Fix overload resolution of static member extension

docs/release-notes/.FSharp.Compiler.Service/11.0.100.md

@@ -47,6 +47,7 @@
 * Fix signature generation: SRTP constraints use postfix syntax that fails conformance, now uses explicit type param declarations. ([Issue #19594](https://github.com/dotnet/fsharp/issues/19594), [PR #19609](https://github.com/dotnet/fsharp/pull/19609))
 * Fix signature generation: type params with special characters missing backtick escaping. ([Issue #19595](https://github.com/dotnet/fsharp/issues/19595), [PR #19609](https://github.com/dotnet/fsharp/pull/19609))
 * Fix internal error when using custom attribute with `[<Optional>]` value type parameter and no `[<DefaultParameterValue>]`. ([Issue #8353](https://github.com/dotnet/fsharp/issues/8353), [PR #19484](https://github.com/dotnet/fsharp/pull/19484))
+* Fix overload resolution of static member extension if one or more intrinsics candidates exist ([Issue #19664](https://github.com/dotnet/fsharp/issues/19664), [PR #19698](https://github.com/dotnet/fsharp/pull/19698))
 * Fix parallel compilation of scripts ([PR #19649](https://github.com/dotnet/fsharp/pull/19649))
 
 ### Added

src/Compiler/Checking/NameResolution.fs

@@ -2874,6 +2874,20 @@ let rec ResolveLongIdentInTypePrim (ncenv: NameResolver) nenv lookupKind (resInf
             | Some(MethodItem msets) when isLookUpExpr ->
                 let minfos = msets |> ExcludeHiddenOfMethInfos g ncenv.amap m
 
+                let isAmbivalent =
+                    minfos
+                    |> List.exists (fun minfo ->
+                        match isInstanceFilter with
+                        | LookupIsInstance.Yes -> not minfo.IsInstance
+                        | LookupIsInstance.No -> minfo.IsInstance
+                        | LookupIsInstance.Ambivalent -> true)
+
+                let isInstanceFilter =
+                    if isAmbivalent then
+                        LookupIsInstance.Ambivalent
+                    else
+                        isInstanceFilter
+
                 // fold the available extension members into the overload resolution
                 let extensionMethInfos = ExtensionMethInfosOfTypeInScope ResultCollectionSettings.AllResults ncenv.InfoReader nenv ad optFilter isInstanceFilter m ty
 

tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/MethodResolution/StaticMethodResolution.fs

@@ -0,0 +1,33 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace Conformance.BasicGrammarElements
+
+open FSharp.Test.Compiler
+open Xunit
+
+module StaticMethodResolution =
+
+    // So that the compiler doesn't treat an extension method as intrinsic
+    // we place a method to another module.
+    [<Fact>]
+    let ``Extension static method is resolved correctly when one or many intrinsic candidates are found``() =
+        Fsx """
+module Extensions =
+
+    type StaticGeneric<'T>() =
+        static member Bar() = ()
+
+    [<AutoOpen>]
+    module StaticGenericExtensions =
+        type StaticGeneric<'T> with
+            static member Bar(_: int) = ()
+
+module Program =
+    open Extensions
+
+    StaticGeneric.Bar(42) // StaticGeneric is just an ident
+    StaticGeneric<int>.Bar(42) // StaticGeneric<int> is an expression
+        """
+        |> withOptions ["--nowarn:1125"]
+        |> typecheck
+        |> shouldSucceed

tests/FSharp.Compiler.ComponentTests/FSharp.Compiler.ComponentTests.fsproj

@@ -64,6 +64,7 @@
     <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\OptionalDefaultParamArgs\OptionalDefaultParamArgs.fs" />
     <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\OverloadingMembers\OverloadingMembers.fs" />
     <Compile Include="Conformance\BasicGrammarElements\MethodResolution\MethodResolution.fs" />
+	<Compile Include="Conformance\BasicGrammarElements\MethodResolution\StaticMethodResolution.fs" />
     <Compile Include="Conformance\BasicGrammarElements\ModuleAbbreviations\ModuleAbbreviations.fs" />
     <Compile Include="Conformance\BasicGrammarElements\ModuleDefinitions\ModuleDefinitions.fs" />
     <Compile Include="Conformance\BasicGrammarElements\NamespaceDeclGroups\NamespaceDeclGroups.fs" />