feat: Warn on deprecated enum values used as arguments (#5277)

Summary:
GraphQL allows `deprecated` on enum values, but Relay wasn't warning when a deprecated enum value was used as a field or directive argument. This PR adds that validation alongside the existing deprecated field/argument checks.

```graphql
enum Status {
  ACTIVE
  LEGACY deprecated(reason: "Use ACTIVE instead.")
}

# Before: no warning
# After: The enum value `LEGACY` of type `Status` is deprecated. Deprecation reason: "Use ACTIVE instead."
fragment Foo on Query {
  user(status: LEGACY)
}

```

The warning message wording follows the existing patterns in the codebase. Open to suggestions if there's a better way to phrase it!

> [!NOTE]
> Variable values (`$status`) and deeply nested enum values inside constant objects/arrays are not yet covered. Left a TODO comment in the code.

Pull Request resolved: #5277

Reviewed By: captbaritone

Differential Revision: D106030387

Pulled By: evanyeung

fbshipit-source-id: 16617aa66259c233780624767dfe457f93c9c9d3

Author: jungwoo3490

compiler/crates/graphql-ir/src/errors.rs

@@ -498,6 +498,17 @@ pub enum ValidationMessage {
         deprecation_reason: Option<StringKey>,
     },
 
+    #[error("The enum value `{enum_value}` of type `{enum_name}` is deprecated.{}",
+    match deprecation_reason {
+        Some(reason) => format!(" Deprecation reason: \"{reason}\""),
+        None => "".to_string()
+    })]
+    DeprecatedEnumValue {
+        enum_value: StringKey,
+        enum_name: StringKey,
+        deprecation_reason: Option<StringKey>,
+    },
+
     #[error("Missing required {}: `{}`",
         if missing_arg_names.len() > 1 { "arguments" } else { "argument" },
         missing_arg_names

compiler/crates/relay-transforms/src/validations/deprecated_fields.rs

@@ -12,6 +12,7 @@ use common::DiagnosticTag;
 use common::DiagnosticsResult;
 use common::WithLocation;
 use graphql_ir::Argument;
+use graphql_ir::ConstantValue;
 use graphql_ir::Directive;
 use graphql_ir::ExecutableDefinition;
 use graphql_ir::LinkedField;
@@ -24,6 +25,7 @@ use graphql_ir::Value;
 use schema::FieldID;
 use schema::SDLSchema;
 use schema::Schema;
+use schema::Type;
 
 use crate::fragment_alias_directive::FRAGMENT_DANGEROUSLY_UNALIAS_DIRECTIVE_NAME;
 
@@ -81,22 +83,41 @@ impl<'a> DeprecatedFields<'a> {
         }
 
         for arg in arguments {
-            if let Some(arg_definition) = field_definition.arguments.named(arg.name.item)
-                && let Some(directive) = arg_definition.deprecated()
-            {
-                let parent_type = field_definition.parent_type.unwrap();
-                let parent_name = schema.get_type_name(parent_type);
-
-                self.warnings.push(Diagnostic::hint(
-                    ValidationMessage::DeprecatedFieldArgument {
-                        argument_name: arg.name.item,
-                        field_name: field_definition.name.item,
-                        parent_name,
-                        deprecation_reason: directive.reason,
-                    },
-                    arg.name.location,
-                    vec![DiagnosticTag::DEPRECATED],
-                ));
+            if let Some(arg_definition) = field_definition.arguments.named(arg.name.item) {
+                if let Some(directive) = arg_definition.deprecated() {
+                    let parent_type = field_definition.parent_type.unwrap();
+                    let parent_name = schema.get_type_name(parent_type);
+
+                    self.warnings.push(Diagnostic::hint(
+                        ValidationMessage::DeprecatedFieldArgument {
+                            argument_name: arg.name.item,
+                            field_name: field_definition.name.item,
+                            parent_name,
+                            deprecation_reason: directive.reason,
+                        },
+                        arg.name.location,
+                        vec![DiagnosticTag::DEPRECATED],
+                    ));
+                }
+
+                if let Type::Enum(enum_id) = arg_definition.type_.inner() {
+                    let enum_def = schema.enum_(enum_id);
+                    if let Value::Constant(ConstantValue::Enum(value_name)) = &arg.value.item
+                        && let Some(enum_value) =
+                            enum_def.values.iter().find(|v| v.value == *value_name)
+                        && let Some(deprecation) = enum_value.deprecated()
+                    {
+                        self.warnings.push(Diagnostic::hint(
+                            ValidationMessage::DeprecatedEnumValue {
+                                enum_value: *value_name,
+                                enum_name: enum_def.name.item.0,
+                                deprecation_reason: deprecation.reason,
+                            },
+                            arg.value.location,
+                            vec![DiagnosticTag::DEPRECATED],
+                        ));
+                    }
+                }
             }
         }
     }
@@ -121,11 +142,9 @@ impl Validator for DeprecatedFields<'_> {
     }
 
     fn validate_value(&mut self, value: &Value) -> DiagnosticsResult<()> {
-        // TODO: `@deprecated` is allowed on Enum values, so technically we
-        // should also be validating when someone uses a deprecated enum value
-        // as an argument, but that will require some additional methods on our
-        // Schema, and potentially some additional traversal in our validation
-        // trait to traverse into potentially deep constant objects/arrays.
+        // TODO: Deprecated enum values inside deeply nested constant objects/arrays
+        // are not yet validated. Top-level enum values in field and directive arguments
+        // are handled in validate_field and validate_directive respectively.
         self.default_validate_value(value)
     }
 
@@ -143,18 +162,37 @@ impl Validator for DeprecatedFields<'_> {
                 ));
             }
             for arg in &directive.arguments {
-                if let Some(arg_definition) = directive_definition.arguments.named(arg.name.item)
-                    && let Some(deprecation) = arg_definition.deprecated()
-                {
-                    self.warnings.push(Diagnostic::hint(
-                        ValidationMessage::DeprecatedDirectiveArgument {
-                            argument_name: arg.name.item,
-                            directive_name: directive.name.item,
-                            deprecation_reason: deprecation.reason,
-                        },
-                        arg.name.location,
-                        vec![DiagnosticTag::DEPRECATED],
-                    ));
+                if let Some(arg_definition) = directive_definition.arguments.named(arg.name.item) {
+                    if let Some(deprecation) = arg_definition.deprecated() {
+                        self.warnings.push(Diagnostic::hint(
+                            ValidationMessage::DeprecatedDirectiveArgument {
+                                argument_name: arg.name.item,
+                                directive_name: directive.name.item,
+                                deprecation_reason: deprecation.reason,
+                            },
+                            arg.name.location,
+                            vec![DiagnosticTag::DEPRECATED],
+                        ));
+                    }
+
+                    if let Type::Enum(enum_id) = arg_definition.type_.inner() {
+                        let enum_def = self.schema.enum_(enum_id);
+                        if let Value::Constant(ConstantValue::Enum(value_name)) = &arg.value.item
+                            && let Some(enum_value) =
+                                enum_def.values.iter().find(|v| v.value == *value_name)
+                            && let Some(deprecation) = enum_value.deprecated()
+                        {
+                            self.warnings.push(Diagnostic::hint(
+                                ValidationMessage::DeprecatedEnumValue {
+                                    enum_value: *value_name,
+                                    enum_name: enum_def.name.item.0,
+                                    deprecation_reason: deprecation.reason,
+                                },
+                                arg.value.location,
+                                vec![DiagnosticTag::DEPRECATED],
+                            ));
+                        }
+                    }
                 }
             }
         }

compiler/crates/relay-transforms/tests/validate_deprecated_fields/fixtures/deprecated_enum_value.expected

@@ -0,0 +1,20 @@
+==================================== INPUT ====================================
+fragment Foo on MyNewType {
+  some_field(status: LEGACY)
+}
+%extensions%
+enum Status {
+  ACTIVE
+  LEGACY @deprecated
+}
+type MyNewType {
+  some_field(status: Status): String
+}
+==================================== OUTPUT ===================================
+ℹ The enum value `LEGACY` of type `Status` is deprecated.
+
+  deprecated_enum_value.graphql:2:22
+    1 │ fragment Foo on MyNewType {
+    2 │   some_field(status: LEGACY)
+      │                      ^^^^^^
+    3 │ }

compiler/crates/relay-transforms/tests/validate_deprecated_fields/fixtures/deprecated_enum_value.graphql

@@ -0,0 +1,11 @@
+fragment Foo on MyNewType {
+  some_field(status: LEGACY)
+}
+%extensions%
+enum Status {
+  ACTIVE
+  LEGACY @deprecated
+}
+type MyNewType {
+  some_field(status: Status): String
+}

compiler/crates/relay-transforms/tests/validate_deprecated_fields/fixtures/deprecated_enum_value_with_reason.expected

@@ -0,0 +1,20 @@
+==================================== INPUT ====================================
+fragment Foo on MyNewType {
+  some_field(status: LEGACY)
+}
+%extensions%
+enum Status {
+  ACTIVE
+  LEGACY @deprecated(reason: "Use ACTIVE instead.")
+}
+type MyNewType {
+  some_field(status: Status): String
+}
+==================================== OUTPUT ===================================
+ℹ The enum value `LEGACY` of type `Status` is deprecated. Deprecation reason: "Use ACTIVE instead."
+
+  deprecated_enum_value_with_reason.graphql:2:22
+    1 │ fragment Foo on MyNewType {
+    2 │   some_field(status: LEGACY)
+      │                      ^^^^^^
+    3 │ }

compiler/crates/relay-transforms/tests/validate_deprecated_fields/fixtures/deprecated_enum_value_with_reason.graphql

@@ -0,0 +1,11 @@
+fragment Foo on MyNewType {
+  some_field(status: LEGACY)
+}
+%extensions%
+enum Status {
+  ACTIVE
+  LEGACY @deprecated(reason: "Use ACTIVE instead.")
+}
+type MyNewType {
+  some_field(status: Status): String
+}

compiler/crates/relay-transforms/tests/validate_deprecated_fields_test.rs

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<523e6262355cff63df80d9ea70e0d2ef>>
+ * @generated SignedSource<<617806504dd54b22a1692ec28a9db160>>
  */
 
 mod validate_deprecated_fields;
@@ -26,6 +26,20 @@ async fn deprecated_directive_arg_with_reason() {
     test_fixture(transform_fixture, file!(), "deprecated_directive_arg_with_reason.graphql", "validate_deprecated_fields/fixtures/deprecated_directive_arg_with_reason.expected", input, expected).await;
 }
 
+#[tokio::test]
+async fn deprecated_enum_value() {
+    let input = include_str!("validate_deprecated_fields/fixtures/deprecated_enum_value.graphql");
+    let expected = include_str!("validate_deprecated_fields/fixtures/deprecated_enum_value.expected");
+    test_fixture(transform_fixture, file!(), "deprecated_enum_value.graphql", "validate_deprecated_fields/fixtures/deprecated_enum_value.expected", input, expected).await;
+}
+
+#[tokio::test]
+async fn deprecated_enum_value_with_reason() {
+    let input = include_str!("validate_deprecated_fields/fixtures/deprecated_enum_value_with_reason.graphql");
+    let expected = include_str!("validate_deprecated_fields/fixtures/deprecated_enum_value_with_reason.expected");
+    test_fixture(transform_fixture, file!(), "deprecated_enum_value_with_reason.graphql", "validate_deprecated_fields/fixtures/deprecated_enum_value_with_reason.expected", input, expected).await;
+}
+
 #[tokio::test]
 async fn deprecated_field_arg() {
     let input = include_str!("validate_deprecated_fields/fixtures/deprecated_field_arg.graphql");

compiler/crates/schema/src/definitions.rs

@@ -695,6 +695,19 @@ pub struct EnumValue {
     pub description: Option<StringKey>,
 }
 
+impl EnumValue {
+    pub fn deprecated(&self) -> Option<Deprecation> {
+        self.directives
+            .named(*DIRECTIVE_DEPRECATED)
+            .map(|directive| Deprecation {
+                reason: directive
+                    .arguments
+                    .named(*ARGUMENT_REASON)
+                    .and_then(|reason| reason.value.get_string_literal()),
+            })
+    }
+}
+
 #[derive(
     Clone,
     Eq,