don't auto-resolve types from System.Runtime.WindowsRuntime (dotnet#9644)

Author: brettfo

src/fsharp/DotNetFrameworkDependencies.fs

@@ -259,10 +259,23 @@ module internal FSharp.Compiler.DotNetFrameworkDependencies
             if not (assemblies.ContainsKey(referenceName)) then
                 try
                     if File.Exists(path) then
-                        // System.Private.CoreLib doesn't load with reflection
-                        if referenceName = "System.Private.CoreLib" then
+                        match referenceName with
+                        | "System.Runtime.WindowsRuntime"
+                        | "System.Runtime.WindowsRuntime.UI.Xaml" ->
+                            // The Windows compatibility pack included in the runtime contains a reference to
+                            // System.Runtime.WindowsRuntime, but to properly use that type the runtime also needs a
+                            // reference to the Windows.md meta-package, which isn't referenced by default.  To avoid
+                            // a bug where types from `Windows, Version=255.255.255.255` can't be found we're going to
+                            // not default include this assembly.  It can still be manually referenced if it's needed
+                            // via the System.Runtime.WindowsRuntime NuGet package.
+                            //
+                            // In the future this branch can be removed because WinRT support is being removed from the
+                            // .NET 5 SDK (https://github.com/dotnet/runtime/pull/36715)
+                            ()
+                        | "System.Private.CoreLib" ->
+                            // System.Private.CoreLib doesn't load with reflection
                             assemblies.Add(referenceName, path)
-                        else
+                        | _ ->
                             try
                                 let asm = System.Reflection.Assembly.LoadFrom(path)
                                 assemblies.Add(referenceName, path)

tests/FSharp.Compiler.Private.Scripting.UnitTests/CompletionTests.fs

@@ -31,6 +31,17 @@ type CompletionTests() =
             Assert.AreEqual(1, matchingCompletions.Length)
         } |> Async.StartAsTask :> Task
 
+    [<Test>]
+    member _.``Completions from types that try to pull in Windows runtime extensions``() =
+        async {
+            use script = new FSharpScript()
+            script.Eval("open System") |> ignoreValue
+            script.Eval("let t = TimeSpan.FromHours(1.0)") |> ignoreValue
+            let! completions = script.GetCompletionItems("t.", 1, 2)
+            let matchingCompletions = completions |> Array.filter (fun d -> d.Name = "TotalHours")
+            Assert.AreEqual(1, matchingCompletions.Length)
+        } |> Async.StartAsTask :> Task
+
     [<Test>]
     member _.``Static member completions``() =
         async {