"#if" directive around nullness removed fromsrc/Compiler/DependencyManager/DependencyProvider.fs and refactored.

.fantomasignore

@@ -40,6 +40,9 @@ src/Compiler/Checking/SignatureConformance.fs
 src/Compiler/Checking/TypeHierarchy.fs
 src/Compiler/Checking/TypeRelations.fs
 
+# nullness-related problems
+src/Compiler/DependencyManager/DependencyProvider.fs
+
 # Incorrectly formatted: https://github.com/dotnet/fsharp/pull/14645/commits/49443a67ea8a17670c8a7c80c8bdf91f82231e91 or https://github.com/fsprojects/fantomas/issues/2733
 # This CompilerImports.fs behavior is not fixed yet, following up in  https://github.com/fsprojects/fantomas/issues/2733
 src/Compiler/Driver/CompilerImports.fs

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -53,8 +53,8 @@
 * Better ranges for #nowarn error reporting; bring back #nowarn warnings for --langVersion:80; add warnings under feature flag ([PR #17871](https://github.com/dotnet/fsharp/pull/17871))
 * CheckAndThrow can be invoked only from within Cancellable context ([PR #18037](https://github.com/dotnet/fsharp/pull/18037))
 * Make ILTypeDef base type calculation lazy. ([PR #18005](https://github.com/dotnet/fsharp/pull/18005))
-* "#if" directive around nullness removed from src/Compiler/TypedTree/TypedTreePickle.fs and refactored. ([PR #18203](https://github.com/dotnet/fsharp/pull/18203))
+* Removed redundant hash directives around nullness syntax ([Issue #18601](https://github.com/dotnet/fsharp/issues/18061), [PR #18203](https://github.com/dotnet/fsharp/pull/18203), [PR #18207](https://github.com/dotnet/fsharp/pull/18207))
 
 ### Breaking Changes
 
-* Aliasing `StructAttribute` will now produce a warning (part of [Language suggestion #1136](https://github.com/fsharp/fslang-suggestions/issues/1136), [PR #18098](https://github.com/dotnet/fsharp/pull/18098))
+* Aliasing `StructAttribute` will now produce a warning (part of [Language suggestion #1136](https://github.com/fsharp/fslang-suggestions/issues/1136), [PR #18098](https://github.com/dotnet/fsharp/pull/18098))

src/Compiler/DependencyManager/DependencyProvider.fs

@@ -15,7 +15,7 @@ open System.Collections.Concurrent
 module Option =
 
     /// Convert string into Option string where null and String.Empty result in None
-    let ofString (s: string MaybeNull) =
+    let ofString (s: string | null) =
         match s with
         | null -> None
         | "" -> None
@@ -607,7 +607,7 @@ type DependencyProvider
             outputDir: string,
             reportError: ResolvingErrorReport,
             path: string
-        ) : string MaybeNull * IDependencyManagerProvider MaybeNull =
+        ) : string | null * IDependencyManagerProvider | null =
         try
             if path.Contains ":" && not (Path.IsPathRooted path) then
                 let managers =
@@ -637,7 +637,7 @@ type DependencyProvider
             outputDir: string,
             reportError: ResolvingErrorReport,
             key: string
-        ) : IDependencyManagerProvider MaybeNull =
+        ) : IDependencyManagerProvider | null =
         try
             RegisteredDependencyManagers compilerTools (Option.ofString outputDir) reportError
             |> Map.tryFind key
@@ -657,7 +657,7 @@ type DependencyProvider
             packageManagerTextLines: (string * string) seq,
             reportError: ResolvingErrorReport,
             executionTfm: string,
-            [<Optional; DefaultParameterValue(null: string MaybeNull)>] executionRid: string MaybeNull,
+            [<Optional; DefaultParameterValue(null: string | null)>] executionRid: string | null,
             [<Optional; DefaultParameterValue("")>] implicitIncludeDir: string,
             [<Optional; DefaultParameterValue("")>] mainScriptName: string,
             [<Optional; DefaultParameterValue("")>] fileName: string,
@@ -681,8 +681,8 @@ type DependencyProvider
                     try
                         let executionRid =
                             match executionRid with
-                            | Null -> RidHelpers.platformRid
-                            | NonNull executionRid -> executionRid
+                            | null -> RidHelpers.platformRid
+                            | executionRid -> executionRid
 
                         Ok(
                             packageManager.ResolveDependencies(

src/Compiler/DependencyManager/DependencyProvider.fsi

@@ -123,7 +123,7 @@ type DependencyProvider =
         packageManagerTextLines: (string * string) seq *
         reportError: ResolvingErrorReport *
         executionTfm: string *
-        [<Optional; DefaultParameterValue(null: string MaybeNull)>] executionRid: string *
+        [<Optional; DefaultParameterValue(null: string | null)>] executionRid: string *
         [<Optional; DefaultParameterValue("")>] implicitIncludeDir: string *
         [<Optional; DefaultParameterValue("")>] mainScriptName: string *
         [<Optional; DefaultParameterValue("")>] fileName: string *
@@ -133,9 +133,9 @@ type DependencyProvider =
     /// Fetch a dependencymanager that supports a specific key
     member TryFindDependencyManagerByKey:
         compilerTools: string seq * outputDir: string * reportError: ResolvingErrorReport * key: string ->
-            IDependencyManagerProvider MaybeNull
+            IDependencyManagerProvider | null
 
     /// TryFindDependencyManagerInPath - given a #r "key:sometext" go and find a DependencyManager that satisfies the key
     member TryFindDependencyManagerInPath:
         compilerTools: string seq * outputDir: string * reportError: ResolvingErrorReport * path: string ->
-            string MaybeNull * IDependencyManagerProvider MaybeNull
+            string | null * IDependencyManagerProvider | null