Merge pull request #8469 from dotnet/merges/master-to-feature/and-bang

Merge master to feature/and-bang

Author: KevinRansom

src/fsharp/AttributeChecking.fs

@@ -265,9 +265,10 @@ let private CheckILAttributes (g: TcGlobals) isByrefLikeTyconRef cattrs m =
     | _ -> 
         CompleteD
 
+let langVersionPrefix = "--langversion:preview"
+
 /// Check F# attributes for 'ObsoleteAttribute', 'CompilerMessageAttribute' and 'ExperimentalAttribute',
 /// returning errors and warnings as data
-let langVersionPrefix = "--langversion:preview"
 let CheckFSharpAttributes (g:TcGlobals) attribs m =
     let isExperimentalAttributeDisabled (s:string) =
         if g.compilingFslib then

src/fsharp/service/service.fs

@@ -742,7 +742,7 @@ type BackgroundCompiler(legacyReferenceResolver, projectCacheSize, keepAssemblyC
     member bc.ParseAndCheckProject(options, userOpName) =
         reactor.EnqueueAndAwaitOpAsync(userOpName, "ParseAndCheckProject", options.ProjectFileName, fun ctok -> bc.ParseAndCheckProjectImpl(options, ctok, userOpName))
 
-    member __.GetProjectOptionsFromScript(filename, sourceText, loadedTimeStamp, otherFlags, useFsiAuxLib: bool option, useSdkRefs: bool option, assumeDotNetFramework: bool option, extraProjectInfo: obj option, optionsStamp: int64 option, userOpName) = 
+    member __.GetProjectOptionsFromScript(filename, sourceText, previewEnabled, loadedTimeStamp, otherFlags, useFsiAuxLib: bool option, useSdkRefs: bool option, assumeDotNetFramework: bool option, extraProjectInfo: obj option, optionsStamp: int64 option, userOpName) = 
         reactor.EnqueueAndAwaitOpAsync (userOpName, "GetProjectOptionsFromScript", filename, fun ctok -> 
           cancellable {
             use errors = new ErrorScope()
@@ -751,10 +751,16 @@ type BackgroundCompiler(legacyReferenceResolver, projectCacheSize, keepAssemblyC
             let useFsiAuxLib = defaultArg useFsiAuxLib true
             let useSdkRefs =  defaultArg useSdkRefs true
             let reduceMemoryUsage = ReduceMemoryFlag.Yes
+            let previewEnabled = defaultArg previewEnabled false
 
             // Do we assume .NET Framework references for scripts?
             let assumeDotNetFramework = defaultArg assumeDotNetFramework true
-            let otherFlags = defaultArg otherFlags [| |]
+            let extraFlags =
+                if previewEnabled then
+                    [| "--langversion:preview" |]
+                else
+                    [||]
+            let otherFlags = defaultArg otherFlags extraFlags
             let useSimpleResolution = 
 #if ENABLE_MONO_SUPPORT
                 runningOnMono || otherFlags |> Array.exists (fun x -> x = "--simpleresolution")
@@ -1141,9 +1147,9 @@ type FSharpChecker(legacyReferenceResolver,
         backgroundCompiler.ParseAndCheckProject(options, userOpName)
 
     /// For a given script file, get the ProjectOptions implied by the #load closure
-    member __.GetProjectOptionsFromScript(filename, source, ?loadedTimeStamp, ?otherFlags, ?useFsiAuxLib, ?useSdkRefs, ?assumeDotNetFramework, ?extraProjectInfo: obj, ?optionsStamp: int64, ?userOpName: string) = 
+    member __.GetProjectOptionsFromScript(filename, source, ?previewEnabled, ?loadedTimeStamp, ?otherFlags, ?useFsiAuxLib, ?useSdkRefs, ?assumeDotNetFramework, ?extraProjectInfo: obj, ?optionsStamp: int64, ?userOpName: string) = 
         let userOpName = defaultArg userOpName "Unknown"
-        backgroundCompiler.GetProjectOptionsFromScript(filename, source, loadedTimeStamp, otherFlags, useFsiAuxLib, useSdkRefs, assumeDotNetFramework, extraProjectInfo, optionsStamp, userOpName)
+        backgroundCompiler.GetProjectOptionsFromScript(filename, source, previewEnabled, loadedTimeStamp, otherFlags, useFsiAuxLib, useSdkRefs, assumeDotNetFramework, extraProjectInfo, optionsStamp, userOpName)
 
     member __.GetProjectOptionsFromCommandLineArgs(projectFileName, argv, ?loadedTimeStamp, ?extraProjectInfo: obj) = 
         let loadedTimeStamp = defaultArg loadedTimeStamp DateTime.MaxValue // Not 'now', we don't want to force reloading

src/fsharp/service/service.fsi

@@ -228,7 +228,7 @@ type public FSharpChecker =
     /// so that an 'unload' and 'reload' action will cause the script to be considered as a new project,
     /// so that references are re-resolved.</param>
     /// <param name="userOpName">An optional string used for tracing compiler operations associated with this request.</param>
-    member GetProjectOptionsFromScript : filename: string * sourceText: ISourceText * ?loadedTimeStamp: DateTime * ?otherFlags: string[] * ?useFsiAuxLib: bool * ?useSdkRefs: bool * ?assumeDotNetFramework: bool * ?extraProjectInfo: obj * ?optionsStamp: int64 * ?userOpName: string -> Async<FSharpProjectOptions * FSharpErrorInfo list>
+    member GetProjectOptionsFromScript : filename: string * sourceText: ISourceText * ?previewEnabled:bool * ?loadedTimeStamp: DateTime * ?otherFlags: string[] * ?useFsiAuxLib: bool * ?useSdkRefs: bool * ?assumeDotNetFramework: bool * ?extraProjectInfo: obj * ?optionsStamp: int64 * ?userOpName: string -> Async<FSharpProjectOptions * FSharpErrorInfo list>
 
     /// <summary>
     /// <para>Get the FSharpProjectOptions implied by a set of command line arguments.</para>