From 23601a10b80ffa97bd5f0f575fb6d8e971e77aa1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=8E=8B=E6=96=87=E7=92=90?= <kingwenlu@gmail.com>
Date: Thu, 2 Aug 2018 09:44:34 +0800
Subject: [PATCH] improve completions for union type in type arguments

---
 src/services/completions.ts                          |  2 ++
 .../cases/fourslash/completionListForStringUnion.ts  | 12 ++++++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 tests/cases/fourslash/completionListForStringUnion.ts

diff --git a/src/services/completions.ts b/src/services/completions.ts
index 4a62b35310..2b21336141 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -402,6 +402,8 @@ namespace ts.Completions {
                         return stringLiteralCompletionsFromProperties(typeChecker.getTypeFromTypeNode((node.parent.parent as IndexedAccessTypeNode).objectType));
                     case SyntaxKind.ImportType:
                         return { kind: StringLiteralCompletionKind.Paths, paths: PathCompletions.getStringLiteralCompletionsFromModuleNames(sourceFile, node, compilerOptions, host, typeChecker) };
+                    case SyntaxKind.UnionType:
+                        return isTypeReferenceNode(node.parent.parent.parent) ? { kind: StringLiteralCompletionKind.Types, types: getStringLiteralTypes(typeChecker.getTypeArgumentConstraint(node.parent.parent as UnionTypeNode)), isNewIdentifier: false } : undefined;
                     default:
                         return undefined;
                 }
diff --git a/tests/cases/fourslash/completionListForStringUnion.ts b/tests/cases/fourslash/completionListForStringUnion.ts
new file mode 100644
index 0000000000..14e5979efb
--- /dev/null
+++ b/tests/cases/fourslash/completionListForStringUnion.ts
@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+//// type A = 'fooooo' | 'barrrrr';
+//// type B<T extends A> = {};
+//// type C = B<'fooooo' | '/**/'>
+
+
+goTo.marker();
+verify.completionListContains("fooooo");
+verify.completionListContains("barrrrr");
+edit.insert("b");
+verify.completionListContains("barrrrr");