add findDeprecatedUsages.

types/graphql/utilities/findDeprecatedUsages.d.ts

@@ -0,0 +1,13 @@
+import { GraphQLSchema } from '../type/schema';
+import { DocumentNode } from '../language/ast';
+import { GraphQLError } from '../error/GraphQLError';
+
+/**
+ * A validation rule which reports deprecated usages.
+ *
+ * Returns a list of GraphQLError instances describing each deprecated use.
+ */
+export function findDeprecatedUsages(
+    schema: GraphQLSchema,
+    ast: DocumentNode
+): Array<GraphQLError>

types/graphql/utilities/index.d.ts

@@ -73,3 +73,6 @@ export { assertValidName } from './assertValidName';
 // Compares two GraphQLSchemas and detects breaking changes.
 export { findBreakingChanges } from './findBreakingChanges';
 export { BreakingChange } from './findBreakingChanges';
+
+// Report all deprecated usage within a GraphQL document.
+export { findDeprecatedUsages } from './findDeprecatedUsages';