From 199ff4fe7f2cd4b561703e8520c2d6ccc1e2afb7 Mon Sep 17 00:00:00 2001
From: Kristiyan Kostadinov <crisbeto@abv.bg>
Date: Fri, 19 May 2023 09:07:19 +0200
Subject: [PATCH] fix(core): host directives incorrectly validating aliased
 bindings (#50364)

Fixes that the host directives feature was incorrectly throwing the conflicting alias error when an aliased binding was being exposed under the same alias.

Fixes #48951.

PR Close #50364
---
 .../test/ngtsc/host_directives_spec.ts        | 53 ++++++++++++++++
 .../features/host_directives_feature.ts       |  2 +-
 .../test/acceptance/host_directives_spec.ts   | 60 +++++++++++++++++++
 3 files changed, 114 insertions(+), 1 deletion(-)

diff --git a/packages/compiler-cli/test/ngtsc/host_directives_spec.ts b/packages/compiler-cli/test/ngtsc/host_directives_spec.ts
index 7c063356d09..b8dbe627245 100644
--- a/packages/compiler-cli/test/ngtsc/host_directives_spec.ts
+++ b/packages/compiler-cli/test/ngtsc/host_directives_spec.ts
@@ -944,6 +944,59 @@ runInEachFileSystem(() => {
 
            expect(messages).toEqual([]);
          });
+
+      it('should not produce a diagnostic when exposing an aliased binding', () => {
+        env.write('test.ts', `
+          import {Directive, EventEmitter} from '@angular/core';
+
+          @Directive({
+            outputs: ['opened: triggerOpened'],
+            selector: '[trigger]',
+            standalone: true,
+          })
+          export class Trigger {
+            opened = new EventEmitter();
+          }
+
+          @Directive({
+            standalone: true,
+            selector: '[host]',
+            hostDirectives: [{directive: Trigger, outputs: ['triggerOpened']}]
+          })
+          export class Host {}
+        `);
+
+        const diags = env.driveDiagnostics();
+        expect(diags.length).toBe(0);
+      });
+
+      it('should not produce a diagnostic when exposing an inherited aliased binding', () => {
+        env.write('test.ts', `
+          import {Directive, EventEmitter} from '@angular/core';
+
+          @Directive({standalone: true})
+          export abstract class Base {
+            opened = new EventEmitter();
+          }
+
+          @Directive({
+            outputs: ['opened: triggerOpened'],
+            selector: '[trigger]',
+            standalone: true,
+          })
+          export class Trigger extends Base {}
+
+          @Directive({
+            standalone: true,
+            selector: '[host]',
+            hostDirectives: [{directive: Trigger, outputs: ['triggerOpened: hostOpened']}]
+          })
+          export class Host {}
+        `);
+
+        const diags = env.driveDiagnostics();
+        expect(diags.length).toBe(0);
+      });
     });
   });
 });
diff --git a/packages/core/src/render3/features/host_directives_feature.ts b/packages/core/src/render3/features/host_directives_feature.ts
index 6e3e2afde86..82121488786 100644
--- a/packages/core/src/render3/features/host_directives_feature.ts
+++ b/packages/core/src/render3/features/host_directives_feature.ts
@@ -204,7 +204,7 @@ function validateMappings(
 
       const remappedPublicName = hostDirectiveBindings[publicName];
 
-      if (bindings.hasOwnProperty(remappedPublicName) &&
+      if (bindings.hasOwnProperty(remappedPublicName) && remappedPublicName !== publicName &&
           bindings[remappedPublicName] !== publicName) {
         throw new RuntimeError(
             RuntimeErrorCode.HOST_DIRECTIVE_CONFLICTING_ALIAS,
diff --git a/packages/core/test/acceptance/host_directives_spec.ts b/packages/core/test/acceptance/host_directives_spec.ts
index 85b6a951814..03ae81467e4 100644
--- a/packages/core/test/acceptance/host_directives_spec.ts
+++ b/packages/core/test/acceptance/host_directives_spec.ts
@@ -3219,5 +3219,65 @@ describe('host directives', () => {
         fixture.detectChanges();
       }).not.toThrow();
     });
+
+    it('should not throw when exposing an aliased binding', () => {
+      @Directive({
+        outputs: ['opened: triggerOpened'],
+        selector: '[trigger]',
+        standalone: true,
+      })
+      class Trigger {
+        opened = new EventEmitter();
+      }
+
+      @Directive({
+        standalone: true,
+        selector: '[host]',
+        hostDirectives: [{directive: Trigger, outputs: ['triggerOpened']}]
+      })
+      class Host {
+      }
+
+      @Component({template: '<div host></div>', standalone: true, imports: [Host]})
+      class App {
+      }
+
+      expect(() => {
+        const fixture = TestBed.createComponent(App);
+        fixture.detectChanges();
+      }).not.toThrow();
+    });
+
+    it('should not throw when exposing an inherited aliased binding', () => {
+      @Directive({standalone: true})
+      abstract class Base {
+        opened = new EventEmitter();
+      }
+
+      @Directive({
+        outputs: ['opened: triggerOpened'],
+        selector: '[trigger]',
+        standalone: true,
+      })
+      class Trigger extends Base {
+      }
+
+      @Directive({
+        standalone: true,
+        selector: '[host]',
+        hostDirectives: [{directive: Trigger, outputs: ['triggerOpened: hostOpened']}]
+      })
+      class Host {
+      }
+
+      @Component({template: '<div host></div>', standalone: true, imports: [Host]})
+      class App {
+      }
+
+      expect(() => {
+        const fixture = TestBed.createComponent(App);
+        fixture.detectChanges();
+      }).not.toThrow();
+    });
   });
 });