Fix how we assign FSI options

For netcore/netfx we should always explicitly provide the targetprofile,
because the impacts how reference resolution works (ie which primary
assembly we look for and key off of), and we should also provide any
static additional arguments as the 'otherFlags' argument.

In addition, we need to explicitly not provide an mscorlib reference
when targeting netstandard, as that re-enables some of the legacy paths.

Finally, there was a bug in the handling of the 'replace refs' function
that was overwriting all of the OtherOptions instead of modifying just
the framework refs.

src/FsAutoComplete.Core/CompilerServiceInterface.fs

@@ -511,15 +511,14 @@ type FSharpCompilerServiceChecker(backgroundServiceEnabled) =
 
   /// replace any BCL/FSharp.Core/FSI refs that FCS gives us with our own set, which is more probe-able
   let replaceFrameworkRefs (projOptions: FSharpProjectOptions) =
+    let refs, otherOptions = projOptions.OtherOptions |> Array.partition (fun r -> r.StartsWith "-r:")
+
     let fcsAndScriptReferences =
-      projOptions.OtherOptions
-      |> Array.choose (fun r ->
-        if r.StartsWith("-r")
-        then
+      refs
+      |> Array.map (fun r ->
           let path = r.[3..]
           let assemblyName = Path.GetFileNameWithoutExtension path
-          Some(assemblyName, path)
-        else None
+          assemblyName, path
       )
       |> Map.ofArray
 
@@ -531,10 +530,7 @@ type FSharpCompilerServiceChecker(backgroundServiceEnabled) =
       |> Seq.map (fun r -> "-r:" + r)
       |> Array.ofSeq
 
-    { projOptions with OtherOptions = mergedRefs }
-
-  let applyFSIAdditionalArgs (projOptions: FSharpProjectOptions) =
-    { projOptions with OtherOptions = Array.append fsiAdditionalArguments projOptions.OtherOptions }
+    { projOptions with OtherOptions = Array.append otherOptions mergedRefs }
 
   member __.CreateFCSBinder(netFwInfo: Dotnet.ProjInfo.Workspace.NetFWInfo, loader: Dotnet.ProjInfo.Workspace.Loader) =
     Dotnet.ProjInfo.Workspace.FCS.FCSBinder(netFwInfo, loader, checker)
@@ -555,15 +551,16 @@ type FSharpCompilerServiceChecker(backgroundServiceEnabled) =
 
   member private __.GetNetFxScriptOptions(file, source) = async {
     logDebug "[Opts] Getting NetFX options for script file %s" file
-    let! (opts, errors) = checker.GetProjectOptionsFromScript(file, SourceText.ofString source, assumeDotNetFramework = true, useFsiAuxLib = true)
-    let allModifications = applyFSIAdditionalArgs
-    return allModifications opts, errors
+    let allFlags = Array.append [| "--targetprofile:mscorlib" |] fsiAdditionalArguments
+    let! (opts, errors) = checker.GetProjectOptionsFromScript(file, SourceText.ofString source, assumeDotNetFramework = true, useFsiAuxLib = true, otherFlags = allFlags, userOpName = "getNetFrameworkScriptOptions")
+    return opts, errors
   }
 
   member private __.GetNetCoreScriptOptions(file, source) = async {
     logDebug "[Opts] Getting NetCore options for script file %s" file
-    let! (opts, errors) = checker.GetProjectOptionsFromScript(file, SourceText.ofString source, assumeDotNetFramework = false, useSdkRefs = true, useFsiAuxLib = true)
-    let allModifications = replaceFrameworkRefs >> applyFSIAdditionalArgs
+    let allFlags = Array.append [| "--targetprofile:netstandard" |] fsiAdditionalArguments
+    let! (opts, errors) = checker.GetProjectOptionsFromScript(file, SourceText.ofString source, assumeDotNetFramework = false, useSdkRefs = true, useFsiAuxLib = true, otherFlags = allFlags, userOpName = "getNetCoreScriptOptions")
+    let allModifications = replaceFrameworkRefs
     return allModifications opts, errors
   }
 
@@ -577,9 +574,9 @@ type FSharpCompilerServiceChecker(backgroundServiceEnabled) =
 
     match errors with
     | [] ->
-      let refs = projOptions.OtherOptions |> Array.filter (fun o -> o.StartsWith("-r")) |> String.concat "\n"
-      logDebug "[Opts] Resolved options - %A" projOptions
-      logDebug "[Opts] Resolved references:\n%s" refs
+      let refs, otherOpts = projOptions.OtherOptions |> Array.partition (fun o -> o.StartsWith("-r"))
+      logDebug "[Opts] Resolved references:\n%s" (refs |> String.concat "\n")
+      logDebug "[Opts] Resolved other options:\n%s" (otherOpts |> String.concat "\n")
     | errs ->
       logDebug "[Opts] Resolved options with errors\n%A\n%A" projOptions errs
 

src/FsAutoComplete.Core/FSIRefs.fs

@@ -98,7 +98,13 @@ let runtimeDir dotnetRoot runtimeVersion =
 let findRuntimeRefs packDir runtimeDir =
   match packDir, runtimeDir with
   | Some refDir, _
-  | _, Some refDir -> Directory.EnumerateFiles(refDir, "*.dll") |> Seq.toArray
+  | _, Some refDir ->
+    Directory.EnumerateFiles(refDir, "*.dll")
+    // SUPER IMPORTANT: netstandard/netcore assembly resolution _must not_ contain mscorlib or else
+    // its presence triggers old netfx fallbacks, which end up bringing assemblies that aren't part
+    // of netcore.
+    |> Seq.filter (fun r -> not (Path.GetFileNameWithoutExtension(r) = "mscorlib"))
+    |> Seq.toArray
   | None, None -> [||]
 
 /// given the compiler root dir and if to include FSI refs, returns the set of compiler assemblies to references if that dir exists.