fix(schema-compiler) support join inheritance

packages/cubejs-schema-compiler/src/compiler/CubeSymbols.js

@@ -65,6 +65,7 @@ export class CubeSymbols {
     let measures;
     let dimensions;
     let segments;
+    let joins;
 
     const cubeObject = Object.assign({
       allDefinitions(type) {
@@ -106,7 +107,17 @@ export class CubeSymbols {
       },
       set segments(v) {
         // Dont allow to modify
-      }
+      },
+
+      get joins() {
+        if (!joins) {
+          joins = this.allDefinitions('joins');
+        }
+        return joins;
+      },
+      set joins(v) {
+        // Dont allow to modify
+      },
     }, cubeDefinition);
 
     if (cubeDefinition.extends) {

packages/cubejs-schema-compiler/test/integration/postgres/yaml-compiler.test.ts

@@ -482,6 +482,65 @@ cubes:
     );
   });
 
+  it('should correctly handle extensions with joins', async () => {
+    const { compiler, joinGraph, cubeEvaluator } = prepareYamlCompiler(`
+      cubes:
+        - name: base_users
+          sql: "SELECT 1"
+
+          dimensions:
+            - name: time
+              sql: "{CUBE}.timestamp"
+              type: time
+            - name: user_id
+              sql: "user_id"
+              type: number
+              primary_key: true
+              public: true
+
+          joins:
+            - name: base_user_joins
+              sql: "{CUBE}.user_id = {base_user_joins}.user_id"
+              relationship: one_to_one
+
+        - name: base_user_joins
+          sql: "SELECT 1 as user_id, 2 as second_prop"
+
+          dimensions:
+            - name: user_id
+              sql: "user_id"
+              type: number
+              primary_key: true
+            - name: second_prop
+              sql: "second_prop"
+              type: number
+
+        - name: active_users
+          sql: "SELECT 1 as user_id, '2022-01-01' as timestamp"
+          extends: base_users
+
+          `, { yamlExtension: true });
+    await compiler.compile();
+
+    const query = new PostgresQuery({ joinGraph, cubeEvaluator, compiler }, {
+      measures: [],
+      dimensions: ['active_users.user_id', 'active_users.second_prop'],
+      timezone: 'UTC'
+    });
+
+    console.log(query.buildSqlAndParams());
+
+    const res = await dbRunner.testQuery(query.buildSqlAndParams());
+    console.log(JSON.stringify(res));
+
+    expect(res).toEqual(
+      [{
+        active_users__user_id: 1,
+        base_user_joins__second_prop: 2
+      }]
+    );
+  });
+
   it('COMPILE_CONTEXT', async () => {
     const { compiler, joinGraph, cubeEvaluator } = prepareYamlCompiler(`
     cubes: