Remove always-on BetterExceptionPrinting language feature flag

src/Compiler/CodeGen/IlxGen.fs

@@ -12868,8 +12868,7 @@ and GenExnDef cenv mgbuf eenv m (exnc: Tycon) : ILTypeRef option =
                 yield! ilMethodDefsForProperties
 
                 if
-                    cenv.g.langVersion.SupportsFeature(LanguageFeature.BetterExceptionPrinting)
-                    && not (exnc.HasMember g "get_Message" [])
+                    not (exnc.HasMember g "get_Message" [])
                     && not (exnc.HasMember g "Message" [])
                     && not (fspecs |> List.exists (fun rf -> rf.DisplayNameCore = "Message"))
                 then

src/Compiler/FSComp.txt

@@ -1253,7 +1253,6 @@ featureIndexerNotationWithoutDot,"expr[idx] notation for indexing and slicing"
 featureRefCellNotationInformationals,"informational messages related to reference cells"
 featureNonVariablePatternsToRightOfAsPatterns,"non-variable patterns to the right of 'as' patterns"
 featureAttributesToRightOfModuleKeyword,"attributes to the right of the 'module' keyword"
-featureBetterExceptionPrinting,"automatic generation of 'Message' property for 'exception' declarations"
 featureDelegateTypeNameResolutionFix,"fix to resolution of delegate type names, see https://github.com/dotnet/fsharp/issues/10228"
 3090,tcIfThenElseMayNotBeUsedWithinQueries,"An if/then/else expression may not be used within queries. Consider using either an if/then expression, or use a sequence expression instead."
 3091,ilxgenUnexpectedArgumentToMethodHandleOfDuringCodegen,"Invalid argument to 'methodhandleof' during codegen"

src/Compiler/Facilities/LanguageFeatures.fs

@@ -37,7 +37,6 @@ type LanguageFeature =
     | UnionIsPropertiesVisible
     | NonVariablePatternsToRightOfAsPatterns
     | AttributesToRightOfModuleKeyword
-    | BetterExceptionPrinting
     | DelegateTypeNameResolutionFix
     | ReallyLongLists
     | ErrorOnDeprecatedRequireQualifiedAccess
@@ -171,7 +170,6 @@ type LanguageVersion(versionText, ?disabledFeaturesArray: LanguageFeature array)
                 LanguageFeature.DelegateTypeNameResolutionFix, languageVersion60
 
                 // F# 7.0
-                LanguageFeature.BetterExceptionPrinting, languageVersion70
                 LanguageFeature.ReallyLongLists, languageVersion70
                 LanguageFeature.ErrorOnDeprecatedRequireQualifiedAccess, languageVersion70
                 LanguageFeature.RequiredPropertiesSupport, languageVersion70
@@ -376,7 +374,6 @@ type LanguageVersion(versionText, ?disabledFeaturesArray: LanguageFeature array)
         | LanguageFeature.UnionIsPropertiesVisible -> FSComp.SR.featureUnionIsPropertiesVisible ()
         | LanguageFeature.NonVariablePatternsToRightOfAsPatterns -> FSComp.SR.featureNonVariablePatternsToRightOfAsPatterns ()
         | LanguageFeature.AttributesToRightOfModuleKeyword -> FSComp.SR.featureAttributesToRightOfModuleKeyword ()
-        | LanguageFeature.BetterExceptionPrinting -> FSComp.SR.featureBetterExceptionPrinting ()
         | LanguageFeature.DelegateTypeNameResolutionFix -> FSComp.SR.featureDelegateTypeNameResolutionFix ()
         | LanguageFeature.ReallyLongLists -> FSComp.SR.featureReallyLongList ()
         | LanguageFeature.ErrorOnDeprecatedRequireQualifiedAccess -> FSComp.SR.featureErrorOnDeprecatedRequireQualifiedAccess ()

src/Compiler/Facilities/LanguageFeatures.fsi

@@ -27,7 +27,6 @@ type LanguageFeature =
     | UnionIsPropertiesVisible
     | NonVariablePatternsToRightOfAsPatterns
     | AttributesToRightOfModuleKeyword
-    | BetterExceptionPrinting
     | DelegateTypeNameResolutionFix
     | ReallyLongLists
     | ErrorOnDeprecatedRequireQualifiedAccess