From b75b0d7fa6a010c008862708c230cba5ec702311 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=8E=8B=E6=96=87=E7=92=90?= <kingwenlu@gmail.com>
Date: Mon, 5 Mar 2018 18:17:16 +0800
Subject: [PATCH] allow trailing comman in type arguments list

---
 src/compiler/checker.ts                       |  3 +--
 .../allowTrailingCommasInTypeArguments.js     | 17 +++++++++++++
 ...allowTrailingCommasInTypeArguments.symbols | 24 ++++++++++++++++++
 .../allowTrailingCommasInTypeArguments.types  | 25 +++++++++++++++++++
 .../reference/syntaxErrors.errors.txt         |  5 +---
 .../allowTrailingCommasInTypeArguments.ts     |  7 ++++++
 6 files changed, 75 insertions(+), 6 deletions(-)
 create mode 100644 tests/baselines/reference/allowTrailingCommasInTypeArguments.js
 create mode 100644 tests/baselines/reference/allowTrailingCommasInTypeArguments.symbols
 create mode 100644 tests/baselines/reference/allowTrailingCommasInTypeArguments.types
 create mode 100644 tests/cases/compiler/allowTrailingCommasInTypeArguments.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 2c4999e516fd7..e4331b2b531ee 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -27027,8 +27027,7 @@ namespace ts {
         }
 
         function checkGrammarTypeArguments(node: Node, typeArguments: NodeArray<TypeNode>): boolean {
-            return checkGrammarForDisallowedTrailingComma(typeArguments) ||
-                checkGrammarForAtLeastOneTypeArgument(node, typeArguments);
+            return checkGrammarForAtLeastOneTypeArgument(node, typeArguments);
         }
 
         function checkGrammarForOmittedArgument(args: NodeArray<Expression>): boolean {
diff --git a/tests/baselines/reference/allowTrailingCommasInTypeArguments.js b/tests/baselines/reference/allowTrailingCommasInTypeArguments.js
new file mode 100644
index 0000000000000..5c3b845db47bd
--- /dev/null
+++ b/tests/baselines/reference/allowTrailingCommasInTypeArguments.js
@@ -0,0 +1,17 @@
+//// [allowTrailingCommasInTypeArguments.ts]
+class FooClass<A, B, C,> {
+	a: A;
+	b: B;
+	c: C;
+}
+
+var a = new FooClass<number, number, number,>();
+
+
+//// [allowTrailingCommasInTypeArguments.js]
+var FooClass = /** @class */ (function () {
+    function FooClass() {
+    }
+    return FooClass;
+}());
+var a = new FooClass();
diff --git a/tests/baselines/reference/allowTrailingCommasInTypeArguments.symbols b/tests/baselines/reference/allowTrailingCommasInTypeArguments.symbols
new file mode 100644
index 0000000000000..acc5884057d90
--- /dev/null
+++ b/tests/baselines/reference/allowTrailingCommasInTypeArguments.symbols
@@ -0,0 +1,24 @@
+=== tests/cases/compiler/allowTrailingCommasInTypeArguments.ts ===
+class FooClass<A, B, C,> {
+>FooClass : Symbol(FooClass, Decl(allowTrailingCommasInTypeArguments.ts, 0, 0))
+>A : Symbol(A, Decl(allowTrailingCommasInTypeArguments.ts, 0, 15))
+>B : Symbol(B, Decl(allowTrailingCommasInTypeArguments.ts, 0, 17))
+>C : Symbol(C, Decl(allowTrailingCommasInTypeArguments.ts, 0, 20))
+
+	a: A;
+>a : Symbol(FooClass.a, Decl(allowTrailingCommasInTypeArguments.ts, 0, 26))
+>A : Symbol(A, Decl(allowTrailingCommasInTypeArguments.ts, 0, 15))
+
+	b: B;
+>b : Symbol(FooClass.b, Decl(allowTrailingCommasInTypeArguments.ts, 1, 6))
+>B : Symbol(B, Decl(allowTrailingCommasInTypeArguments.ts, 0, 17))
+
+	c: C;
+>c : Symbol(FooClass.c, Decl(allowTrailingCommasInTypeArguments.ts, 2, 6))
+>C : Symbol(C, Decl(allowTrailingCommasInTypeArguments.ts, 0, 20))
+}
+
+var a = new FooClass<number, number, number,>();
+>a : Symbol(a, Decl(allowTrailingCommasInTypeArguments.ts, 6, 3))
+>FooClass : Symbol(FooClass, Decl(allowTrailingCommasInTypeArguments.ts, 0, 0))
+
diff --git a/tests/baselines/reference/allowTrailingCommasInTypeArguments.types b/tests/baselines/reference/allowTrailingCommasInTypeArguments.types
new file mode 100644
index 0000000000000..8b9ecff6ac859
--- /dev/null
+++ b/tests/baselines/reference/allowTrailingCommasInTypeArguments.types
@@ -0,0 +1,25 @@
+=== tests/cases/compiler/allowTrailingCommasInTypeArguments.ts ===
+class FooClass<A, B, C,> {
+>FooClass : FooClass<A, B, C>
+>A : A
+>B : B
+>C : C
+
+	a: A;
+>a : A
+>A : A
+
+	b: B;
+>b : B
+>B : B
+
+	c: C;
+>c : C
+>C : C
+}
+
+var a = new FooClass<number, number, number,>();
+>a : FooClass<number, number, number>
+>new FooClass<number, number, number,>() : FooClass<number, number, number>
+>FooClass : typeof FooClass
+
diff --git a/tests/baselines/reference/syntaxErrors.errors.txt b/tests/baselines/reference/syntaxErrors.errors.txt
index 25276af3956e5..ebb7ba25acd82 100644
--- a/tests/baselines/reference/syntaxErrors.errors.txt
+++ b/tests/baselines/reference/syntaxErrors.errors.txt
@@ -1,17 +1,14 @@
 tests/cases/conformance/jsdoc/badTypeArguments.js(1,15): error TS1099: Type argument list cannot be empty.
-tests/cases/conformance/jsdoc/badTypeArguments.js(2,22): error TS1009: Trailing comma not allowed.
 
 
 ==== tests/cases/conformance/jsdoc/dummyType.d.ts (0 errors) ====
     declare class C<T> { t: T }
     
-==== tests/cases/conformance/jsdoc/badTypeArguments.js (2 errors) ====
+==== tests/cases/conformance/jsdoc/badTypeArguments.js (1 errors) ====
     /** @param {C.<>} x */
                   ~~
 !!! error TS1099: Type argument list cannot be empty.
     /** @param {C.<number,>} y */
-                         ~
-!!! error TS1009: Trailing comma not allowed.
     // @ts-ignore
     /** @param {C.<number,>} skipped */
     function f(x, y, skipped) {
diff --git a/tests/cases/compiler/allowTrailingCommasInTypeArguments.ts b/tests/cases/compiler/allowTrailingCommasInTypeArguments.ts
new file mode 100644
index 0000000000000..691992e84993a
--- /dev/null
+++ b/tests/cases/compiler/allowTrailingCommasInTypeArguments.ts
@@ -0,0 +1,7 @@
+class FooClass<A, B, C,> {
+	a: A;
+	b: B;
+	c: C;
+}
+
+var a = new FooClass<number, number, number,>();