Merge branch 'master' of https://github.com/Microsoft/VisualFSharp into csharp-optional-param-compat

Author: eiriktsarpalis

src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ListModule.fs

@@ -1024,6 +1024,6 @@ type ListModule() =
     member this.``pairwise should return pairs of the input list``() =
         Assert.AreEqual(([] : (obj*obj) list), List.pairwise [])
         Assert.AreEqual(([] : (int*int) list), List.pairwise [1])
-        Assert.AreEqual([1,2],List.pairwise [1;2])
-        Assert.AreEqual([1,2; 2,3],List.pairwise [1;2;3])
-        Assert.AreEqual(["H","E"; "E","L"; "L","L"; "L","O"],List.pairwise ["H";"E";"L";"L";"O"])
+        Assert.AreEqual([1,2], List.pairwise [1;2])
+        Assert.AreEqual([1,2; 2,3], List.pairwise [1;2;3])
+        Assert.AreEqual(["H","E"; "E","L"; "L","L"; "L","O"], List.pairwise ["H";"E";"L";"L";"O"])

src/fsharp/FSharp.Core/list.fs

@@ -223,10 +223,7 @@ namespace Microsoft.FSharp.Collections
 
         [<CompiledName("Pairwise")>]
         let pairwise (list: 'T list) =
-            let array = List.toArray list
-            if array.Length < 2 then [] else
-            List.init (array.Length-1) (fun i -> array.[i],array.[i+1])
-        
+            Microsoft.FSharp.Primitives.Basics.List.pairwise list
 
         [<CompiledName("Reduce")>]
         let reduce f list = 

src/fsharp/FSharp.Core/local.fs

@@ -84,6 +84,24 @@ module internal List =
                 cons <- cons2
             setFreshConsTail cons []
             res
+    
+    let rec pairwiseToFreshConsTail cons list lastvalue = 
+        match list with
+        | [] -> setFreshConsTail cons []
+        | [h] -> setFreshConsTail cons [(lastvalue, h)]
+        | h::t ->
+            let cons2 = freshConsNoTail (lastvalue, h)
+            setFreshConsTail cons cons2
+            pairwiseToFreshConsTail cons2 t h
+
+    let pairwise list =       
+        match list with
+        | [] -> []
+        | [_] -> []
+        | x1::x2::t ->
+            let cons = freshConsNoTail (x1, x2)
+            pairwiseToFreshConsTail cons t x2
+            cons
 
     let rec chooseToFreshConsTail cons f xs =
         match xs with 

src/fsharp/FSharp.Core/local.fsi

@@ -10,6 +10,7 @@ module internal List =
     val allPairs : 'T1 list -> 'T2 list -> ('T1 * 'T2) list
     val choose: ('T -> 'U option) -> 'T list -> 'U list
     val countBy : System.Collections.Generic.Dictionary<'T1, int> -> ('T1 -> 'T2) -> ('T2 * int) list
+    val pairwise : 'T list -> ('T * 'T) list
     val distinctWithComparer : System.Collections.Generic.IEqualityComparer<'T> -> 'T list -> 'T list
     val distinctByWithComparer : System.Collections.Generic.IEqualityComparer<'Key> -> ('T -> 'Key) -> list:'T list -> 'T list when 'Key : equality
     val init : int -> (int -> 'T) -> 'T list

vsintegration/tests/unittests/Tests.LanguageService.Script.fs

@@ -570,14 +570,24 @@ type UsingMSBuild() as this =
     [<Test>]
     [<Category("fsx closure")>]
 
-    // 'Microsoft.VisualStudio.Shell.15.0.dll' is resolved via AssemblyFoldersEx over recent VS releases
+    // 'Microsoft.VisualStudio.QualityTools.Common.dll' is resolved via AssemblyFoldersEx over recent VS releases
     member public this.``Fsx.NoError.HashR.ResolveFromAssemblyFoldersEx``() =  
         let fileContent = """
             #light
-            #r "Microsoft.VisualStudio.Shell.15.0.dll"
+            #r "Microsoft.VisualStudio.QualityTools.Common.dll"
             """
         this.VerifyFSXNoErrorList(fileContent)
 
+    [<Test>]
+    [<Category("fsx closure")>]
+    // Can be any assembly that is in AssemblyFolders but not AssemblyFoldersEx
+    member public this.``Fsx.NoError.HashR.ResolveFromAssemblyFolders``() = 
+        let fileContent = """
+            #light
+            #r "Microsoft.SqlServer.SString"
+            """
+        this.VerifyFSXNoErrorList(fileContent) 
+
     [<Test>]
     [<Category("fsx closure")>]
     member public this.``Fsx.NoError.HashR.ResolveFromFullyQualifiedPath``() =         
@@ -967,14 +977,6 @@ type UsingMSBuild() as this =
             """#r "mscorcfg" """        // 'mscorcfg' is loaded from the GAC _and_ it is available on XP and above.
             "#r \"mscor" "Global Assembly Cache"
 
-    // as it used to be.
-    [<Test;Category("fsx closure"); Category("NO_CI")>] 
-    member public this.``Fsx.HashR_QuickInfo.ResolveFromAssemblyFoldersEx``() = 
-        let fileContent = """#r "Microsoft.VisualStudio.Shell.15.0.dll" """     // 'Microsoft.VisualStudio.Shell.15.0' is located via AssemblyFoldersEx
-        let marker = "#r \"Microsoft.Vis"
-        this.AssertQuickInfoContainsAtEndOfMarkerInFsxFile fileContent marker "Microsoft.VisualStudio.Shell.15.0, Version="
-        this.AssertQuickInfoContainsAtEndOfMarkerInFsxFile fileContent marker "Microsoft.VisualStudio.Shell.15.0.dll"
-
     [<Test>]
     [<Category("fsx closure")>]
     member public this.``Fsx.HashR_QuickInfo.ResolveFromFullyQualifiedPath``() =