From 3d9ca2f1730689232f0ba1d6eddbd7dcedd1da39 Mon Sep 17 00:00:00 2001
From: cexbrayat <cedric@ninja-squad.com>
Date: Tue, 2 Jun 2026 12:11:49 +0200
Subject: [PATCH] fix(compiler-cli): bind switch exhaustive check expressions

Ensure switch exhaustive check parameters are visited during template binding so local template symbols are resolved correctly.

This allows:

```html
@let state = this.state();
@switch (state.mode) {
  @case ('show') { {{ state.menu }}; }
  @case ('hide') {}
  @default never(state);
}
```

(cherry picked from commit e8430032e131bbcbede2e30c71b891b425f3574a)
---
 .../ngtsc/typecheck/test/diagnostics_spec.ts  | 21 +++++++++++++++++++
 packages/compiler/src/combined_visitor.ts     |  1 +
 2 files changed, 22 insertions(+)

diff --git a/packages/compiler-cli/src/ngtsc/typecheck/test/diagnostics_spec.ts b/packages/compiler-cli/src/ngtsc/typecheck/test/diagnostics_spec.ts
index de794ea506c..bc7bf7b4f86 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/test/diagnostics_spec.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/test/diagnostics_spec.ts
@@ -1487,6 +1487,27 @@ class TestComponent {
 
       expect(messages).toEqual([]);
     });
+
+    it('should narrow a let declaration with the same name as a component property', () => {
+      const messages = diagnose(
+        `
+          @let state = this.state();
+          @switch (state.mode) {
+            @case ('show') { {{ state.menu }}; }
+            @case ('hide') {}
+            @default never(state);
+          }
+        `,
+        `
+          import {InputSignal} from '@angular/core';
+          export class TestComponent {
+            state: InputSignal<{ mode: 'hide' } | { mode: 'show'; menu: number }>;
+          }
+        `,
+      );
+
+      expect(messages).toEqual([]);
+    });
   });
 
   // https://github.com/angular/angular/issues/43970
diff --git a/packages/compiler/src/combined_visitor.ts b/packages/compiler/src/combined_visitor.ts
index e18876634e4..942dcba373c 100644
--- a/packages/compiler/src/combined_visitor.ts
+++ b/packages/compiler/src/combined_visitor.ts
@@ -90,6 +90,7 @@ export class CombinedRecursiveAstVisitor extends RecursiveAstVisitor implements
   visitSwitchBlock(block: t.SwitchBlock): void {
     this.visit(block.expression);
     this.visitAllTemplateNodes(block.groups);
+    block.exhaustiveCheck?.visit(this);
   }
 
   visitSwitchBlockCase(block: t.SwitchBlockCase): void {