Ship FSharp.Core with a net10.0 target framework by T-Gro · Pull Request #20229 · dotnet/fsharp

T-Gro · 2026-08-07T08:49:11Z

Ships FSharp.Core with an additional net10.0 target framework alongside netstandard2.0 and netstandard2.1. External .NET consumers resolve the net10.0 asset through normal nearest-TFM resolution instead of falling back to netstandard2.1.

The net version is a pinned knob (FSharpCoreShippedNetTargetFramework, default net10.0) that deliberately lags the in-development product TFM: F# built on net11 still ships lib/net10.0, and the pin moves only as an explicit, reviewed step when the product advances. Proto stays a single netstandard2.0 bootstrap; the extra target is added to non-Proto builds only.

net10.0 is a package-only asset. In-repo .NET consumers stay pinned to the netstandard2.1 asset (a central Directory.Build.targets rule for direct references, plus one direct pin in FSharp.Compiler.Service.Tests whose reference is only transitive), so the in-box compiler, the tools, and their IL and surface-area baselines are unchanged by adding the target. Removing that pin makes the in-repo test harnesses compile against net10.0 FSharp.Core — whose split-BCL references don't resolve in those contexts — and churns every EmittedIL baseline, so the pin stays.

The point of a real net target is to let FSharp.Core grow net-specific API and behavior over time rather than stay pinned to the netstandard2.1 surface; today it is built from the same sources, and future net-only additions live behind the widened #if … || NET guards.

Not done here (cross-repo, must follow this PR): the shipped-in-SDK path flows dotnet/fsharp → dotnet/dotnet (VMR) → dotnet/sdk, and full source-build validation needs a real VMR leg (DotNetBuildFromVMR). Those cannot be exercised from this repo.

Draft: opening for CI signal and review of the pinned-TFM policy before finalizing.

…b (net10.0) + lag guard The shipped FSharp.Core net TFM is a pinned-stable knob that lags the in-dev product TFM (FSharpNetCoreProductTargetFramework=net11.0) and tracks the latest stable released .NET. A build/pack-time guard scoped to the FSharp.Core project fails if the pin is not strictly less than the product TFM. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Add $(FSharpCoreShippedNetTargetFramework) (net10.0) to the non-Proto TFMs and make FSharp.Core actually compile against the net10 BCL: - prim-types.fs: move the #endif of the '#if !NET5_0_OR_GREATER' block so the structural 'namespace Microsoft.FSharp.Core' + opens are unconditional (they were trapped inside the pre-.NET5 polyfill guard and vanished on any net TFM, causing ~100 'System type not defined' errors). ns2.x output is unchanged. - prim-types.fsi: guard the System.Diagnostics.CodeAnalysis polyfill with the matching '#if !NET5_0_OR_GREATER' so the signature drops it on net (the impl already did), fixing the sig/impl mismatch (FS0193). - prim-types.{fs,fsi}: floor the .NET8+ CollectionBuilder/ScopedRef polyfills with '#if !NET8_0_OR_GREATER' (net BCL provides them). - Widen collection-expression / IAsyncDisposable guards to '|| NET' (set.{fs,fsi}, tasks.{fs,fsi}, prim-types.{fs,fsi} List builders). - local.fs / Query.fs: disambiguate net10 BCL overloads (String.Format ReadOnlySpan<obj>, ElementAt/Take Index/Range) by pinning the original obj[]/int overloads. No public-surface change. Builds clean on netstandard2.0, netstandard2.1 and net10.0 (no warnings). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

- FSharp.Core.nuspec: add a net10.0 dependency group and lib/net10.0 file entries (dll, xml, satellite resources), all driven by a $FSharpCoreShippedNetTargetFramework$ token so the package layout tracks the single pinned knob rather than hardcoding the TFM in the manifest. - FSharp.Core.fsproj: surface the knob to the nuspec via <NuspecProperty Include="FSharpCoreShippedNetTargetFramework=..."> (non-Proto). - Microsoft.FSharp.Compiler.fsproj: include the pinned TFM in the shipping-path pack override so the shipped FSharp.Core is packed for net10.0 too, not just netstandard2.0/2.1. Verified via Arcade pack: nupkg contains lib/{netstandard2.0,netstandard2.1,net10.0} with dll+xml+satellites and a <group targetFramework="net10.0" /> dependency group. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Modern .NET hosts (net11+) now bind lib/net10.0, so the SurfaceArea test must verify against a net baseline (references System.Runtime, not netstandard). Reorder platform detection to '#if NET' first, add FSharp.Core.SurfaceArea.net.{debug,release}.bsl, and document that the netstandard2.1 baselines are intentionally retained but no longer exercised (ns2.1 coverage moves to the ApiCompat identity gate). The net member surface is byte-identical to ns2.1 (only assembly- reference lines differ), confirming the net10.0 == ns2.1 invariant. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Add a dedicated FSharp.Core.ApiCompat project that runs the SDK's Microsoft.DotNet.ApiCompat.Task.ValidateAssembliesTask (registered by Sdk.targets, not Arcade, not package validation) comparing the freshly built netstandard2.1 (contract) and net10.0 implementation assemblies in strict/bidirectional mode with an empty suppression set. This enforces the net10.0 == netstandard2.1 public-surface invariant. Wire it as a required, blocking FSharpCore_ApiCompat job (no continueOnError) in azure-pipelines-PR.yml. Verified locally: passes clean on identically-built DLLs; strict mode correctly FAILS on injected additions (ns2.0-vs-net10), non-strict silently passes them (why strict is mandated). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Allow-list audit of every TFM-discriminating #if/#elif guard in src/FSharp.Core/**/*.{fs,fsi}: each must be a reviewed <file>:<expr> pair, so a bare '#if NETSTANDARD2_1' (excludes the net TFM) or bare '#if !NET' (drops a BCL polyfill on every net TFM) or any un-reviewed new TFM guard fails. Implemented as a portable F# fsx (git ls-files + .NET regex, not 'git grep -P' which needs PCRE) and wired as a blocking step in the required CheckCodeFormatting job, matching the repo's FSCompCheck.fsx / TestSplit.fsx source-hygiene idiom. Verified: self-test OK; passes on the shipped tree (10 allow-listed guards); FAILS on an injected bare '#if NETSTANDARD2_1'. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

…rifier Portable fsx that discovers the shipped net TFM lib folder from the produced FSharp.Core nupkg (never a hard-coded literal) and asserts lib/{netstandard2.0, netstandard2.1,<pin>} DLL+XML present and non-degenerate, satellites present, a <group targetFramework> dependency group in the nuspec, and a UNIFORM AssemblyVersion across all three lib assemblies. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Isolated net-TFM consumer (targets $(FSharpCoreShippedNetTargetFramework)) that source-maps FSharp.Core to the locally built package and STRUCTURALLY witnesses, from obj/project.assets.json, that both compile and runtime bind to lib/<pin>/FSharp.Core.dll and NOT to any netstandard asset. Driver pins the exact built version, purges only the cached fsharp.core/<ver>, and runs a widened IAsyncDisposable task member as the runtime smoke (roll-forward for the net run). Verified locally: net10.0 -> lib/net10.0 (compile+runtime) + smoke green; net8.0 control -> lib/netstandard2.1 (witness bites). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Multi-target the AheadOfTime Trimming (x3) and NativeAOT consumers on net9.0;$(FSharpCoreShippedNetTargetFramework) so the shipped net-TFM lib is exercised under PublishTrimmed/PublishAot. The gate is publish SUCCESS under TreatWarningsAsErrors=true (IL2xxx/IL3050 => errors); trimmed sizes for the net pin are report-only (-expected_len -1) since byte counts churn per preview. Both check.ps1 scripts derive the pin from the knob (no literal net10.0 to drift). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

…nto PR pipeline - e2e-1 runs in EndToEndBuildTests right after the -pack step. - e2e-2 runs in Build_And_Test_AOT_Windows after the AheadOfTime checks, with the consumer's project.assets.json published as always()/continueOnError failure evidence. e2e-5 (trim/AOT net-TFM legs) needs no new wiring: the existing AheadOfTime check.ps1 chain already runs the multi-targeted projects. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

github-actions · 2026-08-07T08:49:30Z

❗ Release notes required

You can open this PR in browser to add release notes: open in github.dev

✅ Found changes and release notes in following paths:

Change path Release notes path Description
`src/FSharp.Core` docs/release-notes/.FSharp.Core/11.0.100.md
`src/Compiler` docs/release-notes/.FSharp.Compiler.Service/11.0.100.md

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

T-Gro · 2026-08-07T08:52:38Z

/azp run

azure-pipelines · 2026-08-07T08:52:44Z

Azure Pipelines will not run the associated pipelines, because the pull request was updated after the run command was issued. Review the pull request again and issue a new run command.

T-Gro · 2026-08-07T08:53:48Z

/azp run

azure-pipelines · 2026-08-07T08:53:55Z

Azure Pipelines will not run the associated pipelines, because the pull request was updated after the run command was issued. Review the pull request again and issue a new run command.

…0-tfm-plan

T-Gro · 2026-08-07T08:58:12Z

/azp run

azure-pipelines · 2026-08-07T08:58:22Z

Azure Pipelines: Successfully started running 1 pipeline(s).

…chronouslyImmediate The merge from main introduced the new public member Async.RunSynchronouslyImmediate. The dedicated net SurfaceArea baselines (created before that merge) did not include it; regenerate both the debug and release net baselines. The netstandard2.1 baseline already carried the member via the merge, and the ApiCompat net10-vs-netstandard2.1 identity gate still passes, so the surfaces remain identical. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

T-Gro · 2026-08-07T09:08:14Z

/azp run

azure-pipelines · 2026-08-07T09:08:24Z

Azure Pipelines: Successfully started running 1 pipeline(s).

…ding (NoBloat) Remove step-by-step and design-justification narration from the new e2e scripts, the ApiCompat project, the #ifdef audit, and the SurfaceArea platform-selection comment; keep only the non-obvious 'why' (the ApiCompat-vs-package-validation trap, the macOS git-grep portability note, the net<->baseline mapping invariant). No functional change; all gates still pass locally. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Drop the fsproj header that duplicated the driver script's intent and a redundant inline comment in the runtime smoke. The remaining comments are non-obvious MSBuild 'why' (CPM/RollForward/implicit-ref opt-outs). No functional change; e2e-2 still passes. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Removes an agent-plan breadcrumb (files/plan.md 4e) from the ApiCompat proj header comment and a (Milestone B) phase tag from a VerifyNetResolution.fsx error string, per NoBloat. No behavior change. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

…1 baseline - VerifyFSharpCorePackage.fsx: checkAsset helper collapses the duplicated dll/xml exists+size-floor assertions. - VerifyNetResolution.fsx: close a fail-open in the structural witness (empty dllPaths without _._ now fails). - AuditFSharpCoreTfmGuards.fsx: self-test now drives the real tfmGuardsIn extractor (was bypassing the #if/#elif line parser) + #elif coverage. - SurfaceArea.fs: drop the unreachable #elif NETCOREAPP netstandard21 branch (a modern host defines NET); delete the now-orphaned netstandard21 baselines (ns2.1 surface is covered by the FSharp.Core.ApiCompat gate). - Program.fs / ApiCompat proj / PR yaml: comment accuracy + trims. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Route closure generic arguments through guarded type generation to prevent FS0073, and cover the shipped net10 FSharp.Core API, package assets, and IL verification. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 8f25b087-cec7-4d86-a31a-f1f6f00ccf1a

…core-net10-tfm-plan

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 8f25b087-cec7-4d86-a31a-f1f6f00ccf1a

kerams · 2026-08-18T08:10:31Z

A dream come true.

T-Gro · 2026-08-18T09:33:46Z

@kerams :

I will revisit places that have been waiting for this and write a pointer to this PR ;; offering if-def-based solutions for FSharp.Core evolution.

T-Groand others added 12 commits August 6, 2026 14:57

docs(release-notes): FSharp.Core net10.0 target framework entry
6c1b1bd
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

docs(release-notes): fill PR#20224into FSharp.Core net10.0 entry
2bb06af
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

github-project-automationBot added this to F# Compiler and Tooling Aug 7, 2026

github-project-automationBot moved this to New in F# Compiler and Tooling Aug 7, 2026

docs(release-notes): point net10.0 entry at PR#20229
9c0fc9a
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: dd0ca93f-cf73-450a-8a5a-f9e59841802e

Merge remote-tracking branch 'origin/main' into t-gro-fsharpcore-net1…
e4b80c5
…0-tfm-plan

CopilotAI added 4 commits August 7, 2026 11:14

T-Gro requested review from abonie and baronfel August 12, 2026 17:44

baronfel approved these changes Aug 12, 2026
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T-Gro mentioned this pull request Aug 13, 2026
Runtime async via intrinsic #20235
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T-Gro added 3 commits August 13, 2026 17:49

Merge remote-tracking branch 'origin/main' into pr/20229/t-gro-fsharp…
8ace798
…core-net10-tfm-plan

Include Async ValueTask APIs in net10 FSharp.Core
e6903f1
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 8f25b087-cec7-4d86-a31a-f1f6f00ccf1a

abonie approved these changes Aug 17, 2026
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T-Gro merged commit 1928203 into mainAug 17, 2026
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xperiandri pushed a commit to xperiandri/fsharp that referenced this pull request Aug 17, 2026
Ship FSharp.Core with a net10.0 target framework (dotnet#20229)
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This was referenced Aug 17, 2026
[release/11.0.1xx-rc1] Source code updates from dotnet/fsharp dotnet/dotnet#8335
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[release/11.0.1xx] Source code updates from dotnet/fsharp dotnet/dotnet#8351
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[Automated] PRs inserted in VS build main-12117.157 #20279
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[main] Source code updates from dotnet/fsharp dotnet/dotnet#8299
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majocha mentioned this pull request Aug 21, 2026
net10.0 FSharp.Core surface area test #20309
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Ship FSharp.Core with a net10.0 target framework - #20229

Ship FSharp.Core with a net10.0 target framework#20229
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