Name resolution: CheckIWSAM only needs the intrinsic methods

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

@@ -163,6 +163,7 @@
 * Debug: rework conditional erasure, fix stepping over literals ([PR #19897](https://github.com/dotnet/fsharp/pull/19897))
 * Record spreads ([RFC FS-1151](https://github.com/fsharp/fslang-design/pull/805), [PR #18927](https://github.com/dotnet/fsharp/pull/18927), [PR #20206](https://github.com/dotnet/fsharp/pull/20206))
 * Debug: fix if and match condition sequence points ([PR #19932](https://github.com/dotnet/fsharp/pull/19932))
+* Name resolution: CheckIWSAM only needs the intrinsic methods ([PR #20490](https://github.com/dotnet/fsharp/pull/20490))
 * Surface the synthesized all-fields constructor of F# record types to F# code under the `RecordConstructorSyntax` preview feature, via a new `MethInfo.RecdCtor` case. ([PR #19974](https://github.com/dotnet/fsharp/pull/19974))
 * Under `--reflectionfree`, discriminated unions, records and anonymous records now get a [generated `ToString`](../../reflectionfree-printing.md) (rendering each field like `Option` does) instead of falling back to the namespace-qualified type name. ([PR #19976](https://github.com/dotnet/fsharp/pull/19976))
 * Support common types of `NotNullIfNotNullAttribute` usage. If a method parameter is marked with `NotNullIfNotNullAttribute`, the compiler will now honor this attribute and mark the return type as non-null. ([PR #19977](https://github.com/dotnet/fsharp/pull/19977))

src/Compiler/Checking/Expressions/CheckExpressions.fs

@@ -4678,7 +4678,7 @@ and CheckIWSAM (cenv: cenv) (env: TcEnv) checkConstraints iwsam m tcref =
     let ty = generalizedTyconRef g tcref
 
     if iwsam = WarnOnIWSAM.Yes && isInterfaceTy g ty && checkConstraints = CheckCxs then
-        let meths = AllMethInfosOfTypeInScope ResultCollectionSettings.AllResults cenv.infoReader env.NameEnv None env.eAccessRights IgnoreOverrides m ty
+        let meths = IntrinsicMethInfosOfType cenv.infoReader None env.eAccessRights AllowMultiIntfInstantiations.Yes IgnoreOverrides m ty
 
         if meths |> List.exists (fun meth -> not meth.IsInstance && meth.IsDispatchSlot && not meth.IsExtensionMember) then
             let tcref = tcrefOfAppTy g ty

src/Compiler/Checking/NameResolution.fsi

@@ -687,6 +687,18 @@ val internal ExtensionPropInfosOfTypeInScope:
     ty: TType ->
         PropInfo list
 
+/// Get the intrinsic methods of a type (both declared and inherited), without the extension methods in
+/// scope. Callers that filter extension members out again should use this and skip the extension scan.
+val internal IntrinsicMethInfosOfType:
+    infoReader: InfoReader ->
+    optFilter: string option ->
+    ad: AccessorDomain ->
+    allowMultiIntfInst: TypeHierarchy.AllowMultiIntfInstantiations ->
+    findFlag: FindMemberFlag ->
+    m: range ->
+    ty: TType ->
+        MethInfo list
+
 /// Get the available methods of a type (both declared and inherited)
 val internal AllMethInfosOfTypeInScope:
     collectionSettings: ResultCollectionSettings ->