fix(zmodel): check cyclic inheritance

fixes #1229

Author: ymc9

packages/schema/src/language-server/validator/datamodel-validator.ts

@@ -33,6 +33,10 @@ export default class DataModelValidator implements AstValidator<DataModel> {
         validateDuplicatedDeclarations(dm, getModelFieldsWithBases(dm), accept);
         this.validateAttributes(dm, accept);
         this.validateFields(dm, accept);
+
+        if (dm.superTypes.length > 0) {
+            this.validateInheritance(dm, accept);
+        }
     }
 
     private validateFields(dm: DataModel, accept: ValidationAcceptor) {
@@ -407,6 +411,26 @@ export default class DataModelValidator implements AstValidator<DataModel> {
             });
         }
     }
+
+    private validateInheritance(dm: DataModel, accept: ValidationAcceptor) {
+        const seen = [dm];
+        const todo: DataModel[] = dm.superTypes.map((superType) => superType.ref!);
+        while (todo.length > 0) {
+            const current = todo.shift()!;
+            if (seen.includes(current)) {
+                accept(
+                    'error',
+                    `Circular inheritance detected: ${seen.map((m) => m.name).join(' -> ')} -> ${current.name}`,
+                    {
+                        node: dm,
+                    }
+                );
+                return;
+            }
+            seen.push(current);
+            todo.push(...current.superTypes.map((superType) => superType.ref!));
+        }
+    }
 }
 
 export interface MissingOppositeRelationData {

packages/schema/tests/schema/validation/cyclic-inheritance.test.ts

@@ -0,0 +1,39 @@
+import { loadModelWithError } from '../../utils';
+
+describe('Cyclic inheritance', () => {
+    it('abstract inheritance', async () => {
+        const errors = await loadModelWithError(
+            `
+    abstract model A extends B {}
+    abstract model B extends A {}
+    model C extends B {
+        id Int @id
+    }
+        `
+        );
+        expect(errors).toContain('Circular inheritance detected: A -> B -> A');
+        expect(errors).toContain('Circular inheritance detected: B -> A -> B');
+        expect(errors).toContain('Circular inheritance detected: C -> B -> A -> B');
+    });
+
+    it('delegate inheritance', async () => {
+        const errors = await loadModelWithError(
+            `
+    model A extends B { 
+        typeA String 
+        @@delegate(typeA)
+    }
+    model B extends A {
+        typeB String 
+        @@delegate(typeB)
+    }
+    model C extends B {
+        id Int @id
+    }
+        `
+        );
+        expect(errors).toContain('Circular inheritance detected: A -> B -> A');
+        expect(errors).toContain('Circular inheritance detected: B -> A -> B');
+        expect(errors).toContain('Circular inheritance detected: C -> B -> A -> B');
+    });
+});

packages/sdk/src/utils.ts

@@ -544,16 +544,24 @@ export function getModelFieldsWithBases(model: DataModel, includeDelegate = true
     }
 }
 
-export function getRecursiveBases(dataModel: DataModel, includeDelegate = true): DataModel[] {
+export function getRecursiveBases(
+    dataModel: DataModel,
+    includeDelegate = true,
+    seen = new Set<DataModel>()
+): DataModel[] {
     const result: DataModel[] = [];
+    if (seen.has(dataModel)) {
+        return result;
+    }
+    seen.add(dataModel);
     dataModel.superTypes.forEach((superType) => {
         const baseDecl = superType.ref;
         if (baseDecl) {
             if (!includeDelegate && isDelegateModel(baseDecl)) {
                 return;
             }
             result.push(baseDecl);
-            result.push(...getRecursiveBases(baseDecl, includeDelegate));
+            result.push(...getRecursiveBases(baseDecl, includeDelegate, seen));
         }
     });
     return result;