied
     --> fail/input-object/derive_incompatible_object.rs:6:10

integration_tests/codegen_fail/fail/interface/additional_non_nullable_argument.stderr

@@ -1,7 +0,0 @@
-error[E0080]: evaluation of constant value failed
-  --> fail/interface/additional_non_nullable_argument.rs:14:1
-   |
-14 | #[graphql_interface(for = ObjA)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!` isn't present on the interface and so has to be nullable.', $DIR/fail/interface/additional_non_nullable_argument.rs:14:1
-   |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/attr_wrong_item.stderr

@@ -0,0 +1,5 @@
+error: GraphQL interface #[graphql_interface] attribute is applicable to trait and struct definitions only
+ --> fail/interface/attr_wrong_item.rs:9:1
+  |
+9 | enum Character {}
+  | ^^^^^^^^^^^^^^^^^

integration_tests/codegen_fail/fail/interface/derive_wrong_item.rs

@@ -0,0 +1,12 @@
+use juniper::{GraphQLInterface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+pub struct ObjA {
+    test: String,
+}
+
+#[derive(GraphQLInterface)]
+#[graphql(for = ObjA)]
+enum Character {}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/derive_wrong_item.stderr

@@ -0,0 +1,6 @@
+error: GraphQL interface can only be derived on structs
+  --> fail/interface/derive_wrong_item.rs:9:1
+   |
+9  | / #[graphql(for = ObjA)]
+10 | | enum Character {}
+   | |_________________^

integration_tests/codegen_fail/fail/interface/field_non_output_return_type.stderr

@@ -1,7 +0,0 @@
-error[E0277]: the trait bound `ObjB: IsOutputType<__S>` is not satisfied
- --> fail/interface/field_non_output_return_type.rs:8:1
-  |
-8 | #[graphql_interface]
-  | ^^^^^^^^^^^^^^^^^^^^ the trait `IsOutputType<__S>` is not implemented for `ObjB`
-  |
-  = note: this error originates in the attribute macro `graphql_interface` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/missing_field.stderr

@@ -1,7 +0,0 @@
-error[E0080]: evaluation of constant value failed
- --> fail/interface/missing_field.rs:9:1
-  |
-9 | #[graphql_interface(for = ObjA)]
-  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id` isn't implemented on `ObjA`.', $DIR/fail/interface/missing_field.rs:9:1
-  |
-  = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/missing_field_argument.stderr

@@ -1,7 +0,0 @@
-error[E0080]: evaluation of constant value failed
-  --> fail/interface/missing_field_argument.rs:14:1
-   |
-14 | #[graphql_interface(for = ObjA)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!` was expected, but not found.', $DIR/fail/interface/missing_field_argument.rs:14:1
-   |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/non_subtype_return.stderr

@@ -1,7 +0,0 @@
-error[E0080]: evaluation of constant value failed
- --> fail/interface/non_subtype_return.rs:9:1
-  |
-9 | #[graphql_interface(for = ObjA)]
-  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: implementor is expected to return a subtype of interface's return object: `[String!]!` is not a subtype of `String!`.', $DIR/fail/interface/non_subtype_return.rs:9:1
-  |
-  = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/attr_additional_non_nullable_argument.rs

@@ -0,0 +1,19 @@
+use juniper::{graphql_interface, graphql_object};
+
+pub struct ObjA {
+    id: String,
+}
+
+#[graphql_object(impl = CharacterValue)]
+impl ObjA {
+    fn id(&self, is_present: bool) -> &str {
+        is_present.then(|| self.id.as_str()).unwrap_or("missing")
+    }
+}
+
+#[graphql_interface(for = ObjA)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_additional_non_nullable_argument.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/struct/attr_additional_non_nullable_argument.rs:16:5
+   |
+16 |     id: String,
+   |     ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!` isn't present on the interface and so has to be nullable.', $DIR/fail/interface/struct/attr_additional_non_nullable_argument.rs:16:5
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/attr_field_double_underscored.rs

@@ -0,0 +1,8 @@
+use juniper::graphql_interface;
+
+#[graphql_interface]
+struct Character {
+    __id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_field_double_underscored.stderr

@@ -0,0 +1,7 @@
+error: All types and directives defined within a schema must not have a name which begins with `__` (two underscores), as this is used exclusively by GraphQL’s introspection system.
+ --> fail/interface/struct/attr_field_double_underscored.rs:5:5
+  |
+5 |     __id: String,
+  |     ^^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Schema

integration_tests/codegen_fail/fail/interface/struct/attr_field_non_output_return_type.rs

@@ -0,0 +1,13 @@
+use juniper::{graphql_interface, GraphQLInputObject};
+
+#[derive(GraphQLInputObject)]
+pub struct ObjB {
+    id: i32,
+}
+
+#[graphql_interface]
+struct Character {
+    id: ObjB,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_field_non_output_return_type.stderr

@@ -0,0 +1,5 @@
+error[E0277]: the trait bound `ObjB: IsOutputType<__S>` is not satisfied
+  --> fail/interface/struct/attr_field_non_output_return_type.rs:10:9
+   |
+10 |     id: ObjB,
+   |         ^^^^ the trait `IsOutputType<__S>` is not implemented for `ObjB`

integration_tests/codegen_fail/fail/interface/struct/attr_fields_duplicate.rs

@@ -0,0 +1,11 @@
+use juniper::graphql_interface;
+
+#[graphql_interface]
+struct Character {
+    id: String,
+
+    #[graphql(name = "id")]
+    id2: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_fields_duplicate.stderr

@@ -0,0 +1,12 @@
+error: GraphQL interface must have a different name for each field
+ --> fail/interface/struct/attr_fields_duplicate.rs:4:1
+  |
+4 | / struct Character {
+5 | |     id: String,
+6 | |
+7 | |     #[graphql(name = "id")]
+8 | |     id2: String,
+9 | | }
+  | |_^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Interfaces

integration_tests/codegen_fail/fail/interface/struct/attr_implementers_duplicate_pretty.rs

@@ -0,0 +1,14 @@
+use juniper::{graphql_interface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: String,
+}
+
+#[graphql_interface(for = [ObjA, ObjA])]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_implementers_duplicate_pretty.stderr

@@ -0,0 +1,11 @@
+error: duplicated attribute argument found
+ --> fail/interface/struct/attr_implementers_duplicate_pretty.rs:9:34
+  |
+9 | #[graphql_interface(for = [ObjA, ObjA])]
+  |                                  ^^^^
+
+error[E0412]: cannot find type `CharacterValue` in this scope
+ --> fail/interface/struct/attr_implementers_duplicate_pretty.rs:4:18
+  |
+4 | #[graphql(impl = CharacterValue)]
+  |                  ^^^^^^^^^^^^^^ not found in this scope

integration_tests/codegen_fail/fail/interface/struct/attr_implementers_duplicate_ugly.rs

@@ -0,0 +1,16 @@
+use juniper::{graphql_interface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: String,
+}
+
+type ObjAlias = ObjA;
+
+#[graphql_interface(for = [ObjA, ObjAlias])]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_implementers_duplicate_ugly.stderr

@@ -0,0 +1,21 @@
+error[E0119]: conflicting implementations of trait `std::convert::From<ObjA>` for type `CharacterValueEnum<ObjA, ObjA>`
+  --> fail/interface/struct/attr_implementers_duplicate_ugly.rs:11:1
+   |
+11 | #[graphql_interface(for = [ObjA, ObjAlias])]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | first implementation here
+   | conflicting implementation for `CharacterValueEnum<ObjA, ObjA>`
+   |
+   = note: this error originates in the attribute macro `graphql_interface` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0119]: conflicting implementations of trait `<CharacterValueEnum<ObjA, ObjA> as juniper::GraphQLInterface<__S>>::mark::_::{closure#0}::MutuallyExclusive` for type `ObjA`
+  --> fail/interface/struct/attr_implementers_duplicate_ugly.rs:11:1
+   |
+11 | #[graphql_interface(for = [ObjA, ObjAlias])]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | first implementation here
+   | conflicting implementation for `ObjA`
+   |
+   = note: this error originates in the macro `::juniper::sa::assert_type_ne_all` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/attr_missing_field.rs

@@ -0,0 +1,14 @@
+use juniper::{graphql_interface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    test: String,
+}
+
+#[graphql_interface(for = ObjA)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_missing_field.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/struct/attr_missing_field.rs:11:5
+   |
+11 |     id: String,
+   |     ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id` isn't implemented on `ObjA`.', $DIR/fail/interface/struct/attr_missing_field.rs:11:5
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/attr_missing_for_attr.rs

@@ -0,0 +1,14 @@
+use juniper::{graphql_interface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: String,
+}
+
+#[graphql_interface]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_missing_for_attr.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+ --> fail/interface/struct/attr_missing_for_attr.rs:3:10
+  |
+3 | #[derive(GraphQLObject)]
+  |          ^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing implementer reference in interface's `for` attribute.', $DIR/fail/interface/struct/attr_missing_for_attr.rs:3:10
+  |
+  = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/attr_missing_impl_attr.rs

@@ -2,10 +2,12 @@ use juniper::{graphql_interface, GraphQLObject};
 
 #[derive(GraphQLObject)]
 pub struct ObjA {
-    test: String,
+    id: String,
 }
 
 #[graphql_interface(for = ObjA)]
-impl ObjA {}
+struct Character {
+    id: String,
+}
 
 fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_missing_impl_attr.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+ --> fail/interface/struct/attr_missing_impl_attr.rs:8:1
+  |
+8 | #[graphql_interface(for = ObjA)]
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing interface reference in implementer's `impl` attribute.', $DIR/fail/interface/struct/attr_missing_impl_attr.rs:8:1
+  |
+  = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/attr_name_double_underscored.rs

@@ -0,0 +1,8 @@
+use juniper::graphql_interface;
+
+#[graphql_interface]
+struct __Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_name_double_underscored.stderr

@@ -0,0 +1,7 @@
+error: All types and directives defined within a schema must not have a name which begins with `__` (two underscores), as this is used exclusively by GraphQL’s introspection system.
+ --> fail/interface/struct/attr_name_double_underscored.rs:4:8
+  |
+4 | struct __Character {
+  |        ^^^^^^^^^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Schema

integration_tests/codegen_fail/fail/interface/struct/attr_no_fields.rs

@@ -0,0 +1,6 @@
+use juniper::graphql_interface;
+
+#[graphql_interface]
+struct Character {}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_no_fields.stderr

@@ -0,0 +1,7 @@
+error: GraphQL interface must have at least one field
+ --> fail/interface/struct/attr_no_fields.rs:4:1
+  |
+4 | struct Character {}
+  | ^^^^^^^^^^^^^^^^^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Interfaces

integration_tests/codegen_fail/fail/interface/struct/attr_non_subtype_return.rs

@@ -0,0 +1,14 @@
+use juniper::{graphql_interface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: Vec<String>,
+}
+
+#[graphql_interface(for = ObjA)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_non_subtype_return.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/struct/attr_non_subtype_return.rs:11:5
+   |
+11 |     id: String,
+   |     ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: implementor is expected to return a subtype of interface's return object: `[String!]!` is not a subtype of `String!`.', $DIR/fail/interface/struct/attr_non_subtype_return.rs:11:5
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/attr_unnamed_field.rs

@@ -0,0 +1,6 @@
+use juniper::graphql_interface;
+
+#[graphql_interface]
+struct Character(i32);
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/attr_unnamed_field.stderr

@@ -0,0 +1,7 @@
+error: GraphQL interface expected named struct field
+ --> fail/interface/struct/attr_unnamed_field.rs:4:18
+  |
+4 | struct Character(i32);
+  |                  ^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Interfaces

integration_tests/codegen_fail/fail/interface/struct/derive_additional_non_nullable_argument.rs

@@ -0,0 +1,20 @@
+use juniper::{graphql_object, GraphQLInterface};
+
+pub struct ObjA {
+    id: String,
+}
+
+#[graphql_object(impl = CharacterValue)]
+impl ObjA {
+    fn id(&self, is_present: bool) -> &str {
+        is_present.then(|| self.id.as_str()).unwrap_or("missing")
+    }
+}
+
+#[derive(GraphQLInterface)]
+#[graphql(for = ObjA)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_additional_non_nullable_argument.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/struct/derive_additional_non_nullable_argument.rs:17:5
+   |
+17 |     id: String,
+   |     ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!` isn't present on the interface and so has to be nullable.', $DIR/fail/interface/struct/derive_additional_non_nullable_argument.rs:17:5
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/derive_field_double_underscored.rs

@@ -0,0 +1,8 @@
+use juniper::GraphQLInterface;
+
+#[derive(GraphQLInterface)]
+struct Character {
+    __id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_field_double_underscored.stderr

@@ -0,0 +1,7 @@
+error: All types and directives defined within a schema must not have a name which begins with `__` (two underscores), as this is used exclusively by GraphQL’s introspection system.
+ --> fail/interface/struct/derive_field_double_underscored.rs:5:5
+  |
+5 |     __id: String,
+  |     ^^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Schema

integration_tests/codegen_fail/fail/interface/struct/derive_field_non_output_return_type.rs

@@ -0,0 +1,13 @@
+use juniper::{GraphQLInputObject, GraphQLInterface};
+
+#[derive(GraphQLInputObject)]
+pub struct ObjB {
+    id: i32,
+}
+
+#[derive(GraphQLInterface)]
+struct Character {
+    id: ObjB,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_field_non_output_return_type.stderr

@@ -0,0 +1,5 @@
+error[E0277]: the trait bound `ObjB: IsOutputType<__S>` is not satisfied
+  --> fail/interface/struct/derive_field_non_output_return_type.rs:10:9
+   |
+10 |     id: ObjB,
+   |         ^^^^ the trait `IsOutputType<__S>` is not implemented for `ObjB`

integration_tests/codegen_fail/fail/interface/struct/derive_fields_duplicate.rs

@@ -0,0 +1,11 @@
+use juniper::GraphQLInterface;
+
+#[derive(GraphQLInterface)]
+struct Character {
+    id: String,
+
+    #[graphql(name = "id")]
+    id2: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_fields_duplicate.stderr

@@ -0,0 +1,12 @@
+error: GraphQL interface must have a different name for each field
+ --> fail/interface/struct/derive_fields_duplicate.rs:4:1
+  |
+4 | / struct Character {
+5 | |     id: String,
+6 | |
+7 | |     #[graphql(name = "id")]
+8 | |     id2: String,
+9 | | }
+  | |_^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Interfaces

integration_tests/codegen_fail/fail/interface/struct/derive_implementers_duplicate_pretty.rs

@@ -0,0 +1,15 @@
+use juniper::{GraphQLInterface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: String,
+}
+
+#[derive(GraphQLInterface)]
+#[graphql(for = [ObjA, ObjA])]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_implementers_duplicate_pretty.stderr

@@ -0,0 +1,11 @@
+error: duplicated attribute argument found
+  --> fail/interface/struct/derive_implementers_duplicate_pretty.rs:10:24
+   |
+10 | #[graphql(for = [ObjA, ObjA])]
+   |                        ^^^^
+
+error[E0412]: cannot find type `CharacterValue` in this scope
+ --> fail/interface/struct/derive_implementers_duplicate_pretty.rs:4:18
+  |
+4 | #[graphql(impl = CharacterValue)]
+  |                  ^^^^^^^^^^^^^^ not found in this scope

integration_tests/codegen_fail/fail/interface/struct/derive_implementers_duplicate_ugly.rs

@@ -0,0 +1,17 @@
+use juniper::{GraphQLInterface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: String,
+}
+
+type ObjAlias = ObjA;
+
+#[derive(GraphQLInterface)]
+#[graphql(for = [ObjA, ObjAlias])]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_implementers_duplicate_ugly.stderr

@@ -0,0 +1,21 @@
+error[E0119]: conflicting implementations of trait `std::convert::From<ObjA>` for type `CharacterValueEnum<ObjA, ObjA>`
+  --> fail/interface/struct/derive_implementers_duplicate_ugly.rs:11:10
+   |
+11 | #[derive(GraphQLInterface)]
+   |          ^^^^^^^^^^^^^^^^
+   |          |
+   |          first implementation here
+   |          conflicting implementation for `CharacterValueEnum<ObjA, ObjA>`
+   |
+   = note: this error originates in the derive macro `GraphQLInterface` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0119]: conflicting implementations of trait `<CharacterValueEnum<ObjA, ObjA> as juniper::GraphQLInterface<__S>>::mark::_::{closure#0}::MutuallyExclusive` for type `ObjA`
+  --> fail/interface/struct/derive_implementers_duplicate_ugly.rs:11:10
+   |
+11 | #[derive(GraphQLInterface)]
+   |          ^^^^^^^^^^^^^^^^
+   |          |
+   |          first implementation here
+   |          conflicting implementation for `ObjA`
+   |
+   = note: this error originates in the macro `::juniper::sa::assert_type_ne_all` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/derive_missing_field.rs

@@ -0,0 +1,15 @@
+use juniper::{GraphQLInterface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    test: String,
+}
+
+#[derive(GraphQLInterface)]
+#[graphql(for = ObjA)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_missing_field.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/struct/derive_missing_field.rs:12:5
+   |
+12 |     id: String,
+   |     ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id` isn't implemented on `ObjA`.', $DIR/fail/interface/struct/derive_missing_field.rs:12:5
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/derive_missing_for_attr.rs

@@ -0,0 +1,14 @@
+use juniper::{GraphQLInterface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: String,
+}
+
+#[derive(GraphQLInterface)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_missing_for_attr.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+ --> fail/interface/struct/derive_missing_for_attr.rs:3:10
+  |
+3 | #[derive(GraphQLObject)]
+  |          ^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing implementer reference in interface's `for` attribute.', $DIR/fail/interface/struct/derive_missing_for_attr.rs:3:10
+  |
+  = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/derive_missing_impl_attr.rs

@@ -0,0 +1,14 @@
+use juniper::{GraphQLInterface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+pub struct ObjA {
+    id: String,
+}
+
+#[derive(GraphQLInterface)]
+#[graphql(for = ObjA)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_missing_impl_attr.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+ --> fail/interface/struct/derive_missing_impl_attr.rs:8:10
+  |
+8 | #[derive(GraphQLInterface)]
+  |          ^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing interface reference in implementer's `impl` attribute.', $DIR/fail/interface/struct/derive_missing_impl_attr.rs:8:10
+  |
+  = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/derive_name_double_underscored.rs

@@ -0,0 +1,8 @@
+use juniper::GraphQLInterface;
+
+#[derive(GraphQLInterface)]
+struct __Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_name_double_underscored.stderr

@@ -0,0 +1,7 @@
+error: All types and directives defined within a schema must not have a name which begins with `__` (two underscores), as this is used exclusively by GraphQL’s introspection system.
+ --> fail/interface/struct/derive_name_double_underscored.rs:4:8
+  |
+4 | struct __Character {
+  |        ^^^^^^^^^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Schema

integration_tests/codegen_fail/fail/interface/struct/derive_no_fields.rs

@@ -0,0 +1,6 @@
+use juniper::GraphQLInterface;
+
+#[derive(GraphQLInterface)]
+struct Character {}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_no_fields.stderr

@@ -0,0 +1,7 @@
+error: GraphQL interface must have at least one field
+ --> fail/interface/struct/derive_no_fields.rs:4:1
+  |
+4 | struct Character {}
+  | ^^^^^^^^^^^^^^^^^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Interfaces

integration_tests/codegen_fail/fail/interface/struct/derive_non_subtype_return.rs

@@ -0,0 +1,15 @@
+use juniper::{GraphQLInterface, GraphQLObject};
+
+#[derive(GraphQLObject)]
+#[graphql(impl = CharacterValue)]
+pub struct ObjA {
+    id: Vec<String>,
+}
+
+#[derive(GraphQLInterface)]
+#[graphql(for = ObjA)]
+struct Character {
+    id: String,
+}
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_non_subtype_return.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/struct/derive_non_subtype_return.rs:12:5
+   |
+12 |     id: String,
+   |     ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: implementor is expected to return a subtype of interface's return object: `[String!]!` is not a subtype of `String!`.', $DIR/fail/interface/struct/derive_non_subtype_return.rs:12:5
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/struct/derive_unnamed_field.rs

@@ -0,0 +1,6 @@
+use juniper::GraphQLInterface;
+
+#[derive(GraphQLInterface)]
+struct Character(i32);
+
+fn main() {}

integration_tests/codegen_fail/fail/interface/struct/derive_unnamed_field.stderr

@@ -0,0 +1,7 @@
+error: GraphQL interface expected named struct field
+ --> fail/interface/struct/derive_unnamed_field.rs:4:18
+  |
+4 | struct Character(i32);
+  |                  ^^^
+  |
+  = note: https://spec.graphql.org/June2018/#sec-Interfaces

integration_tests/codegen_fail/fail/interface/trait/additional_non_nullable_argument.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/trait/additional_non_nullable_argument.rs:16:8
+   |
+16 |     fn id(&self) -> &str;
+   |        ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!` isn't present on the interface and so has to be nullable.', $DIR/fail/interface/trait/additional_non_nullable_argument.rs:16:8
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/trait/argument_double_underscored.stderr

@@ -1,5 +1,5 @@
 error: All types and directives defined within a schema must not have a name which begins with `__` (two underscores), as this is used exclusively by GraphQL’s introspection system.
- --> fail/interface/argument_double_underscored.rs:5:18
+ --> fail/interface/trait/argument_double_underscored.rs:5:18
   |
 5 |     fn id(&self, __num: i32) -> &str;
   |                  ^^^^^

integration_tests/codegen_fail/fail/interface/trait/argument_non_input_type.stderr

@@ -1,13 +1,11 @@
 error[E0277]: the trait bound `ObjA: IsInputType<__S>` is not satisfied
- --> fail/interface/argument_non_input_type.rs:8:1
+  --> fail/interface/trait/argument_non_input_type.rs:10:23
-  |
+   |
-8 | #[graphql_interface]
+10 |     fn id(&self, obj: ObjA) -> &str;
-  | ^^^^^^^^^^^^^^^^^^^^ the trait `IsInputType<__S>` is not implemented for `ObjA`
+   |                       ^^^^ the trait `IsInputType<__S>` is not implemented for `ObjA`
-  |
-  = note: this error originates in the attribute macro `graphql_interface` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `ObjA: FromInputValue<__S>` is not satisfied
-    --> fail/interface/argument_non_input_type.rs:8:1
+    --> fail/interface/trait/argument_non_input_type.rs:8:1
      |
 8    | #[graphql_interface]
      | ^^^^^^^^^^^^^^^^^^^^ the trait `FromInputValue<__S>` is not implemented for `ObjA`

integration_tests/codegen_fail/fail/interface/trait/argument_wrong_default_array.stderr

@@ -1,14 +1,14 @@
 error[E0277]: the trait bound `[bool; 2]: From<[bool; 3]>` is not satisfied
- --> fail/interface/argument_wrong_default_array.rs:3:1
+ --> fail/interface/trait/argument_wrong_default_array.rs:3:1
   |
 3 | #[graphql_interface]
   | ^^^^^^^^^^^^^^^^^^^^ the trait `From<[bool; 3]>` is not implemented for `[bool; 2]`
   |
   = help: the following implementations were found:
             <&'a [ascii::ascii_char::AsciiChar] as From<&'a ascii::ascii_str::AsciiStr>>
+            <&'a [u32; 4] as From<&'a ppv_lite86::x86_64::vec128_storage>>
             <&'a [u8] as From<&'a ascii::ascii_str::AsciiStr>>
             <&'a mut [ascii::ascii_char::AsciiChar] as From<&'a mut ascii::ascii_str::AsciiStr>>
-            <[T; LANES] as From<Simd<T, LANES>>>
+          and 11 others
-            <[bool; LANES] as From<Mask<T, LANES>>>
   = note: required because of the requirements on the impl of `Into<[bool; 2]>` for `[bool; 3]`
   = note: this error originates in the attribute macro `graphql_interface` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/trait/field_double_underscored.stderr

@@ -1,5 +1,5 @@
 error: All types and directives defined within a schema must not have a name which begins with `__` (two underscores), as this is used exclusively by GraphQL’s introspection system.
- --> fail/interface/field_double_underscored.rs:5:8
+ --> fail/interface/trait/field_double_underscored.rs:5:8
   |
 5 |     fn __id(&self) -> &str;
   |        ^^^^

integration_tests/codegen_fail/fail/interface/trait/field_non_output_return_type.stderr

@@ -0,0 +1,5 @@
+error[E0277]: the trait bound `ObjB: IsOutputType<__S>` is not satisfied
+  --> fail/interface/trait/field_non_output_return_type.rs:10:21
+   |
+10 |     fn id(&self) -> ObjB;
+   |                     ^^^^ the trait `IsOutputType<__S>` is not implemented for `ObjB`

integration_tests/codegen_fail/fail/interface/trait/fields_duplicate.stderr

@@ -1,5 +1,5 @@
 error: GraphQL interface must have a different name for each field
- --> fail/interface/fields_duplicate.rs:4:1
+ --> fail/interface/trait/fields_duplicate.rs:4:1
   |
 4 | / trait Character {
 5 | |     fn id(&self) -> &str;

integration_tests/codegen_fail/fail/interface/trait/implementers_duplicate_pretty.stderr

@@ -1,11 +1,11 @@
 error: duplicated attribute argument found
- --> fail/interface/implementers_duplicate_pretty.rs:9:34
+ --> fail/interface/trait/implementers_duplicate_pretty.rs:9:34
   |
 9 | #[graphql_interface(for = [ObjA, ObjA])]
   |                                  ^^^^
 
 error[E0412]: cannot find type `CharacterValue` in this scope
- --> fail/interface/implementers_duplicate_pretty.rs:4:18
+ --> fail/interface/trait/implementers_duplicate_pretty.rs:4:18
   |
 4 | #[graphql(impl = CharacterValue)]
   |                  ^^^^^^^^^^^^^^ not found in this scope

integration_tests/codegen_fail/fail/interface/trait/implementers_duplicate_ugly.stderr

@@ -1,5 +1,5 @@
 error[E0119]: conflicting implementations of trait `std::convert::From<ObjA>` for type `CharacterValueEnum<ObjA, ObjA>`
-  --> fail/interface/implementers_duplicate_ugly.rs:11:1
+  --> fail/interface/trait/implementers_duplicate_ugly.rs:11:1
    |
 11 | #[graphql_interface(for = [ObjA, ObjAlias])]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -10,7 +10,7 @@ error[E0119]: conflicting implementations of trait `std::convert::From<ObjA>` fo
    = note: this error originates in the attribute macro `graphql_interface` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0119]: conflicting implementations of trait `<CharacterValueEnum<ObjA, ObjA> as juniper::GraphQLInterface<__S>>::mark::_::{closure#0}::MutuallyExclusive` for type `ObjA`
-  --> fail/interface/implementers_duplicate_ugly.rs:11:1
+  --> fail/interface/trait/implementers_duplicate_ugly.rs:11:1
    |
 11 | #[graphql_interface(for = [ObjA, ObjAlias])]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

integration_tests/codegen_fail/fail/interface/trait/method_default_impl.stderr

@@ -1,5 +1,5 @@
 error: GraphQL interface trait method can't have default implementation
- --> fail/interface/method_default_impl.rs:5:26
+ --> fail/interface/trait/method_default_impl.rs:5:26
   |
 5 |       fn id(&self) -> &str {
   |  __________________________^

integration_tests/codegen_fail/fail/interface/trait/missing_field.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/trait/missing_field.rs:11:8
+   |
+11 |     fn id(&self) -> &str;
+   |        ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id` isn't implemented on `ObjA`.', $DIR/fail/interface/trait/missing_field.rs:11:8
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/trait/missing_field_argument.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/trait/missing_field_argument.rs:16:8
+   |
+16 |     fn id(&self, is_present: bool) -> &str;
+   |        ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!` was expected, but not found.', $DIR/fail/interface/trait/missing_field_argument.rs:16:8
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/trait/missing_for_attr.stderr

@@ -1,7 +1,7 @@
 error[E0080]: evaluation of constant value failed
- --> fail/interface/missing_for_attr.rs:3:10
+ --> fail/interface/trait/missing_for_attr.rs:3:10
   |
 3 | #[derive(GraphQLObject)]
-  |          ^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing implementer reference in interface's `for` attribute.', $DIR/fail/interface/missing_for_attr.rs:3:10
+  |          ^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing implementer reference in interface's `for` attribute.', $DIR/fail/interface/trait/missing_for_attr.rs:3:10
   |
   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/trait/missing_impl_attr.stderr

@@ -1,7 +1,7 @@
 error[E0080]: evaluation of constant value failed
- --> fail/interface/missing_impl_attr.rs:8:1
+ --> fail/interface/trait/missing_impl_attr.rs:8:1
   |
 8 | #[graphql_interface(for = ObjA)]
-  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing interface reference in implementer's `impl` attribute.', $DIR/fail/interface/missing_impl_attr.rs:8:1
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: missing interface reference in implementer's `impl` attribute.', $DIR/fail/interface/trait/missing_impl_attr.rs:8:1
   |
   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/trait/name_double_underscored.stderr

@@ -1,5 +1,5 @@
 error: All types and directives defined within a schema must not have a name which begins with `__` (two underscores), as this is used exclusively by GraphQL’s introspection system.
- --> fail/interface/name_double_underscored.rs:4:7
+ --> fail/interface/trait/name_double_underscored.rs:4:7
   |
 4 | trait __Character {
   |       ^^^^^^^^^^^

integration_tests/codegen_fail/fail/interface/trait/no_fields.stderr

@@ -1,5 +1,5 @@
 error: GraphQL interface must have at least one field
- --> fail/interface/no_fields.rs:4:1
+ --> fail/interface/trait/no_fields.rs:4:1
   |
 4 | trait Character {}
   | ^^^^^^^^^^^^^^^^^^

integration_tests/codegen_fail/fail/interface/trait/non_subtype_return.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/trait/non_subtype_return.rs:11:8
+   |
+11 |     fn id(&self) -> &str;
+   |        ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: implementor is expected to return a subtype of interface's return object: `[String!]!` is not a subtype of `String!`.', $DIR/fail/interface/trait/non_subtype_return.rs:11:8
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/trait/wrong_argument_type.stderr

@@ -0,0 +1,7 @@
+error[E0080]: evaluation of constant value failed
+  --> fail/interface/trait/wrong_argument_type.rs:16:8
+   |
+16 |     fn id(&self, is_present: bool) -> &str;
+   |        ^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent`: expected type `Boolean!`, found: `Int!`.', $DIR/fail/interface/trait/wrong_argument_type.rs:16:8
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/wrong_argument_type.stderr

@@ -1,7 +0,0 @@
-error[E0080]: evaluation of constant value failed
-  --> fail/interface/wrong_argument_type.rs:14:1
-   |
-14 | #[graphql_interface(for = ObjA)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent`: expected type `Boolean!`, found: `Int!`.', $DIR/fail/interface/wrong_argument_type.rs:14:1
-   |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

integration_tests/codegen_fail/fail/interface/wrong_item_enum.stderr

@@ -1,7 +0,0 @@
-error: #[graphql_interface] attribute is applicable to trait definitions only
- --> fail/interface/wrong_item_enum.rs:8:1
-  |
-8 | #[graphql_interface(for = ObjA)]
-  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-  |
-  = note: this error originates in the attribute macro `graphql_interface` (in Nightly builds, run with -Z macro-backtrace for more info)