fix(ivy): fix bug with banana-in-a-box expressions in nested templates (#25321)

Inside of a nested template, an attempt to generate code for a banana-
in-a-box expression would cause a crash in the _AstToIrVisitor, as it
was not handling the case where a write would be generated to a local
variable.

This change supports such a mode of operation.

PR Close #25321

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

@@ -640,4 +640,21 @@ describe('ngtsc behavioral tests', () => {
     expect(emptyFactory).toContain(`import * as i0 from '@angular/core';`);
     expect(emptyFactory).toContain(`export var ɵNonEmptyModule = true;`);
   });
+
+  it('should compile a banana-in-a-box inside of a template', () => {
+    writeConfig();
+    write('test.ts', `
+        import {Component} from '@angular/core';
+
+        @Component({
+          template: '<div *tmpl [(bananaInABox)]="prop"></div>',
+          selector: 'test'
+        })
+        class TestCmp {}
+    `);
+
+    const exitCode = main(['-p', basePath], errorSpy);
+    expect(errorSpy).not.toHaveBeenCalled();
+    expect(exitCode).toBe(0);
+  });
 });

packages/compiler/src/compiler_util/expression_converter.ts

@@ -449,14 +449,28 @@ class _AstToIrVisitor implements cdAst.AstVisitor {
 
   visitPropertyWrite(ast: cdAst.PropertyWrite, mode: _Mode): any {
     const receiver: o.Expression = this._visit(ast.receiver, _Mode.Expression);
+
+    let varExpr: o.ReadPropExpr|null = null;
     if (receiver === this._implicitReceiver) {
-      const varExpr = this._getLocal(ast.name);
+      const localExpr = this._getLocal(ast.name);
-      if (varExpr) {
+      if (localExpr) {
-        throw new Error('Cannot assign to a reference or variable!');
+        if (localExpr instanceof o.ReadPropExpr) {
+          // If the local variable is a property read expression, it's a reference
+          // to a 'context.property' value and will be used as the target of the
+          // write expression.
+          varExpr = localExpr;
+        } else {
+          // Otherwise it's an error.
+          throw new Error('Cannot assign to a reference or variable!');
+        }
       }
     }
-    return convertToStatementIfNeeded(
+    // If no local expression could be produced, use the original receiver's
-        mode, receiver.prop(ast.name).set(this._visit(ast.value, _Mode.Expression)));
+    // property as the target.
+    if (varExpr === null) {
+      varExpr = receiver.prop(ast.name);
+    }
+    return convertToStatementIfNeeded(mode, varExpr.set(this._visit(ast.value, _Mode.Expression)));
   }
 
   visitSafePropertyRead(ast: cdAst.SafePropertyRead, mode: _Mode): any {