From 64cf510f373f98918241e78a649de77c0b4e4d2e Mon Sep 17 00:00:00 2001
From: Keen Yee Liau <kyliau@google.com>
Date: Thu, 31 Oct 2019 16:15:11 -0700
Subject: [PATCH] fix(language-service): Should not crash if expr ends
 unexpectedly

If there is any parser errors when parsing template, we should stop
immediately and not proceed with template expression diagnostics.

This regression is caused by https://github.com/angular/angular/commit/6d111546527812ab48f48e156f09ef41cb9be1ca
and affected v9.0.0-next.4 onwards.

PR closes https://github.com/angular/vscode-ng-language-service/issues/436
---
 packages/language-service/src/diagnostics.ts       | 11 ++++-------
 packages/language-service/test/diagnostics_spec.ts | 13 +++++++++++++
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/packages/language-service/src/diagnostics.ts b/packages/language-service/src/diagnostics.ts
index 9e92a2dd32749..6f613055dbfee 100644
--- a/packages/language-service/src/diagnostics.ts
+++ b/packages/language-service/src/diagnostics.ts
@@ -21,26 +21,23 @@ import {findPropertyValueOfType, findTightestNode, offsetSpan, spanOf} from './u
  * @param ast contains HTML and template AST
  */
 export function getTemplateDiagnostics(ast: AstResult): ng.Diagnostic[] {
-  const results: ng.Diagnostic[] = [];
   const {parseErrors, templateAst, htmlAst, template} = ast;
-  if (parseErrors) {
-    results.push(...parseErrors.map(e => {
+  if (parseErrors && parseErrors.length) {
+    return parseErrors.map(e => {
       return {
         kind: ng.DiagnosticKind.Error,
         span: offsetSpan(spanOf(e.span), template.span.start),
         message: e.msg,
       };
-    }));
+    });
   }
-  const expressionDiagnostics = getTemplateExpressionDiagnostics({
+  return getTemplateExpressionDiagnostics({
     templateAst: templateAst,
     htmlAst: htmlAst,
     offset: template.span.start,
     query: template.query,
     members: template.members,
   });
-  results.push(...expressionDiagnostics);
-  return results;
 }
 
 /**
diff --git a/packages/language-service/test/diagnostics_spec.ts b/packages/language-service/test/diagnostics_spec.ts
index daaa615435ec9..4e309e665555d 100644
--- a/packages/language-service/test/diagnostics_spec.ts
+++ b/packages/language-service/test/diagnostics_spec.ts
@@ -56,6 +56,19 @@ describe('diagnostics', () => {
     }
   });
 
+  it('should report error for unexpected end of expression', () => {
+    const content = mockHost.override(TEST_TEMPLATE, `{{ 5 / }}`);
+    const diags = ngLS.getDiagnostics(TEST_TEMPLATE);
+    expect(diags.length).toBe(1);
+    const {messageText, start, length} = diags[0];
+    expect(messageText)
+        .toBe(
+            'Parser Error: Unexpected end of expression: {{ 5 / }} ' +
+            'at the end of the expression [{{ 5 / }}] in /app/test.ng@0:0');
+    expect(start).toBe(0);
+    expect(length).toBe(content.length);
+  });
+
   // https://github.com/angular/vscode-ng-language-service/issues/242
   it('should support $any() type cast function', () => {
     mockHost.override(TEST_TEMPLATE, `<div>{{$any(title).xyz}}</div>`);