Add a simple test

tests/FSharp.Compiler.ComponentTests/FSharp.Compiler.ComponentTests.fsproj

@@ -169,6 +169,7 @@
     <Compile Include="Language\ComputationExpressionTests.fs" />
     <Compile Include="Language\CastingTests.fs" />
     <Compile Include="Language\NameofTests.fs" />
+    <Compile Include="Language\DotLambdaTests.fs" />
     <Compile Include="ConstraintSolver\PrimitiveConstraints.fs" />
     <Compile Include="ConstraintSolver\MemberConstraints.fs" />
     <None Include="**\*.cs;**\*.fs;**\*.fsx;**\*.fsi" Exclude="@(Compile)">

tests/FSharp.Compiler.ComponentTests/Language/DotLambdaTests.fs

@@ -0,0 +1,29 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace FSharp.Compiler.ComponentTests.Language
+
+open Xunit
+open FSharp.Test.Compiler
+
+module DotLambdaTests =
+
+    [<Fact>]
+    let ``Script: _.ToString()`` () =
+        Fsx "_.ToString()"
+        |> compile
+        |> shouldSucceed
+
+    let ``Simple anonymous unary function shorthands compile`` () =
+        FSharp """
+module One
+let a1 : {| Foo : {| Bar : string |}|} -> string = _.Foo.Bar
+let a2 : {| Foo : int array |} -> int = _.Foo.[5]
+let a3 : {| Foo : int array |} -> int = _.Foo[5]
+let a4 : {| Foo : unit -> string |} -> string = _.Foo()
+let a5 : {| Foo : int -> {| X : string |} |} -> string = _.Foo(5).X
+
+open System
+let a6 = [1] |> List.map _.ToString()
+        """
+        |> compile
+        |> shouldSucceed