Compiler error when declaring abstract members on static classes (#14593)

* Compiler error when declaring abstract members on static classes

* Compiler error only for inteface instance member

src/Compiler/Checking/CheckDeclarations.fs

@@ -1668,8 +1668,12 @@ let private ReportErrorOnStaticClass (synMembers: SynMemberDefn list) =
             errorR(Error(FSComp.SR.chkInstanceMemberOnStaticClasses(), m))
         | SynMemberDefn.LetBindings(isStatic = false; range = range) ->
             errorR(Error(FSComp.SR.chkInstanceLetBindingOnStaticClasses(), range))
-        | SynMemberDefn.Interface(range = range) ->
-            errorR(Error(FSComp.SR.chkImplementingInterfacesOnStaticClasses(), range))
+        | SynMemberDefn.Interface(members= Some(synMemberDefs)) ->
+            for mem in synMemberDefs do
+                match mem with
+                | SynMemberDefn.Member(SynBinding(valData = SynValData(memberFlags = Some memberFlags)), m) when memberFlags.MemberKind = SynMemberKind.Member && memberFlags.IsInstance ->
+                    errorR(Error(FSComp.SR.chkImplementingInterfacesOnStaticClasses(), m))
+                | _ -> ()
         | _ -> ()
 
 /// Check and generalize the interface implementations, members, 'let' definitions in a mutually recursive group of definitions.
@@ -1778,6 +1782,11 @@ let TcMutRecDefns_Phase2 (cenv: cenv) envInitial mBinds scopem mutRecNSInfo (env
               let isStaticClass = HasFSharpAttribute cenv.g cenv.g.attrib_SealedAttribute tcref.Attribs && HasFSharpAttribute cenv.g cenv.g.attrib_AbstractClassAttribute tcref.Attribs
               if isStaticClass && cenv.g.langVersion.SupportsFeature(LanguageFeature.ErrorReportingOnStaticClasses) then
                   ReportErrorOnStaticClass synMembers
+                  match tyconOpt with
+                  | Some tycon ->
+                        for slot in tycon.FSharpObjectModelTypeInfo.fsobjmodel_vslots do
+                            errorR(Error(FSComp.SR.chkAbstractMembersDeclarationsOnStaticClasses(), slot.Range))
+                  | None -> ()
               
               let envForDecls = 
                 // This allows to implement protected interface methods if it's a DIM.

src/Compiler/FSComp.txt

@@ -1670,4 +1670,5 @@ featureEscapeBracesInFormattableString,"Escapes curly braces before calling Form
 3553,chkAdditionalConstructorOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Additional constructor is not allowed."
 3554,chkInstanceMemberOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Instance members are not allowed."
 3555,chkInstanceLetBindingOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Instance let bindings are not allowed."
-3556,chkImplementingInterfacesOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Implementing interfaces is not allowed."
\ No newline at end of file
+3556,chkImplementingInterfacesOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Implementing interfaces is not allowed."
+3557,chkAbstractMembersDeclarationsOnStaticClasses,"If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Abstract member declarations are not allowed."
\ No newline at end of file

src/Compiler/xlf/FSComp.txt.cs.xlf

@@ -22,6 +22,11 @@
         <target state="translated">Soubor {0} má nerozpoznanou příponu. Zdrojové soubory musí mít příponu .fs, .fsi, .fsx nebo .fsscript.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.de.xlf

@@ -22,6 +22,11 @@
         <target state="translated">Die Dateierweiterung von „{0}“ wurde nicht erkannt. Quelldateien müssen die Erweiterung .fs, .fsi, .fsx oder .fsscript haben</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.es.xlf

@@ -22,6 +22,11 @@
         <target state="translated">No se reconoce la extensión de archivo de '{0}'. Los archivos de código fuente deben tener las extensiones .fs, .fsi, .fsx o .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.fr.xlf

@@ -22,6 +22,11 @@
         <target state="translated">L'extension de fichier de '{0}' n'est pas reconnue. Les fichiers sources doivent avoir l'extension .fs, .fsi, .fsx, ou .fsscript.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.it.xlf

@@ -22,6 +22,11 @@
         <target state="translated">Estensione di file di '{0}' non riconosciuta. I file di origine devono avere estensione .fs, .fsi, .fsx or .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.ja.xlf

@@ -22,6 +22,11 @@
         <target state="translated">'{0}' のファイル拡張子は認識されません。ソース ファイルの拡張子は .fs、.fsi、.fsx、または .fsscript にする必要があります。</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.ko.xlf

@@ -22,6 +22,11 @@
         <target state="translated">'{0}'의 파일 확장명을 인식할 수 없습니다. 원본 파일의 확장명은 .fs, .fsi, .fsx 또는 .fsscript여야 합니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.pl.xlf

@@ -22,6 +22,11 @@
         <target state="translated">Rozszerzenie pliku "{0}" nie zostało rozpoznane. Pliki źródłowe muszą mieć rozszerzenie .fs, .fsi, .fsx lub .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.pt-BR.xlf

@@ -22,6 +22,11 @@
         <target state="translated">A extensão do arquivo de '{0}' não foi reconhecida. Os arquivos de origem devem ter a extensão .fs, .fsi, .fsx or .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.ru.xlf

@@ -22,6 +22,11 @@
         <target state="translated">Расширение файла "{0}" не распознано. Исходные файлы должны иметь расширения FS, FSI, FSX или FSSCRIPT</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.tr.xlf

@@ -22,6 +22,11 @@
         <target state="translated">'{0}' kaynak dosyasının dosya uzantısı tanınmadı. Kaynak dosyaların uzantısı .fs, .fsi, .fsx veya .fsscript olmalıdır.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.zh-Hans.xlf

@@ -22,6 +22,11 @@
         <target state="translated">无法识别“{0}”的文件扩展名。源文件必须具有扩展名 .fs、.fsi、.fsx 或 .fsscript</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

src/Compiler/xlf/FSComp.txt.zh-Hant.xlf

@@ -22,6 +22,11 @@
         <target state="translated">無法辨識 '{0}' 的副檔名。來源檔案的副檔名必須是 .fs、.fsi、.fsx 或 .fsscript。</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkAbstractMembersDeclarationsOnStaticClasses">
+        <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</source>
+        <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Abstract member declarations are not allowed.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkAdditionalConstructorOnStaticClasses">
         <source>If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</source>
         <target state="new">If a type uses both [&lt;Sealed&gt;] and [&lt;AbstractClass&gt;] attributes, it means it is static. Additional constructor is not allowed.</target>

tests/FSharp.Compiler.ComponentTests/Language/StaticClassTests.fs

@@ -401,7 +401,7 @@ type C() =
          |> compile
          |> shouldFail
          |> withDiagnostics [
-            (Error 3556, Line 7, Col 5, Line 8, Col 29, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Implementing interfaces is not allowed.")
+            (Error 3556, Line 8, Col 9, Line 8, Col 29, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Implementing interfaces is not allowed.")
          ]
          
     [<Fact>]
@@ -419,5 +419,134 @@ type C =
          |> compile
          |> shouldFail
          |> withDiagnostics [
-            (Error 3556, Line 7, Col 5, Line 8, Col 29, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Implementing interfaces is not allowed.")
-         ]
\ No newline at end of file
+            (Error 3556, Line 8, Col 9, Line 8, Col 29, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Implementing interfaces is not allowed.")
+         ]
+         
+    [<Fact>]
+    let ``Sealed and AbstractClass on a type implicit constructor declaring abstract members in Lang 70`` () =
+        Fsx """
+[<Sealed; AbstractClass>]
+type T =
+    abstract A : int
+    abstract B : int with get, set
+    abstract C : i:int -> int
+    abstract D : i:int -> int
+        """
+         |> withLangVersion70
+         |> compile
+         |> shouldSucceed
+    
+    [<Fact>]
+    let ``Sealed and AbstractClass on a type declaring abstract members in Lang 70`` () =
+        Fsx """
+[<Sealed; AbstractClass>]
+type T() =
+    abstract A : int
+    abstract B : int with get, set
+    abstract C : i:int -> int
+    abstract D : i:int -> int
+        """
+         |> withLangVersion70
+         |> compile
+         |> shouldSucceed
+         
+    [<Fact>]
+    let ``Sealed and AbstractClass on a type with implicit constructor declaring abstract members in Lang preview`` () =
+        Fsx """
+[<Sealed; AbstractClass>]
+type T =
+    abstract C : i:int -> int
+    abstract D : i:int -> int
+        """
+         |> withLangVersionPreview
+         |> compile
+         |> shouldFail
+         |> withDiagnostics [
+             (Error 3557, Line 4, Col 14, Line 4, Col 15, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Abstract member declarations are not allowed.")
+             (Error 3557, Line 5, Col 14, Line 5, Col 15, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Abstract member declarations are not allowed.")
+         ]
+         
+    [<Fact>]
+    let ``Sealed and AbstractClass on a type declaring abstract members in Lang preview`` () =
+        Fsx """
+[<Sealed; AbstractClass>]
+type T() =
+    abstract C : i:int -> int
+    abstract D : i:int -> int
+        """
+         |> withLangVersionPreview
+         |> compile
+         |> shouldFail
+         |> withDiagnostics [
+             (Error 3557, Line 4, Col 14, Line 4, Col 15, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Abstract member declarations are not allowed.")
+             (Error 3557, Line 5, Col 14, Line 5, Col 15, "If a type uses both [<Sealed>] and [<AbstractClass>] attributes, it means it is static. Abstract member declarations are not allowed.")
+         ]
+
+    #if !NETCOREAPP
+    [<Fact(Skip = "IWSAMs are not supported by NET472.")>]
+    #else
+    [<Fact>]
+    #endif
+    let ``Sealed and AbstractClass on a type implementing an interface with static abstract members in Lang 70`` () =
+        Fsx """
+[<Interface>]
+type InputRetriever<'T when 'T:>InputRetriever<'T>> =
+    static abstract Read: unit -> string
+
+[<AbstractClass;Sealed>]
+type ConsoleRetriever = 
+    interface InputRetriever<ConsoleRetriever> with
+        static member Read() = 
+            stdout.WriteLine("Please enter a value and press enter")
+            stdin.ReadLine()
+        """
+         |> withNoWarn 3535
+         |> withLangVersion70
+         |> compile
+         |> shouldSucceed
+         
+    #if !NETCOREAPP
+    [<Fact(Skip = "IWSAMs are not supported by NET472.")>]
+    #else
+    [<Fact>]
+    #endif
+    let ``Sealed and AbstractClass on a type implicit constructor implementing an interface with static abstract members in Lang preview`` () =
+        Fsx """
+[<Interface>]
+type InputRetriever<'T when 'T:>InputRetriever<'T>> =
+    static abstract Read: unit -> string
+
+[<AbstractClass;Sealed>]
+type ConsoleRetriever = 
+    interface InputRetriever<ConsoleRetriever> with
+        static member Read() = 
+            stdout.WriteLine("Please enter a value and press enter")
+            stdin.ReadLine()
+        """
+         |> withNoWarn 3535
+         |> withLangVersionPreview
+         |> compile
+         |> shouldSucceed
+         
+    #if !NETCOREAPP
+    [<Fact(Skip = "IWSAMs are not supported by NET472.")>]
+    #else
+    [<Fact>]
+    #endif
+    let ``Sealed and AbstractClass on a type implementing an interface with static abstract members in Lang preview`` () =
+        Fsx """
+[<Interface>]
+type InputRetriever<'T when 'T:>InputRetriever<'T>> =
+    static abstract Read: unit -> string
+
+[<AbstractClass;Sealed>]
+type ConsoleRetriever() = 
+    interface InputRetriever<ConsoleRetriever> with
+        static member Read() = 
+            stdout.WriteLine("Please enter a value and press enter")
+            stdin.ReadLine()
+        """
+         |> withNoWarn 3535
+         |> withLangVersionPreview
+         |> compile
+         |> shouldSucceed
\ No newline at end of file