Preserve old FSIExtraParameters; pick reasonable options

Bring the old `FSIExtraParameters` option back to not break existing clients.
Implement logic to mimic old behavior if the old option is used, warning if the
old option is mixed with either of the new.

Introduce a new private helper method
`AdaptiveFSharpLspServer.oldOrNewExtraParams` for use in RPC calls that parse
config options: `Initialize` and `DidChangeConfiguration`. This helper ensures
that any clients using the old parameter get the expected behavior from before
this PR. Both RPC methods will send a warning to the client if they mix
parameters.

In the future, we can update warnings to support deprecation in that helper
function.

The signature of the helper is not the best, and to work with the CEs where the
RPC happens, we need to have our message sent at the top level of the CE, so we
can use `do!`. This means that we read the Dto, then break our pipeline so we
can consume the message, then have a second pipeline that consumes the fixed up
Dto. Given that this is in support of a to-be-deprecated option, and that upon
deprecation we can remove the helper, it seems okay to have this ugliness.

README.md

@@ -199,8 +199,10 @@ Options that should be send as `initializationOptions` as part of `initialize` r
 * `FSharp.ResolveNamespaces` - enables resolve namespace quick fix (add `open` if symbol is from not yet opened module/namespace), recommended default value: `true`
 * `FSharp.EnableReferenceCodeLens` - enables reference count code lenses, recommended default value: `true` if `--background-service-enabled` is used by default, `false` otherwise
 * `FSharp.dotNetRoot` - sets the root path for finding dotnet SDK references. Primarily used for FSX Scripts. Default value: operating-system dependent. On windows, `C:\Program Files\dotnet`; on Unix, `/usr/local/share/dotnet`
-* `FSharp.FSIExtraInteractiveParameters` - currently unused by FSAC, but available to editor plugins for interactive `dotnet fsi` parameters that are not shared by the compiler. Future intentions are to manage the interpreter from FSAC, at which point FSAC will utilize this parameter. [Check this reference for parameters that are interactive-only or shared with the compiler](https://learn.microsoft.com/en-us/dotnet/fsharp/language-reference/fsharp-interactive-options).
-* `FSharp.FSIExtraSharedParameters` - an array of additional runtime arguments that are passed to FSI; specifically parameters that are shared with the compiler. These are used when typechecking scripts to ensure that typechecking has the same context as your FSI instances.  An example would be to set the following parameters to enable Preview features (like opening static classes) for typechecking. [Check this reference for parameters that are interactive-only or shared with the compiler](https://learn.microsoft.com/en-us/dotnet/fsharp/language-reference/fsharp-interactive-options).
+* Extra parameters for FSI: use only `FSharp.FSIExtraParameters` on its own *or* a combination of `FSharp.FSIExtraInteractiveParameters` and `FSharp.FSIExtraSharedParameters`. The former is expected to be deprecated in favor of the second two. See #1210 for more detail. FSAC will send a warning if you mix usage improperly.
+  * `FSharp.FSIExtraParameters` - an array of additional runtime arguments that are passed to FSI. These are used when typechecking scripts to ensure that typechecking has the same context as your FSI instances.  An example would be to set the following parameters to enable Preview features (like opening static classes) for typechecking.
+  * `FSharp.FSIExtraInteractiveParameters` - currently unused by FSAC, but available to editor plugins for interactive `dotnet fsi` parameters that are not shared by the compiler. Future intentions are to manage the interpreter from FSAC, at which point FSAC will utilize this parameter. [Check this reference for parameters that are interactive-only or shared with the compiler](https://learn.microsoft.com/en-us/dotnet/fsharp/language-reference/fsharp-interactive-options).
+  * `FSharp.FSIExtraSharedParameters` - an array of additional runtime arguments that are passed to FSI; specifically parameters that are shared with the compiler. These are used when typechecking scripts to ensure that typechecking has the same context as your FSI instances.  An example would be to set the following parameters to enable Preview features (like opening static classes) for typechecking. [Check this reference for parameters that are interactive-only or shared with the compiler](https://learn.microsoft.com/en-us/dotnet/fsharp/language-reference/fsharp-interactive-options).
 
     ```json
         "FSharp.fsiExtraSharedParameters": ["--langversion:preview"]

src/FsAutoComplete/LspHelpers.fs

@@ -673,6 +673,7 @@ type FSharpConfigDto =
     LineLens: LineLensConfig option
     UseSdkScripts: bool option
     DotNetRoot: string option
+    FSIExtraParameters: string array option
     FSIExtraInteractiveParameters: string array option
     FSIExtraSharedParameters: string array option
     FSICompilerToolLocations: string array option
@@ -816,6 +817,9 @@ type FSharpConfig =
     LineLens: LineLensConfig
     UseSdkScripts: bool
     DotNetRoot: string
+    // old, combines both shared and interactive. To be deprecated. Either use
+    // only this one, or some combination of the new ones.
+    FSIExtraParameters: string array
     // for parameters only used in interactive FSI sessions; currently unused
     FSIExtraInteractiveParameters: string array
     // for parameters used both in the compiler and interactive FSI
@@ -868,6 +872,7 @@ type FSharpConfig =
       LineLens = { Enabled = "never"; Prefix = "" }
       UseSdkScripts = true
       DotNetRoot = Environment.dotnetSDKRoot.Value.FullName
+      FSIExtraParameters = [||]
       FSIExtraInteractiveParameters = [||]
       FSIExtraSharedParameters = [||]
       FSICompilerToolLocations = [||]
@@ -925,6 +930,7 @@ type FSharpConfig =
         dto.DotNetRoot
         |> Option.bind (fun s -> if String.IsNullOrEmpty s then None else Some s)
         |> Option.defaultValue Environment.dotnetSDKRoot.Value.FullName
+      FSIExtraParameters = defaultArg dto.FSIExtraParameters FSharpConfig.Default.FSIExtraParameters
       FSIExtraInteractiveParameters =
         defaultArg dto.FSIExtraInteractiveParameters FSharpConfig.Default.FSIExtraInteractiveParameters
       FSIExtraSharedParameters = defaultArg dto.FSIExtraSharedParameters FSharpConfig.Default.FSIExtraSharedParameters
@@ -1036,6 +1042,7 @@ type FSharpConfig =
         dto.DotNetRoot
         |> Option.bind (fun s -> if String.IsNullOrEmpty s then None else Some s)
         |> Option.defaultValue FSharpConfig.Default.DotNetRoot
+      FSIExtraParameters = defaultArg dto.FSIExtraParameters FSharpConfig.Default.FSIExtraParameters
       FSIExtraInteractiveParameters =
         defaultArg dto.FSIExtraInteractiveParameters FSharpConfig.Default.FSIExtraInteractiveParameters
       FSIExtraSharedParameters = defaultArg dto.FSIExtraSharedParameters FSharpConfig.Default.FSIExtraSharedParameters

src/FsAutoComplete/LspHelpers.fsi

@@ -301,6 +301,7 @@ type FSharpConfigDto =
     LineLens: LineLensConfig option
     UseSdkScripts: bool option
     DotNetRoot: string option
+    FSIExtraParameters: string array option
     FSIExtraInteractiveParameters: string array option
     FSIExtraSharedParameters: string array option
     FSICompilerToolLocations: string array option
@@ -403,6 +404,7 @@ type FSharpConfig =
     LineLens: LineLensConfig
     UseSdkScripts: bool
     DotNetRoot: string
+    FSIExtraParameters: string array
     FSIExtraInteractiveParameters: string array
     FSIExtraSharedParameters: string array
     FSICompilerToolLocations: string array

src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs

@@ -284,6 +284,41 @@ type AdaptiveFSharpLspServer
 
     Helpers.ignoreNotification
 
+  ///<summary>
+  /// Transform a config DTO to use (old FSIExtraParameters) xor (new FSIExtraInteractiveParameters and FSIExtraSharedParameters).
+  ///</summary>
+  ///<remarks>
+  /// We expect to eventually deprecate FSIExtraParameters in favor of the two
+  /// new, specialized versions. For now, mimic old behavior either silently
+  /// or loudly, depending on the client's combination of config options. This
+  /// method and the consumption of it can be removed after deprecation.
+  ///</remarks>
+  static member private oldOrNewExtraParams(dto: FSharpConfigDto) =
+    match dto.FSIExtraParameters, dto.FSIExtraInteractiveParameters, dto.FSIExtraSharedParameters with
+    // old-style, silent success; start warning when we plan to
+    // deprecate
+    | Some p, None, None ->
+      let c =
+        { dto with
+            FSIExtraSharedParameters = Some p }
+
+      None, c
+    // mix old and new, warn and mimic old behavior
+    | Some p, Some _, _
+    | Some p, _, Some _ ->
+      let m =
+        { Type = MessageType.Warning
+          Message =
+            "Do not mix usage of FSIExtraParameters and (FSIExtraInteractiveParameters or FSIExtraSharedParameters)." }
+
+      let c =
+        { dto with
+            FSIExtraSharedParameters = Some p }
+
+      Some m, c
+    // no old parameter, proceed happily
+    | None, _, _ -> None, dto
+
   interface IFSharpLspServer with
     override x.Shutdown() = (x :> System.IDisposable).Dispose() |> async.Return
 
@@ -295,10 +330,19 @@ type AdaptiveFSharpLspServer
         try
           logger.info (Log.setMessage "Initialize Request {p}" >> Log.addContextDestructured "p" p)
 
-          let c =
+          let configMessage =
             p.InitializationOptions
             |> Option.bind (fun options -> if options.HasValues then Some options else None)
             |> Option.map Server.deserialize<FSharpConfigDto>
+            |> Option.map AdaptiveFSharpLspServer.oldOrNewExtraParams
+
+          match Option.bind fst configMessage with
+          | Some message -> do! lspClient.WindowShowMessage message
+          | None -> ()
+
+          let c =
+            configMessage
+            |> Option.map snd
             |> Option.map FSharpConfig.FromDto
             |> Option.defaultValue FSharpConfig.Default
 
@@ -1684,9 +1728,18 @@ type AdaptiveFSharpLspServer
             >> Log.addContextDestructured "params" p
           )
 
-          let dto = p.Settings |> Server.deserialize<FSharpConfigRequest>
+          let dto =
+            p.Settings
+            |> Server.deserialize<FSharpConfigRequest>
+            |> (fun f -> f.FSharp)
+            |> Option.map AdaptiveFSharpLspServer.oldOrNewExtraParams
+
+          match Option.bind fst dto with
+          | Some message -> do! lspClient.WindowShowMessage message
+          | None -> ()
 
-          dto.FSharp
+          dto
+          |> Option.map snd
           |> Option.iter (fun fsharpConfig ->
             let c = state.Config
             let c = c.AddDto fsharpConfig

test/FsAutoComplete.Tests.Lsp/Helpers.fs

@@ -263,6 +263,7 @@ let defaultConfigDto: FSharpConfigDto =
     LineLens = None
     UseSdkScripts = Some true
     DotNetRoot = None
+    FSIExtraParameters = None
     FSIExtraInteractiveParameters = None
     FSIExtraSharedParameters = None
     FSICompilerToolLocations = None