Fixed not struct constraint for anon records.

src/fsharp/TastOps.fs

@@ -1773,7 +1773,8 @@ let isRefTy g ty =
         isFunTy g ty || 
         isReprHiddenTy g ty || 
         isFSharpObjModelRefTy g ty || 
-        isUnitTy g ty
+        isUnitTy g ty ||
+        (isAnonRecdTy g ty && not (isStructAnonRecdTy g ty))
     )
 
 // ECMA C# LANGUAGE SPECIFICATION, 27.2

tests/FSharp.Compiler.UnitTests/Compiler.fs

@@ -0,0 +1,59 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace FSharp.Compiler.UnitTests
+
+open System
+open Microsoft.FSharp.Compiler.Text
+open Microsoft.FSharp.Compiler.SourceCodeServices
+
+open NUnit.Framework
+
+[<RequireQualifiedAccess>]
+module Compiler =
+
+    let checker = FSharpChecker.Create()
+
+    let private defaultProjectOptions =
+        {
+            ProjectFileName = "Z:\\test.fsproj"
+            ProjectId = None
+            SourceFiles = [|"test.fs"|]
+            OtherOptions = [||]
+            ReferencedProjects = [||]
+            IsIncompleteTypeCheckEnvironment = false
+            UseScriptResolutionRules = false
+            LoadTime = DateTime()
+            UnresolvedReferences = None
+            OriginalLoadReferences = []
+            ExtraProjectInfo = None
+            Stamp = None
+        }
+
+    let AssertPass (source: string) =
+        let parseResults, fileAnswer = checker.ParseAndCheckFileInProject("test.fs", 0, SourceText.ofString source, defaultProjectOptions) |> Async.RunSynchronously
+
+        Assert.True(parseResults.Errors.Length = 0, sprintf "Parse errors: %A" parseResults.Errors)
+
+        match fileAnswer with
+        | FSharpCheckFileAnswer.Aborted _ -> Assert.Fail("Type Checker Aborted")
+        | FSharpCheckFileAnswer.Succeeded(typeCheckResults) ->
+
+        Assert.True(typeCheckResults.Errors.Length = 0, sprintf "Type Check errors: %A" typeCheckResults.Errors)
+
+    let AssertSingleErrorTypeCheck (source: string) (expectedErrorNumber: int) (expectedErrorRange: int * int * int * int) (expectedErrorMsg: string) =
+        let parseResults, fileAnswer = checker.ParseAndCheckFileInProject("test.fs", 0, SourceText.ofString source, defaultProjectOptions) |> Async.RunSynchronously
+
+        Assert.True(parseResults.Errors.Length = 0, sprintf "Parse errors: %A" parseResults.Errors)
+
+        match fileAnswer with
+        | FSharpCheckFileAnswer.Aborted _ -> Assert.Fail("Type Checker Aborted")
+        | FSharpCheckFileAnswer.Succeeded(typeCheckResults) ->
+
+        Assert.True(typeCheckResults.Errors.Length = 1, sprintf "Expected one type check error: %A" typeCheckResults.Errors)
+        typeCheckResults.Errors
+        |> Array.iter (fun info ->
+            Assert.AreEqual(FSharpErrorSeverity.Error, info.Severity)
+            Assert.AreEqual(expectedErrorNumber, info.ErrorNumber, "expectedErrorNumber")
+            Assert.AreEqual(expectedErrorRange, (info.StartLineAlternate, info.StartColumn, info.EndLineAlternate, info.EndColumn), "expectedErrorRange")
+            Assert.AreEqual(expectedErrorMsg, info.Message, "expectedErrorMsg")
+        )

tests/FSharp.Compiler.UnitTests/FSharp.Compiler.UnitTests.fsproj

@@ -16,7 +16,9 @@
     <Compile Include="HashIfExpression.fs" />
     <Compile Include="ProductVersion.fs" />
     <Compile Include="EditDistance.fs" />
+    <Compile Include="Compiler.fs" />
     <Compile Include="ILHelpers.fs" />
+    <Compile Include="Language\AnonRecords.fs" />
     <Compile Include="Language\StringConcat.fs" />
     <Compile Include="SourceTextTests.fs" />
   </ItemGroup>

tests/FSharp.Compiler.UnitTests/ILHelpers.fs

@@ -10,9 +10,10 @@ open NUnit.Framework
 
 open Microsoft.FSharp.Compiler.SourceCodeServices
 
+[<RequireQualifiedAccess>]
 module ILChecker =
 
-    let checker = FSharpChecker.Create()
+    let checker = Compiler.checker
 
     let private (++) a b = Path.Combine(a,b)
 

tests/FSharp.Compiler.UnitTests/Language/AnonRecords.fs

@@ -0,0 +1,47 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace FSharp.Compiler.UnitTests
+
+open NUnit.Framework
+
+[<TestFixture>]
+module AnonRecords =
+
+    [<Test>]
+    let NotStructConstraintPass() =
+        Compiler.AssertPass
+            """
+type RefClass<'a when 'a : not struct>() = class end
+let rAnon = RefClass<{| R: int |}>()
+            """
+
+    [<Test>]
+    let StructConstraintPass() =
+        Compiler.AssertPass
+            """
+type StructClass<'a when 'a : struct>() = class end
+let sAnon = StructClass<struct {| S: int |}>()
+            """
+
+    [<Test>]
+    let NotStructConstraintFail() =
+        Compiler.AssertSingleErrorTypeCheck 
+            """
+    type RefClass<'a when 'a : not struct>() = class end
+    let rAnon = RefClass<struct {| R: int |}>()
+            """ 
+            1
+            (3, 16, 3, 45)
+            "A generic construct requires that the type 'struct {|R : int|}' have reference semantics, but it does not, i.e. it is a struct"
+
+    [<Test>]
+    let StructConstraintFail() =
+        Compiler.AssertSingleErrorTypeCheck 
+            """
+type StructClass<'a when 'a : struct>() = class end
+let sAnon = StructClass<{| S: int |}>()
+            """ 
+            1
+            (3, 12, 3, 37)
+            "A generic construct requires that the type '{|S : int|}' is a CLI or F# struct type"
+