Simplify generics

src/EditorFeatures/CSharpTest/SimplifyTypeNames/SimplifyTypeNamesTests.cs

@@ -4412,6 +4412,90 @@ class Base
 ");
         }
 
+        [WorkItem(40649, "https://github.com/dotnet/roslyn/issues/40649")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsSimplifyTypeNames)]
+        public async Task SimplifyAliasToGeneric1()
+        {
+            await TestInRegularAndScript1Async(
+@"using System.Collections.Generic;
+using MyList = System.Collections.Generic.List<int>;
+
+class Base
+{
+    public [|System.Collections.Generic.List<int>|] Goo;
+}
+",
+@"using System.Collections.Generic;
+using MyList = System.Collections.Generic.List<int>;
+
+class Base
+{
+    public MyList Goo;
+}
+");
+        }
+
+        [WorkItem(40649, "https://github.com/dotnet/roslyn/issues/40649")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsSimplifyTypeNames)]
+        public async Task SimplifyAliasToGeneric2()
+        {
+            await TestInRegularAndScript1Async(
+@"using System.Collections.Generic;
+using MyList = System.Collections.Generic.List<int>;
+
+class Base
+{
+    public [|List<int>|] Goo;
+}
+",
+@"using System.Collections.Generic;
+using MyList = System.Collections.Generic.List<int>;
+
+class Base
+{
+    public MyList Goo;
+}
+");
+        }
+
+        [WorkItem(40649, "https://github.com/dotnet/roslyn/issues/40649")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsSimplifyTypeNames)]
+        public async Task SimplifyAliasToGeneric3()
+        {
+            await TestInRegularAndScript1Async(
+@"using System.Collections.Generic;
+using MyList = System.Collections.Generic.List<int>;
+
+class Base
+{
+    public [|List<System.Int32>|] Goo;
+}
+",
+@"using System.Collections.Generic;
+using MyList = System.Collections.Generic.List<int>;
+
+class Base
+{
+    public MyList Goo;
+}
+");
+        }
+
+        [WorkItem(40649, "https://github.com/dotnet/roslyn/issues/40649")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsSimplifyTypeNames)]
+        public async Task DoNotSimplifyIncorrectInstantiation()
+        {
+            await TestMissingAsync(
+@"using System.Collections.Generic;
+using MyList = System.Collections.Generic.List<int>;
+
+class Base
+{
+    public [|List<string>|] Goo;
+}
+");
+        }
+
         [Theory, Trait(Traits.Feature, Traits.Features.CodeActionsSimplifyTypeNames)]
         [InlineData("Boolean")]
         [InlineData("Char")]

src/Workspaces/CSharp/Portable/Extensions/ExpressionSyntaxExtensions.cs

@@ -1088,7 +1088,8 @@ public static bool IsAliasReplaceableExpression(this ExpressionSyntax expression
         {
             if (expression.Kind() == SyntaxKind.IdentifierName ||
                 expression.Kind() == SyntaxKind.QualifiedName ||
-                expression.Kind() == SyntaxKind.AliasQualifiedName)
+                expression.Kind() == SyntaxKind.AliasQualifiedName ||
+                expression.Kind() == SyntaxKind.GenericName)
             {
                 return true;
             }