fix(graphql): keep distinct GraphQL types with identical shape separate

packages/quicktype-core/src/Type/Type.ts

@@ -266,6 +266,13 @@ function identityAttributes(attributes: TypeAttributes): TypeAttributes {
     return mapFilter(attributes, (_, kind) => kind.inIdentity);
 }
 
+export function haveSameIdentityAttributes(a: Type, b: Type): boolean {
+    return areEqual(
+        identityAttributes(a.getAttributes()),
+        identityAttributes(b.getAttributes()),
+    );
+}
+
 export function primitiveTypeIdentity(
     kind: PrimitiveTypeKind,
     attributes: TypeAttributes,

packages/quicktype-core/src/rewrites/CombineClasses.ts

@@ -5,6 +5,7 @@ import {
     type ClassProperty,
     ClassType,
     type Type,
+    haveSameIdentityAttributes,
     setOperationCasesEqual,
 } from "../Type/Type.js";
 import type { TypeGraph } from "../Type/TypeGraph.js";
@@ -110,14 +111,20 @@ function tryAddToClique(
     onlyWithSameProperties: boolean,
 ): boolean {
     for (const prototype of clique.prototypes) {
-        if (prototype.structurallyCompatible(c)) {
+        if (
+            haveSameIdentityAttributes(prototype, c) &&
+            prototype.structurallyCompatible(c)
+        ) {
             clique.members.push(c);
             return true;
         }
     }
 
     for (const prototype of clique.prototypes) {
-        if (canBeCombined(prototype, c, onlyWithSameProperties)) {
+        if (
+            haveSameIdentityAttributes(prototype, c) &&
+            canBeCombined(prototype, c, onlyWithSameProperties)
+        ) {
             clique.prototypes.push(c);
             clique.members.push(c);
             return true;

packages/quicktype-graphql-input/src/index.ts

@@ -15,6 +15,7 @@ import {
     type Input,
     type RunContext,
     StringTypes,
+    TypeAttributeKind,
     type TypeAttributes,
     type TypeBuilder,
     TypeNames,
@@ -77,6 +78,22 @@ function getField(t: GQLType, name: string): Field {
     return panic(`Required field ${name} not defined on type ${t.name}.`);
 }
 
+class GraphQLTypeNameTypeAttributeKind extends TypeAttributeKind<string> {
+    public constructor() {
+        super("graphqlTypeName");
+    }
+
+    public get inIdentity(): boolean {
+        return true;
+    }
+
+    public combine(names: string[]): string {
+        return names[0];
+    }
+}
+
+const graphQLTypeNameTypeAttributeKind = new GraphQLTypeNameTypeAttributeKind();
+
 function makeNames(
     name: string,
     fieldName: string | null,
@@ -422,10 +439,11 @@ class GQLQuery {
             }
         }
 
-        return builder.getClassType(
+        const attributes = new Map(
             makeNames(nameOrOverride, containingFieldName, containingTypeName),
-            properties,
         );
+        attributes.set(graphQLTypeNameTypeAttributeKind, gqlType.name);
+        return builder.getClassType(attributes, properties);
     };
 
     public makeType(