Ship FSharp.Core with a net10.0 target framework

Directory.Build.props

@@ -74,6 +74,9 @@
        Cannot live in eng/TargetFrameworks.props because it's imported before Arcade. -->
   <PropertyGroup Condition="'$(DotNetBuildSourceOnly)' == 'true'">
     <FSharpNetCoreProductTargetFramework>$(NetCurrent)</FSharpNetCoreProductTargetFramework>
+    <!-- The pin is a nuget.org packaging knob; source-build targets only $(NetCurrent), whose ref pack is
+         always present, so collapse the pin to it rather than a lagging TFM the VMR may not carry offline. -->
+    <FSharpCoreShippedNetTargetFramework>$(NetCurrent)</FSharpCoreShippedNetTargetFramework>
   </PropertyGroup>
 
   <!-- It's important we set TFM before this, since FSharpTests.Directory.Build.props uses it.

Directory.Build.targets

@@ -10,6 +10,15 @@
     <NoWarn>$(NoWarn);NU1507</NoWarn>
   </PropertyGroup>
 
+  <!-- FSharp.Core now also builds the shipped-net TFM, but in-repo .NET consumers must keep binding its
+       netstandard2.1 asset so the in-box compiler/tools and their IL / surface-area baselines stay unchanged.
+       Any pre-existing explicit SetTargetFramework pin is preserved. -->
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' and '$(Configuration)' != 'Proto'">
+    <ProjectReference Update="@(ProjectReference)">
+      <SetTargetFramework Condition="'%(ProjectReference.Filename)' == 'FSharp.Core' and '%(ProjectReference.SetTargetFramework)' == ''">TargetFramework=netstandard2.1</SetTargetFramework>
+    </ProjectReference>
+  </ItemGroup>
+
   <!-- Disable R2R when building source-only and not targeting the current SDK bundled TFM. -->
   <PropertyGroup>
     <PublishReadyToRun Condition="'$(DotNetBuildSourceOnly)' == 'true' and

azure-pipelines-PR.yml

@@ -186,6 +186,26 @@ stages:
                 DOTNET_ROLL_FORWARD_TO_PRERELEASE: 1
             displayName: Check published package version
 
+        # Blocking gate enforcing the "net10.0 == netstandard2.1" public-surface invariant
+        # (mechanism documented in FSharp.Core.ApiCompat.proj).
+        - job: FSharpCore_ApiCompat
+          pool:
+            name: $(DncEngPublicBuildPool)
+            demands: ImageOverride -equals $(LinuxMachineQueueName)
+          steps:
+          - checkout: self
+            clean: true
+          - script: ./eng/common/dotnet.sh
+            displayName: Install .NET SDK
+          - script: ./eng/common/dotnet.sh build src/FSharp.Core/FSharp.Core.fsproj -c Release
+            env:
+              DOTNET_ROLL_FORWARD_TO_PRERELEASE: 1
+            displayName: Build FSharp.Core (all shipped TFMs, Release)
+          - script: ./eng/common/dotnet.sh msbuild tests/FSharp.Core.ApiCompat/FSharp.Core.ApiCompat.proj -t:ValidateFSharpCoreApiIdentity -p:Configuration=Release
+            env:
+              DOTNET_ROLL_FORWARD_TO_PRERELEASE: 1
+            displayName: ApiCompat net-vs-netstandard2.1 identity gate (strict, empty suppressions)
+
 
   #-------------------------------------------------------------------------------------------------------------------#
   #                                                    PR builds                                                      #
@@ -564,6 +584,9 @@ stages:
               NativeToolsOnMachine: true
           - script: .\tests\EndToEndBuildTests\EndToEndBuildTests.cmd -c Release
             displayName: End to end build tests
+          - script: .\eng\common\dotnet.cmd fsi .\tests\AheadOfTime\NetPackage\VerifyNetPackage.fsx
+            displayName: 'Verify shipped FSharp.Core nupkg ships lib/<net-pin>'
+            workingDirectory: $(Build.SourcesDirectory)
 
           # Publish artifacts for regression testing
           - task: PublishPipelineArtifact@1

docs/release-notes/.FSharp.Core/11.0.100.md

@@ -7,4 +7,5 @@
 
 ### Added
 
+* Ship `FSharp.Core` with an additional `net10.0` target framework (next to `netstandard2.0` and `netstandard2.1`). The `net`-TFM assembly is public-surface-identical to the `netstandard2.1` one; the target version is a pinned, deliberately advanced knob. ([PR #20229](https://github.com/dotnet/fsharp/pull/20229))
 * `Async.RunSynchronouslyImmediate`: runs work on the calling thread until the first asynchronous suspension (as opposed to `RunSynchronously`, which immediately offloads if not on a background and/or threadpool thread). ([Issue #1042](https://github.com/fsharp/fslang-suggestions/issues/1042), [PR #19804](https://github.com/dotnet/fsharp/pull/19804))

eng/TargetFrameworks.props

@@ -15,6 +15,9 @@
 
     <!-- Derive major version by stripping 'net' prefix and '.0' suffix (e.g., net10.0 -> 10) -->
     <FSharpNetCoreProductMajorVersion>$([System.Text.RegularExpressions.Regex]::Replace('$(FSharpNetCoreProductTargetFramework)', '^net(\d+)\.0$', '$1'))</FSharpNetCoreProductMajorVersion>
+
+    <!-- Net TFM shipped in the FSharp.Core NuGet package. Lags the in-dev product TFM; bump deliberately. -->
+    <FSharpCoreShippedNetTargetFramework Condition="'$(FSharpCoreShippedNetTargetFramework)' == ''">net10.0</FSharpCoreShippedNetTargetFramework>
   </PropertyGroup>
 
 </Project>

src/FSharp.Core/FSharp.Core.fsproj

@@ -5,7 +5,7 @@
   <PropertyGroup>
     <OutputType>Library</OutputType>
     <TargetFrameworks Condition="'$(Configuration)' == 'Proto'">netstandard2.0</TargetFrameworks>
-    <TargetFrameworks Condition="'$(Configuration)' != 'Proto'">netstandard2.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks Condition="'$(Configuration)' != 'Proto'">netstandard2.0;netstandard2.1;$(FSharpCoreShippedNetTargetFramework)</TargetFrameworks>
     <NoWarn>$(NoWarn);75</NoWarn> <!-- InternalCommandLineOption -->
     <NoWarn>$(NoWarn);1204</NoWarn> <!-- This construct is for use in the FSharp.Core library and should not be used directly -->
     <AllowCrossTargeting>true</AllowCrossTargeting>
@@ -36,6 +36,12 @@
     <Configurations>Debug;Release;Proto</Configurations>
   </PropertyGroup>
 
+  <!-- Pinned .NET TFM for the shipped FSharp.Core, surfaced to FSharp.Core.nuspec as a $token$
+       so the package lib/dependency group stay driven by the single knob in eng/TargetFrameworks.props. -->
+  <ItemGroup Condition="'$(Configuration)' != 'Proto'">
+    <NuspecProperty Include="FSharpCoreShippedNetTargetFramework=$(FSharpCoreShippedNetTargetFramework)" />
+  </ItemGroup>
+
     <!-- .FSharp.Core always uses the old style initialization mechanism because of SQL CLR requirements -->
   <PropertyGroup Condition="'$(BUILDING_USING_DOTNET)' != 'true' and '$(Configuration)' != 'Proto'">
     <OtherFlags>$(OtherFlags) --realsig-</OtherFlags>

src/FSharp.Core/FSharp.Core.nuspec

@@ -6,6 +6,7 @@
         <dependencies>
             <group targetFramework=".NETStandard2.0" />
             <group targetFramework=".NETStandard2.1" />
+            <group targetFramework="$FSharpCoreShippedNetTargetFramework$" />
         </dependencies>
     </metadata>
     <files>
@@ -22,5 +23,11 @@
 
         <!-- resources -->
         <file src="FSharp.Core\$Configuration$\netstandard2.1\**\FSharp.Core.resources.dll" target="lib\netstandard2.1" />
+
+        <file src="FSharp.Core\$Configuration$\$FSharpCoreShippedNetTargetFramework$\FSharp.Core.dll" target="lib\$FSharpCoreShippedNetTargetFramework$" />
+        <file src="FSharp.Core\$Configuration$\$FSharpCoreShippedNetTargetFramework$\FSharp.Core.xml" target="lib\$FSharpCoreShippedNetTargetFramework$" />
+
+        <!-- resources -->
+        <file src="FSharp.Core\$Configuration$\$FSharpCoreShippedNetTargetFramework$\**\FSharp.Core.resources.dll" target="lib\$FSharpCoreShippedNetTargetFramework$" />
     </files>
 </package>

src/FSharp.Core/Query.fs

@@ -107,7 +107,7 @@ type QueryBuilder() =
     member _.Head (source: QuerySource<'T, 'Q>) =
         Enumerable.First source.Source
 
-    member _.Nth (source: QuerySource<'T, 'Q>, index) =
+    member _.Nth (source: QuerySource<'T, 'Q>, index: int) =
         Enumerable.ElementAt (source.Source, index)
 
     member _.Skip (source: QuerySource<'T, 'Q>, count) : QuerySource<'T, 'Q> =
@@ -116,7 +116,7 @@ type QueryBuilder() =
     member _.SkipWhile (source: QuerySource<'T, 'Q>, predicate) : QuerySource<'T, 'Q> =
         QuerySource (Enumerable.SkipWhile (source.Source, Func<_, _>(predicate)))
 
-    member _.Take (source: QuerySource<'T, 'Q>, count) : QuerySource<'T, 'Q> =
+    member _.Take (source: QuerySource<'T, 'Q>, count: int) : QuerySource<'T, 'Q> =
         QuerySource (Enumerable.Take (source.Source, count))
 
     member _.TakeWhile (source: QuerySource<'T, 'Q>, predicate) : QuerySource<'T, 'Q> =
@@ -246,7 +246,7 @@ type QueryBuilder() =
         QuerySource (Enumerable.GroupJoin(outerSource.Source, innerSource.Source, Func<_, _>(outerKeySelector), Func<_, _>(innerKeySelector), Func<_, _, _>(resultSelector)))
 
     member _.LeftOuterJoin (outerSource: QuerySource<_, 'Q>, innerSource: QuerySource<_, 'Q>, outerKeySelector, innerKeySelector, resultSelector: _ ->  seq<_> -> _) : QuerySource<_, 'Q> =
-        QuerySource (Enumerable.GroupJoin(outerSource.Source, innerSource.Source, Func<_, _>(outerKeySelector), Func<_, _>(innerKeySelector), Func<_, _, _>(fun x g -> resultSelector x (g.DefaultIfEmpty()))))
+        QuerySource (Enumerable.GroupJoin(outerSource.Source, innerSource.Source, Func<_, _>(outerKeySelector), Func<_, _>(innerKeySelector), Func<_, _, _>(fun x (g: seq<_>) -> resultSelector x (g.DefaultIfEmpty()))))
 
     member _.RunQueryAsValue  (q: Quotations.Expr<'T>) : 'T =
         ForwardDeclarations.Query.Execute q
@@ -475,8 +475,8 @@ module Query =
         MakeOrCallContainsOrElementAt FQ FE
 
     let MakeElementAt, CallElementAt =
-        let FQ = methodhandleof (fun (x, y) -> Queryable.ElementAt(x, y))
-        let FE = methodhandleof (fun (x, y) -> Enumerable.ElementAt(x, y))
+        let FQ = methodhandleof (fun (x, y) -> Queryable.ElementAt(x, (y: int)))
+        let FE = methodhandleof (fun (x, y) -> Enumerable.ElementAt(x, (y: int)))
         MakeOrCallContainsOrElementAt FQ FE
 
     let MakeOrCallMinByOrMaxBy FQ FE =
@@ -886,8 +886,8 @@ module Query =
 
     let MakeTake =
         MakeSkipOrTake
-            (methodhandleof (fun (x, y) -> Queryable.Take (x, y)))
-            (methodhandleof (fun (x, y) -> Enumerable.Take (x, y)))
+            (methodhandleof (fun (x, y) -> Queryable.Take (x, (y: int))))
+            (methodhandleof (fun (x, y) -> Enumerable.Take (x, (y: int))))
 
     let MakeSkipWhile =
         GenMakeSkipWhileOrTakeWhile

src/FSharp.Core/local.fs

@@ -10,17 +10,17 @@ module internal DetailedExceptions =
     open Microsoft.FSharp.Core
 
     /// takes an argument, a formatting string, a param array to splice into the formatting string
-    let inline invalidArgFmt (arg:string) (format:string) paramArray =
+    let inline invalidArgFmt (arg:string) (format:string) (paramArray: obj[]) =
         let msg = String.Format (format, paramArray)
         raise (ArgumentException(msg, arg))
 
     /// takes an argument, a formatting string, a param array to splice into the formatting string
-    let inline invalidArgOutOfRangeFmt (arg:string) (format:string) paramArray =
+    let inline invalidArgOutOfRangeFmt (arg:string) (format:string) (paramArray: obj[]) =
         let msg = String.Format (format, paramArray)
         raise (ArgumentOutOfRangeException(arg, msg))
 
     /// takes a formatting string and a param array to splice into the formatting string
-    let inline invalidOpFmt (format:string) paramArray =
+    let inline invalidOpFmt (format:string) (paramArray: obj[]) =
         let msg = String.Format (format, paramArray)
         raise (InvalidOperationException(msg))
 

src/FSharp.Core/prim-types.fs

@@ -443,13 +443,14 @@ namespace System.Diagnostics.CodeAnalysis
         member this.DynamicallyAccessedMembersAttribute(memberTypes: DynamicallyAccessedMemberTypes) =
             this.MemberTypes <- memberTypes
 
+#endif
+
 namespace Microsoft.FSharp.Core
     open System
     open System.Collections
     open System.Collections.Generic
     open System.Globalization
     open System.Reflection
-    #endif
 
     [<MeasureAnnotatedAbbreviation>] type float<[<Measure>] 'Measure> = float 
     [<MeasureAnnotatedAbbreviation>] type float32<[<Measure>] 'Measure> = float32
@@ -4096,6 +4097,7 @@ namespace Microsoft.FSharp.Core
     and 'T voption = ValueOption<'T>
 
 // These attributes only exist in .NET 8 and up.
+#if !NET8_0_OR_GREATER
 namespace System.Runtime.CompilerServices
     open System
     open Microsoft.FSharp.Core
@@ -4111,6 +4113,7 @@ namespace System.Runtime.CompilerServices
     [<AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = false)>]
     type internal ScopedRefAttribute () =
         inherit Attribute ()
+#endif
 
 namespace Microsoft.FSharp.Collections
 
@@ -4128,7 +4131,7 @@ namespace Microsoft.FSharp.Collections
     open Microsoft.FSharp.Core.LanguagePrimitives.IntrinsicFunctions
     open Microsoft.FSharp.Core.BasicInlinedOperations
 
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
     [<System.Runtime.CompilerServices.CollectionBuilder(typeof<List>, "Create")>]
 #endif
     [<DefaultAugmentation(false)>]
@@ -4156,7 +4159,7 @@ namespace Microsoft.FSharp.Collections
 
     and 'T list = List<'T>
 
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
     and [<CompilerMessage("This type is for compiler use and should not be used directly", 1204, IsHidden=true);
           Sealed;
           AbstractClass;

src/FSharp.Core/prim-types.fsi

@@ -1008,6 +1008,7 @@ namespace Microsoft.FSharp.Core.CompilerServices
     [<CompilerMessage("This type is for compiler use and should not be used directly", 1204, IsHidden = true)>]
     type SupportsWhenTEnum = class end
 
+#if !NET5_0_OR_GREATER
 namespace System.Diagnostics.CodeAnalysis
 
     open System
@@ -1047,6 +1048,8 @@ namespace System.Diagnostics.CodeAnalysis
         new: DynamicallyAccessedMemberTypes -> DynamicallyAccessedMembersAttribute
         member MemberTypes: DynamicallyAccessedMemberTypes
 
+#endif
+
 namespace Microsoft.FSharp.Core
 
     open System
@@ -2606,6 +2609,7 @@ namespace Microsoft.FSharp.Core
       | Error of ErrorValue:'TError
 
 // These attributes only exist in .NET 8 and up.
+#if !NET8_0_OR_GREATER
 namespace System.Runtime.CompilerServices
     open System
     open Microsoft.FSharp.Core
@@ -2637,6 +2641,7 @@ namespace System.Runtime.CompilerServices
     type internal ScopedRefAttribute =
         inherit Attribute
         new: unit -> ScopedRefAttribute
+#endif
 
 namespace Microsoft.FSharp.Collections
 
@@ -2654,7 +2659,7 @@ namespace Microsoft.FSharp.Collections
     /// </remarks>
     ///
     /// <exclude />
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
     [<System.Runtime.CompilerServices.CollectionBuilder(typeof<List>, "Create")>]
 #endif
     [<DefaultAugmentation(false)>]
@@ -2730,7 +2735,7 @@ namespace Microsoft.FSharp.Collections
     /// </remarks>
     and 'T list = List<'T>
 
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
     /// <summary>Contains methods for compiler use related to lists.</summary>
     and [<CompilerMessage("This type is for compiler use and should not be used directly", 1204, IsHidden=true);
           Sealed;

src/FSharp.Core/set.fs

@@ -768,7 +768,7 @@ module internal SetTree =
     let ofArray comparer l =
         Array.fold (fun acc k -> add comparer k acc) empty l
 
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
 [<System.Runtime.CompilerServices.CollectionBuilder(typeof<Set>, "Create")>]
 #endif
 [<Sealed>]
@@ -1097,7 +1097,7 @@ type Set<[<EqualityConditionalOn>] 'T when 'T: comparison>(comparer: IComparer<'
                 .Append("; ... ]")
                 .ToString()
 
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
 and [<CompilerMessage("This type is for compiler use and should not be used directly", 1204, IsHidden = true);
       Sealed;
       AbstractClass;

src/FSharp.Core/set.fsi

@@ -13,7 +13,7 @@ open Microsoft.FSharp.Collections
 /// <remarks>See the <see cref="T:Microsoft.FSharp.Collections.SetModule"/> module for further operations on sets.
 ///
 /// All members of this class are thread-safe and may be used concurrently from multiple threads.</remarks>
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
 [<System.Runtime.CompilerServices.CollectionBuilder(typeof<Set>, "Create")>]
 #endif
 [<Sealed>]
@@ -263,7 +263,7 @@ type Set<[<EqualityConditionalOn>] 'T when 'T: comparison> =
     interface System.Collections.IStructuralEquatable
     interface IReadOnlyCollection<'T>
 
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET
 /// <summary>Contains methods for compiler use related to sets.</summary>
 and [<CompilerMessage("This type is for compiler use and should not be used directly", 1204, IsHidden = true);
       Sealed;

src/FSharp.Core/tasks.fs

@@ -89,7 +89,7 @@ type TaskBuilderBase() =
     member inline _.For(sequence: seq<'T>, body: 'T -> TaskCode<'TOverall, unit>) : TaskCode<'TOverall, unit> =
         ResumableCode.For(sequence, body)
 
-#if NETSTANDARD2_1
+#if NETSTANDARD2_1 || NET
     member inline internal this.TryFinallyAsync
         (body: TaskCode<'TOverall, 'T>, compensation: unit -> ValueTask)
         : TaskCode<'TOverall, 'T> =

src/FSharp.Core/tasks.fsi

@@ -93,7 +93,7 @@ type TaskBuilderBase =
     member inline TryWith:
         body: TaskCode<'TOverall, 'T> * catch: (exn -> TaskCode<'TOverall, 'T>) -> TaskCode<'TOverall, 'T>
 
-#if NETSTANDARD2_1
+#if NETSTANDARD2_1 || NET
     /// <summary>
     /// Specifies a unit of task code which binds to the resource implementing IAsyncDisposable and disposes it asynchronously
     /// </summary>

src/Microsoft.FSharp.Compiler/Microsoft.FSharp.Compiler.fsproj

@@ -45,7 +45,7 @@
         <AdditionalProperties>TargetFrameworks=netstandard2.0</AdditionalProperties>
     </DependentProjects>
     <DependentProjects Include="$(MSBuildThisFileDirectory)..\FSharp.Core\FSharp.Core.fsproj">
-        <AdditionalProperties>TargetFrameworks=netstandard2.1;netstandard2.0</AdditionalProperties>
+        <AdditionalProperties>TargetFrameworks=netstandard2.1;netstandard2.0;$(FSharpCoreShippedNetTargetFramework)</AdditionalProperties>
     </DependentProjects>
     <DependentProjects Include="$(MSBuildThisFileDirectory)..\Compiler\FSharp.Compiler.Service.fsproj">
         <AdditionalProperties>TargetFrameworks=netstandard2.0</AdditionalProperties>

tests/AheadOfTime/NativeAOT/NativeAOT_Test.fsproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFrameworks>net9.0</TargetFrameworks>
+    <TargetFrameworks>net9.0;$(FSharpCoreShippedNetTargetFramework)</TargetFrameworks>
     <LangVersion>preview</LangVersion>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>