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Set the default F# language version to 11.0 #20219

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Merged
T-Gro merged 5 commits into from
Aug 10, 2026
Merged

Set the default F# language version to 11.0 #20219

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bd18e1e
Set default F# language version to 11.0
T-Gro Aug 6, 2026
f89f986
Pin feature-off tests to F# 10.0 for the 11.0 default bump
T-Gro Aug 6, 2026
9e5ec3d
Merge commit '93659f336bd5c4fe9029225e3ea13f5b20d508bc' into t-gro-en…
T-Gro Aug 6, 2026
9f03bb3
Pin StaticMember delegate-codegen tests to F# 10.0 for the 11.0 defau…
T-Gro Aug 6, 2026
3a8aac9
Pin Desktop-only feature-off tests to F# 10.0 for the 11.0 default bump
T-Gro Aug 6, 2026
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2 changes: 1 addition & 1 deletion src/Compiler/Facilities/LanguageFeatures.fs
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Expand Up @@ -128,7 +128,7 @@ type LanguageVersion(versionText, ?disabledFeaturesArray: LanguageFeature array)
static let languageVersion100 = 10.0m
static let languageVersion110 = 11.0m
static let previewVersion = 9999m // Language version when preview specified
static let defaultVersion = languageVersion100 // Language version when default specified
static let defaultVersion = languageVersion110 // Language version when default specified
static let latestVersion = defaultVersion // Language version when latest specified
static let latestMajorVersion = defaultVersion // Language version when latestmajor specified

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2 changes: 2 additions & 0 deletions tests/FSharp.Compiler.ComponentTests/Conformance/Signatures/SignatureEnforcedAttributes.fs
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Expand Up @@ -16,6 +16,7 @@ module SignatureEnforcedAttributes =
|> FS
|> withAdditionalSourceFile (fs implSrc)
|> asLibrary
|> withLangVersion10 // FS3888 is a warning pre-11 and an error at 11.0 (ErrorOnMissingSignatureAttribute); pin to the warning behavior
|> ignoreWarnings
|> compile

Expand Down Expand Up @@ -265,6 +266,7 @@ let inline f (x: int) = x + 1
|> FS
|> withAdditionalSourceFile (fs implSrc)
|> asLibrary
|> withLangVersion10 // #nowarn suppresses FS3888 only while it is a warning (pre-11); at 11.0 it is an error
|> compile
|> shouldSucceed

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2 changes: 2 additions & 0 deletions tests/FSharp.Compiler.ComponentTests/EmittedIL/DirectDelegates/DirectDelegates.fs
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Expand Up @@ -17,6 +17,7 @@ let private coreOptions compilation =
let verifyCompilation compilation =
compilation
|> coreOptions
|> withLangVersion10 // default baseline captures the pre-11 closure IL; DirectDelegateConstruction (11.0) is covered by the preview twin

@auduchinok auduchinok Aug 11, 2026

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This comment is likely not going to age well.

@T-Gro Should we try to not add these comments after all? I think they distract more than they help, especially because we're getting more of them.

@T-Gro T-Gro Aug 11, 2026

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The comment as well as the test can be removed once the feature is stabilized.

Until then, its good to have anything proving that:

  • both variants (feature on/off) are tested
  • what tests can be removed (rather then rewritten) when feature stabilizes

I do agree comments are not the optimal tool, maybe named function call would be better?

TLDR:
I would love to keep anything around that tells the future maintainers "this test has to be ported" vs "this test can be removed".

|> compile
|> shouldSucceed
|> verifyPEFileWithSystemDlls
Expand Down Expand Up @@ -212,6 +213,7 @@ let main _ =
if d.Method.Name <> "Invoke" then failwithf "expected closure Method.Name 'Invoke' but got '%s'" d.Method.Name
0
"""
|> withLangVersion10 // "without the feature": DirectDelegateConstruction is off pre-11, so the delegate goes through a closure
|> compileExeAndRun
|> shouldSucceed

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1 change: 1 addition & 0 deletions tests/FSharp.Compiler.ComponentTests/EmittedIL/Nullness/NullnessMetadata.fs
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Expand Up @@ -70,6 +70,7 @@ module NullnessMetadata =
let ``Nullable attr for exception types`` compilation =
compilation
|> getCompilation
|> withLangVersion10 // ExceptionFieldSerializationSupport (11.0) changes exception IL; pin to pre-11 (nullness stays on, gated at 9.0)
|> verifyCompilation DoNotOptimize

[<Theory; FileInlineData("ReferenceDU.fs")>]
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1 change: 1 addition & 0 deletions ...s/FSharp.Compiler.ComponentTests/EmittedIL/SerializableAttribute/SerializableAttribute.fs
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Expand Up @@ -15,6 +15,7 @@ module SerializableAttribute =
|> withEmbeddedPdb
|> withEmbedAllSource
|> ignoreWarnings
|> withLangVersion10 // baselines capture pre-11 serialization IL; ExceptionFieldSerializationSupport (11.0) is off here
|> compile
|> verifyILBaseline

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1 change: 1 addition & 0 deletions tests/FSharp.Compiler.ComponentTests/Miscellaneous/FsharpSuiteMigrated.fs
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Expand Up @@ -86,6 +86,7 @@ module TestFrameworkAdapter =
match version with
| LangVersion.V80 -> "8.0",bonusArgs
| LangVersion.V90 -> "9.0",bonusArgs
| LangVersion.V10 -> "10.0",bonusArgs
| LangVersion.Preview -> "preview",bonusArgs
| LangVersion.Latest -> "latest", bonusArgs

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4 changes: 3 additions & 1 deletion tests/FSharp.Compiler.ComponentTests/Miscellaneous/MigratedTypeCheckTests.fs
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Expand Up @@ -46,7 +46,9 @@ let ``type check neg10_a`` () = singleNegTest ( "typecheck/sigs") "neg10_a"
let ``type check neg11`` () = singleNegTest ( "typecheck/sigs") "neg11"

[<FactForDESKTOP>]
let ``type check neg12`` () = singleNegTest ( "typecheck/sigs") "neg12"
// Pinned to 10.0: at 11.0 AccessProtectedBaseFieldFromClosure lets the protected-member-from-closure
// cases compile, dropping baseline errors. 11.0 behavior is covered by dedicated conformance tests.
let ``type check neg12`` () = singleVersionedNegTest ("typecheck/sigs") LangVersion.V10 "neg12"

[<FactForDESKTOP>]
let ``type check neg13`` () = singleNegTest ( "typecheck/sigs") "neg13"
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2 changes: 2 additions & 0 deletions tests/FSharp.Test.Utilities/ScriptHelpers.fs
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Expand Up @@ -16,6 +16,7 @@ open FSharp.Test
type LangVersion =
| V80
| V90
| V10
| Preview
| Latest

Expand All @@ -40,6 +41,7 @@ type FSharpScript(?additionalArgs: string[], ?quiet: bool, ?langVersion: LangVer
| LangVersion.Latest -> "--langversion:latest"
| LangVersion.V80 -> "--langversion:8.0"
| LangVersion.V90 -> "--langversion:9.0"
| LangVersion.V10 -> "--langversion:10.0"
|]

let argv = Array.append baseArgs additionalArgs
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15 changes: 10 additions & 5 deletions tests/fsharp/Compiler/CodeGen/EmittedIL/StaticMember.fs
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Expand Up @@ -8,9 +8,13 @@ open Xunit

module ``Static Member`` =

// The delegate-from-method cases below are pinned to --langversion:10.0: at F# 11.0 (now the default)
// DirectDelegateConstruction builds the delegate straight from the target method, dropping the closure
// class this IL expects. The 11.0 form is covered by EmittedIL/DirectDelegates.

[<Fact>]
let ``Action on Static Member``() =
CompilerAssert.CompileLibraryAndVerifyILRealSig(
CompilerAssert.CompileLibraryAndVerifyILWithOptions([| "--realsig+"; "--langversion:10.0" |],
"""
module StaticMember01

Expand Down Expand Up @@ -74,7 +78,7 @@ type C =

[<Fact>]
let ``Action on Static Member with lambda``() =
CompilerAssert.CompileLibraryAndVerifyILRealSig(
CompilerAssert.CompileLibraryAndVerifyILWithOptions([| "--realsig+"; "--langversion:10.0" |],
"""
module StaticMember02

Expand Down Expand Up @@ -247,7 +251,7 @@ let main _ =

[<Fact>]
let ``Func on Static Member``() =
CompilerAssert.CompileLibraryAndVerifyILRealSig(
CompilerAssert.CompileLibraryAndVerifyILWithOptions([| "--realsig+"; "--langversion:10.0" |],
"""
module StaticMember04

Expand Down Expand Up @@ -313,7 +317,7 @@ type C =

[<Fact>]
let ``Func on Static Member with lambda``() =
CompilerAssert.CompileLibraryAndVerifyILRealSig(
CompilerAssert.CompileLibraryAndVerifyILWithOptions([| "--realsig+"; "--langversion:10.0" |],
"""
module StaticMember05

Expand Down Expand Up @@ -434,7 +438,8 @@ let main _ =
#if !FX_NO_WINFORMS
[<Fact>]
let ``EventHandler from Regression/83``() =
CompilerAssert.CompileLibraryAndVerifyILRealSig(
// Same pin as the cases above; WinForms-gated, so this one only runs on Windows CI.
CompilerAssert.CompileLibraryAndVerifyILWithOptions([| "--realsig+"; "--langversion:10.0" |],
"""
module StaticMember07

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7 changes: 5 additions & 2 deletions tests/fsharp/tests.fs
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Expand Up @@ -66,11 +66,14 @@ module CoreTests =
exec cfg cfg.DotNetExe ($"msbuild {projectFile} /p:Configuration={cfg.BUILD_CONFIG} -property:FSharpRepositoryPath={FSharpRepositoryPath}")

#if !NETCOREAPP
// Pinned to 10.0: at 11.0 ErrorOnMissingSignatureAttribute turns FS3888 (attribute on impl but
// not signature) from warning into error, which this test deliberately exercises. 11.0 behavior is
// covered by Conformance/Signatures/SignatureEnforcedAttributes.
[<Fact>]
let ``attributes-FSC_OPTIMIZED`` () = singleTestBuildAndRun "core/attributes" FSC_OPTIMIZED
let ``attributes-FSC_OPTIMIZED`` () = singleTestBuildAndRunVersion "core/attributes" FSC_OPTIMIZED "10.0"

[<Fact>]
let ``attributes-FSI`` () = singleTestBuildAndRun "core/attributes" FSI
let ``attributes-FSI`` () = singleTestBuildAndRunVersion "core/attributes" FSI "10.0"

[<Fact>]
let span () =
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