LexFilter: drop non-strict mode (#20106)

T-Gro · Aug 5, 2026 · Jul 8, 2026 · Jul 9, 2026 · Jul 9, 2026 · Jul 9, 2026
commit ea778bb414648883fca4219bf7a69286bf82dd6b
@@ -339,78 +339,6 @@ stages:
                 ArtifactType: Container
                 parallel: true
 
-        - job: WindowsStrictIndentation
-          pool:
-            name: $(DncEngPublicBuildPool)
-            demands: ImageOverride -equals $(_WindowsMachineQueueName)
-          timeoutInMinutes: 120
-          steps:
-          - checkout: self
-            clean: true
-
-          - script: eng\CIBuildNoPublish.cmd -compressallmetadata -configuration Release /p:AdditionalFscCmdFlags=--strict-indentation+
-            env:
-              DOTNET_DbgEnableMiniDump: 1
-              DOTNET_DbgMiniDumpType: 2 # 1=mini, 2=heap, 3=triage, 4=full. Heap dumps include managed object data for debugging.
-              DOTNET_DbgMiniDumpName: $(Build.SourcesDirectory)\artifacts\log\Release\$(Build.BuildId)-%e-%p-%t.dmp
-              NativeToolsOnMachine: true
-            displayName: Build
-
-          - task: PublishBuildArtifacts@1
-            displayName: Publish Build BinLog
-            condition: always()
-            continueOnError: true
-            inputs:
-                PathToPublish: '$(Build.SourcesDirectory)\artifacts\log/Release\Build.VisualFSharp.slnx.binlog'
-                ArtifactName: 'Windows Release build binlogs'
-                ArtifactType: Container
-                parallel: true
-          - task: PublishBuildArtifacts@1
-            displayName: Publish Dumps
-            condition: failed()
-            continueOnError: true
-            inputs:
-                PathToPublish: '$(Build.SourcesDirectory)\artifacts\log\Release'
-                ArtifactName: 'Windows Release WindowsStrictIndentation process dumps'
-                ArtifactType: Container
-                parallel: true
-
-        - job: WindowsNoStrictIndentation
-          pool:
-            name: $(DncEngPublicBuildPool)
-            demands: ImageOverride -equals $(_WindowsMachineQueueName)
-          timeoutInMinutes: 120
-          steps:
-          - checkout: self
-            clean: true
-
-          - script: eng\CIBuildNoPublish.cmd -compressallmetadata -configuration Release /p:AdditionalFscCmdFlags=--strict-indentation-
-            env:
-              DOTNET_DbgEnableMiniDump: 1
-              DOTNET_DbgMiniDumpType: 2 # 1=mini, 2=heap, 3=triage, 4=full. Heap dumps include managed object data for debugging.
-              DOTNET_DbgMiniDumpName: $(Build.SourcesDirectory)\artifacts\log\Release\$(Build.BuildId)-%e-%p-%t.dmp
-              NativeToolsOnMachine: true
-            displayName: Build
-
-          - task: PublishBuildArtifacts@1
-            displayName: Publish Build BinLog
-            condition: always()
-            continueOnError: true
-            inputs:
-                PathToPublish: '$(Build.SourcesDirectory)\artifacts\log/Release\Build.VisualFSharp.slnx.binlog'
-                ArtifactName: 'Windows Release build binlogs'
-                ArtifactType: Container
-                parallel: true
-          - task: PublishBuildArtifacts@1
-            displayName: Publish Dumps
-            condition: failed()
-            continueOnError: true
-            inputs:
-                PathToPublish: '$(Build.SourcesDirectory)\artifacts\log\Release'
-                ArtifactName: 'Windows Release WindowsNoStrictIndentation process dumps'
-                ArtifactType: Container
-                parallel: true
-
         # Windows With Compressed Metadata
         - job: WindowsCompressedMetadata
           variables:

@@ -165,3 +165,4 @@
 
 * `FSharp.Compiler.Syntax.SynInterpolatedStringPart.FillExpr` now carries a `SynInterpolationFormatting` value (separating .NET alignment/format from printf specifiers) instead of an `Ident option`. ([PR #19971](https://github.com/dotnet/fsharp/pull/19971))
 * Optimizer: don't inline named functions in debug builds ([PR #19548](https://github.com/dotnet/fsharp/pull/19548)
+* LexFilter: drop non-strict mode ([PR #20106](https://github.com/dotnet/fsharp/pull/20106))
@@ -598,8 +598,6 @@ type TcConfigBuilder =
         /// If true - every expression in quotations will be augmented with full debug info (fileName, location in file)
         mutable emitDebugInfoInQuotations: bool
 
-        mutable strictIndentation: bool option
-
         mutable alwaysInline: bool option
 
         mutable exename: string option
@@ -854,7 +852,6 @@ type TcConfigBuilder =
                 }
             dumpSignatureData = false
             realsig = false
-            strictIndentation = None
             alwaysInline = None
             compilationMode = TcGlobals.CompilationMode.Unset
         }
@@ -1255,7 +1252,6 @@ type TcConfig private (data: TcConfigBuilder, validate: bool) =
     member _.bufferWidth = data.bufferWidth
     member _.fsiMultiAssemblyEmit = data.fsiMultiAssemblyEmit
     member _.FxResolver = data.FxResolver
-    member _.strictIndentation = data.strictIndentation
 
     member _.alwaysInline =
         data.alwaysInline

@@ -470,8 +470,6 @@ type TcConfigBuilder =
 
         mutable emitDebugInfoInQuotations: bool
 
-        mutable strictIndentation: bool option
-
         mutable alwaysInline: bool option
 
         mutable exename: string option
@@ -814,8 +812,6 @@ type TcConfig =
 
     member FxResolver: FxResolver
 
-    member strictIndentation: bool option
-
     member alwaysInline: bool
 
     member GetTargetFrameworkDirectories: unit -> string list

@@ -1200,14 +1200,6 @@ let languageFlags tcConfigB =
 
         CompilerOption("define", tagString, OptionString(defineSymbol tcConfigB), None, Some(FSComp.SR.optsDefine ()))
 
-        CompilerOption(
-            "strict-indentation",
-            tagNone,
-            OptionSwitch(fun switch -> tcConfigB.strictIndentation <- Some(switch = OptionSwitch.On)),
-            None,
-            Some(FSComp.SR.optsStrictIndentation (formatOptionSwitch (Option.defaultValue false tcConfigB.strictIndentation)))
-        )
-
         CompilerOption(
             "always-inline",
             tagNone,

@@ -648,7 +648,7 @@ let parseInputStreamAux
 
     // Set up the LexBuffer for the file
     let lexbuf =
-        UnicodeLexing.StreamReaderAsLexbuf(not tcConfig.compilingFSharpCore, tcConfig.langVersion, tcConfig.strictIndentation, reader)
+        UnicodeLexing.StreamReaderAsLexbuf(not tcConfig.compilingFSharpCore, tcConfig.langVersion, reader)
 
     // Parse the file drawing tokens from the lexbuf
     ParseOneInputLexbuf(tcConfig, lexResourceManager, lexbuf, fileName, isLastCompiland, diagnosticsLogger)
@@ -658,7 +658,7 @@ let parseInputSourceTextAux
     =
     // Set up the LexBuffer for the file
     let lexbuf =
-        UnicodeLexing.SourceTextAsLexbuf(not tcConfig.compilingFSharpCore, tcConfig.langVersion, tcConfig.strictIndentation, sourceText)
+        UnicodeLexing.SourceTextAsLexbuf(not tcConfig.compilingFSharpCore, tcConfig.langVersion, sourceText)
 
     // Parse the file drawing tokens from the lexbuf
     ParseOneInputLexbuf(tcConfig, lexResourceManager, lexbuf, fileName, isLastCompiland, diagnosticsLogger)
@@ -670,7 +670,7 @@ let parseInputFileAux (tcConfig: TcConfig, lexResourceManager, fileName, isLastC
 
     // Set up the LexBuffer for the file
     let lexbuf =
-        UnicodeLexing.StreamReaderAsLexbuf(not tcConfig.compilingFSharpCore, tcConfig.langVersion, tcConfig.strictIndentation, reader)
+        UnicodeLexing.StreamReaderAsLexbuf(not tcConfig.compilingFSharpCore, tcConfig.langVersion, reader)
 
     // Parse the file drawing tokens from the lexbuf
     ParseOneInputLexbuf(tcConfig, lexResourceManager, lexbuf, fileName, isLastCompiland, diagnosticsLogger)

@@ -15,7 +15,6 @@ open FSharp.Compiler.CompilerConfig
 open FSharp.Compiler.CompilerDiagnostics
 open FSharp.Compiler.CompilerImports
 open FSharp.Compiler.DependencyManager
-open FSharp.Compiler.Diagnostics
 open FSharp.Compiler.DiagnosticsLogger
 open FSharp.Compiler.IO
 open FSharp.Compiler.CodeAnalysis
@@ -135,7 +134,7 @@ module ScriptPreprocessClosure =
         let tcConfig = TcConfig.Create(tcConfigB, false)
 
         let lexbuf =
-            UnicodeLexing.SourceTextAsLexbuf(true, tcConfig.langVersion, tcConfig.strictIndentation, sourceText)
+            UnicodeLexing.SourceTextAsLexbuf(true, tcConfig.langVersion, sourceText)
 
         // The root compiland is last in the list of compilands.
         let isLastCompiland = (IsScript fileName, tcConfig.target.IsExe)

@@ -999,7 +999,7 @@ lexhlpIdentifierReserved,"The identifier '%s' is reserved for future use by F#"
 1118,optFailedToInlineValue,"Failed to inline the value '%s' marked 'inline', perhaps because a recursive value was marked 'inline'"
 1119,optRecursiveValValue,"Recursive ValValue %s"
 lexfltIncorrentIndentationOfIn,"The indentation of this 'in' token is incorrect with respect to the corresponding 'let'"
-lexfltTokenIsOffsideOfContextStartedEarlier,"Unexpected syntax or possible incorrect indentation: this token is offside of context started at position %s. Try indenting this further.\nTo continue using non-conforming indentation, pass the '--strict-indentation-' flag to the compiler, or set the language version to F# 7."
+lexfltTokenIsOffsideOfContextStartedEarlier,"Unexpected syntax or possible incorrect indentation: this token is offside of context started at position %s. Try indenting this further."
 lexfltSeparatorTokensOfPatternMatchMisaligned,"The '|' tokens separating rules of this pattern match are misaligned by one column. Consider realigning your code or using further indentation."
 lexfltInvalidNestedTypeDefinition,"Nested type definitions are not allowed. Types must be defined at module or namespace level."
 lexfltInvalidNestedModule,"Modules cannot be nested inside types. Define modules at module or namespace level."
@@ -1560,7 +1560,6 @@ optsGetLangVersions,"Display the allowed values for language version."
 optsSetLangVersion,"Specify language version such as 'latest' or 'preview'."
 optsDisableLanguageFeature,"Disable a specific language feature by name."
 optsSupportedLangVersions,"Supported language versions:"
-optsStrictIndentation,"Override indentation rules implied by the language version (%s by default)"
 optsAlwaysInline,"Always inline 'inline' functions"
 nativeResourceFormatError,"Stream does not begin with a null resource and is not in '.RES' format."
 nativeResourceHeaderMalformed,"Resource header beginning at offset %s is malformed."
@@ -1606,7 +1605,6 @@ featureNestedCopyAndUpdate,"Nested record field copy-and-update"
 featureExtendedStringInterpolation,"Extended string interpolation similar to C# raw string literals."
 featureWarningWhenMultipleRecdTypeChoice,"Raises warnings when multiple record type matches were found during name resolution because of overlapping field names."
 featureImprovedImpliedArgumentNames,"Improved implied argument names"
-featureStrictIndentation,"Raises errors on incorrect indentation, allows better recovery and analysis during editing"
 featureConstraintIntersectionOnFlexibleTypes,"Constraint intersection on flexible types"
 featureChkNotTailRecursive,"Raises warnings if a member or function has the 'TailCall' attribute, but is not being used in a tail recursive way."
 featureWhileBang,"'while!' expression"

@@ -20,7 +20,6 @@ type LanguageFeature =
     | WildCardInForLoop
     | RelaxWhitespace
     | RelaxWhitespace2
-    | StrictIndentation
     | NameOf
     | ImplicitYield
     | OpenTypeDeclaration
@@ -216,7 +215,6 @@ type LanguageVersion(versionText, ?disabledFeaturesArray: LanguageFeature array)
                 LanguageFeature.DiagnosticForObjInference, languageVersion80
                 LanguageFeature.WarningWhenTailRecAttributeButNonTailRecUsage, languageVersion80
                 LanguageFeature.StaticLetInRecordsDusEmptyTypes, languageVersion80
-                LanguageFeature.StrictIndentation, languageVersion80
                 LanguageFeature.ConstraintIntersectionOnFlexibleTypes, languageVersion80
                 LanguageFeature.WhileBang, languageVersion80
                 LanguageFeature.ExtendedFixedBindings, languageVersion80
@@ -425,7 +423,6 @@ type LanguageVersion(versionText, ?disabledFeaturesArray: LanguageFeature array)
         | LanguageFeature.DiagnosticForObjInference -> FSComp.SR.featureInformationalObjInferenceDiagnostic ()
 
         | LanguageFeature.StaticLetInRecordsDusEmptyTypes -> FSComp.SR.featureStaticLetInRecordsDusEmptyTypes ()
-        | LanguageFeature.StrictIndentation -> FSComp.SR.featureStrictIndentation ()
         | LanguageFeature.ConstraintIntersectionOnFlexibleTypes -> FSComp.SR.featureConstraintIntersectionOnFlexibleTypes ()
         | LanguageFeature.WarningWhenTailRecAttributeButNonTailRecUsage -> FSComp.SR.featureChkNotTailRecursive ()
         | LanguageFeature.UnmanagedConstraintCsharpInterop -> FSComp.SR.featureUnmanagedConstraintCsharpInterop ()

@@ -10,7 +10,6 @@ type LanguageFeature =
     | WildCardInForLoop
     | RelaxWhitespace
     | RelaxWhitespace2
-    | StrictIndentation
     | NameOf
     | ImplicitYield
     | OpenTypeDeclaration

@@ -242,8 +242,7 @@ type internal Position =
 
 type internal LexBufferFiller<'Char> = LexBuffer<'Char> -> unit
 
-and [<Sealed>] internal LexBuffer<'Char>
-    (filler: LexBufferFiller<'Char>, reportLibraryOnlyFeatures: bool, langVersion: LanguageVersion, strictIndentation: bool option) =
+and [<Sealed>] internal LexBuffer<'Char>(filler: LexBufferFiller<'Char>, reportLibraryOnlyFeatures: bool, langVersion: LanguageVersion) =
     let context = Dictionary<string, obj>(1)
     let mutable buffer = [||]
     /// number of valid characters beyond bufferScanStart.
@@ -344,14 +343,10 @@ and [<Sealed>] internal LexBuffer<'Char>
 
     member _.SupportsFeature featureId = langVersion.SupportsFeature featureId
 
-    member _.StrictIndentation = strictIndentation
-
     member _.CheckLanguageFeatureAndRecover featureId range =
         FSharp.Compiler.DiagnosticsLogger.checkLanguageFeatureAndRecover langVersion featureId range
 
-    static member FromFunction
-        (reportLibraryOnlyFeatures, langVersion, strictIndentation, f: 'Char[] * int * int -> int)
-        : LexBuffer<'Char> =
+    static member FromFunction(reportLibraryOnlyFeatures, langVersion, f: 'Char[] * int * int -> int) : LexBuffer<'Char> =
         let extension = Array.zeroCreate 4096
 
         let filler (lexBuffer: LexBuffer<'Char>) =
@@ -360,35 +355,34 @@ and [<Sealed>] internal LexBuffer<'Char>
             Array.blit extension 0 lexBuffer.Buffer lexBuffer.BufferScanPos n
             lexBuffer.BufferMaxScanLength <- lexBuffer.BufferScanLength + n
 
-        new LexBuffer<'Char>(filler, reportLibraryOnlyFeatures, langVersion, strictIndentation)
+        new LexBuffer<'Char>(filler, reportLibraryOnlyFeatures, langVersion)
 
     // Important: This method takes ownership of the array
-    static member FromArrayNoCopy(reportLibraryOnlyFeatures, langVersion, strictIndentation, buffer: 'Char[]) : LexBuffer<'Char> =
+    static member FromArrayNoCopy(reportLibraryOnlyFeatures, langVersion, buffer: 'Char[]) : LexBuffer<'Char> =
         let lexBuffer =
-            new LexBuffer<'Char>((fun _ -> ()), reportLibraryOnlyFeatures, langVersion, strictIndentation)
+            new LexBuffer<'Char>((fun _ -> ()), reportLibraryOnlyFeatures, langVersion)
 
         lexBuffer.Buffer <- buffer
         lexBuffer.BufferMaxScanLength <- buffer.Length
         lexBuffer
 
     // Important: this method does copy the array
-    static member FromArray(reportLibraryOnlyFeatures, langVersion, strictIndentation, s: 'Char[]) : LexBuffer<'Char> =
+    static member FromArray(reportLibraryOnlyFeatures, langVersion, s: 'Char[]) : LexBuffer<'Char> =
         let buffer = Array.copy s
 
-        LexBuffer<'Char>.FromArrayNoCopy(reportLibraryOnlyFeatures, langVersion, strictIndentation, buffer)
+        LexBuffer<'Char>.FromArrayNoCopy(reportLibraryOnlyFeatures, langVersion, buffer)
 
     // Important: This method takes ownership of the array
-    static member FromChars(reportLibraryOnlyFeatures, langVersion, strictIndentation, arr: char[]) =
-        LexBuffer.FromArrayNoCopy(reportLibraryOnlyFeatures, langVersion, strictIndentation, arr)
+    static member FromChars(reportLibraryOnlyFeatures, langVersion, arr: char[]) =
+        LexBuffer.FromArrayNoCopy(reportLibraryOnlyFeatures, langVersion, arr)
 
-    static member FromSourceText(reportLibraryOnlyFeatures, langVersion, strictIndentation, sourceText: ISourceText) =
+    static member FromSourceText(reportLibraryOnlyFeatures, langVersion, sourceText: ISourceText) =
         let mutable currentSourceIndex = 0
 
         LexBuffer<char>
             .FromFunction(
                 reportLibraryOnlyFeatures,
                 langVersion,
-                strictIndentation,
                 fun (chars, start, length) ->
                     let lengthToCopy =
                         if currentSourceIndex + length <= sourceText.Length then

@@ -146,29 +146,21 @@ type internal LexBuffer<'Char> =
     /// True if the specified language feature is supported.
     member SupportsFeature: LanguageFeature -> bool
 
-    member StrictIndentation: bool option
-
     /// Logs a recoverable error if a language feature is unsupported, at the specified range.
     member CheckLanguageFeatureAndRecover: LanguageFeature -> range -> unit
 
     /// Create a lex buffer suitable for Unicode lexing that reads characters from the given array.
     /// Important: does take ownership of the array.
-    static member FromChars:
-        reportLibraryOnlyFeatures: bool * langVersion: LanguageVersion * strictIndentation: bool option * char[] ->
-            LexBuffer<char>
+    static member FromChars: reportLibraryOnlyFeatures: bool * langVersion: LanguageVersion * char[] -> LexBuffer<char>
 
     /// Create a lex buffer that reads character or byte inputs by using the given function.
     static member FromFunction:
-        reportLibraryOnlyFeatures: bool *
-        langVersion: LanguageVersion *
-        strictIndentation: bool option *
-        ('Char[] * int * int -> int) ->
+        reportLibraryOnlyFeatures: bool * langVersion: LanguageVersion * ('Char[] * int * int -> int) ->
             LexBuffer<'Char>
 
     /// Create a lex buffer backed by source text.
     static member FromSourceText:
-        reportLibraryOnlyFeatures: bool * langVersion: LanguageVersion * strictIndentation: bool option * ISourceText ->
-            LexBuffer<char>
+        reportLibraryOnlyFeatures: bool * langVersion: LanguageVersion * ISourceText -> LexBuffer<char>
 
 /// The type of tables for an unicode lexer generated by <c>fslex.exe</c>.
 [<Sealed>]
Original file line number	Diff line number	Diff line change
Expand Up		@@ -165,3 +165,4 @@

		* `FSharp.Compiler.Syntax.SynInterpolatedStringPart.FillExpr` now carries a `SynInterpolationFormatting` value (separating .NET alignment/format from printf specifiers) instead of an `Ident option`. ([PR #19971](https://github.com/dotnet/fsharp/pull/19971))
		* Optimizer: don't inline named functions in debug builds ([PR #19548](https://github.com/dotnet/fsharp/pull/19548)
		* LexFilter: drop non-strict mode ([PR #20106](https://github.com/dotnet/fsharp/pull/20106))