Implement #[derive(GraphQLInterface)] to use structs as GraphQL int…

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