From f8c3a550caaba17f40a80bba7809cefbfe883f5f Mon Sep 17 00:00:00 2001
From: Sheetal Nandi <shkamat@microsoft.com>
Date: Fri, 21 Oct 2016 16:40:11 -0700
Subject: [PATCH] Check type parameters of the type alias declaration Fixes
 #11166

---
 src/compiler/checker.ts                           |  1 +
 .../nounusedTypeParameterConstraint.errors.txt    | 12 ------------
 .../nounusedTypeParameterConstraint.symbols       | 15 +++++++++++++++
 .../nounusedTypeParameterConstraint.types         | 15 +++++++++++++++
 .../reference/typeAliasDeclarationEmit.errors.txt | 10 ++++++++++
 5 files changed, 41 insertions(+), 12 deletions(-)
 delete mode 100644 tests/baselines/reference/nounusedTypeParameterConstraint.errors.txt
 create mode 100644 tests/baselines/reference/nounusedTypeParameterConstraint.symbols
 create mode 100644 tests/baselines/reference/nounusedTypeParameterConstraint.types
 create mode 100644 tests/baselines/reference/typeAliasDeclarationEmit.errors.txt

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 369d61ce484..5d66221df2b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -17418,6 +17418,7 @@ namespace ts {
             checkGrammarDecorators(node) || checkGrammarModifiers(node);
 
             checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0);
+            checkTypeParameters(node.typeParameters);
             checkSourceElement(node.type);
         }
 
diff --git a/tests/baselines/reference/nounusedTypeParameterConstraint.errors.txt b/tests/baselines/reference/nounusedTypeParameterConstraint.errors.txt
deleted file mode 100644
index a5797b44d92..00000000000
--- a/tests/baselines/reference/nounusedTypeParameterConstraint.errors.txt
+++ /dev/null
@@ -1,12 +0,0 @@
-tests/cases/compiler/test.ts(1,10): error TS6133: 'IEventSourcedEntity' is declared but never used.
-
-
-==== tests/cases/compiler/bar.ts (0 errors) ====
-    
-    export interface IEventSourcedEntity { }
-    
-==== tests/cases/compiler/test.ts (1 errors) ====
-    import { IEventSourcedEntity } from "./bar";
-             ~~~~~~~~~~~~~~~~~~~
-!!! error TS6133: 'IEventSourcedEntity' is declared but never used.
-    export type DomainEntityConstructor<TEntity extends IEventSourcedEntity> = { new(): TEntity; };
\ No newline at end of file
diff --git a/tests/baselines/reference/nounusedTypeParameterConstraint.symbols b/tests/baselines/reference/nounusedTypeParameterConstraint.symbols
new file mode 100644
index 00000000000..40364460f50
--- /dev/null
+++ b/tests/baselines/reference/nounusedTypeParameterConstraint.symbols
@@ -0,0 +1,15 @@
+=== tests/cases/compiler/bar.ts ===
+
+export interface IEventSourcedEntity { }
+>IEventSourcedEntity : Symbol(IEventSourcedEntity, Decl(bar.ts, 0, 0))
+
+=== tests/cases/compiler/test.ts ===
+import { IEventSourcedEntity } from "./bar";
+>IEventSourcedEntity : Symbol(IEventSourcedEntity, Decl(test.ts, 0, 8))
+
+export type DomainEntityConstructor<TEntity extends IEventSourcedEntity> = { new(): TEntity; };
+>DomainEntityConstructor : Symbol(DomainEntityConstructor, Decl(test.ts, 0, 44))
+>TEntity : Symbol(TEntity, Decl(test.ts, 1, 36))
+>IEventSourcedEntity : Symbol(IEventSourcedEntity, Decl(test.ts, 0, 8))
+>TEntity : Symbol(TEntity, Decl(test.ts, 1, 36))
+
diff --git a/tests/baselines/reference/nounusedTypeParameterConstraint.types b/tests/baselines/reference/nounusedTypeParameterConstraint.types
new file mode 100644
index 00000000000..8f2de483d26
--- /dev/null
+++ b/tests/baselines/reference/nounusedTypeParameterConstraint.types
@@ -0,0 +1,15 @@
+=== tests/cases/compiler/bar.ts ===
+
+export interface IEventSourcedEntity { }
+>IEventSourcedEntity : IEventSourcedEntity
+
+=== tests/cases/compiler/test.ts ===
+import { IEventSourcedEntity } from "./bar";
+>IEventSourcedEntity : any
+
+export type DomainEntityConstructor<TEntity extends IEventSourcedEntity> = { new(): TEntity; };
+>DomainEntityConstructor : new () => TEntity
+>TEntity : TEntity
+>IEventSourcedEntity : IEventSourcedEntity
+>TEntity : TEntity
+
diff --git a/tests/baselines/reference/typeAliasDeclarationEmit.errors.txt b/tests/baselines/reference/typeAliasDeclarationEmit.errors.txt
new file mode 100644
index 00000000000..2fd71844dc4
--- /dev/null
+++ b/tests/baselines/reference/typeAliasDeclarationEmit.errors.txt
@@ -0,0 +1,10 @@
+tests/cases/compiler/typeAliasDeclarationEmit.ts(4,37): error TS2314: Generic type 'callback' requires 1 type argument(s).
+
+
+==== tests/cases/compiler/typeAliasDeclarationEmit.ts (1 errors) ====
+    
+    export type callback<T> = () => T;
+    
+    export type CallbackArray<T extends callback> = () => T;
+                                        ~~~~~~~~
+!!! error TS2314: Generic type 'callback' requires 1 type argument(s).
\ No newline at end of file