fix(compiler-cli): expand type for native controls with a dynamic type

We recently allowed users to have a dynamic input `type` with signal forms, but the logic that infers the value type falls back to `string` even though in theory it can be any of the other types.

These changes expand the inferred type to `string | number | boolean | Date | null` if we detect a dynamic `type` binding.

(cherry picked from commit 8a3f3a91cf)

packages/compiler-cli/src/ngtsc/typecheck/src/ops/signal_forms.ts

@@ -157,6 +157,25 @@ export class TcbNativeFieldOp extends TcbOp {
         ]);
     }
 
+    const hasDynamicType =
+      this.inputType === null &&
+      this.node.inputs.some(
+        (input) =>
+          (input.type === BindingType.Property || input.type === BindingType.Attribute) &&
+          input.name === 'type',
+      );
+
+    // If the type is dynamic, check it as if it can be any of the types above.
+    if (hasDynamicType) {
+      return ts.factory.createUnionTypeNode([
+        ts.factory.createKeywordTypeNode(ts.SyntaxKind.StringKeyword),
+        ts.factory.createKeywordTypeNode(ts.SyntaxKind.NumberKeyword),
+        ts.factory.createKeywordTypeNode(ts.SyntaxKind.BooleanKeyword),
+        ts.factory.createTypeReferenceNode('Date'),
+        ts.factory.createLiteralTypeNode(ts.factory.createNull()),
+      ]);
+    }
+
     // Fall back to string if we couldn't map the type.
     return ts.factory.createKeywordTypeNode(ts.SyntaxKind.StringKeyword);
   }

packages/compiler-cli/src/ngtsc/typecheck/test/type_check_block_spec.ts

@@ -2603,6 +2603,22 @@ describe('type check blocks', () => {
       expect(block).toContain('_t2.field = (((this).f));');
     });
 
+    it('should generate all possible type for input with a dynamic `type`', () => {
+      const block = tcb('<input [type]="expr" [field]="f"/>', [FieldMock]);
+      expect(block).toContain('var _t1 = null! as string | number | boolean | Date | null;');
+      expect(block).toContain('_t1 = ((this).f)().value();');
+      expect(block).toContain('var _t2 = null! as i0.Field;');
+      expect(block).toContain('_t2.field = (((this).f));');
+    });
+
+    it('should generate all possible type for input with a dynamic attribute `type` binding', () => {
+      const block = tcb('<input [attr.type]="expr" [field]="f"/>', [FieldMock]);
+      expect(block).toContain('var _t1 = null! as string | number | boolean | Date | null;');
+      expect(block).toContain('_t1 = ((this).f)().value();');
+      expect(block).toContain('var _t2 = null! as i0.Field;');
+      expect(block).toContain('_t2.field = (((this).f));');
+    });
+
     [
       {inputType: 'text', expectedType: 'string'},
       {inputType: 'radio', expectedType: 'string'},

packages/compiler-cli/test/ngtsc/signal_forms_spec.ts

@@ -601,5 +601,30 @@ runInEachFileSystem(() => {
       const diags = env.driveDiagnostics();
       expect(diags.length).toBe(0);
     });
+
+    it('should infer an input with a dynamic `type` as being any of the other types', () => {
+      env.write(
+        'test.ts',
+        `
+          import {Component, signal} from '@angular/core';
+          import {Field, form} from '@angular/forms/signals';
+
+          @Component({
+            template: '<input [type]="type" [field]="f"/>',
+            imports: [Field]
+          })
+          export class Comp {
+            type = '';
+            f = form(signal({test: true}));
+          }
+        `,
+      );
+
+      const diags = env.driveDiagnostics();
+      expect(diags.length).toBe(1);
+      expect(extractMessage(diags[0])).toBe(
+        `Type '{ test: boolean; }' is not assignable to type 'string | number | boolean | Date | null'.`,
+      );
+    });
   });
 });